Termite soil as a potential low-cost adsorbent for the removal of methylene blue and malachite green dyes

Abstract

The adsorption of methylene blue (MB) and malachite green (MG) from aqueous solution using a termite soil has been studied by batch adsorption technique. The adsorption experiments were carried out under different conditions of initial concentration (5–100 mg/L). The equilibrium data were fitted to Langmuir and Freundlich isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model with maximum monolayer adsorption capacities found to be 338.98 and 327.21 mg/g at 305 K, respectively. Three kinetic models, pseudo-first-order, pseudo-second-order and intraparticle diffusion were employed to describe the adsorption mechanism. The experimental results showed that the pseudo-second-order equation is the best model that describes the adsorption behaviour with the coefficient of correlation R2 ≥0.99. Fourier transform infra red (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Tunnelling electron microscopy (TEM) studies are evident that the termite soil has an effective adsorbent material.The results suggested that termite soil has high potential to be used as effective adsorbent for MB removal.