Dye Degradation by Heterogeneous and Homogeneous Photocatalysis Processes. A Scaled-up Approach for a CPC Solar Reactor

The comparison of the solar heterogeneous photocatalysis (SHP) and solar photo Fenton (SPF) processes were carried out in a compound parabolic collector reactor, using methyl orange as a model pollutant, and the scaled-up parameters were estimated. As preliminary tests, both processes were carried out at laboratory scale (volume of 200 mL) and the accumulated energy ( Qv ) was registered to achieve high degradation and mineralization rates. The dye degradation by SHP in the solar reactor (volume of 30 L) was carried out using TiO 2 Degussa P25 until a Qv = 300 kJ m −2 was reached. Under acidic condition, color removal of 95% and mineralization of 64% were achieved. The resulting reaction rates were k app = 0.2311 L kJ −1 and k app = 0.0768 L kJ −1 , respectively. On the other hand, dye degradation by SPF was faster than SHP since 99% color removal and 76.5% mineralization were achieved at Qv = 10 kJ m −2 . Both processes were highly efficient in color removal and mineralization rates, at both scales. However, the SPF degradation was achieved at lower accumulated energy. The treatment capacity factor ( Ct ) required for the scaling-up of the solar reactor calculated for the SPF process is Ct = 6.41 kg TOC m −2 y −1 , and the area required for the treatment of a hypothetical textile effluent considering 1000 m 3 y −1 and initial TOC of 800 mg L −1 is 125 m 2 . These results suggest that SPF is an alternative of feasible implementation for the sanitation of textile effluents.