Study of the Influence of Some Ions on the Adsorption of Methyl Red on Clay Materials from Côte d’Ivoire

Industrial dye-containing effluents require effective treatment before discharge. This study investigated the adsorption of methyl red by two clay materials collected in Côte d’Ivoire (KAT2 and KOR), with particular attention to the effects of contact time, solution pH and dissolved metal ions. Fine clay fractions were prepared and examined in untreated form and following saturation with Na⁺ or Mg²⁺. Batch adsorption experiments were conducted with synthetic methyl red solutions at an initial dye concentration of 20 mg/L and a clay mass of 60 mg in a 10 mL mixture. The effects of Cu²⁺, Fe²⁺, Fe³⁺ and Pb²⁺ individually, and of these ions together with Zn²⁺, were considered. Methyl red adsorption efficiency rose rapidly during the first 30 minutes and subsequently approached a plateau. The kinetic data were more closely described by the pseudo-second-order model than by the first-order model, with coefficients of determination of 0.999 for the six clay samples. The intraparticle diffusion model indicated two adsorption stages. Adsorption was greatest under strongly acidic conditions and generally declined as pH increased. The presence of the examined metal ions enhanced methyl red removal, although the concentration at which adsorption levelled off depended on the ions and clay samples. These findings indicate that the adsorption behaviour of the studied clays is sensitive to solution chemistry and that dissolved ions should be considered when evaluating their use for dye removal.