Catalytic degradation and mineralization mechanism of 4-chlorophenol oxidized by phosphomolybdic acid/H2O2

Adsorbable organic halogens (AOX) are used as a parameter to determine the total amount of organic halogens in the environment. 4-chlorophenol (4-CP), as a type of AOX, can persist in the environment for a long time and is not biodegradable. 4-CP has significant carcinogenic and teratogenic effects on humans and animals. In this study, a catalytic system employing phosphomolybdic acid (PMA) and hydrogen peroxide (H 2 O 2 ) was developed for degrading 4-CP. The degradation and the mechanisms of 4-chlorophenol (4-CP) as an AOX simulant was investigated. The removal efficiency of 4-CP, the AOX content, and total organic carbon were used to evaluate its molecular structure. The results show that 4-CP was fully converted, 19.81% to other species of AOX and 44.52% to CO 2 and H 2 O. Moreover, the intermediates were detected and analyzed, and the possible pathways of 4-CP degradation were drawn. 4-CP attached to PMA, there by leading to ring-opening or dichlorination, and the generation of some other chemical species, such as phenol , benzoquinone, cyclohexanone, 4-chlorohexa-2,4-dien-1-ol, and 3-chlorohexa-2,4-diene-1,6-diol. These species would then be mineralized under the effects of free radicals. PMA can promote the formation of free radicals and shows exceptional efficiency in the degradation of 4-CP.