Waste generated for the during the red mud, an industrial ore, aqueous the byproduct, is recycled solution. such processing of were congo of bauxite red from adsorption kinetics Adsorption studied using dose, parameters time as dye concentration, Adsorption adsorption isotherms. dye was followed data The adsorbent first rate both agitation The and red to and pH. | Chemosphere Vol. 34 No. 2 pp. 401-417 1997 Copyright 1997 Elsevier Science Ltd Printed in Great Britain. All rights reserved PII S0045-6535 96 00385-2 0045-6535 97 Pergamon REMOVAL OF CONGO RED FROM WASTEWATER BY ADSORPTION ONTO WASTE RED MUD c NAMASIVAYAM and D. J. s. E. ARASI Environmental Chemistry Division Department of Environmental Sciences Bharathiar University Coimbatore - 641 046 Tamil Nadu - INDIA. Received in USA 23 June 1996 accepted 23 August 1996 ABSTRACT Waste red mud an industrial byproduct generated during the processing of bauxite ore is recycled for the adsorption of Congo red from agueous solution. Adsorption kinetics were studied using the parameters such as dye concentration adsorbent dose agitation time and pH. Adsorption followed first rate expression. The equilibrium adsorption data obeyed both Langmuir and Freundlich isotherms. The adsorption capacity of the red mud for the dye was mg g. Adsorption was found to be nearly quantitative at pH . Effect of pH and desorption studies suggest that the mechanism of adsorption is mostly ion exchange. 1997 Elsevier Science Ltd. All rights reserved Key words Waste red mud Congo red adsorption isotherms pH effect. Author to whom correspondence should be addressed. E-mail sandy@ 401 402 INTRODUCTION Colour is one of the characteristics of an effluent which is easily detected and readily traced back to its source. Most dyes are stable to biological degradation. Coloured waters are often objectionable on aesthetic grounds for drinking and other agricultural purposes. Colour affects the nature of the water by inhibiting sunlight penetration thus reducing photosynthetic action. Some dyes are carcinogenic and mutagenic 1 . Hence there is a need to remove dyes from wastewaters before it mixing with receiving waters. The treatment of dyes in industrial wastewaters poses several problems since dyes are generally stable to photodegradation and oxidation 2 hence they .
