Adsorption of Arsenite onto Kemiron
This study investigated the effect of pH and coexisting ions on As(III) adsorption using batch experiment and discovered that pH strongly influenced As(III) adsorption. However, differences in background ionic strengths of 0.001 N NaNO3 and 0.1 N NaNO3 had no effect on the sorption trend. The isotherms followed Freundlich model with Kf of 27.91, 35.67, and 43.76 (mg/g)(L/mg)n at pH 6, 7, and 9 respectively. The kinetic studies showed Dapp values of (6.52 ± 0.024) × 10-7 cm2/s and (6.22 ± 0.043) × 10-7 cm2/s for the 38 μm and 500 to 600 μm particle sizes. The biot numbers of the sorption derived were 1.84 × 10-2 and 5.89 × 10-1 respectively. The presence of CO32- had more impact than SO42- ion but the presence of 300 mg/L NH4+ - N had no significant impact on As(III) adsorption between pH 4 and 8 and so was the presence of 0.1 mg/L Ca2+ ion between pH 4 and 6.5. However, about 10% loss of the sorption capacity of Kemiron occurred between pH 6.5 and 9 in the presence of Ca2+ ion. The presence of 5 mg/L Ni(II) and Se(IV) also showed that Se(IV) was a stronger inhibitor of As(III) sorption than Ni(II).
Keywords: Arsenite, ground water, Freundlich, diffusion coefficient, Ghana.