Kinetics Modeling for Degradation of Geosmin and 2-Methylisoborneol by Photo-Electrogenerated Radicals

With increasingly severe cyanobacterial blooms, the overflow of off-flavor compounds represented by geosmin (GSM) and 2-methylisoborneol (2-MIB) is becoming a global water quality issue. The UV photo-electrochemical process is considered an environmentally friendly technology for GSM and 2-MIB degradation. In this study, a kinetics model using the pseudo-first-rate constants for the elimination of GSM and 2-MIB was developed in the UV photo-electrochemical process. The model can be applied successfully to predict the degradation of GSM and 2-MIB under different electrolyte concentrations, initial pH values of the solutions, and current densities. The GSM and 2-MIB degradation rates improved with increases in the electrolyte concentration. With an increase in the pH value from 5 to 11, the rate constants for the degradation of GSM and 2-MIB were reduced by 52.9% and 69.5%, respectively. The degradation of GSM and 2-MIB showed positive correlations with the current density in the kinetic model. Furthermore, the significant roles of HO• and Cl• were evaluated by scavenging experiments and kinetics modeling. HO• was the dominant radical for GSM degradation, and Cl• played a crucial role in 2-MIB elimination. The results demonstrate that the UV photo-electrochemical process could be an efficient way for the mineralization of off-flavor compounds.