Application of artificial neural networks and response surface methodology for analysis of malachite green removal from aqueous solution using phosphoric acid-modified pumice powder: kinetic and isotherm studies

The present study aimed at investigating phosphoric acid (1, 6 and 12 N)-modified pumice efficiency in removal of malachite green (MG) dye from aqueous solutions. The effects of different parameters such as pH (3-11), adsorbent dosage (0.2-1.4 g/L), contact time (15-75 min) and the dye initial concentration of 85 mg/L were analyzed. The obtained modified pumice was characterized using the Fourier transform infrared spectroscopy and scanning electron microscopy. Adsorption equilibrium data were analyzed using Langmuir, Freundlich, Temkin and Redlich-Peterson. The results illustrated that the data were following both Langmuir and Freundlich isotherms. Also, the phenol absorption was modeled using pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich models. The best fit being observed with the pseudo-second-order kinetic model. Finally, the process modeling was carried out using response surface method and artificial neural networks.