Biosorption of chromium ions through modified Eichhornia crassipes biomass form the aqueous medium

Abstract

Aim: To explore the potential of water hyacinth biomass as a low cost adsorbent for sequestrating chromium ions from aqueous solution. Methodology: The biosorption behavior of chromium ions (Cr(III) and Cr(VI)) from aqueous solution by powdered water hyacinth biomass was assessed through series of batch experiments using advanced instrumentation techniques like Scanning Electron Microscopy with Energy Dispersive X-ray analysis and Fourier Transform Infra-Red spectroscopy, pH zero point charge. The equilibrium relationship between sorbent and sorbate was determined in solution by using the isotherms Langmuir, Freundlich and Temkin models. Results: The optimum pH for Cr(III) and Cr(VI) adsorption was 5.0 and 2.0 whereas the maximum Cr(III) and Cr(VI) adsorption was 99.80 and 89.15%, respectively. Langmuir isotherm fitted the data well with R2 value of 0.999 for both Cr(III) and Cr(VI) by the biosorbent. Adsorption kinetics showed that the experimental data fitted the pseudo second order kinetic model with R2 value of 0.999 for both Cr(III) and Cr(VI). The EDX spectra peaks of Ca, O, C indicated the presence of functional groups such as –OH and –COOH in the biosorbent. The zeta potential analysis depicted that water hyacinth biomass had negative surface charge of (-) 23.5mV. Interpretation: Water hyacinth based biosorbent can be utilized for the removal of Cr ions from industrial waste water. Further, water hyacinth has additional advantage that it reduces or even eliminates the diverse impact of weeds on the environment. Key words: Biosorption, Chromium removal, Water hyacinth