Composite heavy metal passivator and acidic heavy metal contaminated soil treatment method

Abstract

The invention belongs to the field of heavy metal treatment, and particularly relates to a composite heavy metal passivator and an acid heavy metal contaminated soil treatment method. The composite heavy metal passivator provided by the invention is prepared from octadecyl trimethyl ammonium chloride modified sodium bentonite, calcite powder and calcite sand, wherein the particle size of the calcite powder is smaller than that of calcite sand, and the mass ratio of the octadecyl trimethyl ammonium chloride modified sodium bentonite to the calcite powder to the calcite sand is (1-3): (1-3): 1.The octadecyl trimethyl ammonium chloride modified sodium bentonite, the calcite powder and the calcite sand are compounded, so that the composite heavy metal passivator can show better capabilities of improving soil acidity and stabilizing soil heavy metal components. Moreover, the components contained in the compound heavy metal passivator provided by the invention are mild materials, so that the compound heavy metal passivator can overcome the side effects such as soil hardening caused by the traditional chemical passivator, and does not influence the soil environment.

Description

technical field

[0001] The invention belongs to the field of heavy metal treatment, in particular to a composite heavy metal passivator and a treatment method for acidic heavy metal polluted soil. Background technique

[0002] Soil acidification in my country has a large area, wide distribution, serious acidification and great harm. Soil acidification generally occurs in southern China, especially in southern regions (such as Jiangxi, Fujian, Guangdong and other provinces). The cultivated land in my country is strongly acidic (pH<5.5), with a total area of ​​about 230 million mu. Long-term single application of chemical fertilizers is the cause of soil acidification. One of the main causes. Soil acidification has caused serious harm to agricultural and forestry production and the ecological environment. Acidification causes aluminum in the soil to be released, which is toxic to the roots of crops and affects crop growth; soil acidification will also accelerate the loss o...

Examples

preparation example Construction

[0029] In the step of preparing the modified sodium bentonite provided by the present invention, the sodium bentonite is first burned to realize the activation of the sodium bentonite. Wherein, the cation exchange capacity (CEC) of the sodium-based bentonite is preferably ≥ 800mmol / kg; the proportion of particle size ≤ 200 mesh in the sodium-based bentonite is preferably ≥ 95wt%; the burning temperature is preferably 300-450°C, Specifically, it can be 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, 360°C, 365°C, 370°C, 375°C , 380°C, 385°C, 390°C, 395°C, 400°C, 405°C, 410°C, 415°C, 420°C, 425°C, 430°C, 435°C, 440°C, 445°C or 450°C; The time is preferably 3~5h, specifically 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h, 4h, 4.1h, 4.2h, 4.3h , 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h. After burning, heat-activated sodium bentonite is obtained.

[0030] In the step of preparing the modified sodium-based bentonite provided by the p...

Embodiment 1

[0052] 1) Put the sodium-based bentonite in a muffle furnace and burn it at 300°C for 3 hours, then cool it down to 150°C naturally in the furnace, take it out and put it in a desiccator to cool down for later use.

[0053] 2) Add 250g of deionized water into a 500ml three-port reactor, start stirring, add 60g of sodium bentonite after burning treatment, and raise the temperature inside the reactor at a heating rate of 6-8°C / min to 50°C, dropwise add 10wt% hydrochloric acid aqueous solution thereinto, adjust the pH value of the solution to 3.0, keep the reaction for 2 hours, filter, wash until the filtrate is neutral, and dry.

[0054] 3) Add 250 g of deionized water into the reactor, start stirring, and add the dry bentonite from the reaction product of the previous step. While stirring, raise the temperature inside the reactor to 70°C at a rate of 6-8°C / min. After the temperature is stable, add 5.2g of octadecyltrimethylammonium chloride to it, keep it warm for 3 hours, and ...

Embodiment 2

[0057] 1) Put the sodium bentonite in a muffle furnace and burn it at 300°C for 5 hours, then cool it down to 150°C naturally in the furnace, take it out and put it in a desiccator to cool down for later use.

[0058] 2) Add 250g of deionized water into a 500ml three-port reactor, start stirring, add 60g of sodium bentonite after burning treatment, and raise the temperature inside the reactor at a heating rate of 6-8°C / min to 70°C, dropwise add 10wt% hydrochloric acid aqueous solution thereinto, adjust the pH value of the solution to 3.5, keep the reaction for 3 hours, filter, wash until the filtrate is neutral, and dry.

[0059] 3) Add 250 g of deionized water into the reactor, start stirring, and add the dry bentonite from the reaction product of the previous step. While stirring, raise the temperature inside the reactor to 90°C at a rate of 6-8°C / min. After the temperature stabilizes, add 5.2g of octadecyltrimethylammonium chloride to it, keep it warm for 5 hours, and filte...

technical field

[0001] The invention belongs to the field of heavy metal treatment, in particular to a composite heavy metal passivator and a treatment method for acidic heavy metal polluted soil. Background technique

[0002] Soil acidification in my country has a large area, wide distribution, serious acidification and great harm. Soil acidification generally occurs in southern China, especially in southern regions (such as Jiangxi, Fujian, Guangdong and other provinces). The cultivated land in my country is strongly acidic (pH<5.5), with a total area of ​​about 230 million mu. Long-term single application of chemical fertilizers is the cause of soil acidification. One of the main causes. Soil acidification has caused serious harm to agricultural and forestry production and the ecological environment. Acidification causes aluminum in the soil to be released, which is toxic to the roots of crops and affects crop growth; soil acidification will also accelerate the loss o...

Examples

preparation example Construction

[0029] In the step of preparing the modified sodium bentonite provided by the present invention, the sodium bentonite is first burned to realize the activation of the sodium bentonite. Wherein, the cation exchange capacity (CEC) of the sodium-based bentonite is preferably ≥ 800mmol / kg; the proportion of particle size ≤ 200 mesh in the sodium-based bentonite is preferably ≥ 95wt%; the burning temperature is preferably 300-450°C, Specifically, it can be 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, 360°C, 365°C, 370°C, 375°C , 380°C, 385°C, 390°C, 395°C, 400°C, 405°C, 410°C, 415°C, 420°C, 425°C, 430°C, 435°C, 440°C, 445°C or 450°C; The time is preferably 3~5h, specifically 3h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h, 4h, 4.1h, 4.2h, 4.3h , 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h. After burning, heat-activated sodium bentonite is obtained.

[0030] In the step of preparing the modified sodium-based bentonite provided by the p...

Embodiment 1

[0052] 1) Put the sodium-based bentonite in a muffle furnace and burn it at 300°C for 3 hours, then cool it down to 150°C naturally in the furnace, take it out and put it in a desiccator to cool down for later use.

[0053] 2) Add 250g of deionized water into a 500ml three-port reactor, start stirring, add 60g of sodium bentonite after burning treatment, and raise the temperature inside the reactor at a heating rate of 6-8°C / min to 50°C, dropwise add 10wt% hydrochloric acid aqueous solution thereinto, adjust the pH value of the solution to 3.0, keep the reaction for 2 hours, filter, wash until the filtrate is neutral, and dry.

[0054] 3) Add 250 g of deionized water into the reactor, start stirring, and add the dry bentonite from the reaction product of the previous step. While stirring, raise the temperature inside the reactor to 70°C at a rate of 6-8°C / min. After the temperature is stable, add 5.2g of octadecyltrimethylammonium chloride to it, keep it warm for 3 hours, and ...

Embodiment 2

[0057] 1) Put the sodium bentonite in a muffle furnace and burn it at 300°C for 5 hours, then cool it down to 150°C naturally in the furnace, take it out and put it in a desiccator to cool down for later use.

[0058] 2) Add 250g of deionized water into a 500ml three-port reactor, start stirring, add 60g of sodium bentonite after burning treatment, and raise the temperature inside the reactor at a heating rate of 6-8°C / min to 70°C, dropwise add 10wt% hydrochloric acid aqueous solution thereinto, adjust the pH value of the solution to 3.5, keep the reaction for 3 hours, filter, wash until the filtrate is neutral, and dry.

[0059] 3) Add 250 g of deionized water into the reactor, start stirring, and add the dry bentonite from the reaction product of the previous step. While stirring, raise the temperature inside the reactor to 90°C at a rate of 6-8°C / min. After the temperature stabilizes, add 5.2g of octadecyltrimethylammonium chloride to it, keep it warm for 5 hours, and filte...

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