Modelling and Simulation of the Radiant Field in an Annular Heterogeneous Photoreactor Using a Four-Flux Model

This work focuses on modeling and simulating the absorption and scattering of radiation in a photocatalytic annular reactor. To achieve so, a model based on four fluxes (FFM) of radiation in cylindrical coordinates to describe the radiant field is assessed. This model allows calculating the local volumetric rate energy absorption (LVREA) profiles when the reaction space of the reactors is not a thin film. The obtained results were compared to radiation experimental data from other authors and with the results obtained by discrete ordinate method (DOM) carried out with the Heat Transfer Module of Comsol Multiphysics® 4.4. The FFM showed a good agreement with the results of Monte Carlo method (MC) and the six-flux model (SFM). Through this model, the LVREA is obtained, which is an important parameter to establish the reaction rate equation. In this study, the photocatalytic oxidation of benzyl alcohol to benzaldehyde was carried out, and the kinetic equation for this process was obtained. To perform the simulation, the commercial software COMSOL Multiphysics v. 4.4 was employed

Comparison of AOPs Efficiencies on Phenolic Compounds Degradation

In this work, a comparison of the performances of different AOPs in the phenol and 4-chlorophenol (4-CP) degradation at lab and pilot scale is presented. It was found that, in the degradation of phenol, the performance of a coupled electro-oxidation/ozonation process is superior to that observed by a photo-Fenton process. Phenol removal rate was determined to be 0.83mg L−1 min−1 for the coupled process while the removal rate for photo-Fenton process was only 0.52mg L−1 min−1. Regarding 4-CP degradation, the complete disappearance of the molecule was achieved and the efficiency decreasing order was as follows: coupled electrooxidation/ ozonation > electro-Fenton-like process > photo-Fenton process > heterogeneous photocatalysis. Total organic carbon was completely removed by the coupled electro-oxidation/ozonation process. Also, it was found that oxalic acid is the most recalcitrant by-product and limits the mineralization degree attained by the technologies not applying ozone. In addition, an analysis on the energy consumption per removed gram of TOC was conducted and it was concluded that the less energy consumption is achieved by the coupled electro-oxidation/ozonation process

Paracetamol mineralization by Photo Fenton process catalyzed by a Cu/Fe- PILC under circumneutral pH conditions

This study presents an iron-pillared clay (Fe-PILC) ion-exchanged with copper (Cu/Fe-PILC), as an efficient catalyst to conduct the mineralization of paracetamol through photo-Fenton process at near to neutral pH without precipitation of Fe complexes and without adding any chemicals to modify the initial pH. The specific surface area of the catalyst was of 110m2 g−1 and with the following phases FeO, Fe3O4, Cu2O, CuO determined by XPS analyses. Around 80% of mineralization was reached either by conducting the process at acidic and circumneutral pH conditions, and the efficiency was not significantly higher at pH=2.7. The intermediate reaction products generated at both pH conditions essayed and detected by LC–MS were hydroquinone, acetamide and oxamic acid. Catalyst Cu/Fe-PILC showed an iron leaching of about 3% after reaction while the reusability of the catalyst involved a decrease in mineralization of only 3% under circumneutral conditions. The final TOC of about 20% can be ascribed to the presence of acetamide that was found to be the most reluctant towards oxidation.CONACYT 269093 PRODEP (511-6/178590) CONACYT (Estancia sabática) 26614