The removal of malachite green by adsorption on stishovite-TiO2 nanocomposite as well as on stishovite clay under optimized conditions has been studied. The effect of several parameters such as adsorbent dose, contact time, initial concentration, pH, temperature has been evaluated. The application of pseudo first order, pseudo second order, Elkovich kinetic model and intraparticle diffusion model have been calculated. The adsorption on both the clay and nanocomposite followed pseudo second order kinetics. The equilibrium data fitted well with Langmuir and Freundlich models. Thermodynamic parameters such as free energy change (ΔG0), enthalpy change (ΔH0) and entropy change (ΔS0) indicate the adsorption process to be endothermic and spontaneous. The surface morphology of the adsorbents have been analysed using the scanning electron microscope (SEM). The study revealed that nanocomposite is more effective than clay in removing malachite green by adsorption.
Nanocomposite, Malachite green, Adsorption isotherm, Thermodynamics of adsorption, Kinetics