CN114984917A - Method for efficiently removing metal ions in waste cotton fabric regeneration pulp - Google Patents

Method for efficiently removing metal ions in waste cotton fabric regeneration pulp Download PDF

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CN114984917A
CN114984917A CN202210617696.7A CN202210617696A CN114984917A CN 114984917 A CN114984917 A CN 114984917A CN 202210617696 A CN202210617696 A CN 202210617696A CN 114984917 A CN114984917 A CN 114984917A
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cotton fabric
waste cotton
metal ions
chitosan
acid
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刘克印
罗金兰
纵培培
陈若愚
孔凡功
曹知朋
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Qilu University of Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
    • B01D15/02—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor with moving adsorbents
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/66—Disintegrating fibre-containing textile articles to obtain fibres for re-use

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Abstract

The invention belongs to the technical field of textile printing and dyeing processing, and particularly relates to a method for efficiently removing metal ions in waste cotton fabric regenerated pulp, which comprises the steps of firstly performing deacetylation treatment on chitosan, and then performing chloroacetic acid grafting modification to obtain modified chitosan; then preparing inorganic acid, complexing agent (compound of sodium hexametaphosphate and ethylene diamine tetraacetic acid) and deionized water into removing solution; and finally, mixing the modified chitosan, the removing solution and the waste cotton fabric dissolving pulp, stirring for a certain time, centrifuging to remove the solution in the mixture, and washing. The method for removing the metal ions in the waste cotton fabric dissolving pulp has obvious effect on removing the metal ions in the waste cotton fabric dissolving pulp, is beneficial to subsequent bleaching and spinning, effectively reduces energy consumption and reduces the waste water treatment burden, and has the advantages of simple and easy operation in the whole process, excellent effect and great popularization value.

Description

Method for efficiently removing metal ions in waste cotton fabric regeneration pulp
Technical Field
The invention belongs to the technical field of textile printing and dyeing processing, and particularly relates to a method for efficiently removing metal ions in waste cotton fabric regenerated pulp.
Background
Cotton fiber is one of the most important textile raw materials and is also the highest yield natural fiber. Because the cotton fiber has the characteristics of good moisture absorption and air permeability, excellent hand feeling and strength and the like, the cotton textile is popular with people. Therefore, pure cotton and cotton-containing textiles account for a large proportion of waste textiles. In recent years, with the enhancement of environmental protection consciousness of people, the recycling of cotton fabrics and cotton yarns draws great attention at home and abroad. In the process of recycling waste cotton textiles, certain metal ions can be carried in daily life and part of the metal ions can be attached in the subsequent pulping process, so that certain influence is caused.
Heavy metal pollution is one of the serious environmental problems faced by human beings, and heavy metals in waste water, waste residues, waste gases and other media can enter a food chain through a certain way to cause harm to the health of human beings, so that the heavy metal pollution treatment has attracted great attention of people. Chitosan is a high molecular polymer extracted from the shell of crustacean, namely chitin N-deacetylation product, the molecules of which contain a large amount of-NH and-0H groups, and can form cage-shaped molecules with a net structure by virtue of hydrogen bonds, and can chelate a plurality of metal ions, thereby effectively adsorbing heavy metal ions in the solution. However, in practical application, chitosan as a heavy metal ion adsorbent has the disadvantages of small molecular weight, poor bridging capability, narrow applicable pH value range and the like, so that the application of chitosan is limited.
In the prior art, the method for removing metal ions mainly utilizes acid treatment and complexing agent treatment. It is common at present to combine acid treatment with complexing treatment, wherein the acid treatment is to dissolve metal ion hydroxide attached to pulp by using acid, and then remove acid-soluble impurities by centrifugation, the metal ion is usually present in the form of hydroxide, for example, iron ion is present in the form of iron hydroxide, after the acid solution is added, the iron ion is changed from the iron hydroxide into iron ion, at this time, free iron ion can be removed by water washing, because the solubility product constant of the iron ion is unstable, in the process of removing iron ion, the free iron ion may become iron hydroxide to be attached to fiber due to the rising of pH value, so that the removal rate of metal ion is not high, and the lower the pH value of acid is, the better the effect of removing metal ion is, but the lower the pH value is, the more serious the degradation of fiber is, so that the yield and polymerization degree of pulp are reduced. In the complexing agent treatment, the complexing agent can be used for directly complexing metal ions, but the metal ions exist in the form of hydroxide, the solubility product of the metal ions is low, the complexing agent cannot easily take the metal ions to form a chelate so as to be washed out, the rate of complexing the metal ions by the complexing agent is low, and the removal rate of the metal ions is also low.
Therefore, the research on the method for efficiently removing the metal ions while protecting the cellulose from being excessively degraded when preparing the waste cotton fabric regenerated pulp is of great significance.
Disclosure of Invention
In order to solve the problems of low removal rate of metal ions and degradation of cellulose in the process of preparing the waste cotton fabric regenerated pulp in the prior art, the invention provides a method for efficiently removing the metal ions in the waste cotton fabric regenerated pulp.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for efficiently removing metal ions in waste cotton fabric regeneration pulp takes modified chitosan and sodium hexametaphosphate as composite auxiliaries to assist in removing the metal ions in the waste cotton fabric regeneration pulp, and mainly comprises the following steps:
(1) preparing modified chitosan:
deacetylation treatment of chitosan: accurately weighing the purchased chitosan powder as a raw material, adding the chitosan powder into a three-necked bottle containing 50% NaOH aqueous solution, continuously stirring for a certain time, taking out the three-necked bottle, filtering, repeatedly washing the three-necked bottle with distilled water to be neutral, freezing, and drying in a freeze dryer to finally obtain chitosan powder for further deacetylation;
chloroacetic acid graft modification: then, carrying out graft substitution reaction on deacetylated chitosan powder and chloroacetic acid in a mixed solvent of isopropanol and alkali, neutralizing with dilute hydrochloric acid after the reaction is finished, and dialyzing by a dialysis bag to remove unreacted chloroacetic acid; freezing by a freeze dryer to remove the solvent to obtain a chloroacetic acid grafted modified chitosan product, namely the modified chitosan;
(2) preparation of a removing solution: preparing a removing solution from inorganic acid, a complexing agent (a compound of sodium hexametaphosphate and ethylene diamine tetraacetic acid) and deionized water, wherein the mass ratio of the inorganic acid to the complexing agent is 9-18: 1;
(3) treating waste cotton fabric dissolving pulp: mixing the modified chitosan obtained in the step (1), the removing solution obtained in the step (2) and the waste cotton fabric dissolving pulp to obtain a mixture, and stirring for a certain time; centrifuging to remove the solution in the mixture, and then washing with deionized water, wherein the washing termination condition is that the pH value of the water washing liquid reaches neutral. The invention separates metal ions by adopting a centrifugal washing method, and can ensure that a large amount of metal ions are separated from the waste cotton pulp, thereby achieving the purpose of removing the metal ions.
According to the invention, sodium hexametaphosphate and chloroacetic acid modified chitosan are used as composite auxiliary agents to assist in removing metal ions in the waste cotton regenerated pulp, so that the method has excellent adaptability in a wide pH range, effectively improves the removal rate of the metal ions, and avoids cellulose degradation. The composite additive still has good complexing ability when the pH value is 2-9, and chloroacetic acid modified chitosan is used as a main complexing agent, and sodium hexametaphosphate is used as an auxiliary complexing agent. The structure of the metal chelating agent contains coordination groups such as amino groups and carboxyl groups, the coordination atoms are contained in the groups, the coordination atoms and metal ions such as iron ions form coordination bonds to chelate into compounds, the metal chelate compounds can leave cotton fibers along with cleaning liquid after being washed, and the complexing effect of the ethylene diamine tetraacetic acid and the chloroacetic acid modified chitosan is stronger, so that sodium hexametaphosphate serving as a main complexing agent has the characteristic of a surfactant, can help the ethylene diamine tetraacetic acid and the chloroacetic acid modified chitosan to be fully dispersed in treatment liquid and promote dissolution, further improve the contact probability of the ethylene diamine tetraacetic acid and the chloroacetic acid modified chitosan and metal ions in the waste cotton fabric dissolving pulp, and ensure that the free metal ions and the uniformly dispersed complexing agent can be fully contacted, thereby realizing the efficient removal of the metal ions in the waste cotton fabric dissolving pulp.
Preferably, in the step (1), the mass ratio of the deacetylated chitosan to chloroacetic acid is 1: 0.2-5; the mass ratio of the isopropanol to the alkali in the mixed solvent is 5: 1; neutralizing with dilute hydrochloric acid to pH 6-8.
Preferably, the molar ratio of the sodium hexametaphosphate to the ethylenediamine tetraacetic acid and the chloroacetic acid modified chitosan is 1: 1-2: 0.5-1, because ethylene diamine tetraacetic acid and chloroacetic acid modified chitosan are main complexing agents, the addition amount of ethylene diamine tetraacetic acid is larger than that of sodium hexametaphosphate, and the sodium hexametaphosphate can play a role in dispersing chloroacetic acid modified chitosan, so the addition amount cannot be too small, otherwise the dispersing effect can be influenced.
Preferably, the mass ratio of the acid to the complexing agent in the removing solution is 9-18: 1, the pH value of the removing solution is 2-9, and the acid is inorganic acid (such as dilute hydrochloric acid); the addition of acid can affect the removal of metal ions in the regenerated pulp to a certain extent, the addition of acid with proper dosage can increase the dissolution of metal hydroxide precipitate so as to improve the removal rate of the metal ions, when the addition of acid is too little, the obtained pulp is relatively more, but the dissolution effect of the metal hydroxide precipitate is insufficient, the complexing agent is difficult to fully complex the metal ions, and the removal rate of the metal ions can be reduced.
Preferably, in the step (3), the pulp concentration of the waste cotton regenerated pulp is 5wt%, and the cotton fiber content of the waste cotton fabric is more than 70 wt%. The solid content of the waste cotton fabric regeneration pulp is 20-40%; the addition amount of the modified chitosan is 0.5 to 1 percent; the addition amount of the removing liquid is 1-2%.
Preferably, the stirring is carried out once every 10-15 min at a certain temperature of 30-90 ℃, and the period of time is 70 min.
Preferably, deionized water is adopted for washing, the washing is carried out for 3-5 times, and the condition for stopping the washing is that the pH value of the water washing liquid reaches about 7.0. The washing washes the regeneration slurry to neutral, indicating that the regeneration slurry has been washed in this range.
Testing Hg in the treated waste cotton fabric dissolving pulp 2+ 、Ni 2+ 、Pb 2+ The removal rate of (1) is 75-85%, and Fe 3+ The removal rate of (1) is 75-90%, and Cu 2+ The removal rate of (2) is 60-75%, and Mn is 2+ The removal rate is 66-85%, and the yield of the pulp is more than or equal to 85%. Note: the pulp of the invention is cotton pulp, Fe 3+ The content of (A) is determined by the method described in textile industry Standard FZ/T50010.6-1998 (determination of the iron content of pulp for viscose fibers), Cu 2+ The content of the manganese is measured by the method described in the national standard GB/T8941.3-2008 (measurement of copper content of paper, paperboard and pulp), and Mn 2+ The content of (A) is measured by the method described in the national standard GB/T8943.3-2008 (measurement of manganese content of paper, paperboard and pulp).
The invention aims at removing a large amount of metal ions contained in the regenerated fiber of the waste cotton textile; after the waste cotton textiles are consumed and used, the content of various metal ions is obviously increased. The waste cotton textile regenerated fibers contain a large amount of metal ions which can cause serious harm to human bodies, for example, human tissue cells can be damaged, so that human bones become thin, chronic poisoning is caused, muscle paralysis, growth stop, low fertility function and the like are caused. The developed method for modifying chitosan and removing metal ions in the waste cotton fabric dissolving pulp has obvious effect of removing the metal ions in the waste cotton fabric dissolving pulp, is beneficial to subsequent bleaching and high-value utilization of spinning or regenerated cellulose materials, effectively reduces energy consumption and reduces the waste water treatment burden, and has the advantages of simple and easy operation in the whole process, excellent effect and great popularization value.
Advantageous effects
The invention discloses a method for efficiently removing metal ions in waste cotton fabric regenerated pulp, which at least has the following beneficial effects compared with the prior art:
(1) according to the method for removing metal ions in the chitosan modification and waste cotton regeneration pulp, disclosed by the invention, the chitosan modification is combined with acid-base and a complex compound, so that the effect of removing the metal ions in the waste cotton regeneration pulp is obvious, and the subsequent bleaching, spinning or regenerated cellulose material processing is facilitated;
(2) according to the method for modifying chitosan and removing metal ions in waste cotton regenerated pulp by adsorption, waste cotton does not need to be selected; advanced crushing treatment on the waste cotton is not required; can avoid the excessive degradation of cellulose in the cotton fabric by acid and alkali.
(3) The method for modifying chitosan and adsorbing and removing metal ions in waste cotton regenerated pulp is simple and easy to implement, low in cost and extremely high in popularization value.
Drawings
FIG. 1: preparing a molecular structural formula of the modified chitosan;
FIG. 2 is a schematic diagram: infrared images of chitosan and modified chitosan; the infrared curve comprises acetylated chitosan, chitosan and chloroacetic acid substituted chitosan from bottom to top in sequence.
Detailed Description
Hereinafter, the present invention will be described in detail. Before the description is made, it should be understood that the terms used in the present specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Accordingly, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.
The following examples are given by way of illustration of embodiments of the invention and are not to be construed as limiting the invention, and it will be understood by those skilled in the art that modifications may be made without departing from the spirit and scope of the invention. Unless otherwise specified, reagents and equipment used in the following examples are commercially available products.
Example 1
A method for efficiently removing metal ions in waste cotton fabric regeneration pulp comprises the following specific processes:
(1) preparing modified chitosan:
deacetylation treatment: accurately weighing 20g of purchased chitosan powder as a raw material, adding the raw material into a three-necked bottle containing 550 mL of 50% NaOH aqueous solution, continuously stirring and stirring the mixture for 24 hours at 60 ℃, taking out the three-necked bottle, filtering the mixture, repeatedly washing the mixture by using distilled water to be neutral, freezing the mixture, and drying the mixture in a freeze dryer to finally obtain 18 g of deacetylated chitosan powder with the yield of 90%;
graft modification: taking 1g of deacetylated chitosan powder and 0.2 g of chloroacetic acid to perform graft substitution reaction in a mixed solvent of isopropanol and alkali (the mass ratio of the isopropanol to the alkali in the mixed solvent is 5: 1), neutralizing with dilute hydrochloric acid until the pH value is 6 after the reaction is finished, and dialyzing by a dialysis bag to remove unreacted chloroacetic acid; and (3) freezing by a freeze dryer to remove the solvent to obtain a chloroacetic acid grafted modified chitosan product, namely the modified chitosan.
The molecular structural formula of the modified chitosan is shown in figure 1.
The infrared patterns of chitosan and modified chitosan are shown in figure 2.
(2) Preparation of a removing solution: preparing inorganic acid (dilute sulfuric acid with the concentration of 70 wt%), complexing agent (complex of sodium hexametaphosphate and ethylene diamine tetraacetic acid with the molar ratio of 1: 2) and deionized water into removing solution with the pH value of 2, wherein the mass ratio of the inorganic acid to the complexing agent is 15: 1;
(3) treating waste cotton fabric dissolving pulp: mixing the modified chitosan obtained in the step (1), the removing liquid obtained in the step (2) and waste cotton fabric dissolving pulp with the solid content of 25% to obtain a mixture, and stirring once at intervals of 8min at 50 ℃ for 80 min; wherein the cotton fiber content of the waste cotton fabrics is 72 wt%, and the mass addition amount of the complexing agent is 0.3% of the absolute dry mass of the dissolving pulp of the waste cotton fabrics; the solution in the mixture was removed by centrifugation and then washed 2 times with deionized water under conditions such that the pH of the aqueous wash reached 7.0. The adding amount of the modified chitosan is 0.5 percent of the absolute dry mass of the waste cotton fabric dissolving pulp; the addition of the removing liquid is 1 percent of the oven-dry mass of the waste cotton fabric dissolving pulp.
By the method, Fe in the waste cotton fabric dissolving pulp 3+ The removal rate of (C) was 90% (determined according to the method of F Z/T50010.6-1998), Cu 2+ Has a removal rate of 60% (measured according to the method of GB/T8943.1-2008), Mn 2+ The removal rate of (D) was 82% (measured by the method of GB/T8943.3-2008), and the yield of pulp was 97%.
Example 2
A method for efficiently removing metal ions in waste cotton fabric regeneration pulp comprises the following specific processes:
(1) preparing modified chitosan:
deacetylation treatment: accurately weighing 20g of purchased chitosan powder as a raw material, adding the raw material into a three-necked bottle containing 550 mL of 50% NaOH aqueous solution, continuously stirring and stirring the mixture for 24 hours at 60 ℃, taking out the three-necked bottle, filtering the mixture, repeatedly washing the mixture by using distilled water to be neutral, freezing the mixture, and drying the mixture in a freeze dryer to finally obtain 18 g of deacetylated chitosan powder with the yield of 92.3%;
graft modification: taking 1g of deacetylated chitosan powder and 1.0 g of chloroacetic acid to carry out graft substitution reaction in a mixed solvent of isopropanol and alkali, neutralizing with dilute hydrochloric acid until the pH value is 8 after the reaction is finished, and dialyzing by a dialysis bag to remove unreacted chloroacetic acid; and (3) freezing by a freeze dryer to remove the solvent to obtain a chloroacetic acid grafted modified chitosan product, namely the modified chitosan.
(2) Preparation of a removing solution: preparing inorganic acid (dilute sulfuric acid with the concentration of 66 wt%), complexing agent (compound of sodium hexametaphosphate and ethylene diamine tetraacetic acid with the molar ratio of 1: 1) and deionized water into a removing solution with the pH value of 3, wherein the mass ratio of the inorganic acid to the complexing agent is 9: 1;
(3) treating waste cotton fabric dissolving pulp: mixing the modified chitosan, the removing solution and the waste cotton fabric dissolving pulp with the solid content of 20% to obtain a mixture, and stirring once every 5min at the temperature of 60 ℃ for 60 min; wherein the cotton fiber content of the waste cotton fabrics is 75 wt%, and the mass addition amount of the complexing agent is 0.4% of the absolute dry mass of the waste cotton fabric dissolving pulp; the adding amount of the modified chitosan is 1 percent of the absolute dry mass of the waste cotton fabric dissolving pulp; the addition of the removing liquid is 2% of the oven-dry mass of the waste cotton fabric dissolving pulp.
The solution in the mixture was removed by centrifugation and then washed 2 times with deionized water, the washing being terminated at a pH of 7.3 in the aqueous wash.
By the method, Fe in the waste cotton fabric dissolving pulp 3+ Has a removal rate of 85% (determined according to the method of FZ/T50010.6-1998), Cu 2+ Has a removal rate of 65% (measured according to the method of GB/T8943.1-2008), Mn 2 + The removal rate of (A) was 79% (measured by the method of GB/T8943.3-2008), and the yield of pulp was 90%.
Example 3
A method for efficiently removing metal ions in waste cotton fabric regeneration pulp comprises the following specific processes:
(1) preparing modified chitosan:
deacetylation treatment: accurately weighing 20g of purchased chitosan powder as a raw material, adding the raw material into a three-necked bottle containing 550 mL of 50% NaOH aqueous solution, continuously stirring and stirring the mixture for 24 hours at 60 ℃, taking out the three-necked bottle, filtering the mixture, repeatedly washing the mixture by using distilled water to be neutral, freezing the mixture, and drying the mixture in a freeze dryer to finally obtain 18 g of deacetylated chitosan powder with the yield of 91.5%;
graft modification: taking 1g of deacetylated chitosan powder and 5 g of chloroacetic acid to carry out graft substitution reaction in a mixed solvent of isopropanol and alkali, neutralizing with dilute hydrochloric acid until the pH value is 7 after the reaction is finished, and dialyzing by a dialysis bag to remove unreacted chloroacetic acid; and (3) freezing by a freeze dryer to remove the solvent to obtain a chloroacetic acid grafted modified chitosan product, namely the modified chitosan.
(2) Preparation of a removing solution: preparing inorganic acid (dilute sulfuric acid with the concentration of 68 wt%), complexing agent (compound of sodium hexametaphosphate and ethylene diamine tetraacetic acid with the molar ratio of 1: 1.5) and deionized water into a removing solution with the pH value of 2, wherein the mass ratio of the inorganic acid to the complexing agent is 18: 1;
(3) treating waste cotton fabric dissolving pulp: mixing the modified chitosan, the removing solution and waste cotton fabric dissolving pulp with the solid content of 40% to obtain a mixture, and stirring once at intervals of 4min at 70 ℃ for 40 min; wherein the cotton fiber content of the waste cotton fabrics is 72 wt%, and the mass addition amount of the complexing agent is 0.1% of the absolute dry mass of the waste cotton fabric dissolving pulp; the adding amount of the modified chitosan is 0.8 percent of the absolute dry mass of the waste cotton fabric dissolving pulp; the addition amount of the removing liquid is 1.5 percent of the oven-dry mass of the waste cotton fabric dissolving pulp.
The solution in the mixture was removed by centrifugation and then washed 5 times with deionized water under conditions such that the pH of the aqueous wash reached 7.2.
By the method, Fe in the waste cotton fabric dissolving pulp 3+ Has a removal rate of 93% (determined according to the method of FZ/T50010.6-1998), Cu 2+ Has a removal rate of 75% (measured according to the method of GB/T8943.1-2008), and Mn 2 + The removal rate of (A) is 66% (determined according to the method of GB/T8943.3-2008), and the yield of the pulp is 92%
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing embodiments, or equivalents may be substituted for some of the features thereof; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions.

Claims (8)

1. A method for efficiently removing metal ions in waste cotton fabric regenerated pulp is characterized by comprising the following steps:
(1) preparing modified chitosan: firstly, deacetylating chitosan to obtain deacetylated chitosan, and then carrying out graft modification on the deacetylated chitosan to obtain chloroacetic acid graft modified chitosan, namely the modified chitosan;
(2) preparation of a removing solution: preparing acid, complexing agent and deionized water into a removing solution;
(3) treating the waste cotton fabric regenerated pulp: and (3) mixing the modified chitosan obtained in the step (1), the removing liquid obtained in the step (2) and the waste cotton fabric regenerated pulp to obtain a mixture, stirring for a certain time, then centrifuging to remove the solution in the mixture, and washing.
2. The method for efficiently removing metal ions in the waste cotton fabric regenerated pulp according to claim 1, wherein in the step (1), the specific preparation method of the modified chitosan comprises the following steps:
deacetylation treatment of chitosan: weighing chitosan powder as a raw material, adding the raw material into a reaction container containing 50% NaOH aqueous solution, stirring and reacting for a certain time, taking out, filtering, repeatedly washing with distilled water to be neutral, freezing and drying in a freeze dryer to obtain deacetylated chitosan powder;
and (3) chloroacetic acid grafting modification: performing graft substitution reaction on deacetylated chitosan powder and chloroacetic acid in a mixed solvent of isopropanol and alkali, neutralizing with dilute hydrochloric acid after the reaction is finished, and dialyzing by a dialysis bag to remove unreacted chloroacetic acid; and (3) freezing by a freeze dryer to remove the solvent to obtain a chloroacetic acid grafted modified chitosan product, namely the modified chitosan.
3. The method for efficiently removing metal ions in the waste cotton fabric regenerated pulp according to claim 2, characterized in that in the step (1), the mass ratio of the deacetylated chitosan to chloroacetic acid is 1: 0.2-5; the mass ratio of isopropanol to alkali in the mixed solvent is 5: 1; neutralizing with dilute hydrochloric acid to pH 6-8.
4. The method for efficiently removing metal ions in waste cotton fabric regenerated pulp according to claim 1, wherein in the step (2), the complexing agent comprises sodium hexametaphosphate and ethylene diamine tetraacetic acid, and the molar ratio of the sodium hexametaphosphate to the ethylene diamine tetraacetic acid is 1:1 to 2.
5. The method for efficiently removing metal ions in the waste cotton fabric regeneration pulp according to claim 4, characterized in that in the step (2), the acid is an inorganic acid, and the mass ratio of the acid to the complexing agent in the removal solution is 9-18: 1; the pH value of the removing solution is 2-9.
6. The method for efficiently removing metal ions from waste cotton fabric regeneration pulp according to claim 1, wherein in the step (3), the solid content of the waste cotton fabric regeneration pulp is 20% -40%; the cotton fiber content of the waste cotton fabric is more than 70 wt%; the adding amount of the modified chitosan is 0.5 to 1 percent of the absolute dry mass of the waste cotton fabric dissolving pulp; the addition amount of the removing liquid is 1-2% of the oven-dry mass of the waste cotton fabric dissolving pulp.
7. The method for efficiently removing metal ions from waste cotton fabric regenerated pulp according to claim 6, characterized in that in the step (3), the waste cotton fabric regenerated pulp is stirred once every 10-15 min at a temperature of 30-90 ℃, and the stirring time is 70 min.
8. The method for efficiently removing metal ions in the waste cotton fabric regenerated pulp according to claim 7, characterized in that in the step (3), the washing conditions are as follows: washing with deionized water for 3-5 times, wherein the washing termination condition is that the pH value of the washing liquid reaches neutral.
CN202210617696.7A 2022-06-01 2022-06-01 Method for efficiently removing metal ions in waste cotton fabric regeneration pulp Pending CN114984917A (en)

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CN113307888A (en) * 2021-06-10 2021-08-27 齐鲁工业大学 Carboxyl nano-cellulose and preparation method thereof

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CN105214617A (en) * 2015-09-10 2016-01-06 南京大学 Surface imprinted chitosan microball of high efficiency selected heavy metal ion and preparation method thereof
CN111636101A (en) * 2020-04-24 2020-09-08 赛得利(九江)纤维有限公司 Method for removing metal ions in waste cotton fabric dissolving pulp
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