Effect of Surfactant on Adsorption and Mobility of Lead and Cadmium in Soils

Document Type : Original Article

Abstract

THE PRESENT work investigates the effects of anionic sodium dodecyl sulphate (SDS) surfactant at critical micelles concentration (CMC) value on the sorption of Pb2+ and Cd2+ at different initial concentrations on four selected soil samples with different clay content through batch equilibrium experiments. Langmuir and Freundlich models were used to describe the sorption processes in the absence and presence of the aqueous solution of the surfactant. The sorption data fitted very well with both Langmuir and Freundlich isotherm model which gave high correlation coefficients. The KL and Qm ranged from 0.090-0.140 Lmg−1 and 3000-10000 mgkg−1 for adsorption of Pb2+ in absence of SDS, respectively. While, KL and Qm ranged from 0.030 -0.060 Lmg−1 and 600-2500 mgkg−1 and 0.95-0.0.99 for adsorption of Cd2+ in absence of SDS, respectively. The presence of anionic surfactant SDS in adsorption of Pb2+, KL and Qm ranged from 0.008-0.030 Lmg−1 and 2000-8000 mgkg−1, respectively. While, KL and Qm ranged from 0.010-0.022 Lmg−1 and 500-1200 mgkg−1 for adsorption of Cd2+, respectively. The Kf and n ranged from 90-140 Lkg−1 and 2.0-2.98 for adsorption of Pb2+ in absence of SDS, respectively. While, Kf and n ranged from 58-120 Lkg−1 and 1.5-2.08 for adsorption of Cd2+ in absence of SDS, respectively. The presence of anionic surfactant SDS in adsorption of Pb2+, Kf and n ranged from 74-115 Lkg−1 and 1.64-2.59, respectively. While Kf and n ranged from 22.87-96.18 Lkg−1 and 1.33-1.37 for adsorption of Cd2+, respectively. The results showed that both of Pb2+ and Cd2+ showed a reduction in their adsorption to soil particles when surfactant was present.

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