Kinetics and reaction pathways for the transformation of 4-tert-butylphenol by ferrate(VI)

4-tert-butylphenol (4-tBP) is a phenolic endocrine disrupting chemical that has attracted great attention due to its wide occurrence, environmental persistence, and possible toxic effects. In this study, we systematically investigated the transformation of 4-tBP in ferrate (VI) oxidation process. The second-order reaction rate constant (k(app)) of Fe(VI) with 4-tBP decreases with solution pH, and the k(app) value was determined as 295 M-1.s(-1) at pH 8.0. The removal efficiency of 4-tBP was slightly decreased by g(2+) and HCO3-, while accelerated at varying degrees by the presence of Cu2+ and humic acid. Product analysis revealed that 4-tBP was mainly transformed into hydroxylation products, benzene-ring cleavage products, dimers and higher polymerization products via oxygen atom transfer, ring-opening of the benzene ring and radical coupling reaction. Furthermore, initial reactions of 4-tBP were rationalized by theoretical analysis of atom partial charges, frontier electron densities, and spin densities. Nearly complete removal of 4-tBP (20 M) was achieved after 5 min of reaction in both ultrapure water and natural waters, demonstrating the feasibility of this Fe(VI) oxidation method in treating phenols-contaminated waters.

Automated summary

The study systematically investigated the transformation of 4-tert-butylphenol in ferrate (VI) oxidation process, finding that the reaction rate constant of Fe(VI) with 4-tBP decreases with solution pH and the removal efficiency was slightly affected by certain ions. Product analysis showed that 4-tBP mainly transformed into hydroxylation products, benzene-ring cleavage products, dimers, and higher polymerization products. The feasibility of this Fe(VI) oxidation method in treating phenols-contaminated waters was demonstrated by achieving nearly complete removal of 4-tBP in both ultrapure water and natural waters after 5 minutes of reaction.