Preparation Of Fe-SiO₂Solid Acid Catalyst For Degaration Of Dyeing Wastewater

Solid acid catalyst has been widely applied in industrial catalysis and environmental pollution controll. It is crucial time to enhance Fenton reaction by using acidic Fe-based catalysts instead of Fe ions catalyst, because only in this way the limitations of homogeneous Fenton system, for example, the narrow operating pH range (2-3), the lower reactivity and the high expenditure in labor and reagents, will be gradually removed.In this study, two series of acidic Fe-based catalysts (FS/1and FS/6) have been synthesized by sol-gel method and improved hydrothermal method, and then modified by S=O. After preparation, these chalybeate compounds were characterized by scanning electron microscopy (SEM) for the morphology of the samples, X-ray diffractometer (XRD) for the dispersibility of metal oxides, photoelectron spectroscopy (XPS) for the surface state, Fourier transform infrared spectrometer (FTIR) for the surface groups. In order to evaluate the activities of different catalyst, a series of photo-Fenton reactions have been conducted to decontaminate the simulated dyeing (Direct Red4BS) wastewater. The influence of introduced S=O on the performance of Fe-based catalysts was measured and the reaction mechanism was investigated. The kinetics of acidcatalysis and modified mechanism of catalysts were also discussed at the present work.The acidic Fe-based catalysts have been successfully prepared on different conditions and characterized by different techniques. The characterization results indicated that these catalysts were porous-material, and Fe ions were immobilized in both of these catalysts. Significantly, FT-IR spectrum suggested that the sulfated Fe-Si composite oxide particles exhibited a strong acidic property. XPS analysis proved the presence of S6+(S=0), which led to the generation of acid sites (L acidic sites and B acidic sites). By analyzing the decolorization and TOC removal of a solution containing100mg/L organic dyes, almost thorough decoloration and79%or99%TOC removal were achieved after120min reaction time in respective reaction system. It displayed that these acidic Fe-based catalysts were extremely efficient to degrade organic dyes. By comparing the performances shown by the no-sulfated catalysts with corresponding sulfated catalysts, it evidenced that acid sites played an important role in Fenton-like reactions. Stability test indicated that catalysts in the whole experiment were predominant. Iron leaching in these systems kept at about0.8mg1-1, respectively, indicating both of these catalysts may have long-term stability.