New bio-sorbents in the control of chromium (VI) pollution in waste waters.

ABSTRACT

The sorption abilities of leaves powders of Bhringraj , Aerva lanata, Trianthema portulacastrum L for extracting Chromium (VI) from polluted waters have been studied with respect to various physicochemical parameters such as pH, sorption dosage and equilibrium time. The conditions for maximum removal of Chromium (VI) have been optimized. Ten fold excess of common cation ions present in natural waters, viz., Ca2+, Mg2+ , Cu2+, Zn2+, Ni2+ and Fe2+ have synergistic effect in increasing the % removal of Chromate. SO4 2—and Phosphates are found to be interfering with the extractability of Chromates but NO3 - , Chloride, Fluoride and Carbonate have marginal interference. However, the extraction has never come down below 72.0%. Maximum extractions to an extent of 96.0%, 92.0%, and 84.0% from synthetic waters are observed with the leaves powders of Bhringraj , Aerva lanata, Trianthema portulacastrum L respectively at pH2 and at optimum equilibration time and sorbent concentrations. The methodologies developed are applied to diverse waste water samples collected from industrial effluents and polluted lakes. The procedures are found to be remarkably successful in removing the Chromiume(VI) from waste waters.