Membrane-based photocatalytic systems for process intensification

Development of photocatalytic titanium dioxide membranes for degradation of recalcitrant compounds

“…In general, photocatalytic activity increases with increasing catalyst surface area due to the greater number of reactive sites for the adsorption of micropollutants . The impact of increasing photocatalytic surface area is in line with the need for improved transport of the target compounds to the catalytic surface (which may be subject to mass transport limitations) …”

“…The appropriate hydraulic residence time will be determined, which could be higher than 3 h because each volume of water will not be exposed to the UV radiation during all this period, decreasing degradation rates. Furthermore, future studies should focus on addressing and solving challenges associated with the proposed configuration before large‐scale industrial application: optimization of reactor configurations that combine membrane filtration with irradiation; irradiation sources and wavelengths emitted; mass transfer limitations; reusability of the photocatalytic membranes; possibility of catalyst release …”

“…Membrane fouling development and the formation of a highly concentrated retentate that needs subsequent treatment/disposal are major drawbacks of nanofiltration. Regarding photocatalysis, the possible formation of toxic by‐products and the requirement for the removal of TiO 2 nanoparticles after treatment are well known disadvantages . These limitations might be overcome by combining the two technologies in a photocatalytic membrane reactor.…”

Photocatalytic Membrane Reactors (PMRs) in Water Treatment: Configurations and Influencing Factors

“…Most researchers selected polyvinylidene fluoride (PVDF) polymeric membranes for the photocatalyst entrapment [36][37][38][39][40][41][42][43], while polyethersulfone (PES) [44][45][46], polyacrylonitrile (PAN) [47], cellulose acetate (CA) [48,49], polystyrene (PS) [50] and polysulfone (PSF) [51,52] were also used. For PMRs with free-standing photocatalytic membrane, its production is often performed via the electrochemical anodization of a titanium metallic substrate, followed by the separation of the TiO 2 nanotube film and different annealing treatments [17]. Compared to membrane with coated or blended photocatalyst, the immobilization step is unnecessary for freestanding photocatalytic membrane, thus reducing the possibility of photocatalyst leaching.…”

“…Meanwhile, various organic and inorganic materials have also been used in some researches. Iglesias et al [17] summarized different ways of manufacturing membranes with a catalyst layer on the surface, including dip-coating, electrospraying TiO 2 particles, magnetron sputtering or deposition of gas phase photocatalyst nanoparticles. Table 1 presents several examples of membranes coated with photocatalyst by different methods.…”