Efficiency and mechanism of 2,4-dichlorophenol degradation by the UV/IO4- process

This study explores the efficiency and kinetics of the photoactivated periodate process for the degradation of 2,4-dichlorophenol (2,4-DCP) in water. The obtained results show that the degradation rate was considerably higher for UV/IO4- compared to UV irradiation alone. Pseudo first-order reaction rate kinetics were obtained for all process conditions. The pH did not have a significant impact on the decomposition of 2,4-DCP using photoactivated periodate. Therefore, the applied method can be used to treat (waste)water at various pH. By raising the initial concentration of periodate to 5 mM, the degradation rate increased, while it decreased again at a concentration of 8 mM. As the 2,4-DCP concentration increased, the removal rate decreased. The extent of degradation was observed to be proportional with the UV intensity. A mechanistic study revealed that iodine radicals dominated the degradation of 2,4-DCP by photoactivated periodate. whereas center dot OH and O(P-3) only played a minor role. At pH 5.0. all chlorine atoms in 2,4-DCP were released as chloride ions in the UV/IO4- process, hence reaching a total dechlorination. Finally, the presence of inorganic salts, even at high levels, did not significantly impact the degradation. According to the results achieved in this study, the UV/IOC system can be considered as a valuable alternative to treat effluents containing chlorinated organic compounds such as pulp and paper mill effluents and brine (waste)water. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the efficiency and kinetics of the photoactivated periodate process for degrading 2,4-dichlorophenol in water, finding that UV/IO4- had a higher degradation rate than UV alone, regardless of pH. By adjusting the concentration of periodate and 2,4-DCP, the degradation rate and removal efficiency could be controlled effectively.