Study On Extraction Effect Of Arsenic In Contaminated Soils

This paper takes the gangue weathering soils of Fuxin-xinqiu yujiagou open pit waste dump area as the main research object, carries the monitoring experiments of arsenic of the research area peripheral soil, determining the correlations of arsenic content and the main group elements, the relationship with soil heavy metal content, and carries out the tests of selecting extractants, optimizing extraction conditions, extracted soil and analysising arsenic species optimizing BCR in soils before and after extracted and dissolution experiment of soil extraction components, in order to provide measures against arsenic contaminated soils. The main research conclusions are as follows:(1) The average of the total arsenic content in soil of the research area is 3.035mg/kg, and the distribution of the range was 1.651?5.612 mg/kg, the average of effective arsenic content in soil was 0.602 mg/kg, the distribution of the range was 0.2186?0.8631 mg/kg. Total arsenic have a significant positive correlation with total phosphorus content in the mining area soil. Arsenic content in soil and chromium, copper, zinc, lead, cadmium was not obvious, moderate positive correlation was significantly shown between arsenic contents of soil copper and zinc.(2) To determine the optimum extraction conditions by the tests of selecting extractants incorporation L9(33) screen out C6H8O7, KH2PO4 extraction arsenic-polluted soil. The orthogonal test was employed to test the effects of the three factors including the concentration of liquid-soil ratio, extractant concentration, and extraction time of arsenic extraction ratio. The findings indicated that the best extraction conditions for using C6H8O7 concentration was 0.1 mol/L, extraction time was 6 hours and liquid-soil ratio was 10 mL/g, when maximum extraction efficiency was 89.80%, the best extraction conditions for using KH2PO4 concentration was of 0.02 mol/L, extraction time was 12 hours and liquid-soil ratio was 40 mL/g, when maximum extraction efficiency was 91.56%.(3) The optimized BCR morphological analysis and component dissolution of arsenic in soil before and after extraction experiments show that C6H8O7 and KH2PO4 were able to effectively remove the bioavailability of soil arsenic and biological potential available arsenic. However, acid solution would result in varying degrees of soil acidification with the removal of arsenic CeH8O7, and caused a large amount of calcitonin magnesium etc components dissolving out of soil in different degrees. Because of the effect of KH2PO4 on soil pH was relatively small resulting in the dissolution of soil components were rarely and proved relatively friendly for soil environment, therefor as an ideal restored arsenic-contaminated soil extractant.