An alternative and cost-effective biosorbent derived from napier grass stem for malachite green removal

This work presents an alternative cellulosic biosorbent derived from napier grass stem (NGS) for removing malachite green (MG) from aqueous solution. NGS is modified by a simple process with less reagent usage and low energy required. The removal condition including contact time, initial dye concentration and biosorbent dosage on the adsorption capacity were optimized by using response surface methodology (RSM). The results show that the maximum adsorption capacity of modified NGS (mNGS) was 32.27 mg g^-1 with contact time of 90 min, initial dye concentration of 100 mg L^-1 and biosorbent dosage of 0.05 g. The pseudo second order kinetic model and Langmuir isotherm model were best described the adsorption. It was indicated that the adsorption process take place on localized sites without interaction between dye molecules and a saturated monolayer. Thermodynamic study illustrated that the adsorption was physical in nature, endothermic and spontaneous. The results indicate that mNGS could be employed as an alternative and economical biosorbent for removal of MG from aqueous solution.