Utilization of photochemical circulation between NO3 and NO2 in water to degrade photoinert dimethyl phthalate: Influence of organic media and mechanism study

Lijie Xu, Yang Sun, Lu Gan, Jiangang Han, Ping Wang, Lei Yu, Xiang Mei, Wei Li, Baoling Lyu, Chun Pei, Wei Chu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

13 Citations (Scopus)

Abstract

Photoconversion of NO3/NO2 at wastewater relevant concentrations as an advanced oxidation approach to degrade dimethyl pthalate (DMP), a relatively photoinert endocrine disruptor, were examined. Three different wavelengths (350 nm, 300 nm, 254 nm) were involved. The influence of NO3 or NO2 was found to be wavelength-dependent. The 254 nm UV light could decompose DMP efficiently, but photolysis of DMP was slow at λ =300 nm and noneffective at λ =350 nm, which could be catalyzed by the presence of NO3 or NO2. Both [rad]OH and O2[rad] were detected, while [rad]OH was identified as the primary contributor to DMP decomposition. NO2 plays a dual role as both a source and sink of [rad]OH, depending on the relative abundance between NO2 and DMP. NO3 was more efficient than NO2 for treating low-level DMP. However, higher organic content could effectively inhibit the quenching role of NO2, making NO2 more efficient for catalyzing DMP decomposition. For irradiation at λ =350 nm, NO3 was completely ineffective, while self regeneration of NO2 enabled Δ[NO2]:Δ[[rad]OH] <<1. For irradiation at λ =300 nm, cycling between NO2 and NO3 occurred, and the transformation from NO2 to NO3 proceeded much faster. Complete decomposition of DMP at concentrations higher than those of NO2 or NO3 was observed, and mineralization was also achieved. Based on the identification of the intermediates, [rad]OH addition to the aromatic ring and hydrogen atom abstraction by [rad]OH were the dominant pathways, while nitration products were detected at low levels.

Original languageEnglish
Article number117958
JournalApplied Catalysis B: Environmental
Volume259
DOIs
Publication statusPublished - 15 Dec 2019

Keywords

  • Cycling
  • Dimethyl phthalate
  • Nitrate
  • Nitrite
  • Photochemical

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

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