The efficiency and mechanism of dibutyl phthalate removal by copper-based metal organic frameworks coupled with persulfate

Abstract

Copper-based metal organic framework (Cu-BTC) was prepared and used to remove dibutyl phthalate (DBP) in the presence of persulfate (PS). The surface characteristics, textural properties, and stability of activated Cu-BTC (denoted as Cu-BTC-A) were evaluated by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N₂ physical adsorption–desorption, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The effects of parameters such as initial pH, PS concentration, catalyst dosage, and free-radical quenchers have been investigated. The results showed that DBP could be removed in a wide pH range by Cu-BTC-A via mechanisms of adsorption and heterogeneous catalytic reaction. Unfortunately, the DBP removal was not completed because of radical scavenging reactions in Cu-BTC-A cages where PS can enter freely but DBP is blocked outside. Another explanation was that Cu-BTC-A showed a low adsorption capacity for DBP because the molecular size of DBP (15.84 × 11.00 × 7.56 Å) is larger than microporous cages (approximately 9 × 9 Å in diameter) of Cu-BTC-A.