Degradation of 4-nitrophenol (4-NP) using ZnO nanoparticles supported on zeolites and modeling of experimental results by artificial neural networks

In this paper, we report the synthesis of ZnO, ZnO/HZSM-5, ZnO/HY and ZnO/Clin by a poly acrylamide pyrolysis method for the first time. The presences of carbon network/cages in the poly acrylamide gel can effectively prevent particle agglomeration. The catalytic activity of all specimens was tested by carrying out the 4-nitrophenol degradation, used as a "probe" reaction, in the aqueous medium under ambient visible light. The prepared samples were characterized by X-ray diffraction (XRD), specific surface area (BET) and porosity determination, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), visible-ultraviolet diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FT-IR), to evaluate particle structure, size distribution and composition. The results revealed that among the catalysts, ZnO/HZSM-5 showed higher percentage of adsorption than others. The time required for complete mineralization of 4-NP under ambient visible light over ZnO/HZSM-5 was 75 min. The higher activity of ZnO/HZSM-5 is mainly due to fine dispersion of ZnO and hydrophobicity of the support. An artificial neural networks (ANNs) model was developed to predict the performance of catalytic degradation process over synthesized catalysts based on experimental data. A comparison between the predicted results of the designed ANN model and experimental data was also conducted. (C) 2012 Elsevier B.V. All rights reserved.