Removal of As(III) and As(V) by Tin(II) compounds

摘要

The retention capacity for arsenic species of new nanomaterials based on tin(II) inorganic oxides or hybrid (inorganic and organic) materials was studied. The synthesis of a polymer-metal complex was performed with poly(acrylic acid) and tin(II) chloride. Poly(AA)-Sn (II) with 10 and 20 wt% of tin and a structure with a mol ratio tinxarboxylate group of 1:1, were characterized. These compounds with 10 and 20 wt% of tin content were used to compare the arsenic removal capability through the liquid-phase polymer-based retention, (LPR), technique. Also, tin oxide was prepared by adding alkaline solution to tin(II) chloride salt. The intermediate tin compound was studied by UV-Vis spectroscopy at different pH values and quantified by potentiometric titration. The solid structure is characterized by Fourier transformed infrared spectroscopy, X-ray diffraction, and specific area BET (N_2). Removal of arsenite and arsenate species from solution by hydrolysated tin was carried out by LPR technique with ultrafiltration membranes and a fixed-bed column unsupported or supported on SiO_2. In all these cases, a washing method at constant pH was applied. The arsenic retention ability depended on the class of tin compounds prepared, with a higher efficiency for arsenic being observed at basic pH for soluble complex poly(AA)-Sn(II) than that for tin hydroxide or hydrolysate of Sn~(+2).