Performance of Egg-Shell and Fish-Scale as Adsorbent Materials for Chromium (VI) Removal from Effluents of Tannery Industries in Eastern Uganda

Abstract

The performance of egg-shells and fish-scales biomaterials in separating chromium (VI) ions from tannery effluents obtained from tannery industries in Jinja town of Eastern Uganda was investigated. Using crushed egg-shell and fish-scales as adsorbents, sorption tests were carried out to determine the effects of bio-sorbent concentration and particle size on chromium (VI) removal. The adsorbate concentration in the tannery effluents before and after adsorption was analyzed using the UV-vis Spectrophotometer at wavelength of 540 nm. The adsorbent concentration was calculated from concentration change in aqueous solution before and after equilibrium sorption. Results showed that chromium (VI) ions adsorb on the surfaces of both biomaterials. The optimum conditions for chromium (VI) removal were found at pH of 6.8, particle size of 300 μm and bio-sorbent concentration of 0.5 g. The correlation coefficient (R2) showed that chromium (VI) adsorption fitted Langmuir adsorption isotherms. It was concluded that the adsorption process of chromium (VI) on the fish-scales and egg-shells was highly feasible.