BIOREMEDIATION OF CR (VI) METAL ION FROM AQUEOUS SOLUTIONS USING MODIFIED LIGNOCELLULOSIC AGRICULTURAL WASTE BIOMASS

Abstract

A lignocellulosic nitrogenous waste biomass Acacia saligna Pods were investigated for the sequestering of Cr (VI) metal ion from synthetic wastewater. Studies include the utilization of biosorbent in three different forms, viz. Acacia saligna pods natural form (ASPN), impregnated in the form of hydrated beads, Acacia saligna pods beads (ASPB), and in the form of activated carbon i.e. Acacia saligna pods carbon (ASPC) for comparative studies. Biosorption of Cr (VI) ions from aqueous solutions was studied in a batch adsorption system as a function of pH, adsorbent dose, initial metal ion concentration, stirring speed and contact time. The maximum adsorption was obtained at pH 2. Further the biosorbent was characterized by CHN and Fourier Transformer Infrared Spectroscopy (FT-IR) studies helped to identify the various functional groups contributing in the sorption process. The experimental data was analyzed using sorption kinetic models viz; the pseudo first and second order equations. Results show that the pseudo second order provides the best correlation for the biosorption process. Further the recovery of Cr (VI) from Acacia saligna biomass was found to be 92% using 1M HCl. It was concluded that the Acacia saligna pods biomass can be used potentially as biosorbent for the treatment of wastewater containing Cr (VI) ions. The order of removal efficiency of various forms of biomass is found to be ASPC> ASPB> ASPN with the removal efficiency of 97%, 94% and 92% respectively.