Photooxidation of benzene-structured compounds: Influence of substituent type on degradation kinetic and sum water parameters

The combined influence of substituent type and UV/H2O2 process parameters on the degradation of four aromatic water pollutants was investigated using modified 33 full factorial design and response surface methodology. Degradation kinetics was described by the quadratic polynomial model. According to the applied ANOVA, besides pH and [H2O2], model terms related with the pollutant structure are found to be significant. Different optimal operating conditions and values of observed degradation rate constants were determined for each of the pollutants indicating that the type of substituent influences the overall process effectiveness over structurally defined degradation pathway. Biodegradability (BOD5/COD) and toxicity (TU) were evaluated prior to the treatment and at the reference time intervals t1/2(P), t3/4(P), t1/4(OC) and t1/2(OC) corresponding to the real time required to reduce the concentration of parent pollutant and organic content for 1/2, 3/4, 1/4 and 1/2 of initial amount. The observed differences are correlated to the structural differences of studied aromatics.

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► We study the degradation of monosubstituted benzenes by UV/H2O2 process.
► We investigate the operating parameters using the response surface methodology.
► The type of substituent significantly influences the degradation kinetic.
► Structurally defined degradation pathway influences biodegradability and toxicity.