Functional iron chitosan microspheres synthesized by ionotropic gelation for the removal of arsenic (V) from water

Abstract

Arsenic (As) is considered one of the most serious inorganic contaminants in groundwater. The maximum limit of As in drinking water is 0.010mgAs L−1 according to the World Health Organization. Functional Iron Chitosan Microspheres (F-ICM) were synthesized by ionotropic gelation of chitosan and ferric nitrate for removal of As (V) from water. The effects of iron concentration (0.7, 5.5 and 11.2gFe+3/100g chitosan), pH range (4–9), sorbent dosage, possibility of reuse and presence of interfering anions were analyzed. F-ICM were effective for As (V) adsorption in a wide range of pH with removals higher than 88.9%, reaching concentrations < 0.010mgAs L−1. A higher proportion of iron in the matrix favored the removal of As(V) in a pH range 6 to 9. Kinetic data of As(V) adsorption onto 0.7 F-ICM under all tested initial concentrations fitted well with the pseudo second-order kinetic model. Sorption isotherm experimental data were satisfactorily fitted with the Langmuir equation; the maximum sorption capacity for As(V) was 120.77mgAs(V) (gF-ICM1) and the Langmuir constant was 0.331 L mg1. A good performance of the adsorption capacity was obtained in four successive adsorption cycles of reuse and in the presence of interfering anions, indicating the high adsorption capacity of the synthesized microspheres.