An acid-resistant heavy metal adsorbent, a preparation method and application thereof

Abstract

An acid-resistant heavy metal adsorbent, the adsorbent has both sulfydryl and carboxyl, the adsorbent can form a multi-coordination stable structure after chelating with metal, and the molecular structural formula is.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, specifically to an acid-resistant heavy metal adsorbent, its preparation method, and its application. Background Technology

[0002] Heavy metal pollution is one of the most serious and challenging forms of pollution to address. Due to rapid industrial development, the number of industries and sectors involving heavy metals is increasing, leading to a surge in heavy metal waste emissions and exposing the ecological environment and human health to the threat of heavy metals. Therefore, it is essential to continuously develop new methods and treatment agents to combat the increasingly severe heavy metal pollution. Existing methods for treating heavy metal wastewater include traditional chemical precipitation, chelation adsorption, ferrite methods, ion exchange, ion flotation, membrane separation, electrochemical methods, adsorption, and biological methods. However, these methods require relatively weak acidity; strongly acidic solutions often need to be neutralized before treatment, resulting in large amounts of high-heavy-metal waste residue. Thiol and carboxyl groups have strong coordination abilities for many heavy metals. Therefore, the challenge of directly removing heavy metal ions from strongly acidic wastewater in the non-ferrous metals industry urgently needs to be solved. Summary of the Invention

[0003] To address the above problems, this invention provides an acid-resistant heavy metal adsorbent:

[0004] An acid-resistant heavy metal adsorbent, wherein the adsorbent possesses both thiol and carboxyl groups, and is capable of forming a multi-coordination stable structure upon chelation with a metal, the molecular structural formula of which is:

[0005] .

[0006] A method for preparing an acid-resistant heavy metal adsorbent, comprising the following steps:

[0007] S1: Take 15-20 parts by weight of mercapto acid, add it to an excess of alkaline solution, stir well, and let it stand for more than 20 minutes to allow the reaction to be complete.

[0008] S2: Add 5-10 parts by weight of polyvinyl chloride resin particles, stir and heat to above 50°C, and react for more than 4 hours;

[0009] S3: After the reaction is complete, filter to remove the liquid. Add dilute acid to the obtained filter cake to adjust the pH to 4-5. Continue stirring for 30 minutes and then filter again. Wash the filter cake with water and dry it to obtain the product.

[0010] The reaction equations for steps S1-S3 above are as follows: .

[0011] Preferably, the thioglycolic acid is one or a mixture of thioglycolic acid, thiopropionic acid, or thiosalicylic acid.

[0012] Preferably, the alkaline solution is a methanol solution of 10%-35% sodium methoxide, an ethanol solution of 10%-35% sodium ethoxide, or an ethanol solution of 10%-35% potassium tert-butoxide.

[0013] Preferably, in step S2, after adding the polyvinyl chloride particles, the reaction temperature is 50-80℃ and the reaction time is 4-16h.

[0014] Preferably, the dilute acid used to adjust the pH in step S3 is dilute sulfuric acid or dilute hydrochloric acid.

[0015] Application of an acid-resistant heavy metal adsorbent, wherein the adsorbent is used for the adsorption of heavy metals under strongly acidic conditions.

[0016] Beneficial Effects: This invention is a novel, highly efficient, acid-resistant polymeric adsorbent that possesses both thiol and carboxyl groups. Upon chelation with metals, it forms a stable multi-coordination structure, which facilitates the coordination of heavy metal ions, thereby reducing heavy metal ion concentrations in wastewater in strongly acidic solutions. It can directly complex and adsorb heavy metal ions under strongly acidic conditions, achieving concentrations of various heavy metal ions below 1 mg / L after treatment. Furthermore, because this polymeric material does not contain easily hydrolyzed groups, it can remain stable in strongly acidic solutions for extended periods, making it easy to separate from wastewater. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments.

[0018] The acid-resistant heavy metal adsorbent described in this solution is formed by simultaneously attaching thiol and carboxyl groups to polyvinyl chloride particles under certain conditions to create a high-molecular-weight multidentate complex. This complex can form a stable cyclic chelate with heavy metal elements in wastewater. Due to the stability of this cyclic structure, the chelate can exist stably under strongly acidic conditions, thereby efficiently adsorbing heavy metal ions in wastewater.

[0019] An application of an acid-resistant heavy metal adsorbent, wherein the adsorbent possesses both thiol and carboxyl groups, forming a multi-coordination stable structure after chelation with metals, enabling it to adsorb heavy metals under strongly acidic conditions. The reaction equation is as follows:

[0020] .

[0021] (1) Example:

[0022] A certain highly acidic wastewater contains 81 mg / L of cadmium, 33 mg / L of copper, 8 mg / L of lead, and 5 N of sulfuric acid.

[0023] Procedure: Take 100g of 20% sodium ethoxide ethanol solution, dilute it with 100mL of ethanol, and add 15.60g of mercaptopropionic acid dropwise while stirring. After the addition is complete, react for 30 minutes. Then add 8g of polyvinyl chloride resin particles, heat to 80℃ while stirring, and maintain the temperature for 8 hours. After the reaction is complete, filter to remove the liquid. Add the filter cake to 20mL of water, adjust the pH to 5 with 6N dilute hydrochloric acid, continue stirring for 30 minutes, filter again, wash the filter cake with water, and dry it at 80℃ to obtain the product.

[0024] The following comparison of experimental parameters is based on three samples:

[0025] (1) Original solution: Take 500ml of the above-mentioned strongly acidic wastewater, without adding any reactants or treating it, and take the clear liquid to measure the heavy metal content.

[0026] (2) Take 500ml of the above strong acid wastewater, add 2g of the above product, stir and react for 30min, filter, and take the clear liquid to measure the heavy metal content.

[0027] (3) Take 500ml of the above strongly acidic wastewater, add 4g of the above product, stir and react for 30min, filter, and take the clear liquid to determine the heavy metal content. The relevant water quality test results are shown in Table 1:

[0028] Table 1. Test Results of Water Samples (Unit: mg / L)

[0029] water sample sulfuric acid Cd Cu Pb Original solution 5N 81 33 8 After adding 2g of heavy metal removal agent 5N 0.9 3.1 0.02 After adding 4g of heavy metal removal agent 5N 0.8 0.9 0.02

[0030] Table 1 clearly shows that adding this adsorbent to the original solution resulted in a sharp decrease in the content of various heavy metals such as cadmium, copper, and lead. Because this complex can form stable cyclic chelates with heavy metal elements in wastewater, it is suitable for the adsorption of various heavy metals with significant effects. It can directly complex and adsorb heavy metal ions under strongly acidic conditions, and the concentrations of various heavy metal ions after treatment can be below 1 mg / L.

[0031] Obviously, the above embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A method for preparing an acid-resistant heavy metal adsorbent, characterized in that, The steps include: S1: Take 15-20 parts by weight of mercapto acid, add it to an excess of alkaline solution, stir well, and let it stand for more than 20 minutes to allow the reaction to be complete. The mercapto acid is mercaptopropionic acid. S2: Add 5-10 parts by weight of polyvinyl chloride resin particles, stir and heat to above 50°C, and react for more than 4 hours; S3: After the reaction is complete, filter to remove the liquid, add dilute acid to the obtained filter cake to adjust the pH to 4-5, continue stirring for 30 minutes and filter again, wash the filter cake with water and dry it to obtain the product; the alkaline solution is a 10%-35% sodium ethoxide ethanol solution. The reaction equations for steps S1-S3 above are as follows: 。 2. The method for preparing an acid-resistant heavy metal adsorbent according to claim 1, characterized in that: In step S2, after adding the polyvinyl chloride particles, the reaction temperature is 50-80℃ and the reaction time is 4-16h.

3. The method for preparing an acid-resistant heavy metal adsorbent according to claim 1, characterized in that: In step S3, the dilute acid used to adjust the pH is either dilute sulfuric acid or dilute hydrochloric acid.

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