title: Study on the mechanism of photo-degradation of p-nitrophenol exposed to 254 nm UV light.
abstract: The degradation mechanism of p-nitrophenol (p-NP) exposed to 254 nm UV light was studied in the presence and the absence of oxygen respectively via both steady-state photolysis and time-resolved laser flash photolysis (LFP) experiments. It has been confirmed that p-NP can be photo-ionized to produce its radical cation (p-NP(+)) and hydrated electron (e(aq)(-)) with a quantum yield of 0.52. In neutral solution p-NP(+) will be quickly deprotonated to form its phenoxyl radical (p-NP) which will react with oxygen to promote the breakage of benzene ring of p-NP. The degradation efficiency of p-NP exposed to 254 nm UV is as low as commonly reported. However, oxygen could improve the photo-degradation efficiency, which is due to the reaction of oxygen with p-NP. The reaction between oxygen and p-NP has been experimentally confirmed both in LFP and in pulse radiolysis.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Jiading, Shanghai 201800, PR China.
authors.forename: Sufang
authors.initials: S
authors.lastname: Zhao
authors.forename: Hongjuan
authors.initials: H
authors.lastname: Ma
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Changqing
authors.initials: C
authors.lastname: Cao
authors.forename: Jie
authors.initials: J
authors.lastname: Xiong
authors.forename: Yunshu
authors.initials: Y
authors.lastname: Xu
authors.forename: Side
authors.initials: S
authors.lastname: Yao
mesh_terms: D009596:Nitrophenols / Q000737:chemistry*; D010777:Photochemistry; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
chemical_list: D009596:Nitrophenols; C024836:4-nitrophenol