Silane grafted chitosan for the efficient remediation of aquatic environment contaminated with arsenic(V).

Hypothesis: Chitosan, naturally abundant biomaterial showed an insignificant affinity toward arsenate. The incorporation of organosilane could improve the physical and chemical properties of chitosan for the efficient removal of arsenate from aquatic environment.

Experiment: The hybrid materials were obtained by grafting the natural biopolymer chitosan with 3-mercaptopropyl trimethoxysilane (CHMS) and trimethoxy-octylsilane (CHTS). The hybrid materials along with bare chitosan were characterized with SEM-EDX, FT-IR and BET specific surface area analyses and the solid materials were further employed in the efficient remediation of aqueous solutions contaminated with As(V) under batch and column reactor operations.

Findings: The hybrid materials showed an extremely high percentage of As(V) removal compared to bare chitosan within a wide range of pH. As(V) was aggregated rapidly onto the solid surfaces and relatively high percent removal of As(V) was achieved in a wide range of As(V) initial concentrations. Moreover, As(V) was bound with, relatively, weaker forces and forming an 'outer sphere complexes' at the surface of solids. The presence of co-existing ions could not significantly affect the removal of As(V) from aqueous solutions. Furthermore, breakthrough data confirmed that these two hybrid materials possessed significantly high loading capacity of As(V) even under dynamic conditions.