Graded leaching method for repairing arsenic-cadmium combined polluted soil by organic acid

Through the grading rinsing method of citric acid and oxalic acid, the problem of difficult to synchronously repair the arsenic-cadmium composite contaminated soil in the prior art is solved, and an efficient and low-cost arsenic-cadmium removal effect is achieved.

CN119926958APending Publication Date: 2025-05-06INST OF URBAN ENVIRONMENT CHINESE ACAD OF SCI
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Patent Information

Application Number
CN202510008319.7
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-01-03
Publication Date
2025-05-06

AI Technical Summary

Technical Problem

The prior art is difficult to repair arsenic-cadmium composite contaminated soil synchronously and efficiently. Especially since arsenic exists in the soil in the form of low-mover iron-arsenic minerals, existing leaching agents are difficult to effectively remove, and no relevant research on organic acid grading leaching has been reported.

Method used

The grading rinse method of citric acid and oxalic acid is adopted. First, the first-stage rinse is performed with citric acid, and then the second-stage rinse is performed with oxalic acid. The acid-soluble effect of citric acid and the strong reduction of oxalic acid are used to promote the removal of arsenic and cadmium respectively, and the antagonism between the functional groups of the two is avoided.

Benefits of technology

The removal rates of arsenic and cadmium are significantly improved. The citric acid-oxalic acid grading leaching method can efficiently remove arsenic and cadmium from the soil, and the leaching agent is easy to obtain, low cost, and the process is simple and feasible.

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Patent Text Reader

Abstract

The invention discloses a graded leaching method for repairing arsenic-cadmium combined polluted soil by organic acid, which comprises the following steps: (1) adding a first-stage leaching agent citric acid into the combined polluted soil to carry out oscillation leaching, and carrying out solid-liquid separation after the first-stage leaching is finished; and (2) a second-stage eluting agent oxalic acid is added for oscillation elution, solid-liquid separation is conducted after elution, and elution remediation of the arsenic-cadmium combined contaminated soil is completed. According to the method, the removal rate of arsenic and cadmium in the soil is increased and the arsenic-cadmium combined polluted soil is efficiently repaired by combining the same type of functional group organic acid and pertinently and preferably selecting a specific grading leaching sequence. The leaching method is excellent in remediation effect and easy and convenient to operate, leaching agents are easy to obtain, and the leaching method has good application prospects in the aspect of remediation of the arsenic-cadmium combined contaminated soil.
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Citation Information

Patent Citations

  • Environmental-protection and high-efficiency heavy metal polluted soil elution repair liquid and preparation method thereof

    CN108160698A

  • Chemical leaching repairing method for heavy metal and arsenic mercury contaminated soil

    CN101362145A