Degradation of terephthalic acid in a photocatalytic system able to work also at high pressure

Photocatalytic degradation of terephthalic acid (TPA) has been studied on commercial ZnO immobilized on polystyrene (PS) beads (mean size: 1.5 × 1.5 × 0.1 cm) and located in a stainless steel flat plate reactor with an irradiation window realized in a UV transparent polymethylmethacrylate (PMMA UVT) in order to make the system able to work also at high pressure. In this way, it is possible to overcome, both the problems related to the photocatalysts separation after the wastewater treatment and those ones caused by the inlet pressure (which may be higher than atmospheric one) of incoming wastewater. The solvent casting-method used for photocatalyst preparation is able to induce the formation of ZnO particles in form of isles dispersed on PS macro surface. Moreover XRD analysis evidenced that the PS support didn't influence the crystalline arrangement of ZnO in wurtzite phase. The structured composite photocatalyst ZnO-PS showed high ability in the degradation of TPA giving its total mineralization under UV irradiation at atmospheric pressure. Increasing the pressure, similar levels of TPA removal were observed. This finding demonstrated the possibility, for the developed photocatalytic system, to operate under moderate pressure without worsening the photocatalytic performances.