化学
不饱和度
光降解
芳香性
氧气
热解
有机质
降级(电信)
木质素
辐照
光化学
溶解有机碳
有机化学
环境化学
分子
光催化
催化作用
核物理学
物理
电信
计算机科学
作者
Yan Wang,Yalan Chen,Lanfang Han,Ke Sun,Fanhao Song,Yan Yang,Haoran Sun
标识
DOI:10.1016/j.jhazmat.2021.127817
摘要
Pyrogenic dissolved organic matter (pyDOM) is the photolabile fraction in the dissolved organic matter pool. However, the molecular changes and reactive oxygen species generation of pyDOMs under continuous irradiation, and how these vary with feedstock type and pyrolysis temperature, are not well understood. In this study, the soluble fractions of 300 and 450 ºC biochars (pyDOM300 and pyDOM450) were subjected to photo-irradiation. PyDOM450 was of higher aromaticity, molecular variety, but lower unsaturation than pyDOM300. The molecular weight, aromaticity, and double bond equivalents of pyDOMs generally decreased after photo-irradiation. The degradation pattern of pyDOMs can be divided into two stages. In the initial 24 h, pyDOM300 degraded faster than pyDOM450, with the more profound transformation of condensed aromatics and carbohydrate into aliphatic/proteins, lignins, and tannins in pyDOM300. After 720 h irradiation, however, the degradation ratio of pyDOM450 (36.2-43.9%) exceeded that of pyDOM300 (23.7-30.3%), with the initially preserved condensed aromatics in pyDOM450 further transforming into aliphatic/proteins and tannins. This was potentially attributed to the generation of more reactive oxygen species (·OH and 1O2) in pyDOM450. This study uncovered the photodegradation mechanisms of pyDOMs at molecular scale and helped to understand their cycling and effects on environment.
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