Equilibrium, thermodynamic and kinetic investigations on biosorption of arsenic from aqueous solution by algae ( Maugeotia genuflexa) biomass

Abstract

This study is focused on the investigation of the equilibrium, thermodynamics and kinetics of arsenic(III) biosorption from aqueous solution by dead green algae ( Maugeotia genuflexa) biomass. Optimum biosorptin conditions were determined under the optimum pH, biomass concentration, contact time, and temperature. The equilibrium data were applied to the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. From the Langmuir model, the maximum monolayer biosorption capacity of the biosorbent was found to be 57.48 mg/g at pH 6, biomass concentration 4 g/L, contact time 60 min, and temperature 20 °C. The calculated mean biosorption energy (10.2 kJ/mol) using D–R model indicated that the biosorption process was carried out via chemical ion-exchange. Biosorbent could be regenerated using 0.5 M HCI solution, with up to 96% recovery and permitted a slightly decrease about 20% in recovery of As(III) ions after repeated ten times sorption–desorption processes. Thermodynamic parameters showed that the biosorption of As(III) onto algal biomass was feasible, spontaneous and exothermic under studied conditions. Kinetic results indicated that the pseudo-second-order kinetic model was well fitted to the experimental data. The performance of the algal biosorbent was also compared with that of many other reported sorbents for arsenic removal and it was observed that the proposed biosorbent is effective in terms of its high sorption capacity.