Development and evaluation of an integrated slurry photocatalytic membrane reactor for the degradation of polycyclic aromatic hydrocarbons in aqueous solutions

Abstract

Advanced Oxidation Processes (AOPs) such as photolysis,photocatalysis, ozonation, Fenton processes with or without the addition of oxidants (H2O2) were reported by the researchers as efficient methods for the treatment of several hazardous organic compounds. The various advantages of AOPs are effective operation at room temperature, low pressure condition, high degradation efficiency, non-necessity of adding chemicals, effective reuse of catalyst and complete degradation and mineralization of compound molecules. However, electron-hole recombination is the major limiting factor of these methods which leads to low degradation efficiency and low quantum yields. In addition, the usage of excessive oxidants could act as a scavenger and the free radical scavenger can inhibit pollutant degradation efficiency. Among the two types of photocatalytic reactors; (i) slurry (photocatalyst in suspension and (ii) immobilized (photocatalyst supported on a carrier material), slurry reactors were preferred by the researchers due to the availability of more surface area for adsorption and high degradation rate. However, this type of configuration has an important issue of separation of photocatalyst particles from the treated solution. The process could be optimized by retaining, recovering and recycling photocatalyst particles by adequate means. Hence, in this type of reactors, if membrane filtration has been added as an additional step, it will resolve the problem of photocatalyst separation. newline