Submerged photocatalytic membrane

A partially fluorinated polymer, also soluble in polar solvent, is PVDF. It is characterized by high performance, chemical resistance, good thermal stability, and resistance to UV light and oxidant attack (Chin et al., 2006). PVDF membranes have been used primarily in the construction of submerged modules, widely used in bioreactors because of their lower costs with respect to other types of photocatalytic membranes (Sopajaree et al., 1999 Chin, Lim, Chiang, Fane, 2007 Jia et al., 2006, Fu, Ji, Wang, Jin, An, 2006). 

In recent years some studies were performed using submerged membrane modules coupled to photocatalytic systems for the removal of organic pollutants such as fulvic acid [84], bisphenol-A [85], para-chlorobenzoate [86]. 

Particular attention is addressed to the permeate flux and to this purpose some preliminary experiments were realized on a different configuration of membrane photoreactor with a submerged membrane module located separately from the photoreactor. Bubbled oxygen on the membrane surface has the roles to reduce the catalyst deposition, to increase the flux through the membrane and to facilitate the photocatalytic reaction. 

Chin S S, LimT M, Chiang K and Fane A G (2007b), Factors affecting the f>erfor-mance of a low-pressure submerged membrane photocatalytic reactor , Chem ng 7,130,53-63. 

The catalyst deposition on the membrane surface and fouling caused flux decUne during the photocatalytic process. To overcome these problems the depressurized (submerged) membrane system, in which the membrane module was located separately from the photoreactor, was studied. The achieved results showed pharmaceuticals abatement of 100% after ca. 20 min and mineralization of 44.5% after ca. 150 min in the retentate. The UF membrane used in the submerged system did not allow the rejection of GEM and of its oxidation products compared to the NF membranes of the pressurized system. 

Chin et al. (2007b) used pseudo-first order reaction kinetics combined with the ideal continuous stirred tank reactor (CSTR) model to evaluate the effect of initial concentration of pollutant on the performance of a submerged membrane photocatalytic reactor for the degradation of bisphenol A in water (Equation [21.2]) ... 

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