Immobilizing remediation of arsenic and cadmium in contaminated soil using an FeMnNi-LDH composite modified by fulvic acid
In this study,a stable layered FA@FeMnNi-LDH composite was prepared by co-precipitation method using fulvic acid as the modifier of FeMnNi-LDH,which was applied for the concurrent immobilization of As(Ⅲ)and Cd(Ⅱ)in polluted soil.Taking the Chinese cabbage(Brassica rapa pekinensis)as test crop,the effects of the composite on the remediation efficiencies of soil As(Ⅲ)and Cd(Ⅱ),their transformation in soils and transport and enrichment coefficients in crop plants were studied by pot experiments under different levels pollution levels of As and Cd and initial soil pH.The results showed that the synthesized composite exhibited remarkable synchronous immobilizing effects for As and Cd in soil.The application of the composite at a dosage of 1.0％promoted the both transformations of soil As and Cd from active forms to less liable forms:from non-specific adsorbed and crystalline iron aluminum oxide bound forms to specific adsorbed and amorphous iron aluminum oxide bound and residual forms for As and exchangeable form to residual,carbonate bound,iron manganese oxide bound and organic bound forms for Cd.Meanwhile,the initial soil pH values exhibited significant impacts on the immobilizing effect of As and Cd.1％addition of the composite increased the soil pH by 1.65 and 0.64 units for acidic and neutral soils,respectively.Accordingly,soil available As and Cd contents were deceased by 69.74％and 63.31％and 60.25％and 61.78％,respectively.The fresh weight and plant height of Chinese cabbage increased with the increase of composite material addition,while the transport and enrichment coefficient of As and Cd in each part of tested crop decreased significantly.Consequently,the concentrations of As and Cd in the above-ground part of the crop were lower than the Chinese national food safety standard limit at 1％addition rate of the composite.Correlation analyses showed that non-specific adsorbed As and exchangeable Cd were negatively correlated with soil pH value,the residual As and Cd were positively correlated with soil pH value,and the contents of As and Cd in the ground part and roots of the tested crop were negatively correlated with the residual As and Cd.The results proved that FA@FeMnNi-LDH composite material could increase soil pH,promote the transformation of As and Cd to residual forms,and thus reduce their bioavailability in soils and accumulation in Chinese cabbage plants,providing a new strategy for simultaneous remediation of As(Ⅲ)and Cd(Ⅱ)co-polluted soils.
layered double metal hydroxide(LDH)Fulvic acid(FA)ModificationArsenic and cadmium combined pollution of soilremediation
万方数据
维普
