四乙基愈创木酚液相·OH氧化SOA产率及特征分析:初始浓度的影响  

Secondary Organic Aerosol Mass Yield and Characteristics from 4-ethylguaiacol Aqueous·OH Oxidation: Effects of Initial Concentration

作　　者：庄雨 陈彦彤 李旭东 马帅帅 赵竹子 叶招莲 盖鑫磊 ZHUANG Yu;CHEN Yan-tong;LI Xu-dong;MA Shuai-shuai;ZHAO Zhu-zi;YE Zhao-lian;GAI Xin-lei(School of Chemical and Environmental Engineering,Jiangsu University of Technology,Changzhou 213001,China;Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,School of Environmental Science and Engineering,Nanjing University of Information Science&Technology,Nanjing 210044,China)

机构地区：[1]江苏理工学院化学与环境工程学院,常州213001 [2]南京信息工程大学环境科学与工程学院,江苏省大气环境监测与污染控制高技术研究重点实验室,南京210044

出　　处：《环境科学》2020年第1期146-154,共9页Environmental Science

基　　金：江苏省自然科学基金项目(BK20181476,BK20181048);国家自然科学基金项目(91544220);江苏省普通高校专业学位研究生实践创新计划项目(SJCX18_1013,SJCX19_0736);江苏省高校“青蓝工程”学术带头人培养对象项目

摘　　要：液相化学过程作为二次有机气溶胶(SOA)形成的一种必不可少的途径,引起了学界对大气化学的广泛关注.由于其反应复杂性,反应机制、产物特性及对SOA质量的贡献还没有完全理解.本文选择四乙基愈创木酚(4-ethylguaiacol,EG)为前体物,系统地研究了初始浓度(0.03、0.3和3 mmol·L-1)的EG液相·OH氧化形成的液相二次有机气溶胶(aqSOA)特性的影响.用黑炭-气溶胶质谱(SP-AMS)测定aqSOA产率和氧化特性,气相色谱-质谱联用仪(GC/MS)、离子色谱(IC)测定产物和低分子有机酸.紫外分光光度计(UV-vis)和高效液相色谱测定了类腐殖质(HULIS)等表征光吸光产物的形成.结果表明,不同初始浓度(mmol·L-1)下aqSOA的O/C都表现为随着反应时间延长而升高,分别在0.42~0.61(0.03 mmol·L-1)、0.49~0.84(0.3 mmol·L-1)和0.49~0.63(3 mmol·L-1)之间变化.SP-AMS测定aqSOA组分发现高初始浓度时二聚体(C16H18O2+,m/z302)量明显高,说明高浓度下更容易发生聚合反应.UV-vis分析表明,随光氧化反应的进行,250 nm处吸光明显增强,可能是由于250 nm处新的吸光性产物生成所致.反应过程中生成的HULIS浓度不断升高,与UV-vis测定的300~400 nm区域内吸光度增强结论一致,说明水相反应形成了棕色碳.IC检测到产物中含有小分子有机酸:甲酸、乙醇酸和草酸其中甲酸浓度最高.GC/MS检测到aqSOA中含酮、单聚体和二聚体等,说明发生了官能团化和聚合化过程.Aqueous-phase chemical processing,as an essential formation pathway of secondary organic aerosol(SOA),has attracted widespread attention from within atmospheric chemistry fields.Due to the complicated reaction nature,reaction mechanisms,and product characteristics of aqueous-phase chemical processing,its contribution to the SOA budget is still not fully understood.In this work,we investigate how the initial concentration(0.03-3 mmol·L-1) of 4-ethylguaiacol affects SOA formation of aqueous OH photochemical oxidation.We use soot-particle aerosol mass spectrometry(SP-AMS) to monitor SOA mass yield and oxidation character,and gas chromatography-mass spectrometry(GC-MS) and ion chromatography(IC) to measure products and organic acids.Additionally,we use ultraviolet visible spectroscopy(UV-vis) and high performance liquid spectrometry(HPLS) to track the formation of light-absorbing products such as humic-like substances(HULIS).Our research indicated that the range of the 0/C ratio of EG-aqSOA measured by the SP-AMS exhibited increasing trends with increased reaction time 0.42-0.61(0.03 mmol·L-1),0.49-0.84(0.3 mmol·L-1),and 0.49-0.63(3 mmol·L-1).Dimers(C16 H18O2+,m/z 302) via SP-AMS were obviously higher under a higher initial concentration,thereby demonstrating that the oligomerization reaction proceeded more easily.The absorption at 250 nm recorded by UV-vis was distinctly enhanced,which might be attributed to new light-absorbing products with absorbance at 250 nm.Furthermore,the HULIS concentration increased with reaction time,in accordance with enhancement of absorbance in the 300-400 nm region,thus suggesting that aqueous-phase processing formed brown carbon.Small organic acids,including formic acid,malic acid,and oxalic acid,were detected by IC in all reaction solutions,with the highest concentration being for formic acid.GC/MS detected ketone,an OH monomer,and dimers in the aqSOA,which further indicates that functionalization and oligomerization took place.

关 键 词：四乙基愈创木酚 液相二次有机气溶胶(aqSOA) 黑炭-气溶胶质谱(SP-AMS) 产率 吸光特性 

分 类 号：X513[环境科学与工程—环境工程]