Design Of Ag / BiOBr Photocatalytic - Membrane Distillation Reactor And Its Synergistic Mechanism

Wastewater from the dye, pharmaceutical and agriculture industries poses a severe threat to both environment and health of people and animals. Compared to the traditional physical, bio-degradable and chemical treatment methods, photo-catalysis is a very promising method because of the energy-saving and the efficient decomposition for the organics. However, it is impossible to get rid of the secondary pollutants including organic intermediates and inorganic ions which may have greater toxicity. Even though the high degradation efficiency, there is an unavoidable decrease along with the reaction time. On the other hand, membranes with certain features which are widely used has played a vital role in the sewage disposal, but it is only a physical process without the function of decomposing the organic thus the penetrant fluid would contain quite a mount of organic materials along with the filtration. Focusing on these drawbacks, the technique of combination of photo-catalysis with membrane has been developed.For the current situation, in this coupling system, for photo-catalysis, it mainly concentrate on the pure Ti O2 powders and modified Ti O2 to get a high organic pollutants decomposition rate. For membrane, pressure-driven type including MF(miro-filtration), NF(nano-filtration), UF(ultra-filtration) and thermal-driven DCMD(direct contact membrane distillation) are inevitably along with apparent membrane fouling and decreased flux when applied. The quality of the permeation are still not very high, and the mechanism of the coupling system are still not clear now.In our work, firstly, we design a photocatalysis-membrane reactor(PMR)bonding photo-catalysis in charge of photo-degradation with DCMD which is responsible for separation of photo-catalyst as well as products and by-products of photo-degradation from the reaction solution in order to efficiently prevent the secondary contamination to get high quality clean water. The PTFE membrane is hydrophobic only permitting volatile materials going through, all the non-volatile materials retained on the feed side. Meanwhile, the film catalysts u avoids the issue of recycling the powder catalysts and membrane fouling. Secondly, the mechanism during the organic degradation process and inorganic ions transformation procedure has been studied in detail which has not been researched in recent years. Both the Ag nanoparticles and MD will enhance the degradation speed of organics as well as the speed of transformation from NO2- to NO3-. Here in PMR system picrolonic acid(ahigh N-containing compound 21 wt%) is used for the model dye.Thirdly, we designed a novel film catalyst called Graphene/Ag@Bi OBr/GO/Cu which couple the photo-electric synergetic degradation for the organics and the membrane separation function.This film photocatalyst was used in the rotating photoelectric cataysis-membrane reactor...