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.
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