Groundwater Arsenic Remediation using Amphiphilic Polysiloxane Graft Copolymer Coated Iron Nanoparticles

摘要

Arsenic (As) contamination has aroused attention in many parts of the world because of its toxic effects. The predominant forms of arsenic in groundwater and surface water are the inorganic species arsenite [As(III)] and arsenate [As(V)]. Nanoscale zero-valent iron (NZVI) have been used successfully for the rapid removal of arsenic from water. The present research examined the kinetics of the As(V) degradation with bare NZVI and a novel polymer coated NZVI (CNZVI). The 10-90 nm diameter NZVI particles were synthesized by sodium borohydride reduction of ferrous iron. To be effective for groundwater remediation, the iron nanoparticles must be dispersible and transportable through the aquifer into the contaminant plume (in this case As plumes of industrial or agricultural origin). An amphiphilic polysiloxane graft copolymer (APGC) was synthesized as the surface modifier to enhance nanoparticle colloidal stability in aqueous environment. The polymer promotes colloidal stability of NZVI in aqueous suspension and makes more reactive surface available for contaminant degradation. The results of As degradation using CNZVI showed an increase in reaction rate as compared to bare NZVI.