Photocatalytic-(adsorption)-membrane Separation System For The Removal Of Liquid Organic Pollutants

In recent years,environmental problems are becoming increasingly serious,among which water pollution is worse and worse and has begun to seriously threaten the human living environment.At present,there are many popular ways to treat sewage,such as biological treatment,chemical treatment,photocatalysis and membrane separation.Photocatalyst can absorb sunlight and be excited to generate active species such as electrons and holes to degrade pollutants in water.However,the concentration of pollutants will be lower due to the photocatalytic degradation and then the photocatalytic degradation rate will slow down.And there is still a problem of pollution,which pollutants can not be completely degraded.Membrane separation as a new high efficiency separation technology has been widely used in chemical industry,environmental protection,electronics,light industry,textile,petroleum,food,medicine,biological engineering,energy engineering and so on.In addition,membrane separation technology can be divided into a variety of sewage treatment,such as pressure driven medium microfiltration,nanofiltration,ultrafitration.Membrane separation technology has a good separation effect in the treatment of sewage,but this technology is a simple physical separation process.The separated organic pollutants still exist in the water,and easily result in the membrane fouling.The present situation of combining photocatalysis and membrane separation for water treatment is that?1?the main focus is on the study of power catalysis.There are difficulties in separation and reuse.?2?There is a light shielding effect for dye wastewater.?3?It is easy to cause membrane fouling in the process of treating wastewater.In view of the above problems,this paper mainly carries out the following works:?1?Synergistic system of integrated photocatalysis-membrane separation in rotating reactor for organic pollutant removalA rotating photocatalytic membrane separation reactor was designed and Ag@BiOBr-GO/Ag@BiOBr photocatalyst film was prepared by filtration.The rotating photocatalytic membrane separation reactor is divided into two parts.One is the rotating disk of the Ag@BiOBr rmembrane catalyst,the other is the vacuum filtration device.When the two parts are combined together,photocatalysis plays a significant role in degrading pollutants and solves the problem of membrane fouling.Membrane separation plays a separate role while concentrating pollutants to promote photocatalytic degradation.The photocatalysis and membrane separation are synchronized.?2?Removal of organic pollutants by the synergistic system of photocatalysis,adsorption and membrane separation.Ag@BiOBr/AC/GO photocatalytic-adsorption-membrane separation composite film system was prepared.Each of the three plays its own role.The role of bismuth bromide as photocatalyst is mainly to degrade pollutants.Activated carbon can adsorb pollutants well because of its large specific surface area.The role of graphene oxide is an important component of the preparation of membranes.On the other hand,the water flux and the retention of RhB were changed by adjusting the amount of the membrane.Compared with the treatment process alone,photocatalysis can assist the membrane to maintain the retention rate and promote the continuous adsorption.The membrane separation can effectively concentrate the solution of organic pollutants and improve the photocatalytic degradation.At the same time,it can promote the adsorption.The adsorption can keep the retention rate of the membrane.Therefore,the mixed membrane with synergistic system can effectively concentrate pollutants,accelerate reaction rate and avoid membrane fouling.Meanwhile,the catalyst is easy to be recovered.It provides a theoretical basis for the potential application in the future.?3?Studying on removal of oily pollutants by rGO-TiO₂ photocatalytic film at water-oil interface.Photocatalytic film located at the interface of water and oil was prepared.Hydrophobic film was prepared by reducing graphene oxide and TiO₂.When the film was in contact with trace organic pollutants in water,the film quickly separated the trace oil from water and located on the water-oil interface,which resulted in the complete contact of photocatalyst with the pollutants and then degrade them.