Removal of malachite green from aqueous solution using activated carbon prepared from teak leaf litter

Abstract

Teak leaf litter (TLL) was impregnated with phosphoric acid and activated at 400 °C for 1 h to produce teak leaf litter activated carbon (TLLAC). Equilibrium adsorption, kinetics and thermodynamics study was then used to assess the removal of malachite green (MG) from aqueous solution by the novel adsorbent. Temperature, pH and initial concentration of dye solution as well as dosage and contact time influenced the adsorption process. The optimum TLLAC dosage for adsorption of MG was 0.5 g/L. Removal of MG from aqueous solutions increased up to pH 10. The adsorption process was best described using Langmuir isotherm with 91.74 mg/g as the monolayer capacity of TLLAC. Pseudo-second order kinetic model best fit the adsorbent-dye interactions. The mechanism of uptake of MG by TLLAC was jointly influenced by both liquid film and intraparticle diffusion but neither was the rate controlling step. The exothermic process was spontaneous below 313 K. The value of ΔH° (-83.82 kJ/mol) implies possibility of influence of chemical adsorption in the system. The study revealed that TLLAC exhibited potentials to remove MG from aqueous solutions.