Aminoalkyl-organo-silane treated sand for the adsorptive removal of arsenic from the groundwater: Immobilizing the mobilized geogenic contaminants

Arsenic (As), a geogenic legacy pollutant can be present in environmental matrices (water, soil, plants, or animal) in two redox states (As(III) or As(V)). In the present study, charged mono- and di-amino functionalized triethoxy and methoxyorganosilane (TT1 and TT2- 1% and 5%) were impregnated with quartz sand particles for the treatment of As polluted water. Spectroscopic characterization of organosilane treated sand (STS) indicated the co-existence of minerals (Mg, Mn, Ti), amide, and amidoalkyl groups, which implies the suitability of silanized materials as a metal(loids) immobilization agent from water. Changes in peaks were observed after As sorption in Fourier thermal infrared and EDS images indicating the involvement of chemisorption. Batch sorption studies were performed with the optimized experimental parameters, where an increased removal (>20% for TT2–1% and >60% for TT1–1%) of As was observed with sorbate concentration (50 µg L⁻¹), temp. (25 ± 2 ºC) and sorbent dosages (of 10 g L⁻¹) at 120 min contact time. Among the different adsorbent dosages, 10 g L⁻¹ of both TT1 and TT2 was selected as an optimum dosage (maximum adsorption capacity ≈ 2.91 μg g⁻¹). The sorption model parameters suggested the possibility of chemisorption, charge/ion-dipole interaction for the removal of arsenate.