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

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

Removal of malachite green from aqueous solution using pulverized teak leaf litter: equilibrium, kinetic and thermodynamic studies

Abstract The removal of malachite green (MG) from aqueous solution using teak leaf litter powder (TLLP) was investigated. The process was influenced by initial concentration, pH and temperature of dye solution as well as TLLP dosage. Optimum removal of MG per gram of TLLP occurred at 2 g/L and at pH 6–8. Dubinin–Radushkevich and Freundlich isotherm models fit the batch adsorption data better than Langmuir isotherm. The monolayer capacity of TLLP was 333.33 mg/g at 293–313 K. The mean free energy of 7.07 kJ/mol implied physical adsorption. The pseudo-second order model fit the kinetic data better than the pseudo-first order model. Both intraparticle diffusion and film diffusion mechanisms jointly influenced the adsorption process but the latter was the rate-controlling step. Thermodynamic data indicated that the process was endothermic, spontaneous and feasible. Therefore, TLLP could be an important low-cost adsorbent for removal of MG from aqueous solution