Optimization of photocatalytic degradation of sulphonated diazo dye C.I. Reactive Green 19 using ceramic-coated TiO₂ nanoparticles

Optimization of photocatalytic degradation of C.I. Reactive Green 19 (RG19) under UV light irradiation using ceramic-coated TiO2 nanoparticles in a continuous circulation rectangular photoreactor was studied. The used catalyst was TiO₂ Millennium PC-500 (crystallite mean size 8nm) immobilized on ceramic plates. A central composite design was used for optimization of the UV/TiO₂ process. Predicted values of decolorization efficiency were found to be in good agreement with experimental values (R²=0.97 and Adj-R²=0.91). Optimization results showed that maximum decolorization efficiency was achieved at the optimum conditions of: initial dye concentration 10mg/L, UV light intensity 47.2W/m², flow rate 150mL/min and reaction time 240 min. Photocatalytic mineralization of RG19 was monitored by chemical oxygen demand (COD) decrease and changes in the UV-Vis spectrum.