Removal of Dyes by Biodegradable Flocculants: A Lab Scale Investigation

Abstract

In the present communication, experiments were conducted to investigate the efficiency of mucilage isolated from fruits of Coccinia indica for the treatment of simulated textile wastewater samples containing direct dyes, direct fast scarlet (DFS) and direct fast yellow (DFY) and vat dyes, golden yellow (GY) and nyanthrene yellow (NY). This mucilage (Ku) is an ecofriendly and low cost anionic polysaccharide capable of reducing color from textile effluent through flocculation process. The flocculation efficiency of Ku was improved by grafting polyacrylamide onto it. The copolymer thus obtained (Ku‐g‐PAM) showed much better flocculation capacity than that of its precursor by reducing the flocculant dose and treatment time to half. The results showed that the maximum removal was obtained at acidic pH with both the flocculants. Statistical analysis showed that the change in percent removal with pH was highly significant in case of direct dyes while it was significant in case of vat dyes removal. The plausible mucilage‐dye interaction and flocculation mechanism has been discussed.

Keywords:

• Natural polysaccharide
• grafting
• polyacrylamide
• direct dyes
• vat dyes

Acknowledgement

The authors are grateful to University Grants Commission, New Delhi for financial support of this study [Project No. F. 12‐133/2001 (SR –1)].