Determination of optimum conditions for removal of As (III) and As (V) by polyaniline/polystyrene nanocomposite

A nanocomposite adsorbent was prepared by coated polyaniline (PAn) onto polystyrene (PS) nanoparticles in attendance of different stabilizer. Removal of arsenic (III) (As (III) and arsenic (V) (As (V)) was studied through adsorption on the polymeric absorbents at different temperatures, pHs and concentrations of As (III) and As (V). The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption models and the model parameters were evaluated. The both models represented the experimental data well. The adsorption capacity of the PAn/PS with HPC, as obtained from the Langmuir isotherm, is 56 and 52 mg/g of PAn/PS for As (III) and As (V), respectively. Thermodynamic parameters such as Gibbs free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) were calculated from experimental isotherm at different temperatures. The values of enthalpy (ΔH°) were negative, which confirms the exothermic nature of adsorption process. Also negative values of Gibbs free energy (ΔG°) indicated feasible and spontaneous nature of the adsorption process at different temperatures.