CN108295820A - A kind of preparation method and applications of plant fiber adsorbing material - Google Patents

Abstract

The invention discloses a preparation method and application of a plant fiber-based adsorption material. The method comprises the following steps: 1) dispersing the plant fiber in water; (2) adding periodate; (3) adding a small molecular amine to react 8～12h; (4) dissolve chitosan in the acidic buffer solution; (5) add the monomer containing thiourea group to the solution of step (4); (6) add the solution of step (5) Uniformly disperse in the system described in step (3); (7) Add an appropriate amount of cross-linking material to the system; (8) After reacting for 4-12 hours, adjust the pH to alkaline with lye, and take out the solid after several times of suction filtration After drying to constant weight, the plant fiber-based adsorption material is obtained. When applied, the plant fiber-based absorbent material is ground into powder. The adsorption material prepared by the method of the present invention has good adsorption effect on various heavy metal ions such as Hg ²⁺ , Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , As ⁵⁺ , etc. at room temperature, and the adsorption The material reuse rate is high.

Description

A kind of preparation method and application of plant fiber base adsorption material

technical field

The invention belongs to the technical field of adsorption materials, and in particular relates to a preparation method of a plant fiber-based adsorption material and an application of the adsorption material in treating heavy metal polluted water bodies.

Background technique

With the rapid development of industry, more and more industrial wastewater is discharged into the environment, most of which contain various heavy metal ions. Once heavy metals enter the water body, they can be transferred through the biological chain and enriched in the organism, and this kind of pollution is persistent and difficult to degrade. When people drink water and food contaminated by heavy metals, heavy metal ions are difficult to be absorbed in the human body. Degradation or excretion, resulting in excessive accumulation of heavy metals in the body, leading to various diseases, and even threatening people's lives.

Nowadays, heavy metal wastewater treatment methods mainly include adsorption, flotation, chemical precipitation, extraction of dissolved materials, reverse osmosis, ion exchange, chemical redox, electrochemical treatment, etc. Compared with other treatment methods, the adsorption method has high efficiency, easy operation and low cost of adsorption materials, especially in the treatment of heavy metal wastewater with large capacity and low concentration. Therefore, adsorption method has become the preferred method for treating heavy metal polluted wastewater. Therefore, the development of cheap, efficient, environmentally friendly, and energy-saving heavy metal adsorption materials is of great significance to environmental protection.

Chitosan can be extracted from seafood waste (such as crab shells, shrimp skins) or leftovers. It is an extremely rich natural renewable resource next to cellulose, and chitosan is biodegradable, Safety and non-toxic advantages. Chitosan molecules contain a large number of free amino groups and hydroxyl groups, which can form stable chelates with heavy metals and precious metals, so chitosan itself has a certain adsorption capacity for heavy metal ions. In addition, the amino group and hydroxyl group in its molecule have high activity, and other adsorption groups can be introduced through chemical modification to enhance its adsorption capacity. The adsorption material prepared from chitosan has the advantages of good adsorption performance, environmental friendliness and low cost. However, when chitosan itself is used alone, its adsorption capacity is low, it is easy to lose, its mechanical strength is low, its applicable pH range is narrow, and it cannot be regenerated.

Cellulose is the most abundant renewable resource on the earth. It has the characteristics of biodegradability, good biocompatibility, and non-toxicity. Moreover, cellulose is fibrous, has many capillaries, and has the characteristics of porous and large specific surface area. Therefore, It also has a certain adsorption capacity. Many researchers directly use cellulose as an adsorption material to treat heavy metal wastewater, but its use is limited due to its weak adsorption capacity and poor selectivity. Therefore, in order to achieve better adsorption properties of cellulose, it needs to be chemically modified to introduce more or stronger affinity groups.

Contents of the invention

The technical problem to be solved by the present invention is a preparation method and application of a plant fiber-based adsorption material. In this method, chitosan and cellulose are combined, and the cellulose can form the skeleton of chitosan, and chitosan or other The derivatives are grafted on the cellulose, which can overcome the defects of chitosan's dispersibility and easy loss, and can make the modified cellulose have better adsorption capacity; and the main raw materials used in this method are agricultural products and seafood. Waste, and the raw materials are clean, the prepared adsorption material has good adsorption for Hg ²⁺ , Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , As ⁵⁺ and other heavy metal ions at room temperature effect.

The present invention solves the above technical problems with the following technical solutions:

The preparation method of plant fiber base adsorption material of the present invention, it comprises following operation steps:

(1) Take 0.5-1g of plant fiber and stir in 100mL of water until evenly dispersed;

(2) Add 1-2 g of periodate into the system described in step (1), and react at 45°C for 4-8 hours;

(3) Add 10-20 mL of small molecular amine into the system described in step (2), and react at 25°C-45°C for 8-12 hours;

(4) Dissolve 0.5-1g chitosan in 35-70mL acidic buffer solution and stir until completely dissolved;

(5) Add 0.4-1g monomer containing thiourea group to the solution in step (4), and continue stirring until the monomer is completely dissolved;

(6) Add the solution of step (5) to the system described in step (3), and stir until completely uniformly dispersed;

(7) After being completely dispersed in the reaction system, add an appropriate amount of cross-linking material to the system;

(8) After the reaction is carried out for 4-12 hours, adjust the pH to alkaline with 1%-2% lye, then use deionized water and organic solvent to filter several times, take out the solid, and place it in a refrigerator at 40-105°C. Dry to constant weight under ambient conditions to obtain the plant fiber-based adsorption material.

In step (1), the plant fiber is non-wood cellulose, wood cellulose, microcrystalline cellulose, nanocellulose or carboxymethyl cellulose.

In step (2), the periodate is potassium periodate, sodium periodate or barium periodate.

In step (3), the small molecule amine is ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine or pentaethylenehexamine.

In step (4), the acidic buffer solution is acetic acid-sodium acetate buffer solution, citric acid-sodium citrate buffer solution or disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution; the pH value range of the buffer solution is 5.7～8.0.

In step (5), the monomer containing thiourea group is 2,5-dithiodiurea, amidinothiourea, 3-thio-isothiourea propylsulfonic acid, dithiobiuret or 1,3-Dithiosemicarbazide.

In step (7), the cross-linking material is formaldehyde in an amount of 1-3mL with a concentration of 37% or glutaraldehyde in an amount of 5-10mL with a concentration of 10%.

In step (8), the lye is one of NaOH, KOH and Ca(OH) _solution , and the organic solvent is one of methanol, ethanol, propanol or ether.

When the plant fiber-based adsorbent material of the present invention is applied, the plant fiber-based adsorbent material is first ground with a mortar to obtain a powdered adsorbent material, which can be used for adsorption treatment of heavy metal polluted water at normal temperature; the heavy metal polluted water contains A variety of metal ions including Hg ²⁺ , Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , As ⁵⁺ .

Compared with the prior art, the present invention has the following beneficial effects:

(1) The main raw material for the preparation of the adsorption material in the present invention can be agricultural products and seafood waste, and has a wide range of sources, which can be regenerated, achieve waste utilization, and overcome the defect of energy shortage;

(2) There are many kinds of monomers applicable to the present invention, such as 2,5-dithiodiurea, amidinothiourea, 3-sulfur-isothiourea propylsulfonic acid, 1,3-dithiosemicarbazide, Ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, etc. all have good synergistic effects;

(3) The adsorption material prepared by the method of the present invention has a high removal rate for various metal ions including Hg ²⁺ , Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , and As ⁵⁺ , and has a certain selectivity, a wide range of applications, the adsorption temperature is at room temperature, and can desorb and regenerate heavy metal ions and adsorbent materials. After repeated adsorption and desorption, the adsorption capacity has almost no attenuation.

Detailed ways

The technical content of the present invention will be further described below in conjunction with specific examples, but it should not be construed as a limitation of the present invention. Without departing from the spirit and essence of the present invention, simple modifications or replacements made to the methods, steps or conditions of the present invention all belong to the scope of the present invention; unless otherwise specified, the technical means used in the embodiments are those skilled in the art. well-known conventional means.

Example 1:

Take 0.5g of eucalyptus cellulose and 100mL of water, stir and disperse evenly, add 1g of sodium periodate to the system, react at 45°C for 4h, then take 10mL of diethylenetriamine, add it to the previous system, and add it to the system at 25°C React for 12 hours; dissolve 0.8 chitosan in 55 mL of acetic acid-sodium acetate solution (the ratio of acetic acid to sodium acetate is 93.5:6.5, that is, the pH is 5.7), and stir with a magnetic stirrer at a speed of 700 ^rpm Until it is completely dissolved, add 0.4g of 2,5-dithiodiurea to the above solution, and continue to stir until the 2,5-dithiodiurea is completely dissolved. After the monomer is dissolved in chitosan, the chitosan acidic solution Add the above-mentioned diethylenetriamine/eucalyptus cellulose system until the cellulose is completely and uniformly dispersed in the system, then add 1 mL of formaldehyde solution (concentration: 37%) dropwise to the system, and after the reaction is carried out for 4 hours, use The concentration is 2% NaOH to adjust the pH to 8, then alternately wash and filter with deionized water and methanol for 6 times, take out the solid, and vacuum-dry it to a constant weight at 50°C to obtain a modified adsorption material. Finally, the adsorbent material is ground in a mortar and passed through a 100-mesh sieve to obtain the powdered plant fiber-based adsorbent material of the present invention, which is sealed and stored at room temperature for future use.

Select the adsorption material powder prepared in this example to carry out the adsorption performance test experiment:

Take 0.5g of the adsorption material and place it in a 150mL Erlenmeyer flask, and absorb a mixed solution of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , and Cu ²⁺ at a temperature of 25°C and a pH of 4.26. , the adsorption process was carried out on a constant temperature oscillator for 2.5h, then the sample was centrifuged to take the supernatant, filtered with a 0.45μm filter membrane, and 5mL of the filtrate was tested on the computer by ICP-OES, and finally the 2,5-di The adsorption capacity and rate of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , Cu ²⁺ on the thiodiurea/chitosan modified eucalyptus wood cellulose adsorption material, and then desorbed with hydrochloric acid with a concentration of 0.05mol/L, Metal ions can be recovered after desorption, and the adsorption capacity decreases slightly after more than 5 times of use. See Table 1 and Table 2 for specific adsorption capacity and adsorption rate.

Example 2:

Take 0.8g of microcrystalline cellulose and disperse evenly in 100mL of water, add 1.6g of potassium periodate to the system, react at 45°C for 5h, then take 12mL of triethylenetetramine, add it to the previous system, and put it into the system at 30°C React for 11 hours; dissolve 1 g of chitosan in 60 mL of citric acid-sodium citrate solution (the ratio of citric acid to sodium citrate is 55:45, i.e., the pH is ^6.9 ), and use Stir with a magnetic stirrer until it is completely dissolved, add 0.6 g of amidinyl thiourea to the above solution, and continue stirring until the amidinyl thiourea is completely dissolved. After the monomer is dissolved in chitosan, add the acidic solution of chitosan to the above three In the ethylene tetramine/microcrystalline cellulose system, continue to stir until the cellulose is completely and uniformly dispersed in the system, and then add 2 mL of formaldehyde solution (concentration: 37%) dropwise to the system. After the reaction is carried out for 6 hours, use the concentration Adjust the pH to 9 with 2% KOH, then alternately wash and filter with deionized water and diethyl ether for 5 times, take out the solid, and vacuum-dry it at 60°C to constant weight to obtain a modified adsorption material. After cooling, The adsorbent material is ground in a mortar and passed through an 80-mesh sieve to obtain the powdered plant fiber-based adsorbent material of the present invention, which is sealed and stored at room temperature for future use.

Select the adsorption material powder prepared in this example to carry out the adsorption performance test experiment:

Take 0.5g of the adsorption material and place it in a 150mL Erlenmeyer flask, and absorb a mixed solution of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , and Cu ²⁺ at a temperature of 25°C and a pH of 4.26. , the adsorption process was carried out on a constant temperature oscillator for 2.5h, and then the sample was centrifuged to take the supernatant, filtered with a 0.45μm filter membrane, and 5mL of the filtrate was tested on the computer using ICP-OES, and finally the amidinylthiourea/ Chitosan-modified microcrystalline cellulose adsorption material to Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , Cu ²⁺ adsorption capacity and adsorption rate, and then use hydrochloric acid with a concentration of 0.05mol/L to desorb. After desorption, it can Metal ions are recovered, and the adsorption capacity decreases slightly after more than 5 times of use. The specific adsorption capacity and adsorption rate are shown in Table 1 and Table 2.

Example 3:

Take 1g of nanocellulose and 100mL of water to disperse evenly, add 2g of barium periodate to the system, react at 45°C for 6h, then take 16mL of tetraethylenepentamine, add it to the previous system, and react at 35°C for 10h; Take 0.5g chitosan and dissolve it in 40mL disodium hydrogen phosphate-sodium dihydrogen phosphate solution (the ratio of disodium hydrogen phosphate to sodium dihydrogen phosphate is 87:92, i.e. pH is 5.8), at a speed of 700r min ^- Stir with a magnetic stirrer under ¹ condition until it dissolves completely, add 0.8g dithiobiuret to the above solution, continue stirring until the dithiobiuret is completely dissolved, after the monomer is dissolved in chitosan, put Add chitosan acidic solution into the above-mentioned tetraethylenepentamine/nanocellulose system, continue to stir until the cellulose is completely uniformly dispersed in the system, then add 3mL glutaraldehyde solution drop by drop in the system (concentration is 37% ), after the reaction was carried out for 8h, the pH was adjusted to 10 with 2% Ca(OH) ₂ , then washed and filtered with deionized water and acetone solution alternately for 4 times, the solid was taken out, and vacuum-dried at 80°C The modified adsorption material was obtained at constant weight, and after cooling, the absorbent material was ground in a mortar and passed through a 90-mesh wooden sieve to obtain the powdered plant fiber-based adsorption material of the present invention, which was sealed and stored at room temperature for future use.

Select the adsorption material powder prepared in this example to carry out the adsorption performance test experiment:

Take 0.5g of the adsorption material and place it in a 150mL Erlenmeyer flask, and absorb a mixed solution of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , and Cu ²⁺ at a temperature of 25°C and a pH of 4.26. , the adsorption process was carried out on a constant temperature oscillator for 2.5h, then the sample was centrifuged to take the supernatant, filtered with a 0.45μm filter membrane, and 5mL of the filtrate was tested on the computer using ICP-OES, and finally the The adsorption capacity and rate of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , Cu ²⁺ on the urea/chitosan modified nanocellulose adsorption material, and then use hydrochloric acid with a concentration of 0.05mol/L to desorb. After desorption Metal ions can be recovered, and after more than 5 times of use, the adsorption capacity decreases slightly. The specific adsorption capacity and adsorption rate are shown in Table 1 and Table 2.

Example 4:

Take 0.7g of carboxymethyl cellulose and 100mL of water to disperse evenly, add 1.4g of sodium periodate to the system, react at 45°C for 7h, then take 18mL of pentaethylenehexamine, add it to the previous system, keep at 40°C React for 9 hours; take 0.6g of chitosan and dissolve it in 48mL of acetic acid-sodium acetate solution (the ratio of acetic acid to sodium acetate is 90:80.7, i.e. pH is 5.8), and stir it with magnetic force under the condition of rotating speed 700r·min ^-1 Stir until it is completely dissolved, add 1.0g of 3-thio-isothiourea propylsulfonic acid to the above solution, continue to stir until the dithiobiuret is completely dissolved, and after the monomer is dissolved in chitosan, the shell Add polysaccharide acidic solution to the above-mentioned pentaethylenehexamine/carboxymethyl cellulose system, continue to stir until the cellulose is completely and uniformly dispersed in the system, and then add 5 mL of glutaraldehyde solution (with a concentration of 10 %), after the reaction was carried out for 10 h, adjust the pH to 8 with NaOH with a concentration of 1%, then alternately wash and filter with deionized water and ethanol for 7 times, take out the solid, and vacuum-dry it to a constant weight under the environment of 90 ° C The modified adsorbent material was obtained, and after cooling, the adsorbent material was ground in a mortar and passed through a 110-mesh wooden sieve to obtain the powdered plant fiber-based adsorbent material of the present invention, which was sealed and stored at room temperature for future use.

Select the adsorption material powder prepared in this example to carry out the adsorption performance test experiment:

Take 0.5g of the adsorption material and place it in a 150mL Erlenmeyer flask, and absorb a mixed solution of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , and Cu ²⁺ at a temperature of 25°C and a pH of 4.26. , the adsorption process was carried out on a constant temperature oscillator for 2.5h, then the sample was centrifuged to take the supernatant, filtered with a 0.45μm filter membrane, and 5mL of the filtrate was tested on the computer using ICP-OES, and finally the 3-sulfur-iso The adsorption capacity and rate of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , Cu ²⁺ by thiourea propyl sulfonic acid/chitosan modified carboxymethyl cellulose adsorption material, and then use the concentration of 0.05mol/L Hydrochloric acid desorption, metal ions can be recovered after desorption, and the adsorption capacity decreases slightly after 5 times of use. The specific adsorption capacity and adsorption rate are shown in Table 1 and Table 2.

Example 5:

Take 0.9g of bagasse cellulose and disperse evenly in 100mL of water, add 1.8 g of potassium periodate to the system, react at 45°C for 8h, then take 20mL of ethylenediamine, add it to the previous system, and react at 45°C for 8h; Take 0.7g chitosan and dissolve in 56mL disodium hydrogen phosphate-sodium dihydrogen phosphate solution (the ratio of disodium hydrogen phosphate to sodium dihydrogen phosphate is 12.3:87.7, i.e. the pH is 6), at a speed of 700r min ^- Stir with a magnetic stirrer under ¹ condition until it is completely dissolved, add 0.5g 1,3-dithiosemicarbazide to the above solution, continue stirring until the dithiobiuret is completely dissolved, and after the monomer is dissolved in chitosan, Add the chitosan acidic solution into the above-mentioned ethylenediamine/bagasse cellulose system, continue to stir until the cellulose is completely and uniformly dispersed in the system, and then add 10 mL of glutaraldehyde solution (concentration is 37% ), after the reaction was carried out for 12 hours, the pH was adjusted to 9 with KOH with a concentration of 1%, and then alternately washed with deionized water and methanol and filtered for 6 times, the solid was taken out, and vacuum-dried to a constant weight at 105°C to obtain To modify the adsorbent material, after cooling, place the adsorbent material in a mortar, grind it, pass through a 120-mesh wooden sieve, and obtain the powdered plant fiber-based adsorbent material of the present invention, which is sealed and stored at room temperature for future use.

Select the adsorption material powder prepared in this example to carry out the adsorption performance test experiment:

Take 0.5g of the adsorption material and place it in a 150mL Erlenmeyer flask, and absorb a mixed solution of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , and Cu ²⁺ at a temperature of 25°C and a pH of 4.26. , the adsorption process was carried out on a constant temperature oscillator for 2.5h, and then the sample was centrifuged to take the supernatant, filtered with a 0.45μm filter membrane, and 5mL of the filtrate was tested on the computer using ICP-OES, and finally the 1,3-di The adsorption capacity and rate of Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , Cu ²⁺ on the thiosemicarbazide/chitosan modified bagasse cellulose adsorption material, and then use hydrochloric acid with a concentration of 0.05mol/L to desorb, desorb Metal ions can be recovered after suction, and the adsorption capacity decreases slightly after more than 5 times of use. See Table 1 and Table 2 for specific adsorption capacity and adsorption rate.

Table 1 (Adsorption amount of Pb ²⁺ , Cd ²⁺ , Cu ²⁺ , Cr ⁶⁺ by the plant fiber-based adsorption material of the present invention)

Table 2 (adsorption rate of Pb ²⁺ , Cd ²⁺ , Cu ²⁺ , Cr ⁶⁺ by plant fiber-based adsorbent material of the present invention)

Claims (10)

1. a preparation method of plant fiber base adsorption material, is characterized in that, it comprises following operation steps: (1) Take 0.5-1g of plant fiber and stir in 100mL of water until evenly dispersed; (2) Add 1-2 g of periodate into the system described in step (1), and react at 45°C for 4-8 hours; (3) Add 10-20 mL of small molecular amine into the system described in step (2), and react at 25°C-45°C for 8-12 hours; (4) Dissolve 0.5-1g chitosan in 35-70mL acidic buffer solution and stir until completely dissolved; (5) Add 0.4-1g monomer containing thiourea group to the solution in step (4), and continue stirring until the monomer is completely dissolved; (6) Add the solution of step (5) to the system described in step (3), and stir until completely uniformly dispersed; (7) After being completely dispersed in the reaction system, add an appropriate amount of cross-linking material to the system; (8) After the reaction is carried out for 4-12 hours, adjust the pH to alkaline with 1%-2% lye, then use deionized water and organic solvent to filter several times, take out the solid, and place it in a refrigerator at 40-105°C. Dry to constant weight under ambient conditions to obtain the plant fiber-based adsorption material. 2. according to the preparation method of the described plant fiber base adsorption material of claim 1, it is characterized in that, in step (1), described plant fiber is non-wood cellulose, wood cellulose, microcrystalline cellulose, nano Cellulose or carboxymethyl cellulose. 3. The preparation method of the plant fiber-based adsorption material according to claim 1, characterized in that, in step (2), the periodate is potassium periodate, sodium periodate or barium periodate. 4. according to the preparation method of the described plant fiber base adsorption material of claim 1, it is characterized in that, in step (3), described small molecular amine is ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylene Pentaamine or pentaethylenehexamine. 5. according to the preparation method of the described plant fiber base adsorption material of claim 1, it is characterized in that, in step (4), described acidic buffer solution is acetic acid-sodium acetate buffer solution, citric acid-sodium citrate buffer solution or Disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution; the pH value of the buffer solution ranges from 5.7 to 8.0. 6. according to the preparation method of the described plant fiber-based adsorbent material of claim 1, it is characterized in that, in step (5), the monomer containing thiourea group is 2,5-dithiodiurea, amidinyl sulfide Urea, 3-thio-isothioureapropylsulfonic acid, dithiobiuret or 1,3-dithiosemicarbazide. 7. according to the preparation method of the described plant fiber base adsorption material of claim 1, it is characterized in that, in step (7), described cross-linking material is the formaldehyde that consumption is 1-3mL, concentration is 37% or consumption is 5 - 10 mL of 10% glutaraldehyde. 8. according to the preparation method of the described plant fiber-based adsorption material of claim 1, it is characterized in that, in step (8), described lye is NaOH, KOH and Ca(OH) ₂ a kind of in solution, organic solvent One of methanol, ethanol, propanol or ether. 9. According to the application of any one of claims 1-8, the plant fiber-based adsorbent material is characterized in that, during application, the plant fiber-based adsorbent material is first ground with a mortar to obtain a powdered adsorbent material, which is used at normal temperature Adsorption treatment of heavy metal polluted water bodies. 10. The application of the plant fiber-based adsorption material according to claim 9, characterized in that the heavy metal polluted water contains Hg ²⁺ , Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , Cr ⁶⁺ , As ⁵⁺ various metal ions.