Application of modified clays in the removal of phosphates and E. coli from aqueous solution

Abstract

The presence of microorganisms and inorganic pollutants in water bodies results in adverse effects on nature as well as human health. In this study, clay-based adsorbents were used for the removal of phosphates and Escherichia coli bacteria. Two samples, Na-Zr-50-2.5 and Na-Zr-50-5, were prepared using 2.5 and 5 mmol of zirconium per gram of clay. The former material has shown better Langmuir phosphate adsorption capacity (∼11.5 mg P/g) at pH 4. Chitosan modification was applied to Na-Zr-50-2.5 to improve its performance at higher pH. Post modification, the maximum adsorption attained at pH 4 was 14.5 mg P/g, and it improved from 8.3 to 11.8 mg P/g at pH 7. The possible major governing mechanism responsible for the adsorption of phosphates was the formation of inner-sphere complexes. Application of Na-Zr-50-2.5 was also explored for removing E. coli cells from aqueous saline solution. The E. coli removal efficiency of this sample was found to be 62.64 %. This study reveals that modified clays effectively reduce the phosphate and E. coli levels in aqueous solution and can be proved as environment-friendly, low-budget adsorbent materials in wastewater treatment.