Abstract
The application of adsorption techniques for the treatment of carpet effluents containing mainly Metomega Chrome Orange GL (MCO) using various low-cost materials, i.e. coal, fly ash, china clay and wollastonite, has been tested. In all cases, low initial dye concentration, low temperature and low pH favour the removal process. The maximum uptake of the dye by these materials has been determined at 30°C and a pH of 4.5. The effect of pH on the removal of the said dye has been explained in terms of surface hydroxylation and complexation. Various empirical models have been developed in an attempt to correlate the percentage uptake of dye with the parameters investigated. Dynamic modelling of the dye uptake has been undertaken and found to follow first-order kinetics. The rate constants were determined during the adsorption of the dye under the optimum conditions. Coefficients for mass transfer and intraparticle diffusion were also evaluated in order to explain the mechanism. Langmuir's isotherm was found to be valid. Significant desorption of the dye from the surface of the adsorbents was noted at pH 12.0.
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