Degradation of Phenol in Aqueous System by Solar Photocatalysis, Photolysis and Adsorption Processes

Abstract

Phenol degradation in aqueous solutions using chitosan prepared from Crassostrea gigas (Sea oyster) shells as adsorbent was investigated using photocatalysis and adsorption processes at ambient temperature. Photolysis was carried out to study the effect of light on the degradation of phenol at ambient temperature while adsorption process was carried out without utilizing solar illumination. Effect of initial concentrations of phenol (50, 75, 100 and 150 mg/l), TiO₂ loading (4, 8, 16 and 20 %), and composite mass (adsorbent + TiO₂) (1, 3, 5 and 8 g) were investigated using UV-Visible spectrophotometric technique. The results obtained indicate that phenol removal increases with time and concentration of the catalyst (TiO₂) and decreases with increase in initial concentration of phenol and composite mass. Combination of UV irradiation with TiO₂ loading gave a degradation efficiency ranging from 98.13 - 98.92 % while UV irradiation with composite mass gave a degradation efficiency ranging from 84.80 - 98.51 %. The efficiency of the processes of degradation of phenol followed the trend: photocatalysis>photolysis> adsorption. The kinetics of the degradation fitted the Langmuir and pseudo-second–order models.

Keywords: Adsorption, Crassostrea gigas, Photocatalysis, Photolysis, Titanium dioxide