Removal of chromium from effluent of tannery industries in Bangladesh using rice husks as natural adsorbent

Abstract

Nowadays heavy metals especially Cr have posed a serious threat to water bodies due to environmental pollution. The tannery industries in Bangladesh have been releasing a significant amount of Cr for years to the environment. The current research works focus on the efficient removal of Cr from tannery effluents using rice husks and coconut shell as natural adsorbents. Chromium concentration determined was 1500 mg L-1 which is alarmingly high in effluents just after chrome tanned discharge, and that was 1.30 mg L-1 Cr in effluents from dumping storage. Rice hush and coconut shell adsorbent were applied to remove Cr. Chemical modifications by treating rice husks with coconut shell increased the adsorption ability of rice husks for Cr removed. Among these adsorbents rice husks of 50 mesh size (particle size 0.297 mm) showed the maximum adsorption (98%) within 6 hours without any stirring effect. However, rice husks of 200 mesh size (particle size 0.297 mm) showed the adsorption (67%) within 6 hours with any continuous stirring effect. These results suggest that cheaply available rice husks can be considered as a good adsorbent for the removal of Cr from tannery effluents.

Keywords

• activated carbon
• coconut shell
• treatment
• spectroscopy