Characteristics and Mechanism of Photodegradation of 5-Hydroxymethylfurfural in Water Induced by Ultraviolet Irradiation
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Abstract:
To explore the characteristics and mechanism of ultraviolet (UV) irradiation-induced photodegradation of 5-hydroxymethylfurfural (5-HMF), an aqueous simulation system of 5-HMF was constructed, and the effects of UV irradiation time, light intensity, initial mass concentration of 5-HMF and photosensitizers (FeSO4, TiO2 and VB2) on the degradation of 5-HMF were analyzed. The UV photodegradation reactivity of 5-HMF was analyzed by the density functional theory (DFT), and its UV degradation products were identified by an ultra-high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometer. The results showed that the longer the UV irradiation time, the higher light intensity, the smaller the initial mass concentration of 5-HMF, and the higher the degradation rate. The degradation rate was the highest (83.64%) when the UV irradiation intensity was 400 μW/cm2, the radiation time was 240 min and the initial mass concentration was 31.5 mg/L. Both FeSO4 and TiO2 promoted the UV-induced degradation of 5-HMF, whilst VB2 inhibited the degradation of 5-HMF. The degradation rates of 5-HMF were the highest when the added concentrations and mass fractions of FeSO4 and TiO2 were 1.0 mmol/L and 0.025%: 100.00% (irradiation time 40 min, light intensity 400 μW/cm2) and 76.68% (irradiation time 80 min, light intensity 400 μW/cm2), respectively. The results of DFT analysis showed that the C=O bond of 5-HMF was more susceptible to attack and degradation, and the chemical bonds between C4-C11 and C1-C8 were easily broken. One, two and five degradation products of 5-HMF were identified in the UV, UV/FeSO4 and UV/TiO2 systems, respectively. The results of DFT analysis were consistent with the results of mass spectrometry identification. This study provides a theoretical and applied research basis for the reduction of 5-HMF in foods.
