US2128551A - Method of treating seaweed - Google Patents

Description

193& v@ c. E. LE GLOAHEC T AL 2,128,551

METHOD 6F TREATING SEAWEED Filed Jan. 9, 1935 5 Sheets-Sheet 1 m m'www ATTO NEYS Aug. 30, 1938. v. c. E. LE GLOAHEC ET AL 2,128,551

I METHOD OF TREATING SEAWEED Filed Jain. 9 1935 5 Sheets-Sheet 2 ATTORN Y5 A 30, 1938. v. c. E. LE GLOAHEC ET AL METHOD OF TREATING SEAWEED Filed Jan. 9, 1935 5 Sheets-Sheet 3 4 WHY W ATTORNEYS.

30, 1938- v c. E. LE GLOAHEC ET AL 2,128,551 VMETHOD OF TREATING SEAWEED 7 Filed Jan. '9, 1935 5 sheets-shed '4 If l 931 Wm W ATTO RN EYS Patented Aug. 30, 1938 UNITED STATES PATENT OFFICE METHOD OF TREATING SEAWEED Delaware Application January 9, 1935, Serial No. 1,070 In France January 11, 1934 46 Claims.

This invention relates to algin and alginous materials and the recovery of such substances from seaweed.

An object of the present invention is the treatment of suitable seaweeds, such as Laminaria and Phaeophyceae, Macrocystis, Nereocystis, and the like, in order to extract therefrom a whiteaigin which is very pure and directly soluble in water, and also various lay-products.

The seaweeds above referred to contain a great number of bodies, to-wit: salts, most of which are salts of alkaline metals and/or metalloids (e. g., sodium, potassium, ammonium, magnesium) and various organic matters, the most important of which are: algin, laminarine, mannitol, and algulose (seaweed cellulose).

Features of the practice of this invention include, first, a treatment for the elimination of laminarine, the presence of which would be detrimental to the good preservation of algin and of its properties. For this purpose, we take advantage of the fact that laminarine remains soluble in water in the presence of alkaline-earth salts, contrary to what takes place for algin. The seaweeds are subsequently washed in soft water so as to demineralize them. Then the alginous material is placed in an alkaline solution and the algulose in suspension in the solution is separated by charging this solution with gaseous bubbles I which, when ascending to the surface, carry with them particles of algulose. In the course of this clarification and/or in a subsequent special treatment, we remove chlorophyl pigments which impart color to the solution, by causing the pigments to become coated upon solid.vehicles which are separated from the residual solution. The remaining solution, when treated as by a strong ac d, yields a coagulum of alginous material from which salts and acids are extracted, preferably either by exhaustion by means of a selective solvent for the salts and the acid portions without dissolving the alginous material or causing it to swell, or by dialysis in the presence of a solvent or 'even in the presence of soft water. Algin thus 0 obtained is finally dried. Algin can thus be obtained which is notable for the fact that, even in the absence of substantial quantities of salts or alkalies, it is readily soluble in water. Moreover, algin can be obtained in a substantially white condition and free from cellulose. This high'degree of purity and freedom from ashcan be obtained in the practice of this invention in an economical and practical manner..

In describing this invention more in detail hereinbelow,'reference will be made to the accom- (cl. zoo-41c) panying drawings which are illustrative of the practice of certain embodiments of this invention, wherein Figure 1 is a side view largely diagrammatic and partly in section of one type of apparatus for clarifying alginous material;

Figs. 2, 3 and 4 are side views largely diagrammatic and partly in section of alternate types of apparatus for clarifying alginous material; 10

Fig. 5 is a side view largely diagrammatic and partly in section of apparatus for coagulating an separating alginous material;

Fig. 6 is a side view largely diagrammatic and partly in section 01' apparatus for removing impurities from alginous material; I

Fig. '7 is a side view similar to Fig. 6 of an alternate type of apparatus for removing impurities from alginous material;

Fig. 8 is a side view similar to Figs. 8 and '1 of an alternate type of apparatus for removing impurities from alginous material;

Figs. 9 and 10 are side views largely diagrammatic and partly in section of alternative types of apparatus for clarifying alginous material;

Fig. 11 is a side view largely diagrammatic and partly in section of one type of apparatus for oxidizing alginous material;

Fig. 12 is a side view largely diagrammatic and partly in section of apparatus for drying alginous material;

Fig. 13 is a plan view largely diagrammatic and partly in section of an alternate form of apparatus for removing impurities from and drying alginous material; and

Fig. 14 is a flow sheet on which is indicated certain of the steps involved in the practice of one form of this invention.

Certain modifications of the process of this invention will be described below, the various steps being indicated'on the flow sheet (Fig. 14). Cer- 40 tainof the steps are likewise described in connection with the apparatus shown in Figs. 1 to 7.

, The first treatment, which is intended to eliminate laminarine and in addition mannitol and salts, can be applied either-to dried seaweeds or to fresh seaweeds. In order to obtain a good elimination of laminarine, we preferably, for one thousand parts in weight of dried seaweeds, still containing about thirty per cent. of moisture, make use of from 2.2 to 2.8 parts by weight of calcium chloride (anhydrous) or from 4.9 to 6.2 parts of barium chloride (crystallized with two molecules of water). About 3,000 parts by volume of solution is used for exhausting the amount of seaweedsabove mentioned by'dissolving the above-mentioned impurities. This solution therefore contains from 0.8 to 1% of anhydrous calcium chloride, for example. If the process is carried out with seaweeds as freshly taken from water, the proportion of a1- kaline-earth salt is preferably reduced about five times. The treatment may be carried out either in the hot state or in the cold state. However, we have found that it is advantageous to operate in the cold state.

The seaweeds are then washed with soft water, which removes the excess of alkaline-earth salts and at the same time removes the remainder of the laminarine and the salts of the seaweeds, and also mannitol. This operation of washing with soft water is stopped, merely for the sake of economy, when the exhaustion waters contain only /2% approximately of soluble matters.

In order to facilitate the subsequent recovery of the soluble products removed from the se r weeds that are treated, it is advisable to carry the treatment with solutions of alkaline-earth salts and the subsequent washing with soft water in a systematic manner, according to lrnown methods, in order to render the washing waters rich as possible. The treatment of these waters to recover the alkaline earths and other materials is indicated hereinbelow. ii" the wash waters are re-used, it is then necessary to add a desired amount of alkaline-earth salts thereto before they again come into contact with seaweeds that have not been exhausted.

The seaweeds that have already undergone the first treatment above stated are mixed or mascerated in an alkaline solution to dissolve the alginous material. While the seaweed can be treated immediately with the alkaline solution, certain advantages can be gained by first treating the algulose and alginous material with dilute acid, to dissolve any residual alkaline earth retained therein and to attack the algulose so as to make the alginous material more readily soluble in the alkaline solution. About five per cent. by volume of an acid such as hydrochloric acid or nitric acid which forms soluble salts with alkaline earths is preferred, Before the treatment with alkaline solution, excess acid is removed.

The treatment with alkaline solution is conducted preferably with a solution of sodium carbonate, which disintegrates the cellulosic partitions (algulose) of the plant, while the algin'ous material present in the seaweeds passes into solution. For example, for 1,000 parts in weight of lixiviated seaweeds, still wet, we add from to parts of anhydrous sodium carbonate, dissolved in 2,000 parts by volume of water. In addition to sodium carbonate, other alkaline material such as the carbonates of other alkali metals, the hydroxides of alkali metals, organic amines, etc., may be used. The mixing or masceration may be performed in any suitable apparatus, such as for instance the beaters which are commonly employed in the paper-making industry. Masceration is continued until the algulose is reduced to a state of very fine particles and until a very homogeneous paste is obtained. This result is obtained in about two hours, if the term perature is 40 C., or in three hours if the temperature is ordinary atmospheric temperature (e. g., about 18 to 20 C.).

At the end of the first hour of treatment, the alkalinity of the paste is tested. It must correspond to about five parts of free anhydrous sodium carbonate for one thousand parts of paste, In

the case of an insuidciency, the necessary amount or sodium carbonate, for example, is added.

The paste, after the mixing and masceration above described, is diluted by adding to about 3,000 parts thereof about 7,000 parts of water and mixing the whole, for instance, in any suitable apparatus adapted to be used for this purpose, such as the boaters used in the paper-making industry.

In the diluted solution, which is now quite homogeneous, we inject air in a finely-divided state, with a sufilcient rate of flow for ensuring an energetic agitation, for instance, by means of pipes provided with holes local; at the bottom of the beater or other vessel in w on the treatment is carried out. By way of i1 ration, in Fig. 11 a suitable tank :30 having a tortuous pipe ii such as a coil with a plurality of holes therein is provided. The air is introduced through line 1-3. The action of the oxygen present in air on the alginous material is to increase the viscosity thereof; that is to say, to improve its quality. An analogous effect would tn obtained by causing compounds or oxidizing agents capable of liberating oxygen, such for instance as hydrogen peroxide or ozone, to act on the alginous material, but in such manner as to avoid an excess of oxygen, which would be detrimental. The term oxidizing agent is to be regarded as including air as well as such compounds because inclusion or" oxygen-in the solution is afiorded. Where air is used, it can be introduced with suiiicient force to maintain the material in agitation. However, if desired, an agitator can be used such as agitator id, and in the event a gas such as ozone or hydrogen peroxide is employed, the use of the agitator is desirable to maintain the material in agitation and make eiiicient use of such gases. While the oxidation step is preferable, it is not regarded as essential in the practice of this invention.

The solution containing alginous material still contains in suspension the whole of the algulose present in the seaweeds. In order to eliminate it in a simple manner, advantage is taken of the fact that the viscous solution of alginous material can be readily charged with gaseous bubbles forming an unstable emulsion. After a certain period of quiescence, these gaseous bubbles rise to the surface of the liquid, carrying with them the solid particles in suspension. These particles thus agglomerate on the top of the liquid, forming a kind of compact cake, the clarified solution under this cake being removed without difiiculty.

A portion of the gaseous bubbles remains within said cake and another portion thereunder. It follows not only that the cake is maintained at the upper port of the solution, but that it tends to emerge somewhat, so that the liquid can drip therefrom and the cake does not keep too large an amount of viscous solution. Besides, the residue of algulose' may be again treated with water so as to extract therefrom, in the form of a solution, the soluble matter that it still contains. The solution thus recovered may then be clarified in its turn through the method above described.

The clarification step described generally. above will be illustrated below with reference to the apparatus shown in the drawings (Figs. 1 to 4, and 9 and 10).

In order to clarify the solution of alginous material, said solution in preferred practice is caused to flow in a continuous manner into the vessel of a centrifugal apparatus I (Fig. 1) which rotates at high speed and is adapted to give a continuous flow of solution and to charge the solution with air bubbles. The centrifuging also. acts to mascerate the algulose and alginous material. Suitable centrifuging apparatus for carrying out this step is well known. This emulsion is conveyed into atank 2 through a pipe 2', which is as short as possible and extends down to the bottom of said tank. This tank 2 is preferably of cylindrical shape, with a height equal to twice its diameter. When this tank is full, the solution is left alone until the bubbles have risen to the surface, which requires from six to ten hours, according to the viscosity of the solution. The algulosic particles accumulate at the top of solution 3,

forming a kind of cake .4. It then sufllces to remove the solution, for instance by means of a pump 5, taking ,the liquid at a distance of about 5 centimeters from the bottom so as to leave in the tank the dense matters (sand, for instance) that t I through line 40. The box 46 is surrounded with may have deposited thereon.

Alternatively, to accomplish clarification, the solution to be treated may be introduced directly into a tank where it is charged with a gas in a finely-divided state, this result being obtained through many different means. This is done preferably after preliminary oxidation, but the preliminary oxidation step may be omitted, as has been mentioned above.

As shown by Fig. 2, a closed vessel 6 may be I used in which the liquid is saturated with carbonic acid gas compressed, for instance, by means of a pump 1, after which a slow expansion is obtained by opening valve 8, thereby causing bubbles to form in the solution and carry the algulose to the surface.

In the embodiment illustrated by Fig. 3, use is made of an additional alternative method of even, so as to multiply the points at which gaseous bubbles are formed and to facilitate the distribution of said bubbles in all directions. The pressure of the gas under the false bottom is chosen in such manner that the gaseous fiow may be sufficiently slow for avoiding the formation of eddies in the solution.

Another alternative method of clarification consists in producing the gas through electrolysis in the solution itself. For this purpose, as shown by Fig. 4, we dispose, at a certain distance above the bottom of the tank of treatment I3, a porous diaphragm [4 the edges of which are fixed in a fluid-tight manner to theside walls of the tank. We make use, for instance, of a diaphragm of asbestos, or preferably of cement, such as is used for the electrolysis of sea-salt. On said diaphragm rests a cathode made of metallic cloth l5 of a fine texture, which is disposed laterally across the whole of the section of the tank. Under diaphragm II, and as close thereto as possible, there is provided an anode l6 of an unoxidizable metal,

I having the same area as the cathode. The anodic the gases produced on the anode can escape. We

introduce into this chamber a solution capable of conducting electric current, for instance a solution of sodium carbonate. The density of the 0electrolysis current is so chosen as to produce at the cathode about liters of hydrogen over a period of about three hours for 20 cubic meters of solution to be treated. The difference of potential between. the anode and the cathode is about six volts. The operation is stopped when the solution is clear, which occurs after a period of time of about three hours. The whole is allowed to rest for one hour and the-clear liquid is removed as above indicated. I

It is also possible to immerse in the tank metallic blades, for instance of aluminum, zinc, etc., capable of producing a gaseous ebullitionunder the action of the alkali. In order to facilitate the attack, the metal blades may be heated by any suitable means. For instance, as shown in Fig. 9, in tank 45 a metallic box 48, of steel'for example, is heated by means of steam introduced through line 41. Exhaust steam and condensate is taken of! sheets 49 of aluminum which are attacked by the chemicals in the solution to give 01! gas. Use can also be made of amalgams or compounds capable of giving off a gas in an aqueous medium (calcium hydride. oxylite (sodium dioxide) etc.) Alternatively, the blades or plates 49 can be heated by an electrical heating element 5|! as shown in Fig. 10. In some cases in which the gas is evolved in a rather violent manner, or when the reaction may give rise to the formation of bodies capable of producing secondary reactions with the alginous solutions or when it is desired to more evenly distribute the evolved gases, it is advisable to produce the evolution of gas under afalse bottom consisting of a diaphragm 53 permeable to gases, of 1728 type described above in connection with Fig; I

The above-described methods of clarifying so-' lutions of alginous material from al'gulose and other impurities is of great advantage in the prac tice of this invention. While it is possible to clarify the solution by filtration, the filtration method of clarification is attended with many difficulties due primarily to the pronounced tendency of the alginous material and other substances in the solution to clog the filter.

The alginous solution clarified as above described normally has a considerable amount of colored compounds removed therefrom in the clarification step, but usually the clarified solu-- tion is still colored by chlorophyl pigments not only when the bulk of the alg'ulose has been removed from the solution but also even when substantially all of the algulose has been removed from the solution. The term chlorophyl is used herein and in the claims in a broad sense with reference to all of the coloring material or materials in seaweed. In order to eliminate this coloration, without altering the alginous material, these colored materials are removed, preferably by causing them to be absorbed on material which is subsequently separated from the solution.

For example, a jelly is prepared consisting of hydrated alumina or of a mixture of equal portions of hydrated alumina and previously prepared algin coagulated by a soluble salt of alum'inum. There may be added thereto a small amount I of gelatinous silica, for instance from one to three per cent. To the alginous solution this jelly is added, freed from the excess of water, the amount of jelly amounting to from twenty to fifty per cent. of the weight of dry alginous material. The mixture is stirred and the particles comprised in the gelatinous material become coated with chlorophyl. Then the silico-aluminous jelly carrying the colored substances is separated from the a ginous solution, for example by centrifuging.

Tins jelly may be regenerated in various ways so that it may be used again for another operause. It is possible, for instance, to wash it with a solvent, e. g., alcohol, benzol, acetone, xylenol, etc, for the colored substances and then with water. The solvent can then be recovered by usual known methods.

It is possible, in the practice of this invention, to the absorptive jelly to the alginous solution prior to its clarification by means of gaseous bubbles as above described. But, for practical purposes, we generally obtain in this manner only a cloudy solution and it is commercially impossible to recover the absorptive mineral base. The absorptive base might alternatively consist of the do of another alkaline-earth metal, or even oi a heavier metal, or again of algin rendered insoluble by means of other salts than salts of aluminum. However, gelatinous absorptive bases made aluminum give particularly satisfactory results.

The solution of alglnous material which is now clarified and freed from its colored compounds is subsequently coagulated by means of a strong acid such as sulphuric, hydrochloric, nitric, etc., well as the stronger organic acids such as acetic acid and the like. The amount oisaid acid which is added must be such that the mother liquor of the coagulum shall have a pH value ranging between 2.8 and 3.2. In order that the coagulation may take place readily with good yields, it is advisable to produce it in a continuous manner, and by means of acid which has been diluted. It is, for instance, possible to employ suliurlc acid with a dilution of ten per. cent. in voltune. This acid is preferably caused to flow at the same time as the solution of alginous material is flowed into a suitable mixing tank, the rate of how of each liquid being so regulated that the mother liquor has the degree of acidity above mentioned.

This operation may be carried out in the apparatus diagrammatically shown by Fig. 5. The solution of alginous material flows through pipe iii and the diluted acid flows through pipe 20. The jets of liquids mix on a bafile 2i, suitably inclined and the whole drops into tank 22 where it is stirred by the eddies formed therein. In this manner the liquids are intimately mixed, the baffle affording a desirable device for causing the thorough and rapid mixing of the liquids. Since a substantial interval of time is required for the acid to effect coagulation of the alginous material in the alkaline solution, the mixture of acid and alkaline solution becomes substantially complete and substantially uniform before coagulation occurs to substantial extent. This prevents occlusion in alginous coagulum of alkaline solution which has not been mixed with acid or which has not been mixed with its proper quota of acid. The coagulation begins to occur as the mixed acid and alkaline solution leaves the bafile 2i and becomes substantially complete in the tank 22. One of the upper edges of the tank is at a lower level than the others and is provided with an inclined part 23 by means of which the coagulum and its mother liquor are guided into a tank 24. By mixing the acid and alkaline solution on a bafile and then introducing the mixture into the tank 22, the coagulation occurs in a zone which is removed from the mixing zone and the coagulum Elihuhdill alginous material is permitted to contact fresh acid in the zone, the acid tends to hydrolize the coagulated alginous material and adversely afiects the viscosity characteristic of the alginous product, that is, the capacity of the alginous material to produce viscous aqueous solutions. Moreover, since the outlet at part 23 is spaced from the point at which the mixed acid and alkaline solution are being introduced into the tank 22, the direction of ilow in said tank 22 is from said point of introduction and to the outlet at part 23, thereby minimizing as much as possible the duration or" the contact of the coaguiated alginous material with the mixed acid and alkaline solution in tank 22. The position and inclination of the battle with reierenceto the tank and to the outlet for the tank in the manner,

shown, also is instrumental in causing the coagula to flow downwardly at one end of the tank and upwardly at the opposite end of the tank adjacent the outlet so that the coagula and mother liquor flow out of the outlet promptly and at a rate corresponding approximately to the rate of formation of the coagulum. In this tank, the coagulum, which is rendered lighter than the mother liquor by the line bubbles of carbonic acid gas formed as by reaction between the acid and the sodium carbonate previously employed, floats on the surface of the liquid, where it is collected, while the mother liquor is removed through pipe 25. Since the coagulated alginous material is separated from the bulk of the mother liquor promptly and at approximately the same rate at which the coagulum is formed, the time during which the coagulum remains in contact with the acid mother liquor is minimized. While the partially neutralized acid in the mother liquor is not as injurious as fresh acid that is mixed with the alkaline solution to effect coagulation, it is desirable to remove the coagulum from the bulk of the acid mother liquor promptly so that the hydrolysis of the alginous material may be minimized as completely as possible. The coagulum which is of a gelatinous consistency may be removed to baskets and allowed to drip. It may then be freed, as far as possible, from the excess of mother liquor that is still present therein by pressing or centrifuging.

The use of strong acids, and particularly the more inexpensive strong mineral acids such as sulphuric acid, is preferred in coagulating 'the alginous material. However, there are other coagulents such as ethyl alcohol that might be used but such coagulents would have to be employed in relatively large amounts and would involve such expense as not to be as commercially desirable as acids at the present time.

This coagulum is then subjected to a last treatment the object of which is to remove any salts,

acids and moisture that it still contains. For this U purpose, it is exhausted by means of a solvent. such for instance as ethyl alcohol, which, below a certain concentration, dissolves the impurities in the coagulated alginous material without causing it to swell. While the use of ethyl alcohol as a solvent is preferred, other solvents may be used such as methyl alcohol, butyl alcohol, wood alcohol, acetone and the like. It is desirable that the solvent for the impurities have as high a dissolving power for water as possible. It is also possible to purify the coagulum by dialysis or electro-osmosis and in such case the same liquid of treatment as in the preceding example can be used, or simply water.

The coagulum, which has been first drained,

pressed or freed from its excess of liquid, is torn into pieces or comminuted by means of any suitable shredding or comminuting machine. The comminuted material is placed, for example, in vessels 26 (Fig. 6), any number of which may be provided, ten, for instance. These vessels are provided with a filtering plate 21 located at a distance from ten to fifteen centimeters from the bottom, so that it is possible to collect the liquid at the lower part of each vessel in order to feed it either on the coagulum present in another vessel,

through pipe 28, or in a stock tank 28, throughpipe 28', by means of a pump 38, or by any other equivalent apparatus. The fresh exhausing liquid (ethyl alcohol, either denatured or not, of

is passed over the portions of the coagulum that have not yet been treated. The exhaustion is thus systematically carried out. This operation is generally performed in the cold state. Care should be taken to have the coagulum constantly covered with one or two centimeters of liquid. The time during which the contact is maintained in each vesel is about one-quarter of an hour. The diluted and impure alcohol that collects in tank 29 is, if desired, subjected to a neutralizing treatment and then to a distillation so that it can be recovered in its initial concentration.

The purified alginous material is removed from the vessel in which it is contained and it may be freed from the excess of liquid present therein as by centrifuging. The liquid thus removed may be sent to tank 29 or it may be used as an addition to the vessel in which a mass of coagulum is exhausted for the second time.

The alginous material thus treated is freed, by drying, from the alcohol with which it is impregnated. The removal of the contaminating salt and acid from the coagulum prior to the drying step is important not only from the point of view of producing a product free of these impurities.

but also from the point of view of recovering the ant, since the drying of alginous material in the presence of water also has a similar adverse effect on the alginous material in the coagulum. In making an alkaline solution of alginous material, there is little likelihood of modifying the alginous material. However, the coagulum of alginous material that is precipitated from the alkaline solution is easily afiected so as to modify the alginous material therein and so as to impair its viscosity characteristic. By preventing the coagulum from excessive contact with the fresh acid used in the coagulation step, the alginous material in the coaxes.

agulum is recovered from the seaweed substantially unimpaired.- If one removes the water and any salt, base or contaminating acid from the coagulum by washing the coagulum with a volatile solvent which is adapted to dissolve an aqueous solution of said salt, base or contaminatingacid and in which the coagulum is substantially insoluble, or by removing salt, base or contaminatingacid bydialysis and then removing the water by use of a volatile solvent which is adaptedto dissolve water therein and in which the alginous material is insoluble, and then evaporates the solvent, the alginous material canalso be produced'in a dry condition without modifying the alginous material. This operation may be carried out in an oven provided with means for recovering the volatile liquids. The oven may operate either, in a vacuum or at atmospheric presure. It is advisable not to exceed a temperature of say 60 or 70 C.

A suitable oven 54 is shown in Fig. 12 having trays 55 on which the alginous material 66 is distributed for drying. The oven is preferably heated by any suitable means such as a jacket 51 through which a suitable heating medium such as steam or hot water can be passed by means of inlet 58 and outlet 59. A suitable exhausting pump 60 removes the alcohol from the oven 54 by line 6|. An air inlet 62, controlled by valve 63, per mits air to pass through the oven and carry off the vapors, the valve being adjustable to control the degree of vacuum, if a vacuum is desired.

The systematic exhaustion may also advantageously take place in drums revolving about their The passage from one drum to another may be performed by the action of vacuum or compressed air. When the exhaustion is finished, the alcohol is removed and the amount of alcohol present in the algin that has been treated is driven oif by heating in a vacuum.

An embodiment. of apparatus for washing the alginous material and drying it in rotating drums is shown in Fig. 13. For purposes of illustration a battery of three drums 64, 65 and 66 is shown. The alginous material in comminuted but unwashed condition may be charged into the drums through removable covers 61. If, for example, alginous material to be washed is charged into drum 64 and the cover for the drum is tightly secured, the material can be washed by passing alcohol into the drum as by lines 68, 69, I0 and H, the valves 12 and 13 being open. Suitable means (not shown) for rotating the drum may be provided and the rotation of the drum aids in washing the alginous material. The exhaust alcohol carrying dissolved impurities may be carried continuously or batchwise from drum 64 by means of lines 14 and 15. If the exhaust alcohol is highly contaminated the two way and stop valve I6 may be turned so as to cause the alcohol to pass from the system by line 11 for recovery. If the alcohol can be used for washing futher alginous material, the valve 16 is. adjusted so as to cause the alcohol to flow through lines 18, 19 and 88 into drum to wash alginous material therein. When the Washing in drum 64 has been completed the valve 13 is closed and the drum is heated as by passing steam through inlet 8| and pipes 82 within the drum, the exhaust steam and steam condensate being withdrawn from outlet 83. At the same time valve 16 can be placed in closed position. Moreover, the valve 84 in air inlet 65 is opened and likewise valve 86 in line 81 leading to any suitable source of vacuum (not shown) is opened. The degree of vacuum in the drum 64, if a vacuum is desired,

may be controlled by the valve B4. The rotation of the drum aids in drying the alginous material in the drum, the alcohol vapors passing off through line 81. When the drying is completed the purifled algin can be removed from the drum 64 and the drum 86 can be charged with fresh alginous material to be washed and dried.

In Fig. 13 the arrangement is such that the washing can be continued in drums 65 and 56 while the drying operation is being carried out in drum 6t. When the introduction into drum 85 of exhaust washing alcohol from drum 64 is discontinued, the washing in drum 65 may be continued by opening valve 88 in line 89, which line connects with line 68 carrying fresh alcohol. When drum M is first charged with alginous ma terial to bewashed, it is advisable to contact the material with exhaust alcohol from drums containing alginous material that has already been partially washed. Thus, for example, exhaust alcohol from drum 66 can be passed by lines 9d, 9H, 92, W and ii to drum lid, valves 93 and it being open for this purpose and valve l2 being closed. After the washing of the alginous material in drum 64 has been partially completed the valve 93 may be closed and valve 72 opened so that the washing may be completed with fresh alcohol. In a similar manner the washing and drying of the alginous materials in all the drums of battery may be carried out in a systematic way so as to cause the exhaust alcohol taken from the system to be as rich as possible in dissolved impurities. Further description of the operations including the fiow of liquids in the connecting lines, the opening and closing of the indicated valves and the like to this end, is not regarded as necessary. It is to be understood that any number of washing and drying drums may be employed and that the number of drums and the details of their construction can be varied.

In the washing operation above described impurities such as acid, salts and the like are removed and in addition other impurities soluble in the solvent are removed such as any residual chlorophyl that may be present. While any slight amount of residual chlorophyl is removed by the washing, it is nevertheless very advantageous to employ the clarification step above described in which the alginous material is clarified of chlorophyl by absorption in gelatinous precipitates as after the alginous material has been coagulated the chlorophyl becomes absorbed on the coagula of alginous material and becomes diflicult to remove. Thus, while the clarification step might be omitted, and reliance for removing chlorophyl -be placed on washing with a solvent, such procedure is regarded as normally disadvantageous due to the inability to thoroughly remove the chlorophyl and due to the excessive expense in increased time and increased volume of solvent required to separate the chlorophyl from the alginous coagula.

Alternatively, the comminuted alginous material may be purified by dialysis. If dialysis is employed, the coagulum may be disposed in cells 33 (Fig. 7) having semi-permeablewalls which may merely consist of a very finely woven fabric or a vegetable parchment. These cells are immersed in an exhausting liquid, circulating in a tank 8 into which it flows at 35 and from which it flows out through overflow 36. This liquid may consist simply of pure water. It has been found that with this method the salts, acid or other similar impurities pass into the water and the coagulum is finally transformed into a purified and very viscous liquid, which indicates that dialysis is completed. This liquid is removed from the cells and coagulated by means of alcohol. The alginous material thus treated is separated from the mother liquor by filtration and is finally dried, the alcohol used in the treatment being recovered, for example, by one of the methods above mentioned. Other solvents for the salts and acids mixed with the alginous material may be used, such as alcohol or any of the other solvents mentioned above in connection with the purification of coagulated alginous material by washing. If another solvent than water is used in which the alginous material is insoluble, the

' alginous material remains in a coagulated conillustrated in Fig. 8. Alginous material 95' in' tank 96 is separated from liquid 91 by semipermeable membranes 98 which may be made of a very finely woven fabric or of vegetable parchment. Electrodes 93 connected to a suitable source of electricity are placed in the aqueous electrolyte solution on opposite sides of the body of alginous material. The aqueous liquid about the electrodes is kept in a fresh condition by suitable inlets lul and W3 and outlets tilt and W2. Upon the maintenance of suitable voltage between the electrodes, the alginous material is purified by electro-dialysis.

Instead of coagulating the clarified alginous solution by means of an acid, the solution may be concentrated by ultra-filtration on a septum the size of the pores of which must range between 0.5 and 1 micron. The concentrated paste of alginous material is then coagulated by means of an equal volume of alcohol and subjected to the same treatment as the coagulum resulting from the acid precipitation above described.

By freeing the coagulum of contaminating salts and acid by washing the coagulum with a volatile solvent adapted to dissolve an aqueous solution of the salts and acid or by dialysis, the harmful efiect of excess wash waters in producing hydrolysis of the alginous material and impairing the viscosity characteristic thereof and in producing the alginous material in a more gelatinous and less desirable condition is avoided.

The very white algin obtained according to the present invention is directly dissolved in Water. However, the solution may be somewhat cloudy, because it is substantially at its iso-electric or neutral point, but even in this condition it gives remarkable results for the usual applications of algin. However, if it is desired to obtain transparent solutions, it suifices to add to the cloudy solution a very small amount of a soluble body capable of fixing on the algin OH ions, capable of giving it back its electro-negative charge. For this purpose, organic or inorganic chemicals such as ammonia, soda ash, alkalies, amines, etc.,may its used. Only minute quantities of such materials are necessary to render the solution clear, as only slight alkalinity from the iso-electric point is required to result in clarification of the solution and even as thus clarified the solution may be regarded as substantially free of alkali (a pH- value of '7 or even less). Alternatively, the fixation of OH ions so as to secure a transparent solution of algin can be accomplished at an earlier stage of the treatment above described as by including a small amount of alkaline solution such as ammonium hydroxide in the solvent used in washing the coagulated algin. Care should be taken, however, not to add such an excess of alkaline solution as to dissolve the coagulated alginous material, as the .alginous material should remain insoluble inthe presence of the solvent used for washing.

The-flow sheet of Fig. 14 which summarizes the above description of the process may, of course, undergo modifications without departingfrom the scope of this invention.

The liquids resulting from the first steps of the treatment, whereby laminarine is eliminated to demineralize the seaweeds, may be treated in the following manner:

Laminarine may be precipitated by means of alcohol. The precipitate that is obtained is purifled by successively dissolving it in alkaline earth solutions and again precipitating it by means of alcohol. The alcohol that is utilized for these operations may be subsequently recovered. In this case, it is advantageous to treat the seaweeds by means of barium salts, because the precipitation of laminarine by means of alcohol takes place under better conditions and with a better yield.

It is also possible to precipitate laminarine by means of subacetate of lead in an alkaline medium.

The liquids resulting from the first steps of the process can likewise be treated for the re-' covery of iodine. This can be done after the removal of laminarine as above described or without having previously removed the laminarine. If it is chiefly desired torecover iodine and the salts, the juices are first treated with alkali metal carbonate such as sodium carbonate to form a precipitate which carries down impurities. For this purpose, we add to the juices a solution of sodium carbonate of fifteen per cent. concentration until the end of the precipitation. The operation may be performed in the cold state. The precipitate consisting chiefly of an alkaline-earth carbonate is separated from its mother liquor, for instance by centrifuging in a suitable apparatus of which many types, such as the Sharples centrifugal machines, are well known. The residue is washed twice with a volume of water equal to three times the volume of said residue, with a centrifugal treatment between these two washing operations, and the washing waters are mixed with the initial mother liquors. The whole contains a rather low percentage of iodine, to wit, from one to two kilograms per cubic meter. The iodine can be precipitated as copper iodide by means of a soluble copper salt such as copper sulphate, copper chloride, copper acetate and the like. Usually the use of copper sulphate is to be preferred. Under the conditions mentioned, in order to precipitate iodine in the form of copper iodide with -a good yield, precipitation should take place not only in the presence of an acid but also in the presence of a reducing agent.

By way of example, we obtain satisfactory results through the following method:

The liquid to be treated is contained in a suitable tank, of wood or of stoneware, and

there is added thereto, for each part in weight of iodine:

(a) A solution of copper sulphate containing 3.5 parts of crystallized salt;

(b) 'A concentrated solution of sodium bisulphite containing 1.5 parts of dry salt;

and catalyst. The preclpitation is sumcient after The precipitate a period of twenty-four hours. is then subjected to centrifuging. In the mother liquor, copper is recovered by precipitating the copper in said liquor by means of iron, preferably'after having been neutralized by means of lime, soda ash or the like. This copper may be retransformed into copper sulphate or other soluble copper salt for subsequent operations. The residual liquor freed from copper is then freed from the iron that is contained therein, by

means of lime; then it is filtered. Finally, if desired, the liquor can be evaporated in order to separate the salts and the mannitol present therein by fractional crystallization.

As for the precipitate of copper iodide, it is calcined in the presence of caustic soda or potash, with an excess of alkali of about two or three per cent. Then sodium nitrate is added, in the proportion of about parts in weight for parts of copper iodide, in the form of a paste produced as by centrifuging. Other nitrates such as potassium or calcium nitrates or other mild oxidizing agent may be used as well as sodium nitrate. The mixture is calcined at a temperature of about 350-375 C., for about ten minutes. After cooling, the calcined product is treated with water and the resulting product is filtered. The liquor containing soluble iodides is treated by the known methods for the precipitation of iodine; for instance, it can be treated with chlorine for this p p se. The iodine thus obtained is finally refined by sublimation. The residue of the lixiviation is copper oxide, which may be transformedinto copper sulphate b known methods and recovered.

It is also possible to treat the precipitate of copper iodide to obtain soluble iodides in other ways.

For this purpose, this precipitate is washed twice with five times its volume of water, and it is then treated with a slight excess of baryta water containing about twenty-five per cent. of barium hydroxide at a temperature of 90-l00 C.

The following reaction takes place:

metal, the iodide of which is to be prepared, forinstance, according to the following reaction:

The use of baryt'a water in carrying out the.

foregoing steps is preferable to the use of other metallic hydroxides due to the fact that barium sulphate is more insoluble than the other metallic sulphates and results in a more pure product.

The whole is caused to boil in order-to agglom erate barium sulphate and then it is filtered. 7

not to be limited thereby. Moreover, it is apparent that certain features of this invention are novel and useful in themselves and as such are separate parts of the invention, and that likewise such features may be employed conjointly so that the special advantages of their cooperation may be enjoyed in the practice of this invention.

The alginous material recovered from seaweeds by the process above described has been referred to in certain instances as algin, but this is without limitation as to the chemical character of the material recovered, as alginous material recovered by other methods may result in materials which may be referred to as algin but which have different properties and characteristics. Thus the algin produced as above described has certain properties such as solubility in water, whiteness, freedom from ash, etc., which are believed to be unique. Moreover, in describing the foregoing process, reference has been made to dissolving alginous material to form a solution, but it is to be understood that the words dissolve and solution are to be given a broad interpretation covering any colloidal dispersions of alginous material that may occur as well as true solutions. Reference has been made herein to undissolved alginous material, dissolved alginous material, coagulated alginous material and the like, and in these different states the alginous material may vary in chemical composition or may merely vary in physical state as by change in colloidal characteristics, or in other analogous ways. It is believed, however, that the foregoing explanation is sufficient to enable one to practice this invention readily.

We claim:

1. A method of treating seaweeds which comprises, eliminating laminarine from the seaweeds by washing them in the presence of an alkalineearth metal salt, separating the undissolved a1- ginous material and algulose from the washing liquid, treating the alginous material and algulose with an alkaline solution to dissolve the alginous material, charging the alkaline solution thus obtained with gaseous bubbles which rise to the surface carrying particles of algulose with them, whereby algulose accumulates on the top of the solution in the form of a cake, separating the algulose from the clarified solution, introducing particles absorptive of chlorophyl coloring matter into the clarified solution, removing the particles carrying the chlorophyl coloring matter from the solution, and coagulating alginous material in the clarified solution thus obtained.

2. A method of treating seaweeds which comprises eliminating laminarine from the seaweeds bles which rise to the surface carrying algulose and particles coated with chlorophyl coloring matter to the surface, separating the algulose and coated particles from the clarified solution, and coagulating the alginous material in the clarified solution.

3. A method of treating seaweeds which comprises, eliminating laminarine from the seaweeds by washing them in the presence of an alkalineearth metal salt, separating the undissolved alginous material and algulose from the washing liquid, treating the alginous material and algulose with an alkaline solution to dissolve the alginous material, charging the alkaline solution thus ob-' tained with gaseous bubbles which rise to the surface, whereby particles of algulose are carried up by said bubbles and accumulate on the top of the solution in the form of a cake, separating the algulose from the clarified solution, introducing particles absorptive of chlorophyl coloring matter into the clarified solution, removing the particles carrying chlorophyl coloring matter from the solution, coagulating by means of an acid alginous material contained in the clarified solution thusobtained, and freeing the coagulum from contaminating salts and acid present therein.

4. A method of treating seaweeds which comprises eliminating laminarine from the seaweeds by washing them in the presence of an alkalineearth metal salt, separating the undissolved alginous material and algulose from the washing liquid, treating the alginous material and algulose with an alkaline solution to dissolve the alginous material, charging the alkaline solution thus obtained with gaseous bubbles which rise to the surface, whereby particles of algulose are carried by said bubbles and accumulate on the top of the solution, separating the algulose from the clarified solution, introducing particles absorptive of chlorophyl coloring material into the solution, removing the particles carrying the chlorophyl coloring matter from the solution, coagulating by means of an acid alginous material contained in the clarified solution thus obtained, and washing the coagulum with a solvent for contaminating salts and acid present therein which solvent does not cause the coagulated alginous material to swell.

5. A method of treating seaweeds which comprises eliminating laminarine from the seaweeds by washing them in the presence of an alkalineearth metal salt, separating the undissolved alginous material and algulose from the washing liquid, treating the alginous material and algulose with an alkaline solution to dissolve the alginous material, charging the alkaline solution thus obtained with gaseous bubbles which rise to the surface, whereby particles of algulose are carried by said bubbles and accumulate on the top of the solution, separating the algulose from the clarified solution, introducing particles absorptive of chlorophyl coloring material into the solution, removing the particles carrying the chlorophyl coloring matter from the solution, coagulating by means of an acid alginous material contained in the clarified solution thus obtained, and freeing the coagulum from soluble contaminating material present therein by dialysis.

6. A method of treating seaweeds which'comprises eliminating laminarine from the seaweeds the clarified solution,

ing liquid, treating the alginous material and algulose with an alkaline solution to dissolve the alginous material. charging the alkaline solution thus obtained with gaseous bubbles which rise to the surface carrying particles of algulose with them whereby algulose accumulates on the top of the solution,.separating the algulose from introducing particles absorptive of chlorophyl coloring matter with the clarified solution, ing the chlorophyl coloring matter from the solution, concentrating the alginous material in the clarified solution by filtering through a semipermeable septum, coagulating the alginous material in the solution thus concentrated and washing the coagulated material with alcohol.

'1. A method of recovering alginous material from seaweed which comprises washing the seaweed with an alkaline earth metal salt solution to dissolve out laminarine and other impurities leaving undissolved algulose and alginous material separated from the washing liquor, treating the mixed algulose and alginous material with an alkaline solution to dissolve the alginous material leaving the algulose undissolved, macerating the algulose to reduce it to a finely. divided condition, charging the aqueous mass with a multiplicity of gaseous bubbles which rise and carry to the surface the particles of algulose thus separating the clarified solution from the algulose, coagulating the alginous material in the clarified solution, and separating the coagulated alginous material from the residual liquid.

8. In a process of recovering alginous material from seaweeds, the steps comprising preparing an aqueous mass containing comminuted algulose and dissolved alginous material, charging the aqueous mass with a multiplicity of gaseous bubbles which rise to the surface carrying algulose therewith, thus separating the algulose from the solution to form a clarified solution containing alginous material.

9. In a process of recovering alginous material'from seaweed including preparing an alkaline aqueous mass containing-dissolved alginous material, the step comprising incorporating an oxidizingagent affording oxygen in said alkaline aqueous mass.

10. In a process of recovering alginous material from seaweed, the steps comprising preparing an alkaline aqueous mass containing algulose and dissolved alginous material, reducing the algulose in the mass to a finely divided condition in a continuous operation which introduces air into the mass as a multiplicity of minute bubbles, permitting the bubbles to rise in the solution while it is in a quiescent condition to carry the algulose to the surface, thus separating the {algulose from the liquid to form a clarified solution containing alginous material.

11. In a process of recovering alginous material from seaweed, the steps comprising preparing an alkaline aqueous mass containing finely divided algulose and dissolved alginous material, saturating the aqueous mass with carbonic acid gets under pressure and permitting bubbles of carbonic gas to form in the mass by gradual release of pressure and to carry to the surface the particles of algulose thereby separating the algulose from the solution containing alginous material.

12. In a process of recovering alginous materialfrom seaweed, the steps comprising preparing an alkaline aqueous mass containing algulose and dissolved alginous material, gradually liberating a removing the particles carrymultiplicity of gaseous bubbles from adjacent the bottom of the mass and permitting them to gradually rise and carry the algulose particles to the surface thereby separating the algulose from the solution containing alginous material.

13. In a process of recovering alginous material from seaweed, the steps comprising preparing an alkaline aqueous mass containing finelydivided algulose and dissolved alginous material, generating gas in the mass electrochemically to liberate bubbles in the mass and carry the algulose particles to the surface thereby separating the algulose from the solution containing alginous material.

14. In a process of recovering alginous material froin seaweed, the steps comprising treatin seaweed with an alkaline earth metal salt solution to dissolve laminarine, separating dissolved laminarine from undissolved algulose and alginous material, mixing the algulose and alginous material with an alkaline solution to render the alginous material soluble, reducing the algulose to a finely divided state, and charging the aqueous mass with gaseous bubbles which rise to the surface and carry the alg'ulose therewith, thus separating the algulose from the solution to leave a clarified'solution containing alginous material.

15. In a process of recovering alginous material irom seaweed, the steps comprising treating seaweed with an alkaline earth metal salt solution to dissolve laminarine, separating dissolved laminarine from undissolved algulose and alginous material, mixing the algulose and alginous material with an alkaline solution to render the alginous material soluble, reducing the algulose to a finely divided state, diluting the alkaline solution with water, introducing into the solution an oxidizing agent affording oxygen in said solution, and charging the aqueous mass with gaseous bubbles which rise to the surface and carry the algulose therewith, thus separating the algulose from the solution to leave a clarified solution containing alginous material.

16. In a method of recovering alginous material from seaweed, the steps comprising preparing from the seaweed an alkaline aqueous mass containing dissolved alginous material together with colored matter derived from the seaweed in the preparation of said alkaline aqueous mass, introducing into the mass a vehicle absorptive of the colored matter, and separating the vehicle carrying absorbed colored matter from the solution containing alginous material.

1'7. In a method of recovering alginous material from seaweed, the steps comprising preparing from the seaweed an alkaline aqueous mass containing dissolved alginous material together with colored matter derived from the seaweed in the preparation of said alkaline aqueous mass, introducing into the mass a substance selected from the group consisting of gelatinous metal hydrates and coagulated alginates, said substance being absorptive of the colored matter, and separating the substance carrying separating the altion of chlorophyl coloring matter by introducing a vehicle in the solution absorptive of the coloring matter and separating the vehicle carrying the coloring matter from the solution.

19. In a method of recovering alginous material from seaweed, the steps comprising washing the seaweed with a solvent for laminarine leaving a mixture containing algulose and alginous material, dissolving the alginous material with an alkaline solution, separating the algulose from the dissolved alginous material by an operation including separation of the algulose from the solution by means of gaseous bubbles, and claritying the solution of chlorophyl coloring matter by introducing a vehicle in the solution absorptive of the coloring matter, separating the vehicle carrying the coloring matter from the solution, coagulating the alginous material in the solution and separating the resulting coagulum from the residual liquid.

20. In a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline solution of alginous material and coagulating the alginous material by causing a stream of said alkaline solution of alginous material to become mixed with a stream of 'dilute acid, the mixing of said streams being substantially complete and effecting substantially uniform commingling of said alkaline solution with sufiicient dilute acid to substantially completely coagulate the alginous material in said solution before substantial coagulation of the alginous material occurs.

21. In a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline solution of alginous material and coagulating the alginous material by causing a stream of said alkaline solution of alginous material to become mixed with a stream of dilute acid while the solution of alginous material is flowing down an inclined ballie, causing the resulting mixture to flow from said bafile into a container, and withdrawing the coagulum and mother liquor from said container by an outlet for the container which is spaced from the point at which the mixture of acid and alkaline solution is introduced into said container so that the primary direction of flow in said container is from said point of introduction to said outlet.

22. In a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline solution of alginous material and coagulating the alginous material by adding sufiicient dilute acid to said solution of alginous material to substantially completely coagulate the alginous material contained therein, the substantially complete and substantially .uniform commingling of said acid and of said alkaline alginous solution being effected before substantial coagulation of the alginous material takes place.

23. In a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline solution of alginous material and coagulating the alginous material by intimately mixing in a mixing zone said alkaline solution with sufiicient dilute acid to precipitate the alginous material therein; and moving the resulting mixture away immediately as formed from said mixing zone to a coagulation zone wherein said acid efiects coagulation of said alginous material, thereby preventing the resulting coagulum from being adversely affected by the acid in the freshly made mixture of acid and alkaline solution in said mixing zone.

24. In a method of recovering alginous material from seaweed, the steps according to claim 23 wherein the acid that is added produces a pH of about 2.8 to about 3.2 in the mother liquor in the coagulation zone.

25. In a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline solution of alginous material and coagulating the alginous material by causing a stream of said alkaline solution of alginous material to become mixed with a stream of dilute acid to continuously coagulate the alginous mate rial in a coagulation zone, continuously removing the coagulatedalginous material and mother liquor from the coagulation zone and promptly thereafter separating the coagulum from the bulk of the mother liquor at approximately the same rate at which the coagulum is formed.

26. In a method of recovering alginous material from seaweed, the steps comprising preparing a clarified solution of dissolved alginous material, coagulating the alginous material, separating the coagulated alginous material from the residual liquid, and freeing the coagulated alginous material from contaminating mineral matter contained therein by washing the coagulated alginous material with a volatile solvent adapted to dissolve an aqueous solution of said mineral matter.

2'7. In a method of recovering alginous material from seaweed, the steps comprising preparing a clarified solution of dissolved alginous material, coagulating the alginous material by adding an acid to the solution, separating the coagulated alginous material from the residual liquid, and freeing the coagulated alginous material from salts and acid contained therein by washing the coagulum with a solvent for the salts and acid which solvent contains insufficient water to cause substantial swelling of the coagulated alginous material. I

28. In a method of recovering alginous material from seaweed, the steps comprising preparing a clarified solution of dissolved alginous material, coagulating the alginous material, separating the coagulated alginous material from the residual liquid, and freeing the coagulated alginous material from soluble impurities contained therein by dialysis.

29. In a method of recovering alginous material from seaweed, the steps comprising preparing a clarified solution of dissolved alginous. material, coagulating the alginous material by adding an acid to the solution, separating the coagulated alginous material from the residual liquid, and freeing the coagulated alginous material i'rom contaminating salts and acid contained therein by electro-dialysis.

30. In a method of recovering alginous material from seaweed, the steps comprising preparing from seaweed an alkaline aqueous mass containing algulose and dissolved alginous material, separating the algulose from the dissolved alginous material, and concentrating the solution containing dissolved alginous material by ultra-filtration through a septum.

31. In a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline solution of alginous material sub-- stantially free of laminarine and algulose, coagulating the alginous material, freeing the alginous coagulum from residual liquid and from contaminating soluble impurities, and dissolving the coagulated alginous material in water to produce a substantially neutral solution.

32. As a product, recovered alginous material of seaweed substantially completely free from chemically combined inorganic constituents and characterized by a substantially acid pH value and by ready solubility of the alginous material in water.

33. As a product, the recovered alginous material of claim 32 which is further characterized by the fact that the alginous material is sub stantially free of chlorophyl and is recovered without substantial impairment of the viscosity characteristic of the alginous material of the seaweed.

34. As a product, the recovered alginous material of claim 32 which is further characterized by substantially complete 'freedom from alguiose and laminarine.

35. As a product, the recovered alginous material of claim 32 which is further characterized by substantially complete freedom from salts.

36. As a product, recovered alginous material of seaweed substantially completely free from chemically combined inorganic constituents and characterized by having the capacity to remain dissolved in an aqueous solution having a pH value substantially less than 7' and by being recovered without substantial impairment of the viscosity characteristic of the alginous material in the seaweed.

3'7. As a product, recovered alginous material of seaweed, said product being characterized by substantial freedom from laminarine, algulose and chlorophyl, by substantial freedom from salts and contaminating acid, and by having the capacity to remain dissolved in an aqueous solution having a pH value substantially less than-7.

38. Alginous material recovered from seaweed by a process which comprises making an alkaline solution of the alginous material in the seaweed which solution is free of the bulk of the 1aminarine and algulose in the seaweed, coagulating the alginous material by adding an acid thereto, the coagulum not being subjected tosubstantial contact with acid having a pH value less than about 2.8, and freeing the coagulum of salt and any acid present therein until the coagulum has the capacity to remain dissolved in an aqueous solution having a pH value less than '1 by washing the coagulum with a volatile solvent adapted to dissolve an aqueous solution of the salt and acid and in which the coagulum'is insoluble.

39. Alginous material according to claim 38 which isfurther characterized by substantially complete freedom from chlorophyl.

40. Alginous material recovered from seaweed by a process which comprises making an alkaline solution of the alginous material in the seaweed which solution is free of. the bulk of the laminarine and algulose in the seaweed, coagulating the alginous material by adding an acid thereto, the coagulum not being subjected to substantial contact with acid having a pHvalue lees i materials removing freeing the coagulum of. salt therein by dialysis'until than about 2.8, and and any acid present the coagulum has the solved in an aqueous solution having a pH value less than '1.

41. Alginous material according to claim 40 which is further characterized by substantially complete freedom from chlorophyl.

42. Alginous material recovered from seaweed according to claim 40 and which is recovered in dry form by washing the alginous material, after it has been freed by dialysis from salts and contaminating acid, with a solvent which is adapted to dissolve water therein and in which the alginous material is insoluble until the alginousmaterial is substantially free of water, and then removing said solvent.

43. In a method of recovering alginous material from seaweed, the step comprising washing a coagulum of alginous material with a volatile liquid solvent adapted to dissolve water therein.

44. In a method of recovering alginous material from seaweed wherein a clarified alkaline aqueous mass containing dissolved aiginous material is prepared and the alginous material therein is coagulated, the steps comprising charging the aqueous mass containing coagulated alginous material with a multiplicity of gaseous bubbles and maintaining the mass unagitated while said bubbles rise to the surface carrying the coagulated alginous material therewith, thus separating the alginousmaterial from the residual aqueous liquid.

45. In a method of recovering alginous material from seaweed, the steps comprising washing a coagulum of alginous material with a volatile liquid solvent which is adapted to dissolve water therein and in which the alginous material is insoluble to produce a coagulum freed of water and thereafter removing the solvent from the substantially water-free coagulum to produce the dry condition.

46. a method of recovering alginous material from seaweed, the steps comprising preparing an alkaline aqueous solution of alginous material containing an alkali metal carbonate, adding to said solution-suflicient acid to coagulate said alginous material and to cause said alkali metal carbonate to react with said acid to form bubbles of carbon dioxide gas, eifecting coagulation of the alginous material in a coagulation zone, and while said bubbles remain in said mixed said mixed materials from said coagulation zone to a container wherein the mixed materials are permitted to stand without substantial agitation, said bubbles of carbon dioxide gas causing said coagulated alginous material to be carried at the surface of the mother liquor in said container.

VICTOR CHAR-LE5 EMILE LE GLOAHEC.

JOHN ROBERT HER'IER.

capacity to remain dis-

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