CN111167417A - Modified bagasse, preparation method thereof and application of modified bagasse as adsorbent - Google Patents
Modified bagasse, preparation method thereof and application of modified bagasse as adsorbent Download PDFInfo
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- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/286—Treatment of water, waste water, or sewage by sorption using natural organic sorbents or derivatives thereof
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/308—Dyes; Colorants; Fluorescent agents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/16—Regeneration of sorbents, filters
Abstract
The invention relates to a preparation method of modified bagasse, which comprises the steps of soaking pulverized bagasse in NaOH aqueous solution for 22-26 h at room temperature, then centrifuging, washing with distilled water until the pH value of washing liquid is 7-9, and drying to obtain the modified bagasse. The modified bagasse has simple preparation process, and the modified bagasse has good adsorption performance, and can effectively adsorb heavy metal ions Pb2+、Cd2+And the cationic dye methylene blue.
Description
Technical Field
The invention belongs to the technical field of bagasse modification treatment, and particularly relates to preparation of modified bagasse and application of the modified bagasse in environmental wastewater.
Background
Today, heavy metals (e.g. Pb)2+、Cd2+Etc.) waste water and dye waste water are two types of pollution sources which are extremely harmful to the ecological environment. The dye wastewater has the characteristics of high chroma, difficult biodegradation, high toxicity and the like. Many dyes and their metabolites are toxic and have carcinogenic, teratogenic and mutagenic effects on aquatic animals and humans.
Cadmium in heavy metals is harmful to the human body, it can accumulate in the human body through the food chain, orIt can directly act on human body to induce acute and chronic cadmium poisoning. Acute cadmium poisoning is mainly manifested by fever, cough, hypodynamia, chest distress, limb soreness, etc.; chronic cadmium poisoning is mainly characterized by the increase of urine cadmium, and the continuous development of the disease can cause damage to the kidney, the liver and the lung and is accompanied with osteoporosis and osteomalacia. Cadmium poisoning in polluted areas has occurred both in China and Japan. The harm of cadmium to human bodies draws attention from all countries in the world, and all countries set corresponding national standards. The highest discharge concentration of cadmium in the industrial wastewater regulated in China is 0.1 mg.L-1Before being discharged, the cadmium-containing wastewater must be treated to meet the discharge requirement and avoid pollution poisoning. When a human body takes excessive lead, serious damage is caused to tissue systems such as blood, nerves, intestines and stomach, kidneys and the like. In recent years, media disclose events with overproof blood lead content (overproof shanxi volitake lead and lead poisoning in wugang in Hunan province) in children caused by industrial production, which arouse high social attention and cause adverse effects. Therefore, the effective treatment of the lead and cadmium-containing wastewater is not slow, and the research and development of the efficient and economic wastewater treatment technology have great social, economic and environmental significance.
At present, the treatment methods of heavy metal and dye wastewater mainly comprise a physical chemical method and a biological treatment method. In which the physical and chemical treatment techniques are too expensive or often produce a large amount of solid waste, compared with biological treatment methods, which are economical and effective and do not produce secondary pollution, they are better treatment methods. The raw material source of the biological adsorption method is rich, the variety is many, the cost is low, the adsorption equipment is simple and easy to operate, the speed is high, and the adsorption capacity is large. The biological adsorption provides an economic and feasible technology for the treatment of wastewater, and can achieve the effect of treating the wastewater with waste. With the continuous and deep research on the biological adsorbent, the biological adsorption technology has wide development prospect when being applied to the purification of wastewater in industry. Activated carbon, because of its high adsorption capacity, is a widely used commercial adsorbent]It is the most effective controllable adsorption technology listed by the American environmental protection center, but the price is high and the regeneration treatment cost is high. Many scholars are trying to find a new cheap substitute suckerAnd (4) an auxiliary agent. As a developing country, China especially important to develop new economic and efficient wastewater treatment technologies.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide modified bagasse, the preparation process of the modified bagasse is simple, and the modified bagasse has good adsorption performance and can effectively adsorb heavy metal ions Pb2+And Cd2+And the cationic dye methylene blue.
The invention also provides a preparation method of the modified bagasse and application of the modified bagasse as an adsorbent.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of modified bagasse comprises soaking pulverized bagasse in NaOH aqueous solution at room temperature for 22-26 h, centrifuging, washing with distilled water until pH of washing solution is 7-9, and oven drying to obtain modified bagasse.
Further, the mass ratio of the bagasse to the NaOH is 1: 0.8-1.2.
Specifically, the grain size of the bagasse is 40-160 meshes; the drying temperature is 60-70 ℃.
The invention provides modified bagasse prepared by the preparation method.
The invention also provides application of the modified bagasse as an adsorbent.
The invention further provides application of the modified bagasse as an adsorbent in adsorption of dye wastewater or wastewater containing heavy metal ions.
Further preferably, the dye is the cationic dye methylene blue; the heavy metal ion is Pb2+And Cd2+。
In the application of the modified bagasse as an adsorbent in adsorption of dye wastewater or wastewater containing heavy metal ions, further, the modified bagasse after dye adsorption can be regenerated through the following steps: soaking in acidic titanium dioxide sol, irradiating under mercury arc lamp for 6-7 hr, filtering, and washing.
In the application of the modified bagasse as an adsorbent in adsorption of dye wastewater or wastewater containing heavy metal ions, further, the modified bagasse after adsorption of heavy metal ions can be regenerated through the following steps: soaking in 0.1-0.2mol/L EDTA solution for 15-30 min, filtering, and washing.
Various biological adsorbents are mainly cheap biological materials with wide sources, and the problems of resource waste and environmental pollution are caused because the biological adsorbents cannot be effectively utilized. In recent years, some inexpensive materials have been used as adsorbents]Adsorbing heavy metal ions and dyes from wastewater, these materials including: chitosan, wheat straw, corn cobs, corn stalks, rice hulls, wood chips, sawdust, bark, leaves, coconut fibers, aquatic plants, and the like. Bagasse produced in sugar and ethanol production industry in China is mostly used as fuel or discarded as waste, and is a resource to be developed and utilized. However, natural agricultural wastes have low adsorption capacity and are difficult to meet industrial application, and the adsorption capacity of the natural agricultural wastes can be improved by modifying the natural agricultural wastes. The bagasse comprises 32-48% of cellulose, 19-24% of hemicellulose, 23-32% of lignin and about 4% of ash, and contains a large amount of hydroxyl and phenolic groups, particularly cellulose contains more free alcoholic hydroxyl groups. The application discovers through research that: the bagasse can be introduced with groups with acidic, alkaline or chelating properties through esterification, etherification or chelating reaction to generate the adsorbent capable of adsorbing heavy metals or toxic organic matters in water. On the basis of the previous work, the adsorption behavior of the modified bagasse on heavy metal ions and cationic dye methylene blue is examined, and the influence of factors such as the particle size of an adsorbent, adsorption time and dye concentration on the adsorption process is researched.
Another real problem to be solved in the treatment of dye wastewater by adsorption is the regeneration of the adsorbent. The traditional method is to use higher concentration acid to remove the cationic dye and use alkali to elute the anionic dye. However, the acid and alkali washing method does not completely treat the dye and causes secondary pollution. Among the numerous photocatalytic materials, nano TiO2Has the advantages of no toxicity, high photocatalytic activity, high stability, strong oxidation capacity, low energy consumption, reusability, low price, safe use and the likeHave received increasing attention. In recent years, TiO2Has very attractive application prospect in the aspects of photocatalytic elimination and degradation of organic pollutants, self-cleaning coatings and the like. Acidic TiO is prepared in this application2Sol, adsorbent and high-efficiency TiO2Catalyst combination, TiO2The nanoparticles are not directly put into a water body, but are used as an eluent and a regenerant of an adsorbent to desorb and regenerate the modified bagasse, and the combination of the eluent and the modified bagasse can well solve the problems of catalyst recovery, eluent pollution and the like, so the method has important practical application significance.
The research objects of the present invention mainly include: 1) synthesizing a novel adsorbent with high adsorption capacity by modifying bagasse; 2) fitting an adsorption thermodynamic model through adsorption thermodynamics and kinetic research of removing heavy metal ions and cationic dyes in the aqueous solution, establishing a proper kinetic model and speculating an adsorption mechanism, and providing theoretical guidance for large-scale treatment of the heavy metal ions and the cationic dye wastewater; 3) with acidic TiO2The sol is a desorbent, and through the research of the adsorbent regeneration technology, the regeneration efficiency of the adsorbent is improved, a foundation is laid for the repeated reutilization of the adsorbent, the secondary pollution to the environment is avoided, and the purposes of using waste to prepare waste and changing waste into valuables are achieved.
Based on the above research objectives, the main research contents of the present invention include:
1) preparing modified bagasse: the bagasse is modified by NaOH, the operation is simple and convenient, and the adsorbent with higher adsorption capacity is prepared;
2) in a synthetic water sample, the influence of various adsorption conditions on the adsorption process is examined, the adsorption kinetics and thermodynamics are examined, and the adsorption mechanism is discussed: thermodynamic data are analyzed by using Langmuir and Fruendlich models to discuss the adsorption mechanism of the thermodynamic data. Analyzing kinetic data by using a quasi-first-stage model and a quasi-second-stage model, and discussing the influence of various influencing factors on the reaction speed;
3) desorption and regeneration of modified bagasse: preparation of TiO2The acidic sol is used for inspecting the desorption effect and providing a basis for selecting the optimal regeneration condition.
Drawings
FIG. 1 is a reaction model of bagasse with NaOH;
FIG. 2 shows the modification of bagasse for Pb with different grain sizes2+、Cd2+And the influence of MB adsorption capacity;
FIG. 3 shows Pb at different initial concentrations2+、Cd2+The influence of the solution and MB solution on the adsorption capacity of the modified bagasse;
FIG. 4 shows the adsorption of Pb on modified bagasse2+、Cd2+And the time profile of the MB;
FIG. 5 shows the adsorption of Pb on modified bagasse by acidity of the solution2+、Cd2+And the effects of MB;
FIG. 6 is a graph of visible spectra for different degradation times.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following examples, but the scope of the present invention is not limited thereto.
First, experimental part
(I) laboratory instruments and reagents
The main apparatus is as follows: ICP atomic emission spectrometer (model 8000, PerkinElmer, usa); 722 grating spectrophotometer (xiamen analytical instruments factory); pHS-25 type pH meter (Shanghai Jing Kelei Mag); model 85-1 magnetic stirrers (Changzhou Guohua appliances Co., Ltd.); SHA-C water bath shaker (Ouchi City Yaohua instruments, Inc.).
Reagent: bagasse (collected in the market, crushed and dried); methylene blue (MB, Protochemical Proc. Tianjin).
(II) Experimental method
1. Collecting and treating bagasse
Washing bagasse collected on the market with warm distilled water for 2-3 times to remove residual sugar, fishing out, draining, and drying in a constant-temperature drying oven at 60 ℃ to constant weight; cooling, pulverizing, sieving with 40-160 mesh sieve to obtain bagasse with different particle sizes, and placing in fresh-keeping self-sealing bag.
Accurately weighing 5 g of sugarcane with analytical balanceThe residue was placed in a 250 mL beaker and then 100 mL of 1 mol. L-1Soaking the mixture in NaOH aqueous solution at room temperature (20-30 ℃) for 24 hours. Then centrifuging, washing with distilled water until the pH value of the washing liquid is kept constant (pH is 7-9), and drying at 60 ℃ to obtain the modified bagasse.
2. Static adsorption procedure
A certain amount of modified bagasse was placed in a 50 mL conical flask, and 25 mL of metal ions (Pb) of various concentrations were added2+And Cd2+) Or a cationic dye methylene blue solution, and oscillating at the speed of 150 rpm in a water bath shaker at normal temperature. Sampling at regular time, centrifuging at 5000 rpm, measuring the concentrations of metal ions and the dye methylene blue in the solution by using an ICP atomic emission spectrometer and a spectrophotometer respectively, and calculating the adsorption capacity of the modified bagasse.
3. Regeneration of modified bagasse
The modified bagasse after heavy metal ion adsorption is regenerated through the following steps: soaking in 0.1 mol/L EDTA solution for 20min, filtering, and washing.
The modified bagasse after adsorbing the dye MB is regenerated through the following steps: soaking in acidic titanium dioxide sol, irradiating under mercury arc lamp for 7 hr, filtering, and washing.
The preparation method of the acidic titanium dioxide sol comprises the following steps: dissolving 3 mL tetrabutyl titanate in 25 mL absolute ethanol, slowly dropping vigorously stirred 30 mL secondary water, obtaining white turbid liquid after dropping, heating and stirring the turbid liquid at 70 ℃ to remove most of water and ethanol, adding 80 mL HNO after 45 min3（0.04 mol L-1) The heating and stirring were continued for 5 hours to obtain a clear and transparent acidic titania sol (pH = 2.0).
(III) results and discussion
1. Bagasse and NaOH reaction mechanism
When alkali and monohydric alcohol or polyhydric alcohol act, alcoholate and molecular compound can be generated, and the cellulose molecular chain in bagasse has 3 free hydroxyl groups, which can be regarded as polyhydric alcohol, so that after it absorbs sodium hydroxide aqueous solution, the formed alkali cellulose can also be alcoholate or molecular compound. Of 3 hydroxyl groups on the cellulose molecular chain, the hydroxyl group on the C (2) position has stronger acidity than the hydroxyl groups on the C (3) and C (6) positions, so the hydroxyl group on the C (2) position can generate an alcoholate (A), and the hydroxyl group on the C (6) position with weaker acidity can generate a molecular compound (B), thereby enhancing the adsorption capacity of the bagasse on positively charged substances, as shown in figure 1.
2. Adsorption capacity of bagasse with different grain sizes
Adding Pb2+、Cd2+Prepared with MB to a concentration of 100 mg.L-1Taking 25 mL of the solution, putting the solution into a 250 mL conical flask, respectively weighing 20 mg of modified bagasse with the particle size of 40-60 meshes, 60-80 meshes, 80-100 meshes, 100-120 meshes and 120-140 meshes, putting the modified bagasse into the conical flask, stirring at room temperature, adsorbing and balancing, centrifuging for 5-10 min, transferring a supernatant by using a micro-transfer gun, measuring the concentration of metal ions or the absorbance of dye in the supernatant by using an ICP atomic emission spectrometer and a visible spectrophotometer, calculating the adsorption capacity, and further judging the particle size to Pb2+、Cd2+And the effect of methylene blue adsorption. The results are shown in FIG. 2.
FIG. 2 shows the Pb versus modified bagasse of different particle sizes2+、Cd2+And the influence of the amount of methylene blue adsorbed. As can be seen from fig. 2, the modified bagasse adsorbed amounts were different for different particle sizes, and among them, the bagasse having a particle size of 120-140 mesh was used with the largest adsorbed amount, and therefore, the particle size was the optimum particle size for the bagasse.
3. Adsorption isotherm experiment
The influence of MB or metal ion solutions with different initial concentrations on the adsorption capacity of the modified bagasse is respectively examined. FIG. 3 shows Pb at various initial concentrations2+、Cd2+And the effect of MB solution on the adsorption capacity of the modified bagasse.
As can be seen from fig. 3: the adsorption capacity of the modified bagasse also gradually increased with increasing initial concentrations of metal ions and MB in the solution. However, when the concentration reaches a certain value, the adsorbent reaches the maximum adsorption capacity, and the adsorption capacity does not increase with the increase in the concentration of the metal ions or MB.
The adsorption in the solution has important significance, but because the adsorption of the dye solution is very complex, a plurality of models can be summarized through long-term practice, and most of the models can successfully describe data obtained by experiments. Among the numerous adsorption models, the two-parameter isothermal model has a much wider application, among which the Langmuir and fruendich adsorption models are the main ones.
Langmuir adsorption theory is an ideal monolayer-localized adsorption theory that shows that on a uniform adsorbent surface, there is no interaction of adsorbate molecules with each other, and surface adsorption is the rule that adsorption equilibrium is reached under monolayer conditions. The Langmuir adsorption isotherm equation can be expressed as:
qethe adsorption capacity (mg. g) under the condition of monolayer adsorption-1），CeIs equilibrium concentration (mg. L)-1). b is Langmuir constant (m)3·g-1) Q is the maximum adsorption amount (mg. g)-1) Both Q and b values can be obtained from the slope and intercept of the straight line equation.
The Freundlich adsorption model is a typical multi-molecular layer adsorption model. The model considers that the distribution of the heat of adsorption generated by the solid adsorbent during adsorption is not uniform, but non-uniform multi-molecular layer adsorption occurs on the surface of the adsorbent, and the Freundlich isotherm equation is an empirical formula, and can be expressed as:
taking logarithm on both sides to obtain a linear equation:
in formula (6): q. q.seAdsorption capacity (mg. g) at adsorption equilibrium-1) (ii) a Ce is dye adsorption equilibrium concentration (mg. L)-1)；Q f1/n isEmpirical constants, representing adsorption capacity and adsorption strength, respectively, can be calculated from the slope and intercept of the linear equation.
TABLE 1 Langmuir and Freundlich isothermal adsorption parameters for methylene blue and metal ions
The adsorption data of FIG. 3 were fitted with Langmuir adsorption isotherm equation and Fruendlich adsorption isotherm equation, and the obtained linear correlation coefficients and evaluation constants are shown in Table 1. According to the judgment of the linear correlation coefficient of the two equations, the adsorption process is more consistent with a Langmuir model, and the modified bagasse is proved to adsorb methylene blue and Pb2+、Cd2+The ions are mainly adsorbed by a monomolecular layer.
4. Adsorption kinetics experiment
The purpose of the adsorption kinetics experiment is to understand the rate of the adsorption reaction and its influencing factors. FIG. 4 shows that the concentrations of the modified bagasse were all 100 mg. multidot.L-1Pb of2+、Cd2+And adsorption kinetics curves for MB. It can be seen from the figure that the initial speed of the adsorption reaction is fast, and the adsorption rate gradually decreases with the increase of the adsorption time, and finally approaches to equilibrium. This is mainly because: at the initial stage of the adsorption reaction, a large number of active sites are arranged on the surface of the adsorbent, so that the adsorption reaction is easy to carry out and is high in speed; as the reaction continues, the active sites become increasingly occupied and adsorption becomes increasingly difficult, thus slowing the reaction until equilibrium is finally reached.
To investigate the kinetics of methylene blue adsorption by modified bagasse, the adsorption data of fig. 4 were fitted with a quasi-first order kinetics and a quasi-second order kinetics model. The quasi-first order reaction kinetics equation can be expressed as:
in the formula: q. q.seAnd q is the sum of adsorption equilibriumtAmount of dye adsorbed by adsorbent at that time (mg. g)-1）；k1Is the first order reaction rate constant (min)-1) The value of which can be represented by log: (q e-q) To pairtAnd (4) calculating the slope and the intercept of the linear equation obtained by plotting.
The quasi-second order reaction kinetics equation is expressed as:
in the formula k2Is the second order reaction rate constant (kg. g)-1·min-1) The second order reaction rate constant k can be obtained from the slope and intercept of the t/q-t diagram2And q ise。
The two kinetic equations respectively represent two different kinetic behaviors, the quasi-first-stage kinetic model considers that the adsorption reaction rate is only controlled by the factor of the adsorbate concentration or the number of adsorption active sites, and the quasi-second-stage kinetic model considers that the adsorption reaction is simultaneously controlled by the two factors. The parameters calculated by the two kinetic models are listed in table 2.
TABLE 2 adsorption of Pb by modified bagasse2+、Cd2+And kinetic parameters of methylene blue
As can be seen from Table 2, the quasi-second order linear fitting of the adsorption kinetics curve has a relatively high linear correlation coefficient, which indicates that the quasi-second order kinetic model can better react the modified bagasse to Pb2+、Cd2+And adsorption behavior of methylene blue.
5. Influence of the pH of the solution
The acidity of the solution is one of the most important factors controlling the adsorption of metal ions and dyes. Experiments the effect of acidity on adsorption was investigated by adjusting the acidity of the solution with HCl NaOH, and the results are shown in fig. 5. As can be seen from fig. 5, the pH has a significant effect on the bagasse adsorption, and the modified bagasse adsorption capacity is small at lower pH, and the adsorption capacity of the adsorbent tends to increase with increasing pH. In the subsequent experiments, the pH of the metal ion solution was selected to be 6 and the pH of the methylene blue solution was selected to be 9.00.
6. Adsorbent regeneration
In order to study the regeneration performance of the modified bagasse on dye adsorption, the adsorbent was combined with a high-efficiency photocatalyst, TiO2The nano particles are not directly put into a water body, but are used as an eluent of an adsorbent to desorb and regenerate the adsorbent, and the combination of the nano particles and the eluent can well solve the problems of recovery of the photocatalyst, pollution of eluent and the like, so the method has important practical application significance. The method comprises the following steps: and (3) taking the adsorbent saturated in adsorption, carrying out centrifugal separation, drying, taking the acidic titanium dioxide sol as an eluent, carrying out photocatalytic degradation (irradiation of a mercury arc lamp) on the adsorbent adsorbed with the dye, and then carrying out next cycle adsorption to obtain the regeneration rate.
Fig. 6 is a visible spectrum of the MB solution during photodegradation, from which it can be seen that under the irradiation of the mercury arc lamp, the MB solution gradually fades and the degradation effect gets better and better as the illumination time is prolonged. After degradation due to TiO2The nano particles block part of the adsorbed active sites, and the adsorption capacity of the regenerated adsorbent is reduced to 85-90% of the original adsorption capacity.
The principle of photodegradation may be that under the irradiation of visible light, the photosensitizer absorbs photons to form excited singlet state or excited triplet state to TiO2The conduction band injects 1 electron to generate carbon radicals by itself, and then obtains electrons from the environment to return to the ground state. TiO 22Electrons on the conduction band react with dissolved oxygen to generate active free radicals O with strong oxidizing property2 -.，O2 -.Further oxidizing the substrate and finally changing the substrate into a small molecule. The reaction equation is as follows:
Dye (hv) → Dye*
Dye* + TiO2→ TiO2(e-) + Dye+•
TiO2(e-) + O2→ TiO2+ O2 -•
O2 -•+ Dye+•(Dye) → structure cleavage
the above experimentsIndicating that TiO is present2The sol is a good dye eluent, the acid of the sol is firstly utilized to complete the elution process, then the photocatalytic performance of the sol is utilized to further degrade the eluent, the combined use of the adsorbent and the photocatalyst is simple to operate, and the secondary pollution of the dye to the environment can be reduced.
(IV) Small knot
1. NaOH modified bagasse is prepared by a simple method, and the influence of factors such as particle size, initial concentration of solution, adsorption time, acidity and the like on the adsorption process is examined. The results show that: modified bagasse for Pb2+、Cd2+And the adsorption quantity of methylene blue is obviously improved, the adsorption equilibrium data can be better simulated by a Langmuir isothermal adsorption equation, and the adsorption process follows a two-stage dynamic model. Research results show that the bagasse has good adsorption capacity, and the bagasse has good development prospect in the aspect of actual wastewater treatment in the future.
2. The desorption experiment of the adsorbent shows that the dye molecules can be effectively eluted, and the prepared TiO2The sol is easy to separate from the adsorbent by centrifugation, and the adsorption capacity of the regenerated adsorbent to the dye is basically kept unchanged. Acidic TiO2The sol has good practical application prospect as the regeneration of the dye adsorbent.
Claims (9)
1. A preparation method of modified bagasse is characterized in that the crushed bagasse is soaked in NaOH aqueous solution for 22-26 h at room temperature, then centrifuged, washed with distilled water until the pH of washing liquid is 7-9, and dried to obtain the modified bagasse.
2. A process for producing modified bagasse as claimed in claim 1, wherein the mass ratio of bagasse to NaOH is 1: 0.8-1.2.
3. The process according to claim 1 or 2, wherein the bagasse has a particle size of 40-160 mesh; the drying temperature is 60-70 ℃.
4. Modified bagasse obtained by the production method according to any one of claims 1 to 3.
5. Use of a modified bagasse as defined in claim 4 as an adsorbent.
6. Use of the modified bagasse as defined in claim 4 as an adsorbent for adsorption of dye waste water or waste water containing heavy metal ions.
7. Use of the modified bagasse as an adsorbent in the adsorption of dye wastewater or wastewater containing heavy metal ions according to claim 6, wherein the dye is a cationic dye methylene blue; the heavy metal ion is Pb2+And Cd2+。
8. The use of the modified bagasse as an adsorbent in dye-adsorbing wastewater or wastewater containing heavy metal ions according to claim 7, wherein the modified bagasse after dye adsorption is regenerated by the following steps: soaking in acidic titanium dioxide sol, irradiating under mercury arc lamp for 6-7 hr, filtering, and washing.
9. The use of the modified bagasse as an adsorbent in the adsorption of dye wastewater or wastewater containing heavy metal ions according to claim 7, wherein the modified bagasse after adsorption of heavy metal ions is regenerated by the following steps: soaking in 0.1-0.2mol/L EDTA solution for 15-30 min, filtering, and washing.
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| CN111676713A (en) * | 2020-07-27 | 2020-09-18 | 湖州市千金金耀制丝有限公司 | Digital printing process of high-color-fastness silk fabric |
| CN111672481A (en) * | 2020-06-23 | 2020-09-18 | 天津科技大学 | Bio-based adsorbent for methylene blue dye and aluminum ions in wastewater and application |
| CN112868867A (en) * | 2021-01-22 | 2021-06-01 | 海南热带海洋学院 | Sugarcane chewing bar capable of replacing betel nut and preparation method thereof |
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