Removal of Chromium (VI) From Aqueous Solution Using Modified Bentonite Clay and its Application on Tanneries Waste Water

Removal of Cr+6 From Aqueous Solution

Abstract

 Adsorption is one of the best methods for removing metals from aqueous medium. In the present study, bentonite clay was used as an adsorbent for heavy metal Cr+6 removal from the synthetic solution as well as actual waste water collected from local tanneries. Bentonite was used with and without chemical modification to improve removal efficiency. The adsorbent was modified with HCl, H2SO4 and NaOH. The batch adsorption technique was applied to study the effect of pH, initial concentration of metal ions, adsorbent dose and shaking time on the adsorption process. The chemical oxygen demand and biological oxygen demand of tannery effluents were significantly reduced upto 77.6% and 81.2%, respectively. The original bentonite clay removed upto 59%, while 98% removal was achieved with H2SO4 modified bentonite clay, 68% with HCl modified clay and 89% by NaOH-modified clay. Furthermore, the percentage removal efficiency was reduced by increasing the initial concentration of metal ions. The current study concluded that bentonite clay is a good adsorbent and modifications to bentonite clay can effectively improve the physical characteristics of the clay to adsorb Cr+6 ions. Moreover, bentonite clay is inexpensive and readily available in our country.