heterogeneous photocatalytic degradation of phenol in aqueous suspension of periwinkle shell ash catalyst in the presence of uv from sunlight

The batch photocatalytic degradation of phenol in aqueous solution wasinvestigated using periwinkle shell ash (PSA) as photocatalyst. Chemical characterisation of the PSA revealed that the major oxides present were calcium oxide (CaO), silica (SiO2) and aluminium oxide (Al2O3) which accounted for 41.3, 33.2 and 9.2% of the weight of PSA characterised. The major elements in PSA were iron (19.2%) and zinc (16.5%). FTIR results revealed absorption peaks of 3626.59 cm−1, 1797.58 cm−1, 1561.43 cm−1 and 1374.34 cm−1 in the infrared spectrum of PSA corresponding to O–H, C= O, C= C and C–H bonds respectively. Increasing the initial phenol concentration resulted in a decrease in the degradation efficiency of PSA. Lower catalyst loadings favoured the degradation process. Maximum degradation efficiency was obtained when the initial phenol concentration and catalyst loading were set as 50 g/L and 5 g/L respectively. The kinetics of the degradation process was well described by the pseudo first order equation while the diffusion mechanism was well represented by the intra particle diffusion model (R2>0.90). The adsorption equilibrium data fitted well to the Langmuir isotherm equation with an R2 value of 0.997.