Adsorption Of Cr(?) On Soil By Different Dissolved Humus

The emission of chromium(VI)from industrial waste has caused an increase in the chromium content of the environment,causing serious pollution of hexavalent chromium in soil and groundwater.In situ infiltration is the main way for hexavalent chromium to enter the environment.As a necessary way for chromium to enter the groundwater system,it is an important natural barrier to control the spread of hexavalent chromium pollution.Soil Humus as an important component of soil organic matter has a significant retardation effect on the migration of hexavalent chromium in soil.However,the effect of different dissolved Humus on the adsorption and desorption of hexavalent chromium in soil remains unclear.This article is based on the traditional classification of Humus,according to the Humus dissolution and precipitation properties,it is divided into Dissolved Humus(DH),Dissolving Humus(DIH)and Insolube Humus(IH).The typical black soil in Yanbian Prefecture of Jilin Province was selected as the test soil,and the corresponding soil materials were prepared by gradual removal method.The effect of different dissolved Humus on the adsorption and desorption of hexavalent chromium in soil was investigated by adsorption kinetics batch experiments,and the mechanism of action was revealed.Experimental results show:(1)DH inhibits soil Cr(VI)adsorption.With the gradual removal of readily soluble Humus,the amount of Cr(VI)adsorbed by the soil increased from 1.53 mg/g of the original soil to the final 1.72 mg/g(cumulatively removed Humus dissolved in the soil was 0.096% of the total soil mass).The complexing capacity of easily soluble Humus per unit mass for Cr(VI)is 1.98 mg/g;the form of chromium in soil is not affected.The complexation ability of Cr(VI)per unit mole of carboxyl in the experiment was 6.65 mmol/mol.(2)The DIH is beneficial to the adsorption of hexavalent chromium in soil.With the gradual removal of DIH,the amount of Cr(VI)adsorbed by soil samples decreased from 1.72 mg/g in the DH soil to the final 0.41 mg/g(cumulative removal of DIH in the soil.The total mass of 6.95%),the amount of Cr(VI)adsorbed by the DIH is1.31mg/g,and the DIH can adsorb hexavalent chromium 0.19mg/g;The complexation ability of the carboxyl group to Cr(VI)is 0.91mmol/mol.(3)The IH also facilitates the adsorption of Cr(VI)on soil,but the effect of IH on the adsorption of Cr(VI)on soil is lower than that of DIH.IH accounts for 2.72% of the total soil mass.IH has 0.41 mg/g Cr(VI)adsorption.IH substances per unit can bind 0.15mg/g of hexavalent acid.The organic binding state of IH substances accounts for 2% of the total species.The complexation ability of the carboxyl group to Cr(VI)is 1.44mmol/mol.