Heterogeneous photocatalytic degradation of naphthalene using periwinkle shell ash : effect of operating variables, kinetic and isotherm study

Abstract

This study investigated the potential use of low cost photocatalyst, Periwinkle shell ash (PSA) for the batch photocatalytic degradation of naphthalene in aqueous solutions. The effect of contact time, initial naphthalene concentration, PSA dosage, presence of electron accepting oxidant (H2O2), and the pH of solution on the percentage photodegradation of naphthalene determined. For the treatment conditions considered in this study, the optimum values were obtained to be: contact time, 210 minutes; initial naphthalene concentration, 25 mg/L; PSA dosage, 2 g; pH, 9. The addition of Hydrogen Peroxide (H2O2) enhanced the photodegradation process with almost 100 percent degradation achieved. The adsorption equilibrium data fitted well to the Langmuir isotherm equation (R 2 =0.993) indicating mono layer type adsorption while the kinetics of the process was well described by the Langmuir- Hinshelwood kinetic model with high correlation coefficient value (R 2 =0.998). This study has demonstrated that the low cost photocatalyst, PSA can be used for removal of naphthalene from aqueous solution. Also the kinetic information obtained can be used for designing treatment systems for naphthalene abatement.