Adsorptive material for heavy metal pollution and preparation method thereof

Abstract

The application discloses an adsorbing material for heavy metal pollution and a preparation method thereof, and belongs to the technical field of fine chemical industry. Acetic acid solution and chitosan are added into carboxylated graphene to obtain a carboxylated graphene-chitosan mixed solution through ultrasonic dispersion; then, acetic acid solution, 2-pyrrole formaldehyde and magnetic biochar are added into the mixed solution to obtain a magnetic composite material through water bath stirring; beta-cyclodextrin, NaOH solution and epichlorohydrin are mixed, and the magnetic composite material is added into the mixture to obtain the adsorbing material through reaction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adsorption materials, and particularly relates to an adsorption material for heavy metal pollution and a preparation method thereof. BACKGROUND

[0002] Photoetching process is a key technology in TFT-LCD panel and semiconductor integrated circuit manufacturing, and photoresist stripping liquid is a core auxiliary material for the process, which is used for removing photoresist coated on a wafer. The market size of photoresist stripping liquid can predict that a large amount of waste photoresist stripping liquid will be generated every year, which is composed of impurities such as high molecular resin and photosensitizer and high-value organic solvents.

[0003] On the one hand, since the stripping liquid is used for stripping photoresist, the waste stripping liquid contains many photoresist components, and the photoresist mainly includes photosensitive substances, resins and some other materials beneficial to use such as stabilizers, polymerization inhibitors, viscosity control agents and chemical solubilizers and the like, so the waste stripping liquid has the problems of difficult separation of effective components and low yield. On the other hand, since the stripping liquid is used in the semiconductor industry, the concentration of harmful metal ions in the solution is required to be extremely low.

[0004] Biochar has attracted extensive attention in the field of adsorbing heavy metal ions due to its advantages of wide raw material sources, large specific surface area and low cost. However, the biochar has insufficient adsorption active sites and is difficult to be quickly separated from the aqueous solution, resulting in low adsorption efficiency. SUMMARY

[0005] The application aims to provide an adsorption material for heavy metal pollution and a preparation method thereof, so as to solve the problem of excessive heavy metal ions in waste stripping liquid.

[0006] The application can be achieved by the following technical solutions.

[0007] An adsorption material for heavy metal pollution, characterized in that acetic acid solution and chitosan are added to 5-10 parts by weight of carboxylated graphene to obtain a carboxylated graphene-chitosan mixed solution by ultrasonic dispersion; acetic acid solution, 3-5 parts by weight of 2-pyrrole formaldehyde and 2-4 parts by weight of magnetic biochar are further added to the mixed solution to obtain a magnetic composite material by water bath stirring; 2-4 parts by weight of β-cyclodextrin, NaOH solution and 1-2 parts by weight of epichlorohydrin are mixed, and the magnetic composite material is added to the mixture to obtain the adsorption material by reaction.

[0008] Further, the preparation method of the adsorption material for heavy metal pollution is characterized by comprising the following steps.

[0009] 1) 1:50 to 10-20 parts by weight of carboxylated graphene-chitosan mixed solution, add 5% acetic acid solution with a concentration of 15-25 parts by weight of 2-pyrrole formaldehyde, adjust the water bath temperature to 70-80 DEG C, mechanical stirring for 1-2h, add 15-20 parts by weight of magnetic biochar, after uniform stirring at 25-35 DEG C for 1-2h, drying at 60-80 DEG C to obtain a magnetic composite material;

[0010] 2) 1:10 to 10-20 parts by weight of beta-cyclodextrin is added to 1mol·L –1 of NaOH solution, then 7-15 parts by weight of epichlorohydrin is added as a crosslinking agent, and after reaction at room temperature for 1-2h, 1-3 parts by weight of magnetic composite material is added, and after continuous stirring for 1-2h, it is washed with distilled water and ethanol solution to obtain the adsorbent material.

[0011] Further, the preparation of the carboxylated graphene-chitosan mixed solution is as follows:

[0012] 100-200 parts by weight of 2% acetic acid solution with a mass fraction, 1-2 parts by weight of carboxylated graphene is added, after ultrasonic dispersion, 4-8 parts by weight of chitosan is added, and ultrasonic dispersion is continued for 40-60min to obtain a carboxylated graphene-chitosan mixed solution.

[0013] Further, the preparation of the carboxylated graphene is as follows:

[0014] 10-20 parts by weight of graphene oxide, 10-20 parts by weight of distilled water are ultrasonic dispersed and mixed uniformly, 0.1-0.2 parts by weight of NaOH is added, and after ultrasonic dispersion for 30-50min, 0.2-0.4 parts by weight of bromoacetic acid is added, ultrasonic dispersion for 15-30min, reaction at room temperature for 1-2h, centrifugation, washing, suction filtration, vacuum drying to obtain carboxylated graphene.

[0015] Further, the preparation of the magnetic biochar is as follows:

[0016] Under the protection of nitrogen, 4-8 parts by weight of FeCl3·6H2O, 2-4 parts by weight of FeSO4·7H2O, 4-8 parts by weight of biochar are mixed and stirred in 100 parts by weight of distilled water for 30-40min, the pH value of the solution is adjusted to 10-11 with NH3·H2O, then boiled and stirred for 1h, and then collected by external magnetic field, washed with distilled water and freeze-dried to obtain magnetic biochar.

[0017] The beneficial effects of the present application are:

[0018] (1) Biochar has good application prospects in heavy metal pollution remediation due to its rich carbon content, high specific surface area, developed pore structure, and rich functional groups. However, it still has some shortcomings such as insufficient adsorption active sites, difficulty in rapid separation from aqueous solution, low adsorption efficiency, difficulty in recycling, non-reusability, and potential secondary pollution.

[0019] The introduction of magnetic precursor iron salt solution (FeCl3·6H2O, FeSO4·7H2O) into biochar results in magnetic biochar. The surface functional groups of magnetic biochar are more abundant, the pore structure is more developed, the specific surface area is larger, and it has strong magnetism, which enables it to adsorb heavy metals and easily separate solid-liquid by magnetic force equipment and has high reusability.

[0020] (2) The structure of graphene oxide has a small amount of epoxy and hydroxyl groups in the center of the sheet, and a certain amount of carboxyl and hydroxyl groups on the edges of the sheet. The rich oxygen-containing functional groups on the graphene oxide sheet also give it the advantage of easy functional modification.

[0021] Carboxylation modification mainly involves nucleophilic substitution reaction between halogen atoms and epoxy groups on the graphene sheet, and some hydroxyl groups also participate. After carboxylation modification, the content of carboxyl groups increases and the content of hydroxyl groups decreases. Carboxylation modification can enhance the negative charge of the graphene oxide sheet, thereby improving the compatibility of graphene oxide and chitosan. Chitosan, as a natural polysaccharide organic matter, has the characteristics of environmental friendliness, and contains a large number of nitrogen-containing functional groups that can adsorb metal ions in water. The compatibility of carboxylated graphene with chitosan is higher than that of graphene oxide, and the stability is also improved to some extent.

[0022] Pb 2+ , Cd 2+ , Cu 2+ exist mainly in the form of cations in water, and the increase in negative charge helps to improve the interaction of coordination bonds between the composite material and Pb 2+ , Cd 2+ , Cu 2+ .

[0023] (3) β-cyclodextrin is a non-toxic, green, biodegradable, and low-cost macrocyclic oligosaccharide compound with a cavity structure and a large number of hydroxyl groups, which can form non-toxic complexes with heavy metal ions. However, β-cyclodextrin is easily soluble in water and has poor stability, making it difficult to recover in aqueous phase, which greatly limits its application in water treatment. It can be constructed on other carriers to synthesize water treatment adsorbents with long service life, good mechanical properties, and high dispersion performance.

[0024] The activation of NaOH can promote the development of pore structure, and the magnetization and modification of β-cyclodextrin make the structure of the biochar more fluffy and the surface more rough, so that the specific surface area is increased. The surface of the modified adsorption material contains more hydroxyl and carboxyl groups, which provides more active sites for adsorbing Pb 2+ , Cd 2+ , Cu 2+ , and the oxygen-containing groups on the surface of the β-cyclodextrin-modified adsorption material produce surface complexation and electrostatic interaction with Pb(II), so that the modified adsorption material has strong adsorption effect on Pb 2+ , Cd 2+ , Cu 2+ . DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment 1

[0027] A preparation method of an adsorption material for heavy metal pollution, characterized in that it comprises the following steps:

[0028] (1) Preparation of magnetic biochar:

[0029] 4 parts by weight of FeCl3·6H2O, 2 parts by weight of FeSO4·7H2O and 4 parts by weight of biochar are mixed in 100 parts by weight of distilled water under nitrogen protection and stirred for 30 min, the pH value of the solution is adjusted to 10 with NH3·H2O, then boiled and continuously stirred for 1 h, collected by an external magnetic field, washed with distilled water and freeze-dried to obtain magnetic biochar;

[0030] (2) Preparation of carboxylated graphene:

[0031] 10 parts by weight of graphene oxide and 10 parts by weight of distilled water are uniformly dispersed and mixed by ultrasonic, 0.1 parts by weight of NaOH is added, and ultrasonic is continued for 30 min, then 0.2 parts by weight of bromoacetic acid is added, ultrasonic dispersion is carried out for 15 min, and reaction is carried out at room temperature for 1 h, then centrifugation, washing, suction filtration and vacuum drying are carried out to obtain carboxylated graphene;

[0032] (3) Preparation of carboxylated graphene-chitosan mixed solution:

[0033] 100 parts by weight of a 2% by mass acetic acid solution was added to 1 part by weight of the carboxylated graphene obtained in step (2), and after ultrasonic dispersion, 4 parts by weight of chitosan was added, and ultrasonic dispersion was continued for 40 min to obtain a carboxylated graphene-chitosan mixed solution;

[0034] (4) To 10 parts by weight of the carboxylated graphene-chitosan mixed solution obtained in step (3), 1:50 of a 5% acetic acid solution was added, and after being placed in a 30°C water bath and mechanically stirred for 1 h, 15 parts by weight of 2-pyrrole formaldehyde was added, the water bath temperature was adjusted to 70°C, and mechanical stirring was continued for 1 h. 15 parts by weight of the magnetic biochar obtained in step (1) was added, and after being uniformly stirred at 25°C for 1 h, it was dried at 60°C to obtain a magnetic composite material;

[0035] (5) 10 parts by weight of β-cyclodextrin was added to 1 mol·L –1 of a NaOH solution, and 7 parts by weight of epichlorohydrin was added as a crosslinking agent. After reaction at room temperature for 1 h, 1 part by weight of the magnetic composite material obtained in step (4) was added, and after continuous stirring for 1 h, it was washed with distilled water and an ethanol solution to obtain the adsorption material.

[0036] Example 2

[0037] A preparation method of an adsorption material for heavy metal pollution, characterized in that it comprises the following steps:

[0038] (1) Preparation of magnetic biochar:

[0039] Under nitrogen protection, 8 parts by weight of FeCl3·6H2O, 4 parts by weight of FeSO4·7H2O, and 4-8 parts by weight of biochar were mixed and stirred in 100 parts by weight of distilled water for 40 min. After adjusting the pH of the solution to 11 with NH3·H2O, boiling and continuing to stir for 1 h, it was collected by an external magnetic field, washed with distilled water and freeze-dried to obtain magnetic biochar;

[0040] (2) Preparation of carboxylated graphene:

[0041] 20 parts by weight of graphene oxide and 20 parts by weight of distilled water were ultrasonically dispersed and mixed uniformly, 0.2 parts by weight of NaOH was added, and ultrasonic dispersion was continued for 50 min. After adding 0.4 parts by weight of bromoacetic acid, ultrasonic dispersion was continued for 30 min, and reaction was carried out at room temperature for 2 h. After centrifugation, washing, suction filtration, and vacuum drying, carboxylated graphene was obtained;

[0042] (3) Preparation of a carboxylated graphene-chitosan mixed solution:

[0043] A 200 parts by weight of a 2% by mass acetic acid solution was added to 2 parts by weight of the carboxylated graphene obtained in step (2), and after ultrasonic dispersion, 8 parts by weight of chitosan was added and ultrasonic dispersion was continued for 60 min to obtain a carboxylated graphene-chitosan mixed solution;

[0044] (4) To 20 parts by weight of the carboxylated graphene-chitosan mixed solution obtained in step (3), a 5% by mass acetic acid solution was added at a ratio of 1:50, and after being placed in a 40°C water bath and mechanically stirred for 2 h, 25 parts by weight of 2-pyrrole formaldehyde was added, the water bath temperature was adjusted to 80°C, and mechanical stirring was continued for 2 h. 20 parts by weight of the magnetic biochar obtained in step (1) was added, and after being uniformly stirred at 35°C for 2 h, it was dried at 80°C to obtain a magnetic composite material;

[0045] (5) 20 parts by weight of β-cyclodextrin was added to a 1 mol·L –1 of NaOH solution at a ratio of 1:10, and 15 parts by weight of epichlorohydrin was added as a crosslinking agent. After reaction at room temperature for 2 h, 3 parts by weight of the magnetic composite material obtained in step (4) was added, and after continuous stirring for 2 h, it was washed with distilled water and an ethanol solution to obtain the adsorption material.

[0046] Comparative Example 1

[0047] Compared with Example 1, the biochar in step (1) was not treated, and the remaining steps were the same.

[0048] Comparative Example 2

[0049] Compared with Example 1, the graphene oxide in step (2) was not treated, and the remaining steps were the same.

[0050] Comparative Example 3

[0051] Compared with Example 1, chitosan was not added in step (3), and the remaining steps were the same.

[0052] Comparative Example 4

[0053] Compared with Example 1, β-cyclodextrin was not added in step (5), and the remaining steps were the same.

[0054] Comparative Example 5

[0055] Compared with Example 1, only biochar was added.

[0056] The adsorption materials prepared in Examples 1-2 and Comparative Examples 2-4 were subjected to performance testing, and the results are shown in Table 1:

[0057] The waste stripping solution is a raw material used in our company's production and R&D. 5g of adsorbent material was added to 100mL of the waste stripping solution, and after shaking and adsorption for 4 hours, the adsorbent was separated from the solution using an external magnet. 5mL of the supernatant was collected, filtered through a 0.22µm microfiltration membrane, and the Pb content in the waste stripping solution was determined using an atomic absorption spectrophotometer. 2+ Cd 2+ Cu 2+ The concentration of Pb, the adsorption material for Pb 2+ Cd 2 + Cu 2+ Adsorption amount (q) e (mg / g) and removal rate (R, %):

[0058] q e =(C0-C e )*V / m;R=(C0-C e ) / C0*100%;

[0059] q e Indicates the adsorption material's affinity for Pb 2+ Cd 2+ Cu 2+ The adsorption capacity (mg / g), C0 represents the amount of Pb before adsorption. 2+ Cd 2+ Cu 2+ The initial concentration (mg / L), C e This indicates that Pb adsorption has reached equilibrium. 2+ Cd 2+ Cu 2+ The concentration of adsorbent is (mg / L), m is the mass of adsorbent material (mg), and V is the volume of adsorption solution (mL).

[0060] Table 1

[0061]

[0062] The performance of the waste stripping liquid treated by the adsorption material prepared in Example 1 is as follows:

[0063] Indicators Metal ion concentration Particulate matter (≥ 0.5 um) Active content Moisture Colour (Pt-Co Requirements 1.0 x 10 -12 ]]> 40 per ml 99.9 0.05％ 6

[0064] As shown in Table 1, the adsorbents prepared in Examples 1 and 2 effectively removed Pb from the waste stripping solution. 2+ Cd 2+ Cu 2+ It has a large adsorption capacity and a high removal rate; the adsorption materials prepared in Comparative Examples 1-4 showed good adsorption capacity and removal rate for Pb in waste stripping liquid. 2+ Cd 2+ Cu 2+The adsorption amount of the adsorbent is reduced, and the removal rate is reduced. In the comparative example 5, the biochar is directly added to treat the Pb 2+ , Cd 2+ , Cu 2+ , and the effect is not ideal.

[0065] The recycling performance of the adsorbent obtained in example 1: 20 mg of the adsorbent was added to 20 mL of the waste stripping solution, and after oscillation adsorption for 4 h, the solid-liquid separation was realized by a magnet, 20 mL of 0.1 mol / L HNO3 solution was used to desorb the adsorbent, and after oscillation for 4 h, the solid-liquid separation was realized by an external magnetic field, and then the adsorbent was dried in a 60℃ oven for 2 h. The regeneration experiment was continuously carried out for 5 cycles. After five cycles of desorption, the removal rate of Pb 2+ , Cd 2+ , Cu 2+ still reached more than 89%.

[0066] It should be noted that the relational terms herein, such as first and second, are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between or among the entities or operations. Also, the terms "comprises", "comprising", or any other variations thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or apparatus including a list of elements does not only include those elements, but also includes other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0067] Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An adsorbent material for heavy metal pollution, characterized in that, Add acetic acid solution and chitosan to 5-10 parts by weight of carboxylated graphene, and disperse by ultrasonication to obtain a mixed solution of carboxylated graphene and chitosan; then add acetic acid solution, 3-5 parts by weight of 2-pyrrolecarboxaldehyde, and 2-4 parts by weight of magnetic biochar and stir in a water bath to obtain a magnetic composite material; mix 2-4 parts by weight of β-cyclodextrin, NaOH solution, and 1-2 parts by weight of epichlorohydrin, add the magnetic composite material, and react to obtain the adsorbent material. The carboxyl-based graphene is prepared as follows: 10-20 parts by weight of graphene oxide and 10-20 parts by weight of distilled water are ultrasonically dispersed and mixed evenly. 0.1-0.2 parts by weight of NaOH are added, and ultrasonication is continued for 30-50 min. Then, 0.2-0.4 parts by weight of bromoacetic acid are added, and ultrasonic dispersion is carried out for 15-30 min. The mixture is reacted at room temperature for 1-2 h. After centrifugation, washing, filtration, and vacuum drying, carboxylated graphene is obtained. The magnetic biochar is prepared as follows: Under nitrogen protection, 4-8 parts by weight of FeCl3·6H2O, 2-4 parts by weight of FeSO4·7H2O, and 4-8 parts by weight of biochar were mixed and stirred in 100 parts by weight of distilled water for 30-40 minutes. The pH of the solution was adjusted to 10-11 with NH3·H2O, then boiled and stirred for 1 hour. The mixture was collected by an external magnetic field, washed with distilled water, and freeze-dried to obtain magnetic biochar.

2. The method for preparing an adsorbent material for heavy metal pollution according to claim 1, characterized in that, Includes the following steps: 1) Add a 5% acetic acid solution at a ratio of 1:50 to 10-20 parts by weight of a carboxylated graphene-chitosan mixed solution. After mechanically stirring in a water bath at 30-40℃ for 1-2 hours, add 15-25 parts by weight of 2-pyrrolecarboxaldehyde. Adjust the water bath temperature to 70-80℃ and mechanically stir for 1-2 hours. Then add 15-20 parts by weight of magnetic biochar. After uniformly stirring at 25-35℃ for 1-2 hours, dry at 60-80℃ to obtain a magnetic composite material. 2) Add 10-20 parts by weight of β-cyclodextrin at a ratio of 1:10 to 1 mol∙L⁻¹ –1 In a NaOH solution, 7-15 parts by weight of epichlorohydrin are added as a crosslinking agent. After reacting at room temperature for 1-2 hours, 1-3 parts by weight of magnetic composite material are added. After stirring continuously for 1-2 hours, the mixture is washed with distilled water and ethanol solution to obtain the adsorbent material.

3. The method for preparing an adsorbent material for heavy metal pollution according to claim 2, characterized in that, The carboxylated graphene-chitosan mixed solution was prepared as follows: Add 1-2 parts by weight of carboxylated graphene to 100-200 parts by weight of 2% acetic acid solution, disperse by ultrasonication, add 4-8 parts by weight of chitosan, and continue ultrasonic dispersion for 40-60 minutes to obtain a mixed solution of carboxylated graphene and chitosan.

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