Malachite green removal using modified sphagnum peat moss as a low-cost biosorbent: Kinetic, equilibrium and thermodynamic studies

Abstract

Sphagnum peat moss (SPM) as a low-cost biomaterial was treated using hydrochloric acid for the removal of malachite green (MG) from aqueous solution for the first time. In the batch adsorption experiments, the effects of contact time, sorbent dosage, pH, initial dye concentration and temperature on the SPM adsorption capacity were studied. Results indicated that it was favor of adsorption at pH 6.5. Characterization of the adsorbent has been accomplished by SEM, BET, and FTIR analyses. Equilibrium data were accurately fitted onto Langmuir, Freundlich and Temkin isotherms. Investigations showed that the adsorption isotherm data were fitted well to the Langmuir isotherm and the calculated maximum adsorption capacity was about 121.95 mg/g at 20 °C. The adsorption kinetic was better described by pseudo-second order kinetic model. Besides, the thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were also calculated. Negative value of ΔG° and ΔH° indicated that the adsorption process is spontaneous and exothermic, respectively. It was resulted that the introduced acid modification of SPM is a promising route to prepare a potential biosorbent for MG removal.