Photocatalytic degradation of phenolic syntan using TiO 2 impregnated activated carbon

Abstract

Investigations were carried out to study the photocatalytic degradation of phenolic syntan (PS), a widely used environmentally polluting chemical in the leather tanning industry. Photocatalytic inactive commercial TiO 2 was used as the precursor for the preparation of TiO 2 impregnated activated carbon (Ti-AC) photocatalyst. Experiments were conducted by varying the concentrations of PS solution (50–1000 mg/l), pH (2.5–10) and time intervals to optimize the working parameters. A 254 nm UV light was used throughout the study. The effect of PS degradation using Ti-AC was also compared with direct UV photolysis. The Ti-AC was characterized using X-ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscopy (SEM) and energy dispersive X-ray analysis (EDX) to determine the structural, optical, surface morphology and elemental analysis respectively. X-ray studies revealed the formation of catalytically active anatase phase in Ti-AC. Photodegradation of PS was examined by chemical oxygen demand (COD) method. PS degradation occurred at both the extreme end of acidic and alkaline pH conditions. However, the percentage degradation was comparatively higher at pH 2.5. The photodegradation followed pseudo first order kinetics. UV–Visible studies substantiated the occurrence of bathochromic and hyperchromic effects as a result of ring opening in the PS molecule.