Phenol adsorption on scoria stone as adsorbent - Application of response surface method and artificial neural networks

In this study, adsorption of phenol from aqueous solutions was studied. Scoria stone was modified by different acids (nitric acid, sulfuric acid, acetic acid, phosphoric acid and hydrochloric acid) at various concentrations. The obtained modified scoria was characterized using the Fourier transform infrared spectrograph (FTIR), scanning electron microscopy (SEM) and x-ray fluorescence (XRF). Adsorption equilibrium data were analyzed using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms, the results indicated the best fit by the Langmuir isotherm (qm = 67.11 mg/g) and maximum removal of phenol was obtained for sulfuric acid modified scoria (96.84%). In addition, the phenol adsorption was modeled using the pseudo-first order and pseudo-second order models, the best fit being observed with the pseudo-second order kinetic. Modelling of the process was carried out using Response Surface Method and Artificial Neural Networks. The resulting models were then further applied to optimize the phenol adsorption, different combinations of parameters leading to the maximization of efficiency being obtained.