Photocatalytic degradation of 2,4-dichlorophenol by Co-doped TiO2 (Co/TiO2) nanoparticles and Co/TiO2 containing mixed matrix membranes

Chlorophenols are special groups of organic pollutants which are widespread in water and soil sources. Advanced oxidation processes (AOPs) appear to be well-established techniques for degradation of chlorophenols. In this research, TiO2 nanoparticles containing different amounts of cobalt, Co/TiO2, (as AOP photocatalysts) were synthesized by sol-gel method and characterized by FTIR, XRD, SEM and DRS analysis. According to the XRD patterns, pure TiO2 and Co/TiO2 samples are in anatase phase. According to DRS results, the presence of cobalt in TiO2 lattice shifted the absorption edge to higher wavelengths (red shift) and Co/TiO2 exhibited the higher photocatalytic activity under visible light. The best degradation performance was achieved when TiO2 nanoparticles containing 1.34 mol% −Co (Co/TiO2 (1.34)) was used as photocatalyst for 2,4-dichlorophenol (2,4-DCP) degradation under visible light irradiation. Photocatalytic mixed matrix membranes (MMMs) containing Co/TiO2 (1.34) were fabricated by phase inversion technique and the effect of these nanoparticles on separation, thermal and morphological properties of polymeric (here polyethersulfone (PES)) membranes was investigated by using FESEM, DSC and photocatalytic permeation experiments respectively. Permeation test results showed that addition of Co/TiO2 (1.34) to PES matrix can improve both flux and rejection percent of the resulting membrane. It was found that addition of 1 wt.% Co/TiO2 (1.34) to PES matrix can increase membrane flux and 2,4-DCP rejection percent (under visible light) by 53% and 25.3% respectively in which a nearly 2,4-DCP free solution is achievable in permeate site. Therefore fabricated photocatalytic mixed matrix membranes containing Co/TiO2 nanoparticles are suitable for photocatalytic separation of 2,4-DCP.