KR102210013B1 - Adsorbent based chitin and Method for preparing the same - Google Patents

Abstract

The present invention relates to a chitin-based adsorbent capable of effectively adsorbing anionic dyes or metals by coating chitin with a linker and a cationic polymer, and a method for preparing the same.
The chitin-based adsorbent of the present invention is formed by bonding a linker to the hydroxyl group and amine group of chitin, and then coating a cationic polymer thereon.
The chitin-based adsorbent of the present invention can be used as a renewable biosorbent by increasing the adsorption rate and desorption rate for anionic dyes.
According to the present invention, chitin, which is mostly discarded due to its small surface area, porosity, and high crystallinity, can be recycled as a biosorbent, thereby contributing to environmental protection and waste management.

Description

Adsorbent based chitin and method for preparing the same

The present invention relates to a chitin-based adsorbent and a method for preparing the same, and more particularly, to a chitin-based adsorbent capable of effectively adsorbing anionic dyes or metals by coating chitin with a linker and a cationic polymer, and a method for preparing the same.

In the past decades, dyes have been used in a variety of industries such as textiles, paper, pharmaceuticals, plastics, leather, cosmetics, rubber and food. More than 100,000 different commercial dyes and pigments are used, with over 7105 tonnes produced worldwide each year. A large amount of wastewater is generated during the textile dyeing process, and about 10 to 15% of the dye is contained in the wastewater and discharged. In general, 1,000 mg/L of dye is used as the dyeing solution, and 100 mg/L remains in the dyeing solution after use. Therefore, the discharge of this dark wastewater inhibits the penetration of sunlight through the water's surface, thereby reducing the photosynthetic action of aquatic organisms. In addition, it has been reported that some dyes produce toxic, carcinogenic and mutant intermediates by hydrolysis, oxidation, etc., causing great risk to nature and humans. However, most dyes are non-decomposable synthetic materials composed of chemically complex aromatic molecular structures, and are not easily decomposed or removed by a general wastewater treatment process. Dyeing wastewater can be treated by methods such as coagulation/coagulation, chemical oxidation, adsorption, membrane separation, biological treatment, ozone treatment, photocatalysis, filtration, electrochemistry, membrane treatment, and the like. Among them, the adsorption process is known as an effective technology with large-scale efficiency, capacity and applicability for removing dyes as well as regeneration, recovery and recyclability of adsorbents. Therefore, it is very important to environmentally remove dyes in wastewater using adsorption technology before discharging to the natural environment.

Chitin is the world's second most abundant polysaccharide material and is a low-cost, biodegradable and renewable biopolymer with a dense structure containing hydroxyl and N-acetyl groups. These natural polymers can be extracted from the shells of fungi, insect exoskeletons and crustaceans such as crayfish, shrimp and crab, and are also found in invertebrates such as sponges. In addition, chitin can be obtained from seafood industrial waste, and the recycling of such solid waste can contribute to environmental protection and waste management.

Korean Patent Laid-Open No. 10-2001-0094573 discloses a crab shell biosorbent that removes heavy metal ions. In the above disclosed patent, the crab shell is not processed with chitin, but only pulverized and used as an adsorbent, so there is a limit in adsorption performance.

The present invention is to provide a chitin-based adsorbent with improved adsorption performance for anionic dyes.

The present invention is to provide a method of utilizing chitin, which is rarely used as an adsorbent, as an adsorbent.

The present invention is to provide an eco-friendly adsorption material using chitin.

One aspect of the present invention

Adding chitin powder to the linker solution and reacting to prepare chitin powder to which the linker is bound; And

It relates to a method for preparing a chitin-based adsorbent comprising the step of reacting the chitin powder to which the linker is bonded into a polymer solution containing an amine group.

In another aspect, the present invention

Chitin powder (10);

A linker (20) bonded to the chitin; And

It relates to a chitin-based cationic adsorbent comprising an amine group-containing polymer layer 30 crosslinked with the linker and coated on the chitin surface.

The chitin-based adsorbent of the present invention is formed by coupling a linker to the hydroxyl group and amine group of chitin, and then coating a cationic polymer thereon.

The chitin-based adsorbent of the present invention can be used as a renewable biosorbent by increasing the adsorption rate and desorption rate for anionic dyes.

According to the present invention, chitin, which is mostly discarded due to its small surface area, porosity, and high crystallinity, can be recycled as a biosorbent, thereby contributing to environmental protection and waste management.

1 and 2 are conceptual diagrams of chitin-based adsorbents of the present invention.
Figure 3 shows the reaction process of the preparation of chitin-based adsorbent.
Figure 4 shows the measurement of FE-SEM for raw chitin, GA-chitin, and PEI-chitin.
5 is a graph of FTIR analysis for raw chitin, GA-chitin, and PEI-chitin.
6 is a result of comparing the adsorption amount of samples at each stage for 100 mg/L AB25.
7 is a graph measured by experimenting and measuring the amount of dye adsorption according to the pH concentration according to the dye concentration, FIG. 8A shows the desorption efficiency according to the eluent concentration, and FIG. 8B shows the repeated adsorption and desorption three times. It is a graph measuring the amount of adsorption and desorption afterwards, and FIG. 9 shows an isothermal adsorption curve of PEI-chitin according to temperature (298, 308, 318, 328 K), and FIG. 10 is a dye of PEI-chitin ( AB25) adsorption experiment results, FIG. 11 shows the amount of dye adsorption according to the GA concentration, FIG. 12 shows the adsorption amount of the dye (RY2) according to the PEI concentration, and FIG. 13 is the adsorption amount of the dye (RY2) by chitin size Shows.

Hereinafter, the present invention will be described in more detail.

1 and 2 are conceptual diagrams of a chitin-based adsorbent of the present invention, and FIG. 3 is a diagram illustrating a reaction process for preparing a chitin-based adsorbent.

1 to 3, the chitin-based adsorbent manufacturing method of the present invention includes a linker-bonded chitin powder manufacturing step (hereinafter, a linker-chitin powder manufacturing step) and a cationic polymer-chitin manufacturing step.

The linker-chitin powder manufacturing step is a step of reacting by adding chitin powder to the linker 20 solution.

The chitin 10 may be a known chitin powder.

Chitin is composed of β-1,4 bonds of N-acetyl-D-glucosamine (GlcNAc), structurally very similar to cellulose, but has a structure in which OH at the 2nd carbon position of cellulose is substituted with an acetamide group. Have. In addition, chitin does not exist alone in nature, but differs from cellulose, a homopolymer composed of one type of monomer by forming a copolymer with chitosan.

Recently, bioadsorbents prepared using chitosan have various functional groups, have high chemical reactivity, and have good adsorption efficiency due to their flexible polymer structure, but they are easily soluble in acidic solutions and are difficult to apply to various adsorption processes due to their low physical strength.

The present invention uses chitin, which has excellent chemical stability in various solvents such as acidic, basic, and organic solvents, as a support for a bioadsorbent unlike chitosan to replace or supplement such chitosan.

The powder size of chitin usable in the present invention may be 100 to 850 μm, preferably 100 to 500 μm, and most preferably 180 to 300 μm. When the chitin particle size is in the range of 180 to 300 μm, the adsorbent manufacturing process is advantageous, and when used as an adsorbent, a uniform adsorption amount can be provided.

The linker 20 may include a plurality of reactive moieties (aldehyde group, vinyl group, carboxyl group, oxysilane group, etc.) so as to bind not only chitin but also amine group-containing polymer. The linker may be a compound having two or more reactive moieties. The linker may have a molecular weight of 50 to 500 g/mol.

The linker 20 is glutaraldehyde, bisdiazobenzidine, triazole dialdehyde, glycidyl methacrylate, benzyltiazole carbaldehyde, benzo Cyazole car”K-sylaldehyde (benzothiazole carboxaldehyde), epichlorohydrin, dialdehyde, methylene-bis-acrylamide, glyoxal, acrylic acid, maleic acid ( maleic acid), tetraetoxysilane, and tripolyphosphate.

When glutaraldehyde (GA) is used as the linker, GA is bound to both the hydroxy group and the amine group of chitin, so that a large amount of cationic polymer can be effectively crosslinked.

In the linker-chitin powder manufacturing step, the linker solution concentration may be 0.1 to 10% (w/v), preferably 1 to 3% (w/v), and most preferably 3% (w/v). .

Chitin powder compared to the linker solution may be added 0.01 to 0.05 g/mL, preferably 0.03 to 0.05 g/mL, and most preferably 0.05 g/mL.

When the linker concentration exceeds 3% (w/v), adsorption performance may decrease.

For example, the linker-chitin powder manufacturing step may be stirred at room temperature for a predetermined time using a multi-shaking incubator.

Referring to FIG. 3, the linker may be bonded to a hydroxy group or an amine group of chitin.

The cationic polymer-chitin preparation step is a step of reacting by putting linker-chitin into a polymer solution containing an amine group. In the step of preparing the cationic polymer-chitin, the cationic polymer may be crosslinked with the linker to be coated on the chitin surface.

The amine group-containing polymer usable in the present invention is polyethyleneimine, amine-terminated polyethylene oxide, amine-terminated polyethylene/propylene oxide, polymer of dimethyl amino ethyl methacrylate, and dimethyl aminoethyl methacrylate and vinyl It may be selected from the group consisting of a copolymer of pyrrolidone, a linear polymer of epichlorohydrin and dimethylamine, polydiallyldimethylammonium chloride, polyethanolamine/methylchloride, and modified polyethyleneimine. The amine group-containing polymer may be polyethyleneimine or modified polyethyleneimine.

It is preferable that the amine group-containing polymer has a cationic charge of 70 mol% or more and a weight average molecular weight in the range of 1000 to 200,000.

The cationic polymer-chitin preparation step includes 0.01 to 0.05 g, preferably 0.03 to 0.05 g of the chitin powder to which the linker is bonded, and 1 to 20% (w/v) of the amine group-containing polymer solution, preferably 5 to It can be added to 10% (w/v). In the amine group-containing polymer solution, the polymer concentration may be 1 to 20% (w/v), preferably about 10% (w/v).

If the polymer concentration is an excess of 15% (w/v) or more, the polymer cannot chemically bind to the chitin surface and remains, and may react with the dye during the adsorption process to precipitate.

The cationic polymer-chitin manufacturing step may be stirred for a predetermined time at room temperature using a stirrer.

1 to 3, the chitin-based cationic adsorbent of the present invention is a chitin powder (10), a linker (20) bound to the chitin, and an amine group-containing polymer layer coated on the chitin surface by crosslinking with the linker. It includes (30).

The chitin powder particle size may be 100 to 850 μm, preferably 100 to 500 μm, and most preferably 180 to 300 μm.

For the chitin, linker and amine group-containing polymer, the above description may be referred to.

In the chitin-based cationic adsorbent of the present invention, the linker may be glutaraldehyde, and the amine group-containing polymer layer 30 may be a polyethyleneimine layer.

1 to 3, it was difficult to expect excellent adsorption performance because only hydroxy groups and a small amount of amine groups exist on the surface of the chitin powder. However, the chitin-based adsorbent of the present invention is coated with a cationic polymer having a large amount of amine groups on its surface to provide a large amount of amine groups on the surface of chitin, thereby significantly improving adsorption performance.

Example 1

Into 100 mL of 3% GA solution, 5 g of raw chitin was added and stirred at 25° C. at 160 rpm for 2 hours using a multi-shaking incubator. GA-treated chitin was washed with 400 mL of distilled water to remove unreacted GA from the chitin surface, and GA-chitin was immediately transferred to 100 mL of 10% PEI solution and placed at 25°C and 160 rpm for 30 minutes. Reacted. PEI-chitin separated through solid-liquid separation was washed three times with distilled water and freeze-dried at -100°C for 24 hours and used in the experiment.

Adsorption performance experiment

Various variables such as pH, dye concentration, time and temperature affecting the adsorption process were evaluated through batch adsorption experiments. The experiment was carried out in a polypropylene conical tube of 50 mL with 30 mL of dye (Acid Blue 25, AB25, Sigma-Aldrich Korea) and 0.02 g of PEI-chitin in a multi-stage shaking incubator at 160 rpm and 25 °C.

The pH egde experiment was performed to find out the relationship between the final pH and the amount of dye adsorption in dye adsorption of PEI-chitin. The pH of each tube was adjusted differently from 2 to 12 using 0.1, 1, 5 M HCl and NaOH, and the pH of each tube was maintained for 24 hours. After reaching the adsorption equilibrium, the final pH was measured.

Adsorption kinetics experiments were conducted at initial dye concentrations of 50 mg/L and 100 mg/L to confirm the time required to reach adsorption equilibrium at pH 2. During the experiment, all samples were taken regularly according to a predetermined time interval, and each concentration of the obtained sample was analyzed using a spectrophotometer (X-MA3000PC, Human Co., Ltd., Korea).

The isothermal adsorption experiment was evaluated at four different temperatures to evaluate the maximum adsorption amount of PEI-chitin to AB25. The experiment was carried out for 24 hours by varying the initial concentration of the dye from 0 to 300 mg/L at pH 2. In addition, an analysis sample was prepared to measure the concentration of the dye remaining in each sample.

Analytical samples were prepared by centrifuging at 9,000 rpm for 5 minutes, then taking only the supernatant and diluting it appropriately with distilled water. Absorbance analysis was measured with a spectrophotometer at 600 nm, which is the maximum wavelength of AB25, and the adsorption amount q (mg/g) was calculated using Equation (1).

Here, C _i and C _f (mg/L) are the initial and final concentrations of the dye, and V _i and V _f (L) are the initial and final volumes of the solution. M(g) means the amount of adsorbent used in the experiment.

Desorption and reusability evaluation

PEI-chitin adsorbing AB25 was prepared by adding 0.02 g of PEI-chitin to 30 mL of an aqueous dye solution (100 mg/L) and stirring at pH 2 for 24 hours. Sodium hydroxide (NaOH), sodium hydrogen carbonate (NaHCO3) and sodium carbonate (Na2CO3) were selected as eluents to determine the effective desorption conditions of the adsorbed AB25, and the concentration of the eluent was varied from 0.001 to 1 M, and a desorption experiment was conducted I did. Desorption efficiency was calculated by the following equation (2).

The reusability evaluation of the adsorbent was evaluated by repeatedly performing the adsorption test and desorption test previously performed 3 times. The adsorption experiment was performed at pH 2, and the desorption experiment was performed under the optimum desorption eluent and concentration conditions for each dye.

FIG. 4 is an FE-SEM measurement of raw chitin, GA-chitin, and PEI-chitin. Referring to FIG. 4, in the case of PEI-chitin, it was shown that PEI was well distributed throughout the chitin surface. In image 4c' taken at a factor of 5,000, the above result was more clearly shown, and it was observed that there were larger and more pores on the chitin surface.

5 is a graph of FTIR analysis for raw chitin, GA-chitin, and PEI-chitin. Referring to FIG. 5, looking at 3440, 1423, and 1129 cm ^-1 representing amine peaks, it can be seen that the intensity of all peaks increases as the surface modification step progresses, and cross-linking between amine groups of chitin and PEI The CN peak indicating binding appeared at 1635 cm ^-1 , and the intensity of the corresponding peak increased as the surface modification step proceeded. The main characteristic peaks of PEI, 1423 cm ^-1 (-NH bending and deformation vibration), 1650 cm ^-1 (-NH ₂ or -NH), and 3440 cm ^-1 (NH stretching), showed similar peak changes of raw chitin and GA-chitin. However, the peak intensity of PEI-chitin increased significantly. Through this peak change, it can be confirmed that PEI was successfully introduced.

6 is a result of comparing the adsorption amount of samples at each stage for 100 mg/L of AB25. The adsorption amounts of raw chitin, GA-chitin, and PEI-chitin were 55.93, 44.35, and 144.28 mg/g, respectively, and PEI-chitin, the adsorbent of the present invention, increased the adsorption performance by about 2.6 times compared to that of raw chitin. .

7 is a graph measured by testing the amount of dye adsorption according to the pH concentration according to the dye concentration. Referring to FIG. 7, the change in the overall adsorption amount according to the pH was highest at pH 2, and the adsorption amount showed a tendency to rapidly decrease as it went to the alkaline region. When the dye was at low concentration, it showed high-efficiency adsorption capacity in a wide range of pH 2 to 8.

FIG. 8A is a graph showing the desorption efficiency according to the eluent concentration, and FIG. 8B is a graph in which adsorption and desorption amounts are measured after repeating adsorption and desorption three times. Referring to a of Figure 8, NaOH is 85.2% at 0.01 M, NaHCO3 is 78.7% at 0.01 M, and Na2CO3 is 0.1 M at 47.6%, 0.01 M NaOH showed the highest desorption rate. Referring to b of FIG. 8, the adsorption and desorption amount of the adsorbent of the present invention is slightly lower than that of once, but it can be confirmed that the adsorption amount of the adsorbent of the present invention is similar to that of two and three times, so that it can be repeatedly used several times.

9 shows the isothermal adsorption curve of PEI-chitin according to the temperature (298, 308, 318, 328 K) in the range of 0 ~ 300 mg/L of the initial concentration of the dye (AB25_). Table 1 below is reported in the references. The maximum adsorption amount of the various adsorbents and the adsorbent of the present invention (PEI-chitin) of the present invention is summarized.In terms of the maximum adsorption amount, PEI-chitin is less than 100mg/g hazelnut shell (Ref. Ref. 2), NaOH-treated Ficusracemose (Ref. 3), water lettuce (Ref. 5), Azollapinnate (Ref. 6), and biofilm (Ref. 7) showing 113.4 mg/g. The maximum adsorption amount of waste tea activated carbon (Ref. 4) was 203.34 mg/g, which was higher than that of PEI-chitin, but the affinity value was relatively low at 0.422 L/mg. It can be seen that the polymer (PEI)-chitin bioadsorbent is an excellent adsorbent for adsorption of the dye (AB25).

Sorbent q _max (mg/g) b _L (L/mg) h (mg/g min) Temperature (K) references. Hazelnut shell 60.2 0.043 7.53 293 [One] BTSD sawdust 24.39 0.430 2.65 300 [2] Ficusracemosa (NTFR) 60.2 0.134 2.38 323 [3] Waste tea activated carbon 203.34 0.422 4.35 303 [4] Water lettuce (WL) 24.5 0.070 2.34 297 [5] Azolla pinnata (AP) 50.5 0.027 0.82 297 [6] Biofilm 113.4 1.23 47.30 303 [7] PEI-chitin 177.32 3.276 8.60 297 Example

[Reference] 1. Ferrero, F., “Dye removal by low cost adsorbents: Hazelnut shells in comparison with wood sawdust,” J.Hazard. Mater. 142,144-152(2007).

2. Hanafiah, MAKM, Ngah, WSW, Zolkafly, SH, Teong, LC and Majid, ZAA,” Acid Blue 25 adsorption on base treated Shorea dasyphylla sawdust: Kinetic, isotherm, thermodynamic and spectroscopic analysis,” J.Environ.Sci. 24,261-268 (2012).

3. Jain, S. N. and Gogate, P. R., “NaOH-treated dead leaves of Ficus racemosa as an efficient biosorbent for Acid Blue 25 removal,” Int.J.Environ.Sci.Technol. 14,531-542 (2017).

4. Auta, M. and Hameed, B. H., “Preparation of waste tea activated carbon using potassium acetate as an activating agent for adsorption of Acid Blue 25 dye,” Chem. Eng. J. 171,502-509 (2011).

5. Kooh, MRR, Dahri, MK, Lim, LBL, Lim, LH and Chan, CM, “Separation of acid blue 25 from aqueous solution using water lettuce and agro-wastes by batch adsorption studies,” Appl.WaterSci.8, 61(2018).

6. Kooh, MRR, Dahri, MK, Lim, LBL and Lim, LH, “Batch Adsorption Studies on the Removal of Acid Blue 25 from Aqueous Solution Using Azolla pinnata and Soya Bean Waste,” Arab.J.Sci.Eng.41 ,2453-2464 (2016).

7. Mawad, A. M. M., Yousef, N. M. H. and Shoreit, A. A. M., “Bioremediation of Acid Blue 25 Dye by Anthracene Degrading Pseudomonas Pseudoalcaligenes ASU-016,” Catrina Int.J. Environ.Sci. 10,53-60 (2015).

10 is a result of an experiment for adsorption of dye (AB25) of PEI-chitin over time. The experiment was performed at 25° C. for about 31 hours using 50 mg/L and 100 mg/L of AB25. Referring to FIG. 10, adsorption was very fast at the beginning, gradually progressed after a certain time, and reached adsorption equilibrium after about 120 minutes (50 mg/L) and 500 minutes (100 mg/L). The adsorption amount was about 2 times higher than that of 50 mg/L from 100 mg/L to 150.38 mg/g, but the time to reach adsorption equilibrium increased by about 4.2 times.

Example 2

PEI-chitin was prepared in the same manner as in Example 1, except that a linker (GA) having a concentration of 0.1 to 10% was used. After adsorbing dyes (RY2, Reactive Yellow2) to each PEI-chitin at pH 2, the adsorption amount was measured, and FIG. 11 shows the dye adsorption amount according to the GA concentration.

Referring to FIG. 11, when the concentration of GA was up to 304.0 mg/g at 3%, and when the concentration was further increased to 5% and 10%, the adsorption amount showed a tendency to decrease again.

Example 3

PEI-chitin was prepared in the same manner as in Example 1, except that 1 to 20% of PEI was used, respectively. After measuring the adsorption amount of each PEI-chitin after adsorbing the dye (RY2, Reactive Yellow2) under the condition of pH 2, FIG. 12 shows the adsorption amount of the dye (RY2) according to the PEI concentration.

Referring to FIG. 12, the adsorption amount increased significantly from 147.1 mg/g when 1% PEI was used to a maximum of 430.7 mg/g when 20% PEI was used. However, in the centrifugation process after the adsorption process, it was confirmed that aggregated precipitates of the dye were formed in the samples using more than 15% PEI. This seems to be a phenomenon that appeared when PEI, which was physically bound rather than chemically bound to the surface of chitin, was separated from the adsorption process and bound to RY2. This is a phenomenon that is independent of the adsorption performance of PEI-chitin, and is judged to be a factor that interferes with the evaluation of the adsorption performance of the developed material. In this study, the maximum concentration of 10% PEI without sediment was determined to be the most suitable concentration. .

Example 4

PEI-chitin was prepared in the same manner as in Example 1, except that the size of chitin powder was used as a sample of 5 sizes. After measuring the adsorption amount of each PEI-chitin after adsorbing the dye (RY2, Reactive Yellow2) under the condition of pH 2, FIG. 13 shows the adsorption amount of the dye (RY2) by chitin size.

Referring to FIG. 13, as the particle size of chitin decreases, the adsorption amount increases, and when the adsorption amount is less than 180 μm, the adsorption amount is the highest at 307.8 mg/g. However, in the case of a size of less than 180 μm, not only the manufacturing process of the adsorbent was difficult, and the amount of adsorption of the prepared material was not uniform, so in the present invention, chitin having a size of 180 to 300 μm was determined as a preferred size.

In the above, a preferred embodiment of the present invention has been described in detail, but this description merely describes and discloses an exemplary embodiment of the present invention. Those skilled in the art will readily recognize that various changes, modifications and variations are possible from the above description and accompanying drawings without departing from the scope and spirit of the present invention.

10: chitin 20: linker
30: amine group-containing polymer layer

Claims (13)

Adding chitin powder to the linker solution and reacting to prepare chitin powder to which the linker is bound; And
Including the step of reacting the chitin powder to which the linker is bonded to the polymer solution containing an amine group
In the step of preparing the linker-bonded chitin powder, the concentration of the linker solution is 1-10% (w/v), and the chitin powder is added 0.01-0.05 g/mL compared to the linker solution,
In the reaction step, 0.01 to 0.05 g of the chitin powder to which a linker is bound is added to 1 to 10% (w/v) of the amine group-containing polymer solution,
The chitin powder size is 100 ~ 500㎛,
The linker is a chitin-based adsorbent manufacturing method, characterized in that it is a compound having a plurality of reactive groups to be able to bind to the chitin powder and the amine group-containing polymer. delete delete delete delete The method of claim 1, wherein the linker is glutaraldehyde, bisdiazobenzidine, triazole dialdehyde, glycidyl methacrylate, benzyltiazole carbaldehyde. , Benzothiazole carboxaldehyde, epichlorohydrin, dialdehyde, methylene-bis-acrylamide, glyoxal, acrylic acid, maleic acid ( Maleic acid), tetraethoxysilane (tetraetoxysilane), and a chitin-based adsorbent manufacturing method, characterized in that any one of tripolyphosphate (tripolyphosphate). Chitin powder (10);
A linker (20) bonded to the chitin; And
It includes a polyethyleneimine layer 30 crosslinked with the linker and coated on the chitin surface,
The chitin powder particle size is 100 ~ 500㎛,
The linker is glutaraldehyde, triazole dialdehyde, glycidyl methacrylate, benzyltiazole carbaldehyde, benzothiazole carboxaldehyde , Epichlorohydrin, dialdehyde, methylene-bis-acrylamide, glyoxal, acrylic acid, maleic acid, tetraetoxysilane And a chitin-based cationic adsorbent, characterized in that any one of tripolyphosphate (tripolyphosphate). delete delete delete Contacting the anionic dye or the anionic metal ion solution with the adsorbent of claim 7; And
Adsorption method using a chitin-based adsorbent comprising the step of recovering the adsorbent. The method of claim 11, wherein in the contacting step, the pH of the solution is adjusted to 8 or less. The method of claim 11, wherein the method further comprises the step of desorbing the dye or metal by putting the recovered adsorbent in an alkaline eluent.

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