Binding Characteristics Of Heavy Metals To Natural Humin Fractions Sequentially Extracted From The Lake Sediments

Humin(HM)accounts for a large proportion of humus,and contains a portion of various functional groups,which has a strong adsorption and complexation to heavy metals,as well as the determined factor in controlling the geochemistry behaviors of heavy metals.The heterogeneous with diverse structure,composition properties and functional groups of Humin(HM),can influence the adsorption of heavy metal ions.In order to investigate the sorption characteristics of heavy metals to humans,humans was extracted from natural lake sediments of Wuliangsuhai as sorbent in this work,humans were characterized by topography and spectroscopy.It is helpful to understand the environmental geochemistry behaviors of heavy metals in lakes.All the findings are listed below:1.Characteristics results of humin showed that the type of functional groups among HMi,HMc,HMr and HM were similar,however,the content of functional groups significantly different.The oxygen-containing functional groups and aromaticity of HMi and HMc were larger than HMr and HM whereas aliphatic of HMi and HMc were smaller than HMr and HM.Carboxyl groups and the phenolic groups ranked as HMi>HM>HMr.2.According to the isotherms results,the adsorption capacity of Cu2+,Pb2+,Cd2+on humins followed the order HMi>HM>HMr.3.The adsorption capacity of heavy metals to humin increased with increasing pH within the critical pH,in that the increasing surface negative charges on humin;the adsorption capacity of heavy metals to humin decreased with increasing pH over the critical pH,in that hydrolytic precipitation of heavy metal ions.4.The effect of Ca2+ on the adsorption capacity was larger among different ions types duo to its larger radius.The adsorption capacity of Cu2+,Pb2+,Cd2+ onto humin decreased with increasing ionic strength.5.Comparing with the changes of peak in the FTIR spectrum on humin pre-and post-adsorption,phenolic,carboxyl groups and carbonyl groups participate in the sorption process.According to the EEM results,carboxyl groups,carbonyl groups and quinone groups participate in the sorption process.The increasing f450/500 indicated that aromatic play an important role in the sorption process.