Acid-resistant heavy metal adsorbent as well as preparation method and application thereof

Abstract

The acid-resistant heavy metal adsorbent has sulfydryl and carboxyl at the same time, the adsorbent can form a multi-coordination stable structure after being chelated with metal, and the molecular structural formula of the adsorbent is # imgabs0 #.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to an acid-resistant heavy metal adsorbent, a preparation method and application thereof. Background Art

[0002] Heavy metal pollution is the most serious pollution at present and one of the most difficult pollutions to deal with. Due to the rapid development of industry, the number of industries and fields involving heavy metals is increasing, and the amount of heavy metal waste discharged is increasing, which makes the ecological environment and humans more and more exposed to the threat of heavy metals. Therefore, new methods and treatment agents must be continuously developed to cope with the increasingly serious heavy metal pollution. Among the heavy metal wastewater treatment methods that have been developed, such as traditional chemical precipitation, chelating adsorption, ferrite, ion exchange, ion flotation, membrane separation, electrochemical, adsorption and biological methods. The disadvantage of the above methods is that they need to be used under weak acidic conditions, and strong acidic solutions often need to be neutralized before treatment, resulting in a large amount of high heavy metal waste residue. The thiol group and the carboxyl group have strong coordination ability for many heavy metals. Therefore, the problem that heavy metal ions in strong acidic wastewater in the non-ferrous field cannot be directly removed needs to be solved urgently. Summary of the invention

[0003] In order to solve the above problems, the present invention provides an acid-resistant heavy metal adsorbent: An acid-resistant heavy metal adsorbent, the adsorbent has both a thiol group and a carboxyl group, and the adsorbent can form a multi-coordinated stable structure after chelating with the metal, and its molecular structure is .

[0004] A method for preparing an acid-resistant heavy metal adsorbent, comprising the steps of: S1: Take 15-20 parts by mass of mercapto acid, add it to an excess of alkaline solution, stir evenly, and let it stand for more than 20 minutes to allow it to react completely; S2: adding 5-10 parts by mass of polyvinyl chloride resin particles, heating to above 50°C with stirring, and reacting for more than 4 hours; S3: After the reaction is completed, the liquid is filtered out, and the obtained filter cake is added with dilute acid to adjust the pH to 4-5, and the mixture is stirred for 30 minutes and then filtered again. The filter cake is washed with water and dried to obtain the product; The reaction equations of the above steps S1-S3 are as follows: .

[0005] Preferably, the mercapto acid is a mixture of one or more of thioglycolic acid, mercaptopropionic acid or thiosalicylic acid.

[0006] Preferably, the alkaline solution is a 10%-35% methanol solution of sodium methoxide, a 10%-35% ethanol solution of sodium ethoxide, or a 10%-35% ethanol solution of potassium tert-butoxide.

[0007] Preferably, after adding the polyvinyl chloride particles in step S2, the reaction temperature is 50-80° C. and the reaction time is 4-16 h.

[0008] Preferably, the dilute acid used to adjust the pH in step S3 is dilute sulfuric acid or dilute hydrochloric acid.

[0009] The invention discloses an application of an acid-resistant heavy metal adsorbent, wherein the adsorbent is applied to adsorb heavy metals under strongly acidic conditions.

[0010] Beneficial effects: The present invention is a new type of highly efficient acid-resistant polymer adsorbent, which has both thiol and carboxyl groups. After chelating with metals, it forms a multi-coordinated stable structure, which is conducive to the coordination of heavy metal ions, thereby reducing heavy metal ions in wastewater in strong acidic solutions. It can achieve direct complexation adsorption of heavy metal ions under strong acidic conditions, and the concentration of various heavy metal ions after treatment can be lower than 1 mg / L. At the same time, since there are no easily hydrolyzed groups in the structure of the polymer material, the material can be stably present in a strong acidic solution for a long time and is easy to separate from wastewater. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with the embodiments.

[0012] The acid-resistant heavy metal adsorbent described in this scheme is formed by simultaneously connecting the thiol group and the carboxyl group to the polyvinyl chloride particles under certain conditions, and the polymer multi-dentate complex can form a stable cyclic chelate with the heavy metal elements in the wastewater. Due to the stability of the cyclic structure, the chelate can stably exist under strong acidic conditions, thereby being able to efficiently adsorb heavy metal ions in the wastewater.

[0013] An application of an acid-resistant heavy metal adsorbent, the adsorbent has both a thiol group and a carboxyl group, and forms a multi-coordinated stable structure after chelating with a metal, and can be used for adsorption of heavy metals under strongly acidic conditions. The reaction equation is as follows: .

[0014] (1) Example: A strongly acidic wastewater, in which the cadmium content is 81 mg / L, the copper content is 33 mg / L, the lead content is 8 mg / L, and the sulfuric acid content is 5N.

[0015] Steps: Take 100g of 20% sodium ethanol ethanol solution, dilute it with 100mL ethanol, add 15.60g of mercaptopropionic acid dropwise into it under stirring, react for 30min, then add 8g of polyvinyl chloride resin particles into it, heat to 80℃ and react for 8h under stirring. After the reaction is completed, filter to remove the liquid, add the filter cake into 20mL water, adjust the pH to 5 with 6N dilute hydrochloric acid, continue stirring for 30min and filter again, wash the filter cake with water and dry it at 80℃ to obtain the product.

[0016] The following three samples were used to compare the corresponding experimental parameters: (1) Stock solution: Take 500 ml of the above-mentioned strongly acidic wastewater, without adding any reactants or treating it, and measure the heavy metal content in the clear solution.

[0017] (2) Take 500 ml of the above-mentioned strongly acidic wastewater, add 2 g of the above-mentioned product, stir and react for 30 minutes, filter, and take the clear liquid to measure the heavy metal content.

[0018] (3) Take 500 ml of the above-mentioned strongly acidic wastewater, add 4 g of the above-mentioned product, stir and react for 30 minutes, filter, and take the clear liquid to measure the heavy metal content. The relevant water quality test results are shown in Table 1: Table 1 Water sample test results (unit: mg / L) Water Sample sulfuric acid Cd Cu Pb Original solution 5N 81 33 8 After adding 2g heavy metal removal agent 5N 0.9 3.1 0.02 After adding 4g heavy metal removal agent 5N 0.8 0.9 0.02 From Table 1 above, it can be clearly concluded that after adding the adsorbent to the stock solution, the content of various heavy metals such as cadmium, copper and lead is drastically reduced. Since the complex can form a stable cyclic chelate with heavy metal elements in wastewater, it can be applied to various heavy metal adsorption with significant effect. It can realize direct complexation adsorption of heavy metal ions under strong acidic conditions, and the concentration of various heavy metal ions after treatment can be lower than 1mg / L.

[0019] Obviously, the above embodiments of the present invention are merely examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to exhaust all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. An acid-resistant heavy metal adsorbent, characterized in that: The adsorbent has both a thiol group and a carboxyl group, and can form a multi-coordinated stable structure after chelating with a metal, and its molecular structure is 。 2. A method for preparing an acid-resistant heavy metal adsorbent, characterized in that: The steps include: S1: Take 15-20 parts by mass of mercapto acid, add it to an excess of alkaline solution, stir evenly, and let it stand for more than 20 minutes to allow it to react completely; S2: adding 5-10 parts by mass of polyvinyl chloride resin particles, heating to above 50°C with stirring, and reacting for more than 4 hours; S3: After the reaction is completed, the liquid is filtered out, and the obtained filter cake is added with dilute acid to adjust the pH to 4-5, and the mixture is stirred for 30 minutes and then filtered again. The filter cake is washed with water and dried to obtain the product; The reaction equations of the above steps S1-S3 are as follows: 。 3. The method for preparing an acid-resistant heavy metal adsorbent according to claim 2, characterized in that: The mercapto acid is one or more of thioglycolic acid, mercaptopropionic acid or thiosalicylic acid.

4. The method for preparing an acid-resistant heavy metal adsorbent according to claim 2, characterized in that: The alkaline solution is a 10%-35% methanol solution of sodium methoxide, a 10%-35% ethanol solution of sodium ethoxide or a 10%-35% ethanol solution of potassium tert-butoxide.

5. The method for preparing an acid-resistant heavy metal adsorbent according to claim 2, characterized in that: After adding the polyvinyl chloride particles in step S2, the reaction temperature is 50-80°C and the reaction time is 4-16h.

6. The method for preparing an acid-resistant heavy metal adsorbent according to claim 2, characterized in that: The dilute acid used to adjust the pH in step S3 is dilute sulfuric acid or dilute hydrochloric acid.

7. An application of the acid-resistant heavy metal adsorbent according to claim 1, characterized in that: The adsorbent is used for adsorbing heavy metals under strong acidic conditions.

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