This study used dimethyl sulphide (DMSO) and methanol as radical probes for semi-quantifying the formation concentration of hydroxyl radical in heterogeneous photocatalytic oxidation (PCO) processes. The formation of reactive radicals on the photocatalyst surfaces has been confirmed as a key mechanism in the PCO reactions. The information of the formation concentration of hydroxyl radical is important for investigating reaction mechanisms for PCO reactions and identifying activities of prepared photocatalysts. This study demonstrated that DMSO and methanol work as good radical scavengers for the formation of hydroxyl radicals on photocatalyst surfaces. Formaldehyde (HCHO) is a major reaction intermediate from the reactions of hydroxyl radicals with DMSO or methanol. The initial formation rate of HCHO in various experimental conditions including pH level, catalyst types and dosage, and irradiated light intensity was measured as a base for semi-quantifying the formation concentrations of radicals on catalyst surfaces. The experimental results showed consistent observation of more formation of hydroxyl radicals with faster PCO reaction rates and higher photocatalyst dosage. It was also observed thatradical formation concentration was proportional to irradiated light intensity. This study demonstrate that both DMSO and methanol work as good radical probes for semi-quantifying formation concentration of hydroxyl radicals in a usually laboratory. But their initial concentrations should be carefully selected.

Applying dimethyl sulfoxide and methanol as hydroxyl radical probes in heterogeneous photocatalytic reactions

254th National Meeting (2017)

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