Batch and column studies on the removal of methyl orange by Acalypha indica biomass using gravitational search algorithm as an optimization tool

The biosorption of methyl orange dye from an aqueous solution onto Acalypha indica (A. indica) was examined using batch and continuous processes. The equilibrium dye uptake limit of A. indica was determined by analyzing the impact of different working parameters like adsorbent dose, pH, and time. The biosorbent was exemplified by scanning electron microscopy, Fourier transform infrared spectroscopy, surface area analyzer, point of zero charge, and Boehm titration. In batch experiments, the maximum uptake capacity of sorbent (82 mg g(-1)) was achieved with the biosorbent dosage of 0.03 g 100 mL(-1) and at pH 3.0. Henry's isotherm model was (R-2 = 0.997) proved to be a better fit than Langmuir and Freundlich isotherms. The data acquired from kinetic studies were found to fit well with the Elovich's model (R-2 > 0.99) when compared with pseudo-first-order, pseudo-second-order equation, and intraparticle diffusion model. Optimized parameters from batch studies were further employed for column studies. Maximum uptake capacity of biosorbent (244 mg g(-1 )) was obtained at the bed height of 3 cm and at the flow rate of 5 mL min(-1) . Breakthrough curves showed that the chosen biosorbent reduced the concentration of dye from 30 mg L-1 to appreciable level. Gravitational search algorithm (GSA) was employed to predict the optimal combination of the process parameters. It was observed from the GSA results that the equilibrium uptake capacity of the biosorbent should be maintained at the concentration level of 11.3921 mg L-1 and at the time of 47.35 min.