JP2007169129A - Method for producing aqueous sodium hypochlorite solution and method for producing aqueous sodium hydroxide solution - Google Patents
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本発明は、臭素化合物の含有量の少ない次亜塩素酸ナトリウム水溶液の製造方法およびカリウム元素含有量の少ない水酸化ナトリウム水溶液の製造方法に関する。 The present invention relates to a method for producing a sodium hypochlorite aqueous solution having a low bromine compound content and a method for producing a sodium hydroxide aqueous solution having a low potassium element content.
通常、工業用食塩を電解することで得られる気体塩素と水酸化ナトリウム水溶液を反応させて、次亜塩素酸ナトリウムおよび塩化ナトリウムを含む水溶液を製造する（本明細書では、これを次亜塩素酸ナトリウム水溶液という）。この次亜塩素酸ナトリウム水溶液は、殺菌剤、消毒水として、上下水処理場において浄水処理もしくは廃水処理に使用されたり、病院において食器などの洗浄に使用される。さらに一般家庭においては漂白剤として使用されるなど、幅広い分野で使用されている。上記の用途を含め、使用される次亜塩素酸ナトリウム水溶液において、環境調和性または化学安定性等の観点から、より高純度のものが求められている。 Usually, gaseous chlorine obtained by electrolyzing industrial sodium chloride is reacted with an aqueous sodium hydroxide solution to produce an aqueous solution containing sodium hypochlorite and sodium chloride. Sodium aqueous solution). This sodium hypochlorite aqueous solution is used as a disinfectant and disinfecting water for water purification treatment or wastewater treatment in water and sewage treatment plants, or for washing dishes and the like in hospitals. Furthermore, it is used in a wide range of fields, such as being used as a bleaching agent in general households. From the viewpoints of environmental harmony or chemical stability, the aqueous sodium hypochlorite aqueous solution to be used, including the above applications, has been demanded.
上記のように、次亜塩素酸ナトリウム水溶液は工業用食塩より製造されているが、工業用食塩には種々の不純物が含まれているため、通常は精製してから使用している。しかし臭素は塩素と性質が類似しており、通常の精製方法では除去できないために、微量の臭素化合物を含む工業用食塩が原料として供給されているのが実情である。このため、当該工業用食塩を電解して得られる気体塩素にも微量の気体臭素が混入し、さらに当該気体塩素を原料として製造した次亜塩素酸ナトリウム水溶液にも微量の臭素化合物が含まれる。 As described above, the sodium hypochlorite aqueous solution is manufactured from industrial salt, but since industrial salt contains various impurities, it is usually used after being purified. However, since bromine is similar in nature to chlorine and cannot be removed by ordinary refining methods, industrial salt containing a trace amount of bromine compound is supplied as a raw material. For this reason, a trace amount of gaseous bromine is mixed also in gaseous chlorine obtained by electrolyzing the industrial salt, and a trace amount of bromine compound is also contained in the sodium hypochlorite aqueous solution produced using the gaseous chlorine as a raw material.
従来より、次亜塩素酸ナトリウム水溶液の高純度化を目的とする食塩濃度の低減、または溶液安定化を目的とする重金属の低減などといった各種検討が行われているが、臭素化合物の低減については、何ら検討がなされていない。 Conventionally, various studies such as reduction of salt concentration for the purpose of increasing the purity of sodium hypochlorite aqueous solution or reduction of heavy metals for the purpose of solution stabilization have been conducted. No consideration has been given.
一般に無機物の水溶液中に含まれる臭素化合物を処理する方法としては、処理すべき溶液を活性炭、ゼオライト等の多孔性吸着剤に接触させて吸着させることにより分離除去する方法が知られている。しかし、次亜塩素酸ナトリウム水溶液を、前記の吸着剤に接触させると、吸着剤に吸着している金属等によって次亜塩素酸ナトリウム自体が分解されて、有効塩素濃度が低くなるため好ましくない。また吸着剤として金属フリーの活性炭を使用することもできるが、活性炭の再生、金属処理等の工程が煩雑となるため、工業的製法には適していない。 In general, as a method for treating a bromine compound contained in an inorganic aqueous solution, there is known a method for separating and removing the solution to be treated by bringing it into contact with a porous adsorbent such as activated carbon or zeolite for adsorption. However, when an aqueous sodium hypochlorite solution is brought into contact with the adsorbent, the sodium hypochlorite itself is decomposed by the metal adsorbed on the adsorbent and the effective chlorine concentration is lowered, which is not preferable. Moreover, although metal-free activated carbon can be used as an adsorbent, steps such as regeneration of the activated carbon and metal treatment become complicated, which is not suitable for an industrial production method.
また特許文献１では、次亜塩素酸ナトリウム水溶液を冷却して、次亜塩素酸ナトリウムを５水和物として析出させ、分離することにより、臭素などの不純物と分離する方法が開示されているが、工程が増え、収率も落ちるため、コスト的に不利であるため、工業的製法には適していない。 Patent Document 1 discloses a method of separating an aqueous solution of sodium hypochlorite, separating sodium hypochlorite as a pentahydrate, and separating it from impurities such as bromine. Since the number of processes increases and the yield decreases, it is disadvantageous in terms of cost and is not suitable for an industrial production method.
また一方、水酸化ナトリウム水溶液についても、高品質化の要求がますます高まってきており、特にナトリウム元素と似た性質をもつカリウム元素の含有量が少ないものの要求が高くなってきている。一般に水酸化ナトリウム水溶液は、塩化ナトリウム水溶液の電解により製造されており、工業用水酸化ナトリウム水溶液は、濃度４８％のものが標準である。原料として使用される塩化ナトリウムには、不純物として塩化カリウム等の形でカリウム元素が含まれている。当該塩化ナトリウム中のカリウム含有量は１００〜３００ｐｐｍであるため、原料塩化ナトリウム中のカリウム除去を行わない限り、カリウム含有量が１０ｐｐｍ以下である濃度４８％水酸化ナトリウム水溶液を得ることは困難である。 On the other hand, there is an increasing demand for high-quality sodium hydroxide aqueous solutions, particularly those with a low content of potassium elements having properties similar to sodium elements. In general, an aqueous sodium hydroxide solution is produced by electrolysis of an aqueous sodium chloride solution, and a standard aqueous sodium hydroxide solution having a concentration of 48% is standard. Sodium chloride used as a raw material contains potassium element as impurities such as potassium chloride. Since the potassium content in the sodium chloride is 100 to 300 ppm, it is difficult to obtain a 48% sodium hydroxide aqueous solution having a potassium content of 10 ppm or less unless the potassium in the raw material sodium chloride is removed. .
水酸化ナトリウム水溶液を製造する際に、原料に用いられる塩化ナトリウム水溶液から不純物カリウムを除去する方法として冷析方法が考えられるが、塩化ナトリウムの溶解度は温度に対してほとんど変化しないため、効率が悪い。また、塩化ナトリウム水溶液の濃縮することにより塩化ナトリウムを析出させて精製する方法も考えられるが、蒸気等のエネルギーを使用するため、コストがかかり、いずれの方法も工業的製法には適していない。 When manufacturing an aqueous sodium hydroxide solution, a cooling method can be considered as a method for removing impurity potassium from an aqueous sodium chloride solution used as a raw material, but the solubility of sodium chloride hardly changes with temperature, so the efficiency is poor. . Moreover, although the method of depositing and purifying sodium chloride by concentrating a sodium chloride aqueous solution is also conceivable, since energy such as steam is used, it is costly and neither method is suitable for an industrial production method.
そこで本発明は、工業的に効率よく、臭素化合物の含有量の少ない次亜塩素酸ナトリウム水溶液の製造方法およびカリウム元素含有量の少ない水酸化ナトリウム水溶液の製造方法を提供することを目的とする。 Accordingly, an object of the present invention is to provide an industrially efficient method for producing a sodium hypochlorite aqueous solution having a low bromine compound content and a method for producing a sodium hydroxide aqueous solution having a low potassium element content.
本発明は、以下の次亜塩素酸ナトリウム水溶液の製造方法および水酸化ナトリウム水溶液の製造方法を提供する。 The present invention provides the following method for producing a sodium hypochlorite aqueous solution and a method for producing a sodium hydroxide aqueous solution.
［１］次の工程Ａ〜Ｄをこの順番で有する次亜塩素酸ナトリウム水溶液の製造方法。
工程Ａ：気体塩素と水酸化ナトリウム水溶液を反応させて、析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を得る工程。
工程Ｂ：前記工程Ａで得られる析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を、遠心分離機で処理して、回収塩化ナトリウムを得る工程。
工程Ｃ：前記工程Ｂで得られる回収塩化ナトリウムを水に溶かした回収塩化ナトリウム水溶液を電解し、水酸化ナトリウム水溶液、気体塩素および気体水素を得る工程。
工程Ｄ：前記工程Ｃで得られる気体塩素を、水酸化ナトリウム水溶液と反応させ、次亜塩素酸ナトリウム水溶液を得る工程。
[1] A method for producing an aqueous sodium hypochlorite solution having the following steps A to D in this order.
Step A: A step of reacting gaseous chlorine with a sodium hydroxide aqueous solution to obtain a sodium hypochlorite aqueous solution containing precipitated sodium chloride.
Step B: A step of treating the sodium hypochlorite aqueous solution containing the precipitated sodium chloride obtained in the step A with a centrifuge to obtain recovered sodium chloride.
Step C: Step of electrolyzing a recovered sodium chloride aqueous solution obtained by dissolving the recovered sodium chloride obtained in the step B in water to obtain a sodium hydroxide aqueous solution, gaseous chlorine and gaseous hydrogen.
Step D: A step of reacting the gaseous chlorine obtained in Step C with a sodium hydroxide aqueous solution to obtain a sodium hypochlorite aqueous solution.
［２］前記工程Ｄで得られる次亜塩素酸ナトリウム水溶液に含まれる臭素化合物含有量がＢｒＯ３−換算で、次亜塩素酸ナトリウム水溶液に対して、５ｐｐｍ以下である［１］に記載の次亜塩素酸ナトリウム水溶液の製造方法。
［３］前記工程Ｂで得られる回収塩化ナトリウムに含まれる臭素元素が、塩化ナトリウム固形分に対して、１０ｐｐｍ以下である［１］または［２］に記載の次亜塩素酸ナトリウム水溶液の製造方法。
[2] The content of bromine compound contained in the sodium hypochlorite aqueous solution obtained in the step D is 5 ppm or less in terms of BrO 3- , based on the sodium hypochlorite aqueous solution. A method for producing an aqueous sodium chlorite solution.
[3] The method for producing an aqueous sodium hypochlorite solution according to [1] or [2], wherein elemental bromine contained in the recovered sodium chloride obtained in the step B is 10 ppm or less with respect to the solid content of sodium chloride. .
［４］前記工程Ｃで得られる気体塩素を液化する液化工程を含み、かつ前記液化工程で液化せずに残存した気体塩素を工程Ｄに供給する［１］〜［３］のいずれかに記載の次亜塩素酸ナトリウム水溶液の製造方法。
［５］前記工程Ｃで得られる気体塩素を液化する液化の工程が少なくとも、圧力２００〜３００ｋＰａ、温度−３０〜０℃の範囲の条件下で行われる［４］に記載の次亜塩素酸ナトリウム水溶液の製造方法。
[4] The method according to any one of [1] to [3], including a liquefaction step of liquefying gaseous chlorine obtained in the step C and supplying the gaseous chlorine remaining without being liquefied in the liquefaction step to the step D A method for producing an aqueous sodium hypochlorite solution.
[5] The sodium hypochlorite according to [4], wherein the liquefaction step for liquefying gaseous chlorine obtained in the step C is performed at least under conditions of a pressure of 200 to 300 kPa and a temperature of -30 to 0 ° C. A method for producing an aqueous solution.
［６］次の工程Ａ〜Ｃをこの順番で有する水酸化ナトリウム水溶液の製造方法。
工程Ａ：気体塩素と水酸化ナトリウム水溶液を反応させて、析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を得る工程。
工程Ｂ：前記工程Ａで得られる析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を、遠心分離機で処理して、回収塩化ナトリウムを得る工程。
工程Ｃ：前記工程Ｂで得られる回収塩化ナトリウムを水に溶かした回収塩化ナトリウム水溶液を電解し、水酸化ナトリウム水溶液、気体塩素および気体水素を得る工程。
[6] A method for producing an aqueous sodium hydroxide solution comprising the following steps A to C in this order.
Step A: A step of reacting gaseous chlorine with a sodium hydroxide aqueous solution to obtain a sodium hypochlorite aqueous solution containing precipitated sodium chloride.
Step B: A step of treating the sodium hypochlorite aqueous solution containing the precipitated sodium chloride obtained in the step A with a centrifuge to obtain recovered sodium chloride.
Step C: Step of electrolyzing a recovered sodium chloride aqueous solution obtained by dissolving the recovered sodium chloride obtained in the step B in water to obtain a sodium hydroxide aqueous solution, gaseous chlorine and gaseous hydrogen.
［７］前記工程Ｃで得られる水酸化ナトリウム水溶液を濃度４８％まで濃縮した液のカリウム元素含有量が、濃縮した液に対して、１０ｐｐｍ以下である［６］に記載の水酸化ナトリウム水溶液の製造方法。 [7] The potassium hydroxide content of the liquid obtained by concentrating the sodium hydroxide aqueous solution obtained in the step C to a concentration of 48% is 10 ppm or less with respect to the concentrated liquid. Production method.
本発明者らの検討の結果、従来技術のように次亜塩素酸ナトリウムまたはその水溶液から臭素化合物を除去するのは困難であるが、原料として用いる気体塩素または水酸化ナトリウム水溶液として臭素含有量の少ないものを使用すれば、容易に臭素化合物含有量の少ない次亜塩素酸ナトリウム水溶液が得られることが判明した。また、工程Ａ、工程Ｂを経て、遠心分離機で分離された回収塩化ナトリウムは臭素の含有量が少ないことが判明した。ついで、この回収塩化ナトリウムの水溶液を電解して得られた気体塩素も臭素の含有量が低いことが判明し、そこで当該気体塩素を原料とした次亜塩素酸ナトリウム水溶液は臭素化合物が大幅に低減されることがわかり、本発明に到達した。また、同様に遠心分離機で分離された回収塩化ナトリウムはカリウム元素の含有量が少なく、この回収塩化ナトリウムの水溶液を電解して得られた水酸化ナトリウム水溶液のカリウム元素含有量も大幅に低減されることがわかり、本発明に到達した。 As a result of the study by the present inventors, it is difficult to remove a bromine compound from sodium hypochlorite or an aqueous solution thereof as in the prior art, but the bromine content of gaseous chlorine or sodium hydroxide aqueous solution used as a raw material is difficult. It was found that an aqueous sodium hypochlorite solution having a low bromine compound content can be easily obtained by using a small amount. Moreover, it turned out that the collection | recovery sodium chloride isolate | separated with the centrifuge through the process A and the process B has little bromine content. Next, it was found that the gaseous chlorine obtained by electrolyzing the aqueous solution of this recovered sodium chloride also has a low bromine content, so that the aqueous solution of sodium hypochlorite using the gaseous chlorine as a raw material has greatly reduced bromine compounds. The present invention has been reached. Similarly, the recovered sodium chloride separated by the centrifuge has a low content of potassium element, and the potassium element content of the aqueous sodium hydroxide solution obtained by electrolyzing the aqueous solution of this recovered sodium chloride is greatly reduced. The present invention has been reached.
なお、本発明でいう回収塩化ナトリウムとは、工程Ａ、工程Ｂをこの順番で経て得られる塩化ナトリウムである。 In addition, the collection | recovery sodium chloride as used in the field of this invention is sodium chloride obtained through the process A and the process B in this order.
本発明の方法によれば、臭素化合物含有量がきわめて少ない次亜塩素酸ナトリウム水溶液を工業的に効率よく得ることができる。またカリウム元素の含有量が少ない水酸化ナトリウム水溶液も同様に、工業的に効率よく得ることができる。 According to the method of the present invention, an aqueous sodium hypochlorite solution having an extremely low bromine compound content can be obtained industrially efficiently. Similarly, an aqueous sodium hydroxide solution having a low potassium element content can be obtained industrially efficiently.
本発明では、前記工程Ａを経て得られる析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を、遠心分離機で分離して、回収塩化ナトリウムを得る。次亜塩素酸ナトリウム水溶液を製造する工程Ａにおいて、原料である気体塩素および水酸化ナトリウム水溶液から持ち込まれる不純物がろ液に残存するため、工程Ｂで得られる回収塩化ナトリウムに含まれる臭素やカリウム元素などの不純物は、工業用食塩と比較して、非常に少なくなっている。なお、回収塩化ナトリウムの臭素含有量は、塩化ナトリウム固形分に対して、１０ｐｐｍ以下のものが好ましい。工程Ｂの遠心分離処理に使用する遠心分離機には、例えば、バッチ式で処理するタナベウィルテック社製 ＣＯ−４８−４５型、連続式で処理するＩＨＩ社製 ＧＵＩＮＡＲＤ遠心分離機Ｃ−３０ＨＬＳ型などを用いることができる。また遠心分離処理のときの回転数は、バッチ式の場合は７５０ｒｐｍ以下、連続式の場合は３０００ｒｐｍ程度が好ましい。 In the present invention, a sodium hypochlorite aqueous solution containing precipitated sodium chloride obtained through the step A is separated by a centrifuge to obtain recovered sodium chloride. In process A for producing sodium hypochlorite aqueous solution, impurities brought in from gaseous chlorine and sodium hydroxide aqueous solution as raw materials remain in the filtrate, so bromine and potassium elements contained in the recovered sodium chloride obtained in process B Impurities such as are very low compared to industrial salt. In addition, the bromine content of recovered sodium chloride is preferably 10 ppm or less with respect to the solid content of sodium chloride. Examples of the centrifuge used for the centrifugal treatment in Step B include, for example, TANABE WILTECH CO-48-45 type processed in batch mode, and IHI GUINARD centrifuge C-30HLS type processed in continuous mode. Etc. can be used. In addition, the rotation speed during the centrifugal separation is preferably about 750 rpm or less for the batch type and about 3000 rpm for the continuous type.
次に、前記の臭素含有量の少ない回収塩化ナトリウムを、工程Ｃのように、水に溶かして回収塩化ナトリウム水溶液を調製した後、当該回収塩化ナトリウム水溶液を電解して得られる気体塩素に含まれる臭素の量は、工業用食塩を電解して得られる気体塩素のものと比較して、非常に少なくなる。その結果、工程Ｄのように、当該気体塩素を水酸化ナトリウム水溶液と反応させて得られる次亜塩素酸ナトリウム水溶液に含まれる臭素化合物の量は、従来品に比べ、非常に少なくなる。工程Ｄにおいて、工程Ｃで得られる水酸化ナトリウム水溶液を用いると、なお、次亜塩素酸ナトリウム水溶液に含まれる臭素化合物の量が少なくなる。このとき製造される次亜塩素酸ナトリウム水溶液に含まれる臭素化合物の含有量はＢｒＯ３ −換算で、次亜塩素酸ナトリウム水溶液に対して、５ｐｐｍ以下であることが好ましい。なお臭素化合物とはＮａＢｒやＮａＢｒＯ３等の化合物をいう。 Next, the recovered sodium chloride having a low bromine content is dissolved in water to prepare a recovered sodium chloride aqueous solution as in Step C, and then contained in gaseous chlorine obtained by electrolyzing the recovered sodium chloride aqueous solution. The amount of bromine is very low compared to that of gaseous chlorine obtained by electrolyzing industrial salt. As a result, as in step D, the amount of bromine compound contained in the sodium hypochlorite aqueous solution obtained by reacting the gaseous chlorine with the sodium hydroxide aqueous solution is much smaller than that of the conventional product. In Step D, when the aqueous sodium hydroxide solution obtained in Step C is used, the amount of bromine compound contained in the aqueous sodium hypochlorite solution is reduced. It is preferable that content of the bromine compound contained in the sodium hypochlorite aqueous solution manufactured at this time is 5 ppm or less with respect to the sodium hypochlorite aqueous solution in terms of BrO 3 − . The bromine compound refers to a compound such as NaBr or NaBrO 3 .
また同様に、カリウム元素についても、工程Ｂではより多くがろ液中に残存するので、工程Ｃの電解で得られる水酸化ナトリウム水溶液のカリウム元素含有量も非常に少なくなる。当該水酸化ナトリウム水溶液を濃縮することで得られる、濃度４８％水酸化ナトリウム水溶液のカリウム元素含有量は、濃度４８％水酸化ナトリウム水溶液に対して、１０ｐｐｍ以下であることが好ましい。 Similarly, more potassium element remains in the filtrate in step B, so that the content of potassium element in the aqueous sodium hydroxide solution obtained by the electrolysis in step C is also very low. The potassium element content of the 48% sodium hydroxide aqueous solution obtained by concentrating the sodium hydroxide aqueous solution is preferably 10 ppm or less with respect to the 48% sodium hydroxide aqueous solution.
ところで工程Ｃで得られる気体塩素の一部を液化すると、気体塩素中の不純物である気体臭素の大部分が液化するため、液化工程を加えることでさらに気体塩素の臭素含有量を少なくすることができ、好ましい。液化工程において液化せずに残存した気体塩素を、工程Ｄのように、水酸化ナトリウム水溶液と反応させると、臭素化合物含有量がさらに少ない次亜塩素酸ナトリウム水溶液を製造することができるため、好ましい。なお上記の気体塩素を液化する工程の液化条件は、２００〜３００ｋＰａの圧力下、−３０〜０℃の温度であることが好ましい。さらに圧力が２５０〜２８０ｋＰａ、温度が−１０〜−５℃であるとさらに好ましい。温度が低すぎると、装置上の制約が大きく工程上の負荷が増す傾向がある。また温度が高すぎると液化効率が低くなる傾向があり、液化塩素の製造上好ましくないことがある。一方、圧力が低すぎると液化装置の負荷が大きくなる傾向がある。また圧力が高すぎると装置の耐圧上の負担が大きくなる傾向があり、工業的に好ましくないことがある。 By the way, when a part of gaseous chlorine obtained in the process C is liquefied, most of the gaseous bromine which is an impurity in the gaseous chlorine is liquefied. Therefore, the bromine content of the gaseous chlorine can be further reduced by adding the liquefying process. It is possible and preferable. When gaseous chlorine remaining without being liquefied in the liquefaction step is reacted with a sodium hydroxide aqueous solution as in step D, a sodium hypochlorite aqueous solution having a still lower bromine compound content can be produced, which is preferable. . In addition, it is preferable that the liquefaction conditions of the process of liquefying said gaseous chlorine are the temperature of -30-30 degreeC under the pressure of 200-300 kPa. More preferably, the pressure is 250 to 280 kPa and the temperature is −10 to −5 ° C. If the temperature is too low, there is a tendency that the restrictions on the apparatus are large and the load on the process increases. Moreover, when temperature is too high, there exists a tendency for liquefaction efficiency to become low, and it may be unpreferable on manufacture of liquefied chlorine. On the other hand, if the pressure is too low, the load on the liquefier tends to increase. On the other hand, if the pressure is too high, the burden on the pressure resistance of the apparatus tends to increase, which may be industrially undesirable.
なお本発明において、回収塩化ナトリウムの純度は沈殿滴定法で、また回収塩化ナトリウムに含まれる臭素元素は酸化還元滴定法にて測定することができる。次亜塩素酸ナトリウム水溶液中の臭素化合物含有量はイオンクロマトグラフ法により測定することができる。測定にあたっては、次亜塩素酸ナトリウム水溶液に過酸化水素を加え、次亜塩素酸を分解した液を測定試料とする。また、本発明に係るカリウム元素含有量は炎光光度法にて測定することができる。 In the present invention, the purity of recovered sodium chloride can be measured by precipitation titration, and the elemental bromine contained in recovered sodium chloride can be measured by oxidation-reduction titration. The bromine compound content in the aqueous sodium hypochlorite solution can be measured by ion chromatography. In the measurement, hydrogen peroxide is added to a sodium hypochlorite aqueous solution, and a solution obtained by decomposing hypochlorous acid is used as a measurement sample. The potassium element content according to the present invention can be measured by a flame photometric method.
以下に、本発明を実施例（例１、例２、例４）および比較例（例３、例５）により具体的に説明するが、本発明はこれらに限定されない。特に明示する場合を除き、％は質量％を意味する。 Hereinafter, the present invention will be specifically described with reference to Examples (Examples 1, 2 and 4) and Comparative Examples (Examples 3 and 5), but the present invention is not limited thereto. Unless otherwise specified,% means mass%.
［例１］
濃度４８％の水酸化ナトリウム水溶液７００Ｌを、大気４００Ｎｍ３で希釈した気体塩素１４１Ｎｍ３と、３２℃にて連続的に反応させることにより、析出した塩化ナトリウム３８３ｋｇを含む次亜塩素酸ナトリウム水溶液（有効塩素濃度３３％、ＮａＣｌ濃度４．６％）１１００ｋｇを得た（工程Ａ）。
この水溶液を、４５０ｒｐｍで回転している遠心分離機（タナベウィルテック社製 ＣＯ−４８−４５型）にかけて、ろ液と分離することにより、塩化ナトリウムを回収した（工程Ｂ）。
[Example 1]
A sodium hypochlorite aqueous solution containing 383 kg of sodium chloride precipitated (effective) by continuously reacting 700 L of a 48% sodium hydroxide aqueous solution with gaseous chlorine 141 Nm 3 diluted with 400 Nm 3 of air at 32 ° C. Chlorine concentration 33%, NaCl concentration 4.6%) 1100 kg was obtained (Step A).
This aqueous solution was subjected to a centrifuge (CO-48-45 type, manufactured by Tanabe Wiltech Co., Ltd.) rotating at 450 rpm and separated from the filtrate to recover sodium chloride (Step B).
この回収した塩化ナトリウムの組成はＮａＣｌ ９６．９％、臭素元素１０ｐｐｍであった。この塩化ナトリウムを純水に溶かして水溶液（３００ｇ／Ｌ）にし、電解して（イオン交換膜電解法、電流密度４ｋＡ／ｍ２、電解槽温度９０℃、淡塩水濃度１８％）、得られた気体塩素中の気体臭素の含有量は１７ｐｐｍであった（工程Ｃ）。 The composition of this recovered sodium chloride was NaCl 96.9% and elemental bromine 10 ppm. This sodium chloride was dissolved in pure water to make an aqueous solution (300 g / L) and electrolyzed (ion exchange membrane electrolysis, current density 4 kA / m 2 , electrolytic bath temperature 90 ° C., fresh brine concentration 18%), and obtained. The content of gaseous bromine in gaseous chlorine was 17 ppm (Step C).
次にこの気体塩素を濃度２０％の水酸化ナトリウム水溶液３Ｌ中に吹き込み、反応させることにより次亜塩素酸ナトリウム水溶液を得た。ここで気体塩素の吹き込み量は４．０Ｌ／分とし、反応時間は５０分とした（工程Ｄ）。得られた次亜塩素酸ナトリウム水溶液中の有効塩素濃度、残存ＮａＯＨ濃度、ＮａＣｌ濃度および臭素化合物の含有量（ＢｒＯ３ −換算）を測定した結果を表１に示す。臭素化合物の含有量は測定の検出限界以下であった。 Next, this gaseous chlorine was blown into 3 L of a sodium hydroxide aqueous solution having a concentration of 20% and reacted to obtain a sodium hypochlorite aqueous solution. Here, the amount of gaseous chlorine blown was 4.0 L / min, and the reaction time was 50 minutes (step D). Table 1 shows the results of measuring the effective chlorine concentration, residual NaOH concentration, NaCl concentration, and bromine compound content (BrO 3 − equivalent) in the obtained aqueous sodium hypochlorite solution. The bromine compound content was below the detection limit of measurement.
［例２］
例１の工程Ｃで得られた気体塩素を圧力２６０ｋＰａ、温度−１２℃の条件下で液化した。そのときに液化せずに残存する気体塩素中の気体臭素濃度は検出できなかった。この気体塩素を濃度２０％の水酸化ナトリウム水溶液３Ｌ中に吹き込み、反応させることにより次亜塩素酸ナトリウム水溶液を得た（工程Ｄ）。ここで塩素ガスの吹き込み量は４．０Ｌ／分とし、反応時間は５２分とした。得られた次亜塩素酸ナトリウム水溶液中の各成分濃度（含有量）を例１と同様に測定した結果を表１に示す。臭素化合物の含有量は測定の検出限界以下であった。
[Example 2]
The gaseous chlorine obtained in Step C of Example 1 was liquefied under the conditions of a pressure of 260 kPa and a temperature of −12 ° C. At that time, the concentration of gaseous bromine in the gaseous chlorine remaining without liquefaction could not be detected. This gaseous chlorine was blown into 3 L of a sodium hydroxide aqueous solution having a concentration of 20% and reacted to obtain a sodium hypochlorite aqueous solution (step D). Here, the amount of chlorine gas blown was 4.0 L / min, and the reaction time was 52 minutes. Table 1 shows the results of measuring the concentration (content) of each component in the obtained sodium hypochlorite aqueous solution in the same manner as in Example 1. The bromine compound content was below the detection limit of measurement.
［例３］
工程Ｃで用いる塩化ナトリウムとして、前記回収塩化ナトリウムを使用せずに、従来から使用される工業用塩化ナトリウムを純水に溶かした塩化ナトリウム水溶液を電解して（イオン交換膜電解法、電流密度４ｋＡ／ｍ２、電解槽温度９０℃、淡塩水濃度１８％）、得られる気体塩素をそのまま用いた以外は例１と同様にして次亜塩素酸ナトリウム水溶液を製造した。得られた次亜塩素酸ナトリウム水溶液中の各成分の濃度を例１と同様に測定したので、結果を表１に示す。
この結果より、本発明の方法により製造された次亜塩素酸ナトリウム水溶液は、臭素化合物の含有量がきわめて低く、高純度であることがわかる。
[Example 3]
As sodium chloride used in step C, an aqueous sodium chloride solution obtained by dissolving industrially used sodium chloride in pure water without using the recovered sodium chloride was electrolyzed (ion-exchange membrane electrolysis method, current density 4 kA). / M 2 , electrolytic bath temperature 90 ° C., fresh salt water concentration 18%), and using the resulting gaseous chlorine as it was, an aqueous sodium hypochlorite solution was prepared in the same manner as in Example 1. Since the concentration of each component in the obtained sodium hypochlorite aqueous solution was measured in the same manner as in Example 1, the results are shown in Table 1.
From this result, it can be seen that the sodium hypochlorite aqueous solution produced by the method of the present invention has a very low bromine compound content and high purity.
［例４］
例１の工程Ｂで得られた回収塩化ナトリウムをカリウム元素を含まない純水で濃度３００ｇ／Ｌの回収塩化ナトリウム水溶液とした後、この得られた回収塩化ナトリウム水溶液を例１と同様に電解し、濃度３２％の水酸化ナトリウム水溶液を得た。このときのカリウム元素含有量は６ｐｐｍであった。濃度４８％に換算すると９ｐｐｍである。
[Example 4]
The recovered sodium chloride obtained in Step B of Example 1 was made into a recovered sodium chloride aqueous solution having a concentration of 300 g / L with pure water not containing potassium element, and the recovered sodium chloride aqueous solution thus obtained was electrolyzed in the same manner as in Example 1. An aqueous solution of sodium hydroxide having a concentration of 32% was obtained. The potassium element content at this time was 6 ppm. When converted to a concentration of 48%, it is 9 ppm.
［例５］
工程Ｃで用いる塩化ナトリウムとして、前記回収塩化ナトリウムを使用せずに、工業用塩化ナトリウムを用いた以外は例４と同様にして水酸化ナトリウム水溶液を製造した。得られた濃度３２％の水酸化ナトリウム水溶液中のカリウム元素含有量は６８ｐｐｍであった。濃度４８％に換算すると１０２ｐｐｍである。
[Example 5]
A sodium hydroxide aqueous solution was produced in the same manner as in Example 4 except that industrial sodium chloride was used as the sodium chloride used in Step C, without using the recovered sodium chloride. The potassium element content in the obtained 32% aqueous sodium hydroxide solution was 68 ppm. When converted to a concentration of 48%, it is 102 ppm.
本発明により得られた次亜塩素酸ナトリウム水溶液は、消毒剤、殺菌剤等、従来より公知の各種の用途に好適に使用できる。また、本発明により得られた水酸化ナトリウム水溶液は、医薬品、食品など、高品質が要求される分野に好適に使用できる。
The sodium hypochlorite aqueous solution obtained by the present invention can be suitably used for various conventionally known applications such as disinfectants and disinfectants. Moreover, the sodium hydroxide aqueous solution obtained by this invention can be used conveniently for the field | area where high quality is requested | required, such as a pharmaceutical and a foodstuff.
Claims (7)
工程Ａ：気体塩素と水酸化ナトリウム水溶液を反応させて、析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を得る工程。
工程Ｂ：前記工程Ａで得られる析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を、遠心分離機で処理して、回収塩化ナトリウムを得る工程。
工程Ｃ：前記工程Ｂで得られる回収塩化ナトリウムを水に溶かした回収塩化ナトリウム水溶液を電解し、水酸化ナトリウム水溶液、気体塩素および気体水素を得る工程。
工程Ｄ：前記工程Ｃで得られる気体塩素を、水酸化ナトリウム水溶液と反応させ、次亜塩素酸ナトリウム水溶液を得る工程。 The manufacturing method of the sodium hypochlorite aqueous solution which has the following process AD in this order.
Step A: A step of reacting gaseous chlorine with a sodium hydroxide aqueous solution to obtain a sodium hypochlorite aqueous solution containing precipitated sodium chloride.
Step B: A step of treating the sodium hypochlorite aqueous solution containing the precipitated sodium chloride obtained in the step A with a centrifuge to obtain recovered sodium chloride.
Step C: Step of electrolyzing a recovered sodium chloride aqueous solution obtained by dissolving the recovered sodium chloride obtained in the step B in water to obtain a sodium hydroxide aqueous solution, gaseous chlorine and gaseous hydrogen.
Step D: A step of reacting the gaseous chlorine obtained in Step C with a sodium hydroxide aqueous solution to obtain a sodium hypochlorite aqueous solution.
工程Ａ：気体塩素と水酸化ナトリウム水溶液を反応させて、析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を得る工程。
工程Ｂ：前記工程Ａで得られる析出した塩化ナトリウムを含む次亜塩素酸ナトリウム水溶液を、遠心分離機で処理して、回収塩化ナトリウムを得る工程。
工程Ｃ：前記工程Ｂで得られる回収塩化ナトリウムを水に溶かした回収塩化ナトリウム水溶液を電解し、水酸化ナトリウム水溶液、気体塩素および気体水素を得る工程。 The manufacturing method of the sodium hydroxide aqueous solution which has the following process AC in this order.
Step A: A step of reacting gaseous chlorine with a sodium hydroxide aqueous solution to obtain a sodium hypochlorite aqueous solution containing precipitated sodium chloride.
Step B: A step of treating the sodium hypochlorite aqueous solution containing the precipitated sodium chloride obtained in the step A with a centrifuge to obtain recovered sodium chloride.
Step C: Step of electrolyzing a recovered sodium chloride aqueous solution obtained by dissolving the recovered sodium chloride obtained in the step B in water to obtain a sodium hydroxide aqueous solution, gaseous chlorine and gaseous hydrogen.
The manufacturing method of the sodium hydroxide aqueous solution of Claim 6 whose potassium element content of the liquid which concentrated the sodium hydroxide aqueous solution obtained by the said process C to 48% of a density | concentration is 10 ppm or less with respect to the concentrated liquid.
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| JP2010260758A (en) * | 2009-05-01 | 2010-11-18 | Tsurumi Soda Co Ltd | Sodium hydroxide aqueous solution reduced in potassium content, solid-shaped sodium hydroxide and method for producing them |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2010260758A (en) * | 2009-05-01 | 2010-11-18 | Tsurumi Soda Co Ltd | Sodium hydroxide aqueous solution reduced in potassium content, solid-shaped sodium hydroxide and method for producing them |
| JP2015124110A (en) * | 2013-12-26 | 2015-07-06 | 昭和電工株式会社 | Process for preparing sodium hypochlorite aqueous solution |
| KR20150076088A (en) * | 2013-12-26 | 2015-07-06 | 쇼와 덴코 가부시키가이샤 | Production process of aqueous sodium hypochlorite solution |
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