Removal of Methylene Blue dye from aqueous solutions by illite clay

Abstract

In this study, adsorption of methylene blue (MB) dye on illite from aqueous solutions was investigated as a function of pH, electrolyte concentration and temperature. Illite clay was characterized using FTIR-ATR, BET, SEM, XRF and XRD instruments. Adsorption studies showed that adsorption process attained to equilibrium about 3 h and adsorbed amount of MB on illite increased with increasing pH, electrolyte concentration and temperature. Experimental data were analysed with Temkin, Dubinin-Radushkevich (DR), Freundlich and Langmiur isotherms and correlated reasonably well by Langmuir adsorption isotherm with highest R-2 values. Then, Langmiur isotherm parameters (q(m), and K) were calculated. The value of maximum adsorption capacity (q(m)) was varied from 14.61.10(-5 )to 31.63.10(-5) mol.g(-1) for different experimental conditions. The adsoption heat was calculated as 14.38 kJ.mol(-1) for isosteric conditions (theta = 0.5). The positive and relatively low value of adsorption heat shows that adsorption process is an endothermic process and interaction between the dye and illite is a physical interaction. The values of R-L, calculated dimensionless separation factor, showed that illite can be used for removal of MB from aqueous solutions.