CN104209094A - Preparation method of sepiolite heavy metal absorbent modified with amino acid carboxylic acid - Google Patents

Abstract

The invention provides a method for preparing an aminocarboxylic acid-modified sepiolite heavy metal adsorbent, which belongs to the technical field of environmental protection. Prepare sepiolite suspension according to the ratio of sepiolite: deionized water: absolute ethanol = 2.5～5:40～70:35～55 (w/v/v/), and stir to form a gel; at 7000 Add the N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution with a mass concentration of 10-20% under the stirring condition of ～10000rpm, and the ratio of it to sepiolite is 4.5～9:2～ 3 (v/w); Add absolute ethanol, continue to stir to form a gel system, then use absolute ethanol to filter and collect the gel filter cake; place the filter cake in an oven at a constant temperature of 70-80°C for 18 hours and then bake After drying, the aminocarboxylic acid modified sepiolite can be obtained after grinding. The invention has simple process, low cost, wide application range and no secondary pollution.

Description

Preparation method of aminocarboxylic acid modified sepiolite heavy metal adsorbent

technical field

The invention relates to a preparation technology of a heavy metal adsorption material, in particular to a preparation method of an aminocarboxylic acid-modified sepiolite heavy metal adsorbent, which belongs to the technical field of environmental protection.

Background technique

As an important support for my country's economy, industry has brought about increasingly serious environmental pollution problems with its rapid development, especially with frequent mining, metal smelting and processing, a large amount of waste gas and waste water containing lead, mercury, cadmium, cobalt, copper, etc. and solid waste discharged into the environment, causing serious harm. According to incomplete statistics, the world currently discharges an average of 15,000 tons of mercury, 3.4 million tons of copper, 5 million tons of lead, 15 million tons of manganese, and 1 million tons of nickel, etc. The concentration of heavy metals in the soil was significantly higher than the background value. Heavy metal pollution will not only seriously affect and change the ecological functions of water bodies and soils, but also lead to a decline in crop yield and quality. Excessive accumulation of heavy metals in the food chain will cause great harm to the natural environment and human health, affecting society. sustainable economic development.

At present, people use a variety of methods, such as: chemical precipitation, adsorption, air flotation, redox, etc., to treat heavy metal ions in wastewater, among which chemical precipitation and adsorption are the most widely used.

The chemical formula of sepiolite is Mg ₈ Si ₁₂ O ₃₀ (OH) ₄ (OH ₂ ) ₄ 8H ₂ O, which is a fibrous magnesium-rich silicate mineral with a 2:1 chain layer structure. Usually white, light gray, light yellow and other colors, opaque and dull, hardness 2-3, density 2-2.5g/cm ³ , has the advantages of low shrinkage, good plasticity, large specific surface, strong adsorption and thermal stability, etc. . my country is one of the few countries rich in sepiolite in the world. It is widely distributed in Hunan, Jiangxi and Hebei, but its development and utilization are very backward, and the raw materials are still mainly exported. The theoretical specific surface area of sepiolite is 900m ² /g, which is close to that of activated carbon, but its price is only one tenth of that. In recent years, improving material performance through surface modification methods, preparing materials with advanced functions and outstanding performance, and composite materials have become research hotspots. Therefore, it is extremely important to strengthen the development and utilization of sepiolite, especially to improve the adsorption performance of sepiolite through surface modification.

In 2000, scholar Mercier used 3-mercapto-pro-pyltrimethoxysilane (3-mercapto-pro-pyltrimethoxysilane) to modify the surface of sepiolite in toluene solution, and the modified material had the maximum resistance to Pb ²⁺ and Cd ²⁺ The adsorption amounts were 0.31 mmol/g and 0.21 mmol/g, respectively. But because this reaction is carried out in the organic solution toluene, it will inevitably cause certain pollution and harm. Therefore, it is urgent to develop a fast, low-cost, green and environmentally friendly synthesis process to modify the surface of sepiolite to improve its adsorption performance.

Contents of the invention

The purpose of the present invention is to provide a method for preparing aminocarboxylic acid-modified sepiolite as a heavy metal adsorbent with simple process, low cost, wide application range and no secondary pollution.

In order to achieve the above object, the present invention provides a nano-textured method for preparing aminocarboxylate sepiolite, which can be used as a heavy metal adsorbent, and the preparation method is as follows:

(1) Take sepiolite powder, disperse it in deionized water, add absolute ethanol to form sepiolite suspension, wherein, sepiolite: deionized water: absolute ethanol=2.5～5:40～70: 35～55(w/v/v/);

(2) preparing N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution with a mass concentration of 10-20%, for subsequent use;

(3) Stir the sepiolite suspension on a disperser to form a gel, then add N-(trimethoxysilylpropyl)ethylenediamine prepared in step (2) under the stirring condition of 7000~10000rpm Trisodium triacetate solution, the ratio of N-(trimethoxysilylpropyl) ethylenediamine trisodium trisodium salt solution to sepiolite with a mass concentration of 10-20% is 4.5-9:2-3 (v/w);

(4) Add absolute ethanol, continue stirring to form an aminocarboxylic acid modified sepiolite gel system, transfer the gel system to a Buchner funnel, suction filter with absolute ethanol and collect the gel filter cake;

(5) Transfer the above-mentioned gel filter cake to a jar, place it in an oven at a constant temperature of 70-80°C, and after 18 hours, take out the gel in the jar, dry it, and grind it to obtain aminocarboxylic acid-modified seawater. Sepiolite (TMS-EDTA-Sepiolite).

The present invention has the following advantages:

(1) Wide range of application: the adsorption material prepared by the present invention is mainly used for wastewater treatment containing heavy metal ions, water body restoration, and heavy metal-contaminated soil restoration, etc. Pollution also has a significant effect.

(2) Good adsorption effect: The heavy metal adsorption and separation material prepared by the present invention is aminocarboxylic acid modified sepiolite, which contains a large number of active functional groups, and can adsorb heavy metals through surface complexation reactions such as chemical adsorption. Acid-modified sepiolite has good adsorption effect on lead (Pb), cadmium (Cd) and copper (Cu).

(3) less dosage, easy to popularize: the material of the present invention can achieve better results when the dosage is less, the cost is low, no secondary pollution will occur, and it is easily accepted by the society. It is simple and can be used on a large scale.

(4) The present invention adopts a fast and low-cost one-step synthesis process, uses water as the reaction medium, and is environmentally friendly; the adsorption performance of the product is further improved, and the maximum adsorption capacity for Pb ²⁺ , Cd ²⁺ and Cu ²⁺ is respectively 0.338, 0.357 and 0.469mmol/g; the operation is simple, the yield is high, and it is beneficial to promote large-scale production.

Detailed ways

Example 1

Take by weighing sepiolite powder 3g, add 50ml deionized water, 40ml dehydrated alcohol, form sepiolite suspension; The sepiolite suspension is stirred at a high speed of 8000rpm on the disperser for 8min to form a gel, for subsequent use ( 1); the mass concentration purchased is that 45% N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution 2ml is dissolved in deionized water, and the preparation mass concentration is that 10% salt solution is standby (II); Continue to pour 9ml (II) of N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution consumption amount of 10% under the stirring condition of 8000rpm into (I), Add 1ml of absolute ethanol and continue to stir at 8000rpm for 25min to form an aminocarboxylic acid modified sepiolite gel system, wherein the ratio of sodium salt solution to sepiolite is 9:3 (v/w); the reaction gel system Transfer to a Buchner funnel, filter with absolute ethanol and collect the gel filter cake, transfer the gel filter cake to a jar, place in an oven at a constant temperature of 70°C for 18 hours, then take out the gel in the jar , dried at 80°C, and after grinding, 3.17 g of aminocarboxylic acid-modified sepiolite was obtained.

Example 2

Weigh 2.5g of sepiolite powder, add 70ml of deionized water and 55ml of absolute ethanol to form a sepiolite suspension; stir the sepiolite suspension on a disperser at a speed of 7000rpm for 8min to form a gel, and set aside (1); 45% N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution 2.5ml is dissolved in deionized water by the mass concentration purchased, and the preparation mass concentration is 15% salt The solution is ready for use (II); under the stirring condition of 10000 rpm, the mass concentration of 15% N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution consumption 7.5ml (II) is poured into (I) , add 3ml of absolute ethanol, and continue to stir at 8000rpm for 25min to form an aminocarboxylic acid modified sepiolite gel system, wherein the ratio of sodium salt solution to sepiolite is 7.5:2.5 (v/w); the reaction gel Transfer the system to a Buchner funnel, filter with absolute ethanol and collect the gel filter cake, transfer the gel filter cake to a jar, place it in an oven at a constant temperature of 80°C for 18 hours, and put the gel in the jar Take it out, dry at 80°C, and grind to obtain 2.55 g of aminocarboxylic acid-modified sepiolite.

Example 3

Take by weighing sepiolite 4g, add 40ml deionized water, 35ml dehydrated alcohol, form sepiolite suspension; The sepiolite suspension is formed gel with the speed of 9000rpm high-speed stirring 7min on disperser, standby (1 ); the purchased mass concentration is 45% N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution 4ml is dissolved in deionized water, and the preparation mass concentration is 20% salt solution for subsequent use ( II); under the stirring condition of 9000rpm, the mass concentration is 20% N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution consumption 9ml (II) is poured into (I), add 2ml without Water ethanol, continue stirring at 9000rpm for 25min to form aminocarboxylic acid modified sepiolite gel system, wherein the ratio of sodium salt solution and sepiolite is 4.5:2 (v/w); the reaction gel system is transferred to cloth filter with absolute ethanol to collect the gel filter cake, transfer the gel filter cake to a jar, and place it in an oven at a constant temperature of 80°C for 18 hours, then take out the gel in the jar and heat it at 65°C After drying and grinding, 4.20 g of aminocarboxylic acid-modified sepiolite was obtained.

Example 4

Amino carboxylic acid modified sepiolite for adsorption of Pb ²⁺ , Cd ²⁺ and Cu ²⁺ in aqueous solution.

Prepare Pb ²⁺ , Cd ²⁺ , and Cu ²⁺ solutions with a concentration of 100mg/L as the working solution, measure 25ml each and place them in a 50ml centrifuge tube, and weigh the aminocarboxylic acid-modified seafoam prepared in Example 1 Add 0.025g of sepiolite to the centrifuge tube that has been added with Pb ²⁺ , Cd ²⁺ and Cu ²⁺ contaminated working solution, the ratio of aminocarboxylic acid modified sepiolite to contaminated working solution is 1g/L, shake at 25°C for 6h, After centrifuging at 3800rpm, take the supernatant, measure the concentration of Pb ²⁺ , Cd ²⁺ and Cu ²⁺ in the solution with an atomic absorption spectrophotometer, and calculate the concentration difference of Pb ²⁺ and Cd ²⁺ in the working solution before and after the concentration of amino carboxylic acid Modifies the adsorption amount of sepiolite.

The results show that aminocarboxylic acid modified sepiolite has good adsorption effect on lead, cadmium and copper pollution in solution, and its saturated adsorption capacity is: lead 0.338mmol/g, cadmium 0.357mmol/g and copper 0.469mmol/g .

Claims (1)

1. the preparation method of aminocarboxylic acid modified sepiolite heavy metal adsorbent, is characterized in that: comprise the following steps: (1) Take sepiolite powder, disperse it in deionized water, add absolute ethanol to form sepiolite suspension, wherein, sepiolite: deionized water: absolute ethanol=2.5～5:40～70: 35～55(w/v/v/); (2) preparing N-(trimethoxysilylpropyl) ethylenediaminetriacetic acid trisodium salt solution with a mass concentration of 10-20%, for subsequent use; (3) Stir the sepiolite suspension on a disperser to form a gel, then add N-(trimethoxysilylpropyl)ethylenediamine prepared in step (2) under the stirring condition of 7000~10000rpm Trisodium triacetate solution, the ratio of N-(trimethoxysilylpropyl) ethylenediaminetriacetate trisodium salt solution to sepiolite is 4.5-9:2-3 (v/w); (4) Add absolute ethanol, continue stirring to form an aminocarboxylic acid modified sepiolite gel system, transfer the gel system to a Buchner funnel, suction filter with absolute ethanol and collect the gel filter cake; (5) Transfer the above-mentioned gel filter cake to a jar, place it in an oven at a constant temperature of 70-80°C, and after 18 hours, take out the gel in the jar, dry it, and grind it to obtain aminocarboxylic acid-modified seawater. pumice.