Hydrous ferric oxide-resin nanocomposites of tunable structure for arsenite removal: effect of the host pore structure.

Hydrous ferric oxide (HFO) loaded hybrid sorbents are considered to be excellent materials for arsenic removal from water. However, role of the host pore structure in the performance of the composites is still unclear. In the current study five HFO nanocomposites of similar HFO loadings (3.9-5.3% in Fe mass) were fabricated for arsenite removal, using self-synthesized polystyrene (PS) resins of similar particle sizes but different pore structures as hosts. Structure analysis demonstrated that the particle size of HFO aggregates decreased with decreasing pore size of PS. The adsorption of arsenite onto the nanocomposites with PS of smaller average pore size achieved equilibrium faster. Analysis of kinetic data with the intraparticle diffusion model demonstrated that arsenite adsorption onto PS-HFO nanocomposites with larger HFO particles was controlled by intraparticle diffusion whereas the limitation caused by intraparticle diffusion was weakened as the particle size of HFO decreased. The adsorption capacity of the hybrid adsorbents increased with decreased pore size of PS. These results indicated that the pore structure of the support materials would play a significant role in the performance of nanoparticle-loaded porous adsorbents.