Photodegradation of 2-naphthol in water by artificial light illumination using TiO2 photocatalyst: Identification of intermediates and the reaction pathway

The kinetics of the photocatalytic degradation of 2-naphthol has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions, which is essential from application point of view. The degradation was studied using different parameters such as types of TiO2, catalyst concentration, substrate concentration, reaction pH and in the presence of different electron acceptors such as hydrogen peroxide (H2O2), potassium bromate (KBrO3) and potassium persulphate (K2S2O8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst “Degussa P-25” was found to be more efficient as compared with other photocatalysts. The degradation kinetics fit well to the Langmuir–Hinshelwood rate law. It was found that an optimal concentration of 5 × 10−4 mol/l Ag+ in TiO2 achieved the fastest 2-naphthol degradation under the experimental conditions. However, with the addition of Na+, K+, Mg2+, Ca2+, Zn2+, Co2+ and Ni2+, there are no obvious effects on the reactions. An analysis of total organic carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved. The intermediate products were identified by HPLC–MS technique. A detailed degradation pathway could be proposed.

The photo catalytic degradation of 2-naphthol was investigated in aqueous suspensions of TiO2 under a variety of conditions. An analysis of total organic carbon (TOC) showed that a complete mineralization of 2-naphthol can be easily achieved. The intermediate products were identified. A detailed degradation pathway was proposed.Figure optionsDownload as PowerPoint slide