As(V) removal from aqueous solution using a low-cost adsorbent coir pith ash: Equilibrium and kinetic study

In this study, the adsorptive removal of As(V) from aqueous solution by using a low-cost adsorbent coir pith ash (CPA) was analysed in a batch system. The adsorption capacity of CPA was investigated under different process parameters, these being pH, adsorbent dose, initial As(V) concentration and contact time. The CPA was found to adsorb As(V) over the initial solution pH range of 2-12, and the best adsorbent dose was 5 g/L. Adsorption kinetics data were best fitted to the pseudo-second-order kinetic model. The Langmuir and Dubinin-Radushkevich (D-R) isotherms represented the adsorption equilibrium data very well. The maximum adsorption capacity was 36.5 mg/g as per Langmuir isotherm at room temperature (25 °C). The mean free energy (8.64 kJ/mol) obtained from the D-R isotherm model revealed that the type of adsorption depends on the ion-exchange mechanism. The results showed that adsorbent CPA has great potential for removing As(V) from contaminated water.