Effect of Hybrid Photocatalysis and Ceramic Membrane Filtration Process for Humic Acid Degradation

The photocatalytic degradation of humic acid (HA) in aqueous suspension using commercial TiO2 powder (Degussa P 25) irradiated with UV light was investigated. Photocatalytic experiments were carried out as an individual treatment and combined with ceramic membrane filtration. In this study, the photocatalytic oxidation of HA was investigated and compared at different operating conditions. The effects of operating parameters such as TiO2 concentrations, HA concentrations, and UV intensity were evaluated on the performance of photocatalytic oxidation process. The effect of salinity on the performance of combined photocatalysis and ceramic microfiltration (MF) system was investigated. The interaction between the components in the system, HA, NaCl, and TiO2 photocatalyst, played an important role in the observed flux change during ceramic MF. The result showed that TiO2 concentrations of 0.5 g/L resulted in significant HA removals of more than 80% after 120 min of photocatalytic oxidation process alone. The result shows that the flux decline was lower in the presence of NaCl compared to absence of NaCl. The observed permeate flux decline behavior during ceramic MF was associated with the composition of HA, and NaCl and TiO2 concentrations after photocatalytic treatment. The results for this hybrid system showed that the DOC removal was 48% in the absence of NaCl and 51 and 55% for 500 and 1000 mg/L NaCl concentrations, respectively after 75 min (15 min dark and 60 min photocatalytic reaction) of photocatalysis and 30 min of ceramic MF. On the other hand, the reduction in UV absorbance with and without NaCl concentrations was more than 75% for this hybrid system.