Reactivity of Pyrogenic Carbonaceous Matter (PCM) in mediating environmental reactions: Current knowledge and future trends

• Pyrogenic Carbonaceous Matter (PCM) promote both chemical and microbial synergies. • Discussion of PCM-enhanced abiotic transformation pathways of organic pollutants. • Conjugated microporous polymers (CMPs) can mimic the performance of PCM. • CMPs offer a platform that allows for systematic variation of individual properties. Pyrogenic Carbonaceous matter (PCM; e.g., black carbon, biochar, and activated carbon) are solid residues from incomplete combustion of fossil fuel or biomass. They are traditionally viewed as inert adsorbents for sequestering contaminants from the aqueous phase or providing surfaces for microbes to grow. In this account, we reviewed the recently discovered reactivity of PCM in promoting both chemical and microbial synergies that are important in pollutant transformation, biogeochemical processes of redox-active elements, and climate change mitigation with respect to the interaction between biochar and nitrous oxide (N₂O). Moreover, we focused on our group’s work in the PCM-enhanced abiotic transformation of nitrogenous and halogenated pollutants and conducted in-depth analysis of the reaction pathways. To understand what properties of PCM confer its reactivity, our group pioneered the use of PCM-like polymers, namely conjugated microporous polymers (CMPs), to mimic the performance of PCM. This approach allows for the controlled incorporation of specific surface properties (e.g., quinones) into the polymer network during the polymer synthesis. As a result, the relationship between specific characteristics of PCM and its reactivity in facilitating the decay of a model pollutant was systematically studied in our group’s work. The findings summarized in this account help us to better understand an overlooked environmental process where PCM synergistically interacts with various environmental reagents such as hydrogen sulfide and water. Moreover, the knowledge gained in these studies could inform the design of a new generation of reactive carbonaceous materials with tailored properties that are highly efficient in contaminant removal.     

广州秋季灰霾污染过程大气颗粒物有机酸的污染特征

收集广州秋季一个灰霾过程大气颗粒物昼夜样品,进行了26种脂肪酸和8种二元羧酸的定量分析(GC/MS).结果表明,大气脂肪酸和二元羧酸的污染水平较高.灰霾与非灰霾期间脂肪酸和二元羧酸浓度之比分别为1.9和2.5.污染上升过程脂肪酸和二元羧酸晚上浓度(653 ng.m-3)高于白天浓度(487 ng.m-3),而在污染降低过程,白天脂肪酸和二元羧酸浓度(412 ng.m-3)要高于晚上浓度(336 ng.m-3).采样期间二元羧酸和脂肪酸日均值浓度总体上与颗粒物和碳质组分的变化趋势一致.脂肪酸和二元羧酸与有机碳比值大体上与颗粒物污染成反比,比值随着大气颗粒物的增加而降低,27号晚上之后,随着颗粒物的降低而开始增加,说明有机酸主要以直接排放为主,而灰霾对有机酸的富集有明显抑制作用.基于特征比值法(C3/C4)及相关性分析,表明秋季灰霾污染过程脂肪酸和二元羧酸都是以一次排放为主.     

常州夏秋季PM2.5中碳质气溶胶特征及来源

为更好地了解碳质组分的特点和来源,在常州市采集了夏季(7~8月)和秋季(10~11月)60个细颗粒物(PM_(2.5))样品.采样期间,夏季PM_(2.5)、OC、EC平均浓度分别为73.0、14.3和3.3μg·m~(-3),秋季为84.2、13.2和3.5μg·m~(-3).总碳质组分(OC+EC)占PM_(2.5)总质量的24.3%(夏季)和20.7%(秋季).采用IMPROVE-A热/光反射法测定的碳质8组分结果表明,OC2、OC3、OC4和EC1相关性好(r0.92),EC2和EC3相关性较好(r0.65),说明可能的相似来源.OC与EC相关性中等,表明碳质组分来源复杂.秋季WSOC/OC(60.9%)略高于夏季(57.4%),而夏季SOC/OC(52.5%)略高于秋季(49.0%).夏季和秋季SOC/OC都低于WSOC/OC,说明部分水溶性有机碳是一次源.WSOC和SOC相关性强,进一步验证了大部分SOC具有水溶性.碳质组分之间的关系及主成分分析表明,采样期间燃煤和机动车尾气排放是碳质组分的两个主要来源.后向轨迹分析表明,采样点PM_(2.5)和碳质组分主要受当地排放源和短距离传输的影响,长距离传输贡献较小.     

天津市夏季PM2.5中碳组分时空变化特征及来源解析

为研究天津市夏季PM_2.5中碳组分的时空变化特征及来源,于2019年7—8月设立2个点位分昼夜采集天津市PM_2.5样品,并测定了其中有机碳(OC)和元素碳(EC)的含量。结果表明,城区PM_2.5、OC和EC浓度日均值分别为(53.4±20.8)μg·m^-3、(8.72±2.56)μg·m^-3和(1.67±0.90)μg·m^-3,郊区PM_2.5、OC和EC浓度日均值分别为(54.2±24.5)μg·m^-3、(7.54±2.50)μg·m^-3和(1.82±1.06)μg·m^-3;白天PM_2.5、OC、EC的平均浓度分别为(47.3±16.1)μg·m^-3、(8.7±2.1)μg·m^-3和(1.5±0.6)μg·m^-3,夜间PM_2.5、OC、EC的平均浓度分别为(60.2±26.2)μg·m^-3、(7.5±2.9)μg·m^-3和(2.0±1.2)μg·m^-3。OC浓度表现为城区高于郊区,白天高于夜间;EC及PM_2.5浓度表现为郊区高于城区,夜间高于白天。OC/EC比值分析得,城区(6.04)高于郊区(5.08);白天(6.58)高于夜间(4.54)。城区OC与EC相关性弱于郊区,白天OC与EC相关性弱于夜间。采用EC示踪法与MRS模型对SOC含量进行估算,得到白天与夜间SOC浓度分别为(5.71±1.35)μg·m^-3和(3.81±1.20)μg·m^-3,白天SOC污染比夜间严重。丰度分析与主成分分析的结果表明,天津市夏季城郊区PM_2.5中碳组分均主要来源于燃煤和机动车尾气排放。     

大气气溶胶碳质组分在线分析仪的研制和应用

大气气溶胶碳质组分主要包括有机碳(Organic Carbon,OC)和元素碳(Elemental Carbon,EC),是大气细粒子的重要组成部分,对大气环境及人体健康具有非常重要的意义.针对目前商品化碳质气溶胶在线分析仪存在的一些问题,研制出大气气溶胶碳质组分在线分析仪(PKUOCEC),实现了对OC和EC的小时浓度测量.仪器同时采用热分解-光学透射(Thermo Optical Transmission,TOT)法和热分解-光学反射(Thermo Optical Reflection,TOR)法分离OC和EC,检测限为0.29μg·m-3(以C计)(采样时间40 min,采样流量8 L·min-1),测量范围最大值为211.50μg·m-3(以C计),可以满足不同环境的大气观测要求.于2016年1月23—31日采用该仪器对北京怀柔大气进行监测,并与商品化在线碳质气溶胶分析仪(RT-4 OCEC,Sunset Lab Inc.)和多角度吸收光度计(5012 MAAP,Thermo Scientific)进行比对.结果显示,PKU-OCEC测得的TC(Total Carbon,TC=OC+EC)和OC浓度均与Sunset-OCEC对应结果显著相关(TC:r=0.986,OC:r=0.984;p0.01),说明两台仪器测量结果具有很好的一致性;Sunset-OCEC测得的EC数据有39.39%低于0.013μg·m-3(以C计),剔除该部分异常值后,其测得的EC数据与PKU-OCEC数据的线性拟合方程由CEC_Sunset=0.9278×CEC_PKU!0.0704(TOT法)和CEC_Sunset=0.9476×CEC_PKU!0.2665(TOR法)变为CE C_Sunset=0.6810×CEC_PKU+1.2842(TOT法)和CEC_Sunset=0.7035×CEC_PKU+1.1179(TOR法),新的方程产生较大正截距,说明Sunset-OCEC的检测限偏高;PKUOCEC测得的EC数据与MAAP测得的BC数据显著相关,其线性拟合度(R2=0.8868(TOT法)、R2=0.8614(TOR法))大于Sunset-OCEC与MAAP的拟合度(R2=0.8047);PKU-OCEC分析仪TOT法和TOR法测得的OC浓度相当(COC_TOR=0.9963×COC_TOT,R2=0.9959).综合结果表明,PKU-OCEC分析仪测量数据可靠,运行稳定且操作简便,可以用于各种环境条件下的大气监测.     

天然碳质吸附剂对典型有机污染物的吸附机制研究进展

综述了天然碳质吸附剂(carbonaceous geosorbent,CG)的分类、来源、基本性质及对典型有机污染物的吸附机制与特点,涉及的有机物污染物涵盖了多环芳烃、多氯联苯、多溴代二苯基醚、农药及抗生素等多种门类,包括极性、弱极性、非极性及离子型等多种化合物,具有较广泛的代表性.CG类物质与有机化合物间的分子间作用力(范德华力)对吸附作用有重要贡献,但这种分子间作用力会受到CG性质(如孔隙结构、特征基团等)和吸附质分子特点(如分子构型、官能团)的影响.深入了解CG对典型有机化合物的吸附机制及其影响因素对污染土壤环境风险评估和污染土壤修复具有重要意义.     

Chemical compositions of PM2.5 aerosol during haze periods in the mountainous city of Yong'an, China

Haze phenomena were found to have an increasing tendency in recent years in Yong'an, a mountainous industrial city located in the center part of Fujian Province, China. Atmospheric fine particles (PM_2.5) in the urban area during haze periods in three seasons (spring, autumn and winter) from 2007 to 2008 were collected, and the mass concentrations and chemical compositions (seventeen elements, water soluble inorganic ions (WSIIs) and carbonaceous species) of PM_2.5 were determined. PM_2.5 mass concentrations did not show a distinct difference among the three seasons. The carbonaceous species organic carbon (OC) and elemental carbon (EC) constituted up to 19.2%-30.4% of the PM_2.5 mass during sampling periods, while WSIIs made up 25.3%-52.5% of the PM_2.5 mass. The major ions in PM_2.5 were SO₄^2-, NO₃^- and NH₄⁺, while the major elements were Si, K, Pb, Zn, Ca and Al. The experimental results (from data based on three haze periods with a 10-day sampling length for each period) showed that the crustal element species was the most abundant component of PM_2.5 in spring, and the secondary ions species (SO₄^2-, NO₃^-, NH₄⁺, etc.) was the most abundant component in PM_2.5 in autumn and winter. This indicated that dust was the primary pollution source for PM_2.5 in spring and combustion and traffic emissions could be the main pollution sources for PM_2.5 in autumn and winter. Generally, coal combustion and traffic emissions were considered to be the most prominent pollution sources for this city on haze days.     

活性污泥1号模型含碳组分测定方法探讨

阐述了活性污泥 1号模型中含碳有机物的分析方法,并用这些方法测定了西安市北石桥、电子村 2个排放口的城市污水水质。实验结果表明快速可生物降解COD(SS)采用间歇实验法、慢速可生物降解COD(XS)采用测定BOD5间接计算法既操作简单又准确可靠,能为利用活性污泥数学模型进行城市污水处理厂的设计、模拟及管理提供含碳组分分析依据     

碳质气溶胶(OC/EC)新型观测方法对比分析

基于热光反射法（IMPROVE A）和热光透射法（RT-Quartz）二种协议分析方法和新型OC/EC分析方法对济南市碳质气溶胶含量进行了对比观测.结果表明，协议方法在OC/EC的观测过程中因分析定义会造成碳质气溶胶质量浓度高估或者低估，且膜采样系统使离线分析的OC约为在线的1.65倍，而新型OC/EC测量方法相对于2种协议方法，去除了原理上和环境参数（如VOCs）可能导致的误差，在OC/EC/TC测量结果上均有一定优势，在实际运行中更具有准确性、稳定性和实用性，更加适合颗粒物中OC/EC长期业务化在线测量.