The paper projects the potential of agricultural waste Saraca indica leaf powder (SILP) in biosorbing chromium from aqueous system. The influence of pH, contact time, metal concentration, biomass dosage and particle size on the selectivity of the removal process was investigated. The maximum sorption efficiency of SILP for Cr(III): 85.23% and Cr(VI): 89.67% was found to be pH dependent giving optimum sorption at pH 6.5 and 2.5 respectively. The adsorption process fitted well to both Freundlich and Langmuir isotherms. Morphological changes observed in Scanning Electron Micrographs of metal treated biomass confirm the existence of biosorption phenomenon. Fourier Transform Infra-red Spectrometry confirms that amino acid-Cr interactions contribute a significant role in the biosorption of chromium using target leaf powder. The successful applications of easily abundant agricultural waste SILP, as a biosorbent have potential for a low technological pretreatment step, prior to economically not viable high-tech chemical treatments for the removal of Cr from water bodies.
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The present study explores the unexploitcd sorption property of the unmodified Ficus religiosa leaf powder (FRLP) for decontamination and a possible method of separation of environmentally important two oxidation states of chromium (Cr(lII) and Cr(VI)) from aqueous media. Sorption studies using standard practices were carried out in batch experiments as functions of biomass dosage, metal concentration, contact time, particle size and pH. Sorption studies result into the standardization of optimum conditions for the removal of Cr(III) 82.47% and Cr(VI) 88.23% as follows: biomass dosage (4.0 g), initial metal concentration in the aqueous system (Cr(III) 25 mg-dm-1, Cr(VI) 50 mg-dm'), particle size (105 urn) at pH (Cr(lll) - 6.5 and Cr(VI) -2.5). The adsorption data were fitted in Freundlich and Langmuir isotherms. Studies of academic interest like kinetics studies revealed that adsorption equilibrium in each case followed first order equation. Morphological changes observed in the scanning electron micrograph of native and exhausted biomass indicate the existence of biosorption phenomenon. Fourier transform infrared spectrometry of exhausted leaf biomass highlights amino acid - Cr interactions responsible for sorption phenomenon. Regeneration of exhausted biomass was attempted for several cycles for its effective reusability.
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