Rapid passivation and repair process for pollution of soil heavy metals Cr, Cu, Pb and Zn

Abstract

The invention provides a rapid passivation and repair process for pollution of soil heavy metals Cr, Cu, Pb and Zn and belongs to the technical field of environment protection. A component of a repairing agent is sodium silicate nonahydrate, namely sodium metasilicate with the chemical formula of Na2SiO3*9H2O. The rapid passivation and repair process provided by the invention is aimed at a fundamental mechanism that the essential effect of effectively reducing heavy metal components in a soil system is to transform a compound containing the metal components into a chemical form which is lower in environmental activity, stronger in stability in the environment and not easy to transfer and not easily absorbed by living bodies (which are mainly plants), so as to strengthen the contribution of a chemical action process in metal shape transformation; silicate is directly selected as a passivation acting agent, so that physiochemical properties of acted soil are not obviously changed and the metal components in the soil system are rapidly acted to form a compound type which is lower in the environmental activity, stronger in the stability in the environment and is not easy to transfer and not easily absorbed by the living bodies; and therefore, the aim of reducing the biological effectiveness of the metal components, namely passivating the metal components, is realized.

Description

technical field [0001] The present invention relates to a remediation method for reducing the bioavailability of polluted heavy metal elements in soil heavy metal pollution remediation, which can make heavy metal elements in the soil refractory to insoluble or The insoluble compound species shifts, thereby rapidly reducing its bioavailability. Background technique [0002] Soil heavy metal pollution has become a serious environmental problem at present, and the demand for pollution remediation and treatment is increasing day by day. The current restoration and treatment methods can be summarized in two aspects: 1. Reduce the bioavailability of heavy metals by adding other substances to the contaminated soil so that they do not enter or less enter the plants growing in the soil; 2. Through engineering Heavy metals are removed from the soil by means of bioabsorption and transfer. The above treatment methods can be divided into three categories: physical restoration, chemical...

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Problems solved by technology

However, the defects or deficiencies of this technology are: 1) It only has a stabilizing effect on the Pb element, and the positive and negative environmental behavior effects on other elements are not clear; these situations are mostly multi-element comprehensive pollution problems in the current soil heavy metal pollution 2) When the sodium silicate filling amount of this technology is at least 0.8% of the treated soil, the soluble Pb content in the treated soil is reduced from 8.98mg / kg (L) to 5.23mg / kg (L), that is, the effective state content after treatment can be reduced by 41.76% compared with that without treatment; the amount of sodium silicate added, which is equivalent to 0.8% of the treated soil, is far beyond the trace range (0.1%), such an amount The specific sodium silicate hydrolysis will cause the pH value of the treated soil to increase significantly, which will seriously affect the normal growth requirements of crops on the soil; 3) The dosage of this technology is too high, and the cost-effectiveness limit makes it difficult to be widely used; 4) The technology The time required for technical treatment of soil (action time between additives and soil) is not clear; this is an obvious defect in the restoration of the normal function of the treated soil and the overall use of the soil

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