Photocatalytic Oxidative Removal of Phenolic Compounds from Wastewater using Ozone and Hydrogen Peroxide Produced by New Electrodes

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The re-use of municipal wastewater is one way to meet the increasing demand for clean water. Although the biological treatment of domestic wastewater has been used all over the world, one faces difficulties to operate when there are toxic and refractory chemicals in the wastewater. Phenolic compounds are examples of these refractory chemicals which are also proved to have toxic effects on both human and environment even at low concentrations. The presence of these phenolic compounds has been confirmed in many different industrial wastewaters from chemical, petro-chemical or even from food-processing industries. Kuwait is an arid country with negligible rainfall and so the re-use of treated wastewater for landscape irrigation and for industrial activities will be of great interest. The proposed project provides high efficient and cost-effective solutions for removal of phenolic compounds from wastewater through their degradation. This will be achieved by introducing a new approach via chemically-assisted photocatalysis using glassy carbon (GC), graphene (G) and/or carbon nanotubes (CNTs)-supported TiO2 nanoparticles (NPs) electrodes in presence of UV/Ozone and UV/ H2 O2 . These combined processes will result in lowering the cost compared to other techniques especially those which are mainly based on separation. e.g. membrane filtration, in which the phenolic compounds will be firstly, separated, then in a second step, will be treated chemically or electro-chemically to degrade it. Through this proposed project, new electrode materials to increase the efficiency of electrochemical generation of ozone will be manufactured in our lab. In addition, a novel electrode that increases the efficiency of the in-situ hydrogen peroxide production via perpetration of TiO2 NPs will be prepared and used for the same goal. Moreover, we aim to harbor a new technology of graphene synthesis and use nanoscience and nanotechnology in Kuwait since they are of great importance to the State of Kuwait for the education, research and technology aspects. It is worth mentioning that this proposed technique not only can be applied for wastewater but also for treating drinking water. To achieve our objectives, the proposed work will be divided into three work packages: the first one is preparation of TiO2 NPs catalyst supported by functionalized G or CNTs. This work package encompasses three successive steps: first of all, synthesis of graphene will be carried out, followed by functionalization of it and, finally, deposition of TiO2 NPs on the functionalized carbon support. The prepared catalysts will be characterized using surface and bulk techniques like X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) scanning electron microscopy (SEM) and X-ray diffractometry (XRD). In addition, the Brunauer-Emmet-Teller (BET) surface area will be measured. Furthermore, electrochemical characterization will be carried out for all samples. The second work package will deal with the manufacturing of a novel electrode to generate ozone that will be used in the presence of our catalyst that is prepared from work package 1 in the presence of a powerful UV lamp. Characterization of wastewater before and after treatment will be carried out using HPLC, TOC, UV-Vis spectrophotometer and electrochemical analysis. Finally, work package 3 relates to manufacturing quinine functionalized glassy carbon (GC/Ti) and GC/TiO2 nanoparticles electrodes. In this step we will functionalize the GC electrode’s surface with different quinines and then electrode position of TiO2 nanoparticles on modified glassy carbon electrode will be conducted. Finally electrolysis of water will be carried out using the prepared electrode to insitu generate H2 O2 within wastewater containing phenolic compounds. A phenolic compound analysis, as mentioned before, will be done before and after this treatment and compared to the case when the generated ozone is coupled with TiO2 NPs that are supported on different carbon materials.