Solar photocatalytic degradation of commercial textile azo dyes: Performance of pilot plant scale thin film fixed-bed reactor

Performances of solar photocatalytic pilot plant using TiO2-P25 (Degussa) were investigated for removal of commercial azo dye chosen as model compound. Experiments were carried out to optimize various parameters, influencing the performance of the operated thin-film fixed-bed reactor (TFFBR) with an area of 25 m2. The results showed kinetic dependency on flow rate, catalyst loading, and initial dye concentration. The best discoloration rate was obtained at the optimum flow rate of 3 m3/h. Increasing catalyst loading density up to 10 g/m2, does not lead to high improvement of the discoloration rate. The photocatalytic degradation kinetic of TOC is discussed in terms of Langmuir–Hinshelwood model. Initial mineralization rate expressed by mg kJ−1 reach a maximum value at initial TOC closed to 30 mg/L.

The study showed the performances of solar photocatalytic pilot-plant equipped with thin film fixed bed reactor for removal of azo-dye chosen as model compound. Effect of important operating parameters such as flow rate, catalyst quantity and pollutant concentration on photocatalytic treatment kinetic is investigated for optimization, which will be very helpful in designing largescale reactors. The results show that there is an optimum amount of TiO2 (10 g/m2), flow rate (3 m3/h) as well as an initial TOC (30 mg/L) value for which the process is most effective. It should also be noted that simple discoloration of the dye solution could be enough relevant for recycling treated wastewater, however conversion of total organic carbon (TOC) into inorganic carbon is important for wide practical applications.