Efficient mineralization of phenol by a temperature-responsive polyoxometalate catalyst under wet peroxide oxidation at lower temperatures

Abstract

Herein, a temperature-responsive polyoxometalate (POM) catalyst [C₁₆H₃₃(CH₃)₃N]₃[PO₄{WO(O₂)₂}₄]/poly(N-isopropylacrylamide) (abbreviated as (C₁₆PW(O₂)₂/PNIPAM) was prepared and used in the catalytic wet peroxide oxidation (CWPO) of phenol under mild conditions. The POM catalyst C₁₆PW(O₂)₂/PNIPAM showed a higher degradation efficiency and mineralization of phenol with H₂O₂ at room temperature or even at lower temperature (0 °C) within a short time (120 min). The high efficiency at lower temperature was attributed to its temperature-responsive property, wherein the lattice of the temperature-sensitive polymer relaxed at lower temperature and then wrinkled at higher temperature. These characteristics also permitted C₁₆PW(O₂)₂/PNIPAM to be easily separated for recycling. The leaching test indicated that the POM catalyst exhibited excellent stability and little leaching and can be used as a thermosensitive catalyst for about six times. C₁₆PW(O₂)₂/PNIPAM has potential application in the CWPO of phenol without the limitation of temperature and pH conditions.