Framework Cu-doped AlPO4 as an effective Fenton-like catalyst for bisphenol A degradation

Abstract

Cu-doped AlPO4 molecular sieve was prepared by a hydrothermal method and characterized by field emission scanning electron microscope, X-ray diffraction, extended X-ray absorption fine structure, X-ray photoelectron spectroscopy and nitrogen adsorption/desorption isotherms. The Cu(0.05)-AlPO4 with Cu/Al molar ratio of 0.05 was highly effective and stable for the degradation of bisphenol A (BPA) in the presence of H2O2 at room temperature and neutral pH conditions. The characterization results confirmed that Cu(II)/Cu(I) was co-incorporated into AlPO4 molecular sieve by chemical bonding of CuOT (T for Al or P) in Cu(0.05)-AlPO4, increasing the BET surface area of AlPO4 for more active sites. Excessive copper species existed in the form of Cu(II) and located in the extraframework sites, blocking the porous structure to decrease the specific surface area of AlPO4. The studies of electron spin resonance, in situ Raman spectra and other experiments verified that H2O2 was predominately converted into OH and HO2/O2− in Cu(0.05)-AlPO4 suspension. Specially, the presence of BPA in Cu(0.05)-AlPO4 suspension promoted the convertion of H2O2 into OH. A mechanism of heterogeneous Fenton catalysis was proposed on the basis of the cycle between Cu(I) and phenoxo-Cu(II) complexes during the interaction of Cu(0.05)-AlPO4, BPA and H2O2.