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
Experimental design to optimise colour removal of diazo dye Congo Red using Zero–Valent Iron
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.