典型固体燃料燃烧排放环境持久性自由基的特征  

Characteristics of environmental persistent free radicals emitted by typical solid fuel combustion

作　　者：高燕 张翠荣 朱礼 李豪 张立欣 陈庆彩 王羽琴 GAO Yan;ZHANG Cuirong;ZHU Li;LI Hao;ZHANG Lixin;CHEN Qingcai;WANG Yuqin(College of Environmental Science and Engineering,Shaanxi University of Science and Technology,Xi’an,710021,China;Xianyang City Environmental Monitoring Station,Xianyang,712000,China)

机构地区：[1]陕西科技大学环境科学与工程学院,西安710021 [2]咸阳市环境监测站,咸阳712000

出　　处：《环境化学》2023年第8期2619-2629,共11页Environmental Chemistry

基　　金：陕西省自然科学基础研究计划(2022JM-076);国家自然科学基金(22076110)资助。

摘　　要：为研究典型固体燃料燃烧排放环境持久性自由基(EPFRs)的污染特征,本文以小麦秸秆和煤粉为研究对象,利用自制的燃料燃烧和颗粒物样品收集装置获得小麦秸秆和煤粉在不同燃烧条件下排放的烟气颗粒样品,基于电子顺磁共振波谱技术(EPR)分别确定EPFRs在第0、1、3、7天的自旋浓度、g因子、ΔH_(P-P),通过萃取实验确定EPFRs可被甲醇和二氯甲烷所萃取的量,以获得其污染、衰变特性.结果表明,低温低氧或无氧条件下,小麦秸秆和煤粉燃烧以阴燃或热解为主,排放的EPFRs主要为氧中心自由基,属于非衰变型,有机溶剂可萃取部分可达67%;随着温度和空气通入量的增加,小麦秸秆和煤粉逐渐燃烧,排放的EPFRs浓度增加,由氧中心自由基逐步转化为含氧官能团的碳中心自由基,衰变缓慢,溶剂可萃取的EPFRs占比仅有2.14%;当温度和空气量足够,小麦秸秆和煤粉完全燃烧,半衰期分别为56 d和43 d,为快速衰变型,溶剂不可萃取的EPFRs部分高达97.01%.温度和空气量对小麦秸秆和煤粉燃烧排放的EPFRs的种类、结构及衰减影响大,而样品含水率无显著影响.To explore the characteristics of environmental persistent free radicals(EPFRs)emitted by the combustion of typical solid fuels(i.e.,the wheat straw and pulverized coal),a self-made device for fuel combustion and particle sample collection was used to obtain the flue gas samples under different combustion conditions.Based on electron paramagnetic resonance spectroscopy(EPR),the spin concentration,g factor and ΔH_(P-P) of EPFRs on the 0th,1st,3rd,and 7th day were determined respectively,while the percentage of EPFRs extracted by the methanol(MeOH)and methylene chloride(DCM)were measured to obtain their pollution and attenuation characteristics.Results showed that under low temperature,hypoxia or anaerobic conditions,the combustion of wheat straw and pulverized coal was mainly smoldering or pyrolysis,and the emitted EPFRs were mainly non-decaying oxygen-centered radicals,about 67% of which were extractable.With the increase of temperature and air intake,wheat straw and pulverized coal were gradually burned,leading to a increase of the spin concentration of the emitted EPFRs.Meanwhile,the oxygencentered radicals gradually converted into slow-decaying carbon-centered free radicals with oxygencontaining functional groups,only 2.14% of which were extractable.When the temperature and air volume were sufficient,wheat straw and pulverized coal were completely burned with half-lives of 56 d and 43 d,respectively,which were fast decay types,and the fraction of EPFRs that could not be extracted by both MeOH and DCM could reach 97.01%.As a conclusion,the characteristics(i.e.type,structure,attenuation)of EPFRs emitted from wheat straw and pulverized coal combustion were significantly influenced by temperature and air supply,while the moisture content of the samples had no significant influence.

关 键 词：小麦秸秆 燃料燃烧 环境持久性自由基 自旋浓度 衰变特性 

分 类 号：X701[环境科学与工程—环境工程]