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.