ELECTROCHEMICAL DEGRADATION AND CHEMICAL ASSESSMENT OF AZO DYES IN THE TEXTILE WASTE WATER

Abstract

Azo dyes are carcinogenic and if taken would lead to debilitating adverse health effects in animals, man and aquatic organisms. In this study, novel Boron Doped Diamond (BDD) electrodes were the anode while stainless steel served the role of cathode to degrade azo dyes. Iron (11) sulphate was used as a supporting electrolyte and silver nanoparticles as electrocatalyst to enhance the degradation efficiency. A sample of synthetic and real wastewater samples were employed in the electrochemical treatments and the variations studied were; voltage, dye concentration, supporting electrolyte, current density, inter-electrode distance, pH and temperature of the effluent. Degradation efficiency was monitored by UV-VIS spectrometry while some of the Physico-chemical parameters were determined by standard methods for examination of water and waste water as outlined in the APHA (2000). The absorption spectra for the four dyes were determined and their λ max ranged between 470 to 590 nm in UV-VIS spectrum. Colour removal of 100% was achieved at the end of the electrochemical degradation. The BOD and COD of the effluent were lowered below the recommended values by the WHO (2002) of 150mg/l and 250 mg/l before the discharge to water course. The colour levels of the treated textile waste water was found to be BDL.The final treated wastewater was compared with National Environmental Management Authority (NEMA) and World Health Organization (WHO) effluent discharge standards for possibility of re-use or direct discharge to a natural water course