Title: Experimental design to optimise colour removal of diazo dye Congo Red using Zero-Valent Iron

Authors: Animesh Debnath; Saswati Chakraborty

Addresses: Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039, India ' Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039, India

Abstract: Two types of zero-valent iron named Iron Powder (IP) and Iron Wool (IW) were used for colour removal of Congo Red (CR) dye from aqueous solution. Strong acidic condition (pH 2–3) favoured 99% colour removal with 2454-2485 mg/g of dye removal capacity by IP and IW. Decolourization of CR followed first order kinetics. At acidic pH, COD (Chemical Oxygen Demand) removal was 14-15% probably by adsorption by various oxidised iron species and at pH 7, it increased to 85%, due to co-precipitation by iron oxide products. IW was reused for three successive cycles without compromising colour removal efficiency of CR.

Keywords: chemical reduction; Congo red; dye removal capacity; iron powder; iron wool; zero-valent iron reuse; colour removal; decolourisation; COD removal; chemical oxygen demand; adsorption; wastewater treatment; textile industry.

DOI: 10.1504/IJEWM.2013.053100

International Journal of Environment and Waste Management, 2013 Vol.11 No.3, pp.267 - 288

Accepted: 29 Jan 2011
Published online: 05 Apr 2013 *

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