CN105219393A - The preparation method of lignin modification heavy metal deactivator - Google Patents

Abstract

The invention discloses a preparation method of a lignin-modified heavy metal passivator. The method comprises the following steps: (11) dissolving a certain amount of lignin in water to form a solution, and adjusting the solution to acidity; (2) according to Add ferrous chloride and hydrogen peroxide sequentially in a certain proportion, heat and react for a period of time and then let it stand; (3) adjust the solution to be alkaline, then add a certain amount of diethylenetriamine and formaldehyde in turn, stir evenly, and heat for a period of time; (4) After the reaction is completed, add hydrochloric acid solution dropwise under stirring to make the product fully separated, and obtain aminated modified lignin after standing and suction filtration; (5) wash off unreacted medicament with water, and then dry the product Grinding to obtain the finished product of lignin amination modified heavy metal deactivator. The method of the invention has the advantages of simple process, low production cost, excellent performance and wide application range, and is suitable for the passivation restoration process of soil polluted by various heavy metal ions and the adsorption and coagulation treatment process of waste water containing heavy metal ions.

Description

Preparation method of lignin modified heavy metal passivator

technical field

The invention relates to the technical field of soil heavy metal pollution passivation treatment, in particular to a preparation method for preparing a heavy metal passivator by amination modification of lignin.

Background technique

With the continuous development of mining, smelting, lead battery, leather, chemical and other industries, the "three wastes" containing heavy metals enter the soil environment through various channels, causing serious pollution to the soil. Heavy metal pollution has the characteristics of wide pollution range, long duration, concealment of pollution, and inability to be biodegraded. It not only causes great harm to the yield and quality of crops, but also continuously accumulates through the food chain, and eventually accumulates in the human body to cause harm. healthy. According to the National Soil Survey Bulletin issued by the Ministry of Environmental Protection and the Ministry of Land and Resources in 2014, the total pollution rate of 6.3 million square kilometers of soil surveyed nationwide was 16.1%, mainly cadmium, mercury, arsenic, copper, lead, Inorganic pollutants such as chromium, zinc and nickel are the main pollutants, and the number of pollution points accounts for 82.8% of all exceeding points. At present, the commonly used soil heavy metal treatment methods at home and abroad mainly include physical remediation, chemical remediation and biological remediation. Physical restoration methods include foreign soil replacement, deep plowing, etc., chemical restoration methods include passivation restoration, soil leaching, etc., and biological restoration methods include animal restoration, plant extraction, etc. Among them, passivation remediation of heavy metal-contaminated soil has the characteristics of low cost, short remediation period, and easy implementation. It can well meet the current conditions and requirements for remediation of heavy metal-contaminated soil in my country, and is especially suitable for remediation of large-scale medium-to-light heavy metal-contaminated farmland soil.

Existing soil heavy metal passivators can be divided into the following two classes at present: (1) inorganic, including lime, ferrous sulfate, phosphates (hydroxyapatite, phosphate fertilizer, etc.), industrial by-products (red mud, flying ash, dolomite residue, etc.), clay minerals (zeolite, attapulgite, sepiolite, bentonite, etc.); (2) organic, including organic compost, straw, urban sludge, livestock manure and synthetic chelate Synthetic organic matter, etc. Among them, organic passivators have the advantages of improving soil fertility, convenient and economical materials, and are of great significance in the restoration of heavy metal pollution in soil. Studies have shown that lignin and modified products have no toxic effect on soil and no secondary pollution. At the same time, lignin has low biodegradability, and the humus produced by degradation also has strong heavy metal adsorption capacity. Therefore, the synthesis of soil heavy metal passivation agent with lignin as raw material has unique advantages in terms of long-term effect. In addition, lignin is the main component of pulping and papermaking waste liquid, and is one of the main sources of environmental pollution caused by the pulping and papermaking industry. Modification of lignin to prepare soil heavy metal passivation agent can not only increase the added value of lignin, but also It can reduce environmental pollution and turn waste into wealth.

Ge Yuanyuan proposed a method for preparing a lignin-based dithiocarbamate heavy metal ion scavenger by using lignin as a raw material in the invention patent with publication number CN102784622A and application number 201210248082.2, but the reaction temperature required for the preparation of the scavenger Higher, longer reaction time, more steps, and lower efficiency. At the same time, the use of highly toxic carbon disulfide as a production raw material in the preparation process of the capture agent not only puts forward higher requirements for the production process, but also causes harm and risks to production personnel and the surrounding environment. Zhao Tao and Pan Hong proposed in the invention patents with publication number CN103408767A and application number 201310317674.X to use alkali lignin and epichlorohydrin as raw materials to synthesize epoxy lignin under certain conditions, and combine this epoxy lignin derivative with The invention discloses a method for preparing aminated lignin by reacting polyamine compounds. However, this preparation method fails to fully expose the modification sites of lignin, and the modification efficiency is low, and only diamine compounds are used as modifiers, which have fewer binding sites for heavy metals.

Contents of the invention

The technical problem to be solved by the present invention is to provide a preparation method of a lignin-modified heavy metal passivator, which uses lignin in papermaking waste liquid as the main component, which not only opens up a new way for the comprehensive utilization of industrial waste, but also can Greatly reduce the cost of heavy metal polluted soil treatment.

The present invention solves the above technical problems with the following technical solutions:

The preparation method of lignin modified heavy metal passivator of the present invention comprises the following steps:

The first step is to weigh a certain amount of lignin and add it to water to form a lignin solution with a mass concentration of 2-10%. After stirring for 0.5 hours, the pH value of the solution is adjusted to 3.5.

In the second step, adding ferrous chloride and hydrogen peroxide with a mass concentration of 30% in turn, reacting at 50° C. for 1 hour and then standing for 0.5 hour,

The third step is to adjust the pH value of the solution to 9.5, then add diethylenetriamine and formaldehyde in sequence, stir evenly, and heat to 50-80°C for 1-4 hours.

In the fourth step, after the reaction is completed, add dropwise a 10% hydrochloric acid solution with a mass concentration of 10% under stirring to adjust the pH value of the above reaction solution to 7.0, so that the modified lignin can be fully separated out, and then suction filtered after standing for 2-3 hours. Aminated modified lignin was obtained,

In the fifth step, unreacted diethylenetriamine and formaldehyde are washed away with water, and then the product is baked at 50°C for 6 hours and ground to below 100 mesh to obtain the finished lignin amination-modified heavy metal deactivator.

The lignin is extracted from papermaking waste liquid, and the alkali lignin or lignin sulfonate is obtained through acid precipitation and filtration.

The volume ratio of hydrogen peroxide and lignin solution in the second step of the preparation step is 1:200, and the dosing ratio of ferrous chloride is 1:4-7 according to the mass ratio of iron ion to H ₂ O ₂ .

The mass ratio of lignin to diethylenetriamine in the third step of the preparation step is 1:0.75-1.5.

The molar ratio of diethylenetriamine and formaldehyde in the third step of the preparation step is 1:0.5-3.

The inventive method has the following advantages:

1) The lignin used is the main component of pulping and papermaking waste liquid. Modification of lignin to prepare soil heavy metal passivation agent can not only increase the added value of lignin, but also reduce environmental pollution and turn waste into treasure.

2) In the present invention, lignin is modified with diethylenetriamine to obtain aminated lignin. The synthesis method is simple, the reaction conditions are relatively mild, and the operability is strong. The prepared heavy metal passivator is neutral, has no toxic effect on soil, has no secondary pollution, has stable properties, and has strong heavy metal adsorption and passivation capabilities.

3) The passivator product produced by the present invention has a wide range of applications, not only for passivation of heavy metals in soil, but also as an adsorbent for heavy metals in water.

detailed description

The method of the present invention will be further described below in conjunction with specific examples.

Example 1

The preparation method of lignin modified heavy metal passivator, the operation steps are as follows:

In the first step, weigh 4.0 g of alkali lignin and add it to 200 mL of distilled water, stir for 0.5 hours, and adjust the pH value of the solution to 3.5 with hydrochloric acid.

In the second step, add ferrous chloride and 1 mL of hydrogen peroxide with a mass concentration of 30% in sequence, and the dosage of ferrous chloride is added according to m(Fe ²⁺ ):m(H ₂ O ₂ )=1:4. After reacting at 50°C for 1 hour, let stand for 0.5 hour,

The third step is to adjust the pH value of the solution to 9.5 with NaOH solution, add 5g of diethylenetriamine, and then add 0.024mol formaldehyde according to the molar ratio of diethylenetriamine and formaldehyde as 1:0.5, stir evenly, and keep the solution at 80 °C for 1 hour,

In the fourth step, after the reaction is completed, add dropwise a hydrochloric acid solution with a mass concentration of 10% under stirring to adjust the pH value of the above-mentioned reaction solution to 7.0, so that the modified lignin is fully separated out, and after standing for 2 hours, filter it with The unreacted diethylenetriamine and formaldehyde were washed away with deionized water, and then the product was baked at 50°C for 6 hours and ground to below 100 mesh to obtain the finished lignin amination-modified heavy metal deactivator.

The obtained lignin amination modified product has a nitrogen content of 4.05%.

Example 2

The preparation method of lignin modified heavy metal passivator, the operation steps are as follows:

In the first step, weigh 10.0 g of alkali lignin and add it to 200 mL of distilled water, stir for 0.5 hours, and adjust the pH value of the solution to 3.5 with hydrochloric acid.

In the second step, add ferrous chloride and 1 mL of hydrogen peroxide with a mass concentration of 30% in sequence. The dosage of ferrous chloride is added according to m(Fe ²⁺ ):m(H ₂ O ₂ )=1:6, After reacting at 50°C for 1 hour, let stand for 0.5 hour,

In the third step, adjust the pH value of the solution to 9.5 with NaOH solution, add 10g of diethylenetriamine, and then add 0.29mol of formaldehyde according to the molar ratio of diethylenetriamine and formaldehyde as 1:3, stir well, and keep the solution at 70°C reaction for 3 hours,

In the fourth step, after the reaction is completed, add dropwise a hydrochloric acid solution with a mass concentration of 10% under stirring to adjust the pH value of the above-mentioned reaction solution to 7.0, so that the modified lignin is fully separated out, and after standing for 2 hours, filter it with The unreacted diethylenetriamine and formaldehyde were washed away with deionized water, and then the product was baked at 50°C for 6 hours and ground to below 100 mesh to obtain the finished lignin amination-modified heavy metal deactivator.

The obtained lignin amination modified product has a nitrogen content of 7.00%.

Example 3

The preparation method of lignin modified heavy metal passivator, the operation steps are as follows:

In the first step, weigh 20.0 g of alkali lignin and add it to 200 mL of distilled water, stir for 0.5 hours, and adjust the pH value of the solution to 3.5 with hydrochloric acid.

In the second step, add ferrous chloride and 1 mL of hydrogen peroxide with a mass concentration of 30% in sequence, and the dosage of ferrous chloride is added according to m(Fe ²⁺ ):m(H ₂ O ₂ )=1:7. After reacting at 50°C for 1 hour, let stand for 0.5 hour,

The third step is to adjust the pH value of the solution to 9.5 with NaOH solution, add 15g of diethylenetriamine, then add 0.29mol of formaldehyde according to the molar ratio of diethylenetriamine and formaldehyde as 1:2, stir well, and keep the solution at 50°C 4 hours of reaction,

In the fourth step, after the reaction is completed, add dropwise a hydrochloric acid solution with a mass concentration of 10% under stirring to adjust the pH value of the above-mentioned reaction solution to 7.0, so that the modified lignin can be fully separated out, and after standing for 3 hours, filter it with The unreacted diethylenetriamine and formaldehyde were washed away with deionized water, and then the product was baked at 50°C for 6 hours and ground to below 100 mesh to obtain the finished lignin amination-modified heavy metal deactivator.

The obtained lignin amination modified product has a nitrogen content of 5.34%.

Example 4

The preparation method of lignin modified heavy metal deactivator, the steps are as follows:

In the first step, weigh 16.0 g of sodium lignosulfonate and add it to 200 mL of distilled water, stir for 0.5 hours, and adjust the pH value of the solution to 3.5 with hydrochloric acid.

In the second step, add ferrous chloride and 1 mL of hydrogen peroxide with a mass concentration of 30% in sequence, and the dosage of ferrous chloride is added according to m(Fe ²⁺ ):m(H ₂ O ₂ )=1:5. After reacting at 50°C for 1 hour, let stand for 0.5 hour,

The third step is to adjust the pH value of the solution to 9.5 with NaOH solution, add 24g of diethylenetriamine, and then add 0.23mol of formaldehyde according to the molar ratio of diethylenetriamine and formaldehyde as 1:1, stir evenly, and keep the solution at 60°C React for 2 hours,

In the fourth step, after the reaction is completed, add dropwise a hydrochloric acid solution with a mass concentration of 10% under stirring to adjust the pH value of the above-mentioned reaction solution to 7.0, so that the modified lignin is fully separated out, and after standing for 2 hours, filter it with The unreacted diethylenetriamine and formaldehyde were washed away with deionized water, and then the product was baked at 50°C for 6 hours and ground to below 100 mesh to obtain the finished lignin amination-modified heavy metal deactivator.

The obtained lignin amination modified product has a nitrogen content of 3.88%.

Test example 1

The heavy metal passivation ability of the modified product is judged by the capacity of the finished product of the lignin amination modified heavy metal passivator of the present invention to absorb heavy metals in the aqueous solution. In Example 1, the saturated adsorption capacity of the finished amination-modified heavy metal passivator to Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ in the solution was 10.48 mg/g, 58.91 mg/g, and 25.13 mg/g, respectively. g, 16.17 mg/g. In Example 2, the saturated adsorption capacity of the finished amination-modified heavy metal passivator to Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ in the solution was 23.73 mg/g, 76.62 mg/g, and 31.69 mg/g, respectively. g, 21.85 mg/g. In Example 3, the saturated adsorption capacity of the finished amination-modified heavy metal passivator to Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ in the solution was 12.40 mg/g, 15.12 mg/g, and 19.52 mg, respectively. /g, 14.64mg/g. In Example 4, the saturated adsorption capacity of the finished amination-modified heavy metal passivator to Cu ²⁺ , Pb ²⁺ , Cd ²⁺ , and Zn ²⁺ in the solution was 12.365 mg/g, 18.84 mg/g, and 10.70 mg, respectively. /g, 5.71mg/g. Comparing the adsorption capacity of aminated lignin to Cu ²⁺ and Cd ²⁺ in Zhou Yan's "Adsorption of Cu(II) and Cd(II) in Water" published in "Journal of Environmental Engineering" in October 2013 6.2 mg/g and 7.1 mg/g have significant advantages.

Test example 2

The simulated compound heavy metal polluted soil was cultivated, and its heavy metal concentration was 21.51 mg/g cadmium, 1968.85 mg/g lead, 2175.63 mg/g zinc, and 1353.43 mg/g copper. Take 10g of air-dried simulated heavy metal-contaminated soil sample and place it in a 250mL clean beaker. The dosage of the finished lignin amination modified heavy metal passivator of the present invention is 5% of the soil quality to ensure that the moisture content of the soil is 30%. Stir evenly , maintenance for 14 days. After 14 days, take the remediation soil, and use HJ/299-2007 toxic leaching method and acid extractable state of BCR method to determine the effect of passivation agent. After adding the passivator, the cadmium concentration in the toxic leachate decreased by 47.40%, the lead concentration decreased by 79.31%, the zinc concentration decreased by 62.36%, and the copper concentration decreased by 95.90%. The cadmium concentration in the acid extractable state decreased by 3.97%, and the lead concentration decreased by 19.51%. , Zinc concentration decreased by 23.60%, copper concentration decreased by 28.76%.

Claims (5)

1. the preparation method of lignin modified heavy metal deactivator is characterized in that, comprises the following steps: The first step is to weigh a certain amount of lignin and add it to water to form a lignin solution with a mass concentration of 2-10%. After stirring for 0.5 hours, the pH value of the solution is adjusted to 3.5. In the second step, adding ferrous chloride and hydrogen peroxide with a mass concentration of 30% in turn, reacting at 50° C. for 1 hour and then standing for 0.5 hour, The third step is to adjust the pH value of the solution to 9.5, then add diethylenetriamine and formaldehyde in sequence, stir evenly, and heat to 50-80°C for 1-4 hours. In the fourth step, after the reaction is completed, add dropwise a 10% hydrochloric acid solution with a mass concentration of 10% under stirring to adjust the pH value of the above reaction solution to 7.0, so that the modified lignin can be fully separated out, and then suction filtered after standing for 2-3 hours. Aminated modified lignin was obtained, In the fifth step, unreacted diethylenetriamine and formaldehyde are washed away with water, and then the product is baked at 50°C for 6 hours and ground to below 100 mesh to obtain the finished lignin amination-modified heavy metal deactivator. 2. the preparation method of lignin-modified heavy metal passivator according to claim 1, is characterized in that: described lignin is extracted from papermaking waste liquid, obtains alkali lignin or lignin sulfonate by acid precipitation and filtration . 3. the preparation method of lignin modified heavy metal deactivator according to claim 1, is characterized in that: hydrogen peroxide and lignin solution described in the second step of preparation step are 1: 200 by volume, ferrous chloride is added The addition ratio is 1:4-7 according to the mass ratio of iron ion to H ₂ O ₂ . 4. The preparation method of lignin-modified heavy metal deactivator according to claim 1, characterized in that: the mass ratio of lignin to diethylenetriamine in the third step of the preparation step is 1:0.75-1.5. 5. The preparation method of lignin modified heavy metal deactivator according to claim 1, characterized in that: the molar ratio of diethylenetriamine and formaldehyde in the third step of the preparation step is 1:0.5-3.