Removal of chromium (VI) from water using bioadsorbents derived from leaves of Salvadora persico and Caesalpinia bonduc plants

Abstract

Bio sorbents derived from leaves of Salvadora persico and Caesalpinia bonduc plants and their ashes are investigated for their affinity towards Cr (VI) ions from polluted water using batch mode of extractions. The influence of different physicochemical characteristics viz., pH, equilibration time, sorbent dosage, the initial concentration of Cr (VI) and presence of co-ions, are studied and optimized for maximum Cr (VI) extraction. The removal is found to be 81.0% and 86.0% respectively with leaves and their ash of Salvadora persico plant while 95.0% and 98.0% for Caesalpinia bonduc plant adsorbents. Some co-cations are synergistically enhancing the % removal. Monovalent anions have a marginal effect but PO43-, SO42- and CO32- are interfering with the extraction of Cr (VI). The adsorption capacity is found to be 16.2 mg/g (leaves) and 22.9 mg/g (ashes) of Salvadora persica plant; 12.7 mg/g (leaves) and 19.6 mg/g (ash) of Caesalpinia bonduc plant. The procedures are successfully applied to the samples collected at various divergent sources.