Adsorption of arsenic from aqueous solution on synthetic hydrous stannic oxide

The hydrated stannic oxide (HSO) was synthesized and arsenic adsorption behaviour is reported. HSO is found to be amorphous, and stable thermally up to 700 degrees C. The adsorption of As(III) is much higher than As(V) in the drinking water pH (6.5-8.5) range. The time required for reaching equilibrium is 4.0 and 3.0 h, respectively for As(III) and As(V). The adsorption kinetic data obtained at pH 7.0 (+/-0.1) and temperature 27(+/-1) degrees C follow the pseudo-second-order kinetic model best (R(2)>0.98). The analyzes of isotherm adsorption data by two parameter isotherm model equations show the order to obey: Langmuir>Freundlich>Temkin for As(III), and Langmuir>Temkin>Freundlich for As(V). The monolayer adsorption capacities (mg/g) obtained for As(III) and As(V) are 15.85 and 4.30, respectively. Excepting phosphate, other anions studied show no adverse effect on adsorption of As(III) onto HSO. A fixed bed HSO packed column (internal diameter 0.70 cm, bed height 3.7 cm and particle size 0.14-0.29 mm) generates 2400 and 450 BV of potable water (As<0.01 mg/L), respectively, for As(III) and As(V) from arsenic spiked (1.0 mg/L) water samples at pH 7.0 (+/-0.1), which indicated that HSO can be used as an efficient scavenger for As(III) from the contaminated water.