Optimization of photocatalytic treatment of dye solution on supported TiO₂ nanoparticles by central composite design: Intermediates identification

Optimization of photocatalytic degradation of C.I. Basic Blue 3 (BB3) under UV light irradiation using TiO₂ nanoparticles in a rectangular photoreactor was studied. The investigated TiO₂ was Millennium PC-500 (crystallites mean size 5-10nm) immobilized on non-woven paper. Central composite design was used for optimization of UV/TiO₂ process. Predicted values of decolorization efficiency were found to be in good agreement with experimental values (R²=0.9686 and Adj-R²=0.9411). Optimization results showed that maximum decolorization efficiency was achieved at the optimum conditions: initial dye concentration 10mg/L, UV light intensity 47.2W/m², flow rate 100mL/min and reaction time 120min. Photocatalytic mineralization of BB3 was monitored by total organic carbon (TOC) decrease, and changes in UV-vis and FT-IR spectra. The photodegradation compounds were analyzed by UV-vis, FT-IR and GC-mass techniques. The degradation pathway of BB3 was proposed based on the identified compounds.