(132d) Adsorption of Arsenic Via Alginate Encapsulated Magnetic Sorption

A novel magnetic sorbent, alginate encapsulated magnetic sorbent has been successfully fabricated to remove metal contaminants such as arsenic. To better understand the sorption properties of the sorbent, the sorption studies of both organic (dimethyl sodium arsenate) and inorganic (sodium hydrogen arsenate) arsenate were conducted. Further investigations were performed to elucidate the adsorption behavior with the existence of humic substances. Using the novel sorbent, adsorption of the metal ion onto the sorbents is elucidated thoroughly by qualitative and quantitative methods: experimental studies, instrumental analyses, mathematical modeling, and simulation. The arsenate adsorption equilibrium time was not affected by the presence of humic substances; it can be attained within 25 h. Complete characterizations of the sorbent were conducted by BET, XRD, ICP, SEM, FT-IR, and XPS. The SEM analysis indicates that the presence of humic substances created irregular homogeneous structures on the surface of the sorbent which consequently reduced the sorbent pores. The XPS analysis also revealed that humic substances and arsenate simultaneously adsorbed onto the sorbent; the competitive adsorption between both occurred. The FT-IR and XPS analyses showed that the ?COOH and Fe-O groups in the sorbent were involved during the arsenate adsorption. Based on both experimental results and instrumental analyses, the adsorption mechanisms have been proposed. Arsenate can be partially adsorbed onto the sorbent and the remaining is further reduced to arsenite. Carbon and divalent iron could provide electrons to achieve the chemical reduction of arsenate.