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Abstract
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The content of heavy metals extremely exceeds from the international level due to the anthropo- genic activities brought from point and nonpoint sources, soil and water contamination occurs and agricultural products become unhealthy for human consumption. This study aimed to apply mod- ified bentonite for adsorption of cadmium (Cd2+), copper (Cu2+) and nickel (Ni2+) from an aqueous phase. The natural Iranian bentonite was mixed s with anionic surfactants, and sodium dodecyl sulfate (SDS) to produce modified bentonite. Batch experiments were performed in two individ- ual and competitive solutions of Cd2+ , Cu 2+ , and Ni 2+ (25–600 mg L –1) in the present of Na-B and SDS (10, 20, and 40 Mm). The results demonstrated that SDS modified bentonite (SDS-B) treat- ments enhanced the sorption capacity of natural adsorbents with increasing pH. The SDS-B in 40 mM is of more adsorption efficiency to adsorb Cd 2+ , Cu 2+ and Ni 2+ than are the other treat- ments. Among common and comprehensive isotherm models, Langmuir was well fitted to eval- uate the data obtained from adsorption experiments. This is a novel study to compare the effect of modified bentonites into both single and comparative solution for heavy metal sorption. The maximum Langmuir adsorption capacity of Cd2+ , Cu 2+ and Ni 2+ was 130.7, 94.4, and 83.06 as shown in SDS-B (40 mM) treatment. SDS-B treatments have the greatest affinity for Cd 2+, but the Na-B adsorbs Ni2+ more than the other cations. Using SDS-B showed remarkable gain in enhancing the adsorption efficiency compared to the Na-B in both individual and competitive batch experiments.
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