Kinetic Study for 4-chlorophenol Photodegredation in the presence of TiO2

Abstract

The effects of non-porous powder samples of TiO2 with specific surface areas
about 55 m2g-1 on the kinetics of disappearance of 4-chlorophenol (4-CP) in water,
under illumination at λ ≥ 340 nm (to avoid the direct photolysis of 4-CP) and 298 K,
were determined.
The photocatalytic character of the 4-CP disappearance in its presence was
shown by (i) the effects of the catalyst mass on the initial rate ro, (ii) the Langmuirian
–type relationship between ro and Co (iii) the very lowl activation energy of 4-CP
disappearance (iV) the effect of pH of the medium, (V) the effect of initial
concentration Co of 4-CP on the rate of photodegradation ro. Hydroquinone HQ is the
main intermediate in the degradation and none of the toxic biphenyl derivatives
produced by direct photolysis was found in presence of TiO2. Complete
mineralization of 4-CP was eventually obtained, the degradation produced more
numerous and more stable aromatic intermediates, as shown by high performance
liquid chromotography HPLC tests.