Pb removal performance of flocculants and adsorption mechanism simulated by molecular dynamics
In response to the problem of adverse effects caused by the continuous enrichment of Pb in the environment,flocculants with chelating properties obtained based on xanthan acidification reactions have become a hot research topic.A performance comparison experiment is conducted on three flocculants,namely polyethyleneimine-sodium xanthogenat(PEX),dithiocarboxyl hydroxymethy-polyacrylamid(DTMPAM),and dithiocarboxyl acrylamide(PDTAM).The order of removal ability of the three flocculants from high to low under different Pb2+mass concentrations,pH values,and coexisting cation influences is determined as PEX,DTMPAM,and PDTAM.Molecular dynamics simulations are used to calculate the interaction energy and radial distribution function between the dithiocarboxyl group and Pb2+,which mainly play a chelating role.The stability and strength of the interaction between the three flocculants and Pb2+are obtained,and the adsorption mechanism of the flocculants is clarified.The reasons for the differences in removal efficiency are analyzed.
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