Efficient Treatment of Pharmaceutical Wastewater By Heterogeneous Fenton-Like Process With Three-Dimensional and Nano-Scaled Perovskite Based Catalyst

Heterogeneous Fenton-like method is a developing and promising advanced oxidation technology for the treatment of non-biodegradable organic pollutants. The studies about exploring heterogeneous catalysts suitable for Fenton-like process have been widely investigated. The general requirements for heterogeneous catalysts in Fenton-like system are: high catalytic oxidation efficiency and H₂O₂ utilization, minimum metal leaching, and effectiveness at extended pH range. Aiming at these developments for heterogeneous Fenton-like system, we proposed a novel BiFeO₃ (BFO)-based catalyst. BiFeO₃ (BFO), as a typical ABO₃ compound, has stable perovskite-type structure in liquid phase and Fe element, which is a powerful candidate for catalytic activation of H₂O₂ with high stability. Considering the catalytic ability of simple BFO was not so strong especially in pure Fenton process to degrade persistent and complex pollutants, thus, in this work we developed the sol-gel method to fabricate a novel BFO/carbon aerogel (CA) as heterogeneous Fenton-like catalyst. Through BET analysis, it was found that BFO/CA nano-scaled composite presented a specific surface area of 404 m² g^-1, being considerably larger than that of pure nano BFO (14 m² g^-1). Apart from high surface area, nano BFO/CA catalyst possessed three-dimensional (3D) network structure, in which BFO active sites not only simply placed on CA surface, but grown along with the 3D structure of CA. The Fenton oxidation reactivity with this novel catalyst was evaluated by its reducibility through TPR measurement and the amount of generated OH radicals through HPLC analysis. Moreover, the catalytic activity was tested in degrading pharmaceutical wastewater. Here, ketoprofen (KP), recognized as a refractory and hazardous component in pharmaceutical wastewater, was selected as a target pollutant to be removed. As a result, this novel nano BFO/CA catalyst exhibited excellent Fenton-like activity towards the KP degradation, retained its efficient catalytic performance in wide pH range of 3-7, and had limited iron leaching (0.59 mg L^-1) even in acidic condition during whole reaction. Further investigations will be focus on improving the Fenton reaction kinetics of KP oxidation by optimizing the ratio of BFO/CA: H₂O₂: KP and operating conditions such as temperature. For respective, this promising Fenton-like composite catalyst has great potential for practical treatment of persistent and complex pollutants, since its high efficiency, stability and friendly working condition. Moreover, this developed coupled system, not only offers a new idea to improve the activity of catalysts, but also inspires us to design new advanced oxidation system for practical refractory treatment.