Resource efficiency analysis for photocatalytic degradation and mineralization of estriol using TiO2 nanoparticles

Abstract

A resource efficiency analysis was developed that evaluated photocatalyst loading and temperature inputs, and assessed hydroxyl radical (OH) production. Catalyst loading (Aeroxide® TiO2 P25) between 1 and 1500 mg L−1 and temperatures between 5 and 50 °C were analyzed as input resources for OH production. After, the best experimental conditions were used to degrade and mineralize estriol (E3). The analysis showed that a low catalyst concentration lead to poor absorption of radiation and a slow reaction. When high catalyst concentrations were tested, most of the radiation was absorbed, which produced results near the top of the slowing rate of OH generation. Temperature was found a relevant resource for increasing interfacial transfer to facilitate OH production following the Arrhenius model. Two indices to measure resource efficiency were proposed: 1) the OH generation index (OHI) and 2) the initial degradation efficiency (IDE). OHI was used to measure the efficiency of a catalyst using photonic flux to generate OH production. IDE evaluated the relationship between the photocatalytic reactor set-up, catalyst, and E3 degradation. It was observed that 1.18 OH was produced when a photon interacts with a photocatalyst particle when a load of 5 mg L−1 of photocatalyst is used at 20 °C. It was found that at initial time, 2.4 OH was generated in the systems to produce a degradation of one E3 molecule when using a photocatalyst load of 20 mg L−1 at 20 °C. Additionally, it was demonstrated that E3 mineralization was feasible under different catalyst loading scenarios.