An Electrochemical Monitor for Air Pollutants

Abstract

A thin-layer electrochemical cell has been developed as a detector for air pollutants, and tested with S0₂-air and Cl₂-air mixtures. The cell gives well-defined, reproducible signals proportional to pollutant concentrations down to 20 ppb. Two electroanalytical procedures are described for monitoring or sampling polluted air with the cell: (1) a controlled-potential experiment in which the current-time response of the cell is related to pollutant concentration, and (2) an experiment similar to stripping analysis in which pollutants are first accumulated at an electrode surface under controlled potential conditions, and then analyzed voltammetrically.     

Theoretical study of the interaction between pyridine derivatives and atomic chlorine. Substituent effect and nature of the bonding

The interaction of pyridine derivatives (H, 4-NH₂, 4-CH₃, 4-F, 4-CN, 4-NO₂) with atomic chlorine is investigated theoretically by the density functional theory (DFT)-based LC-BLYP/aug-cc-pVDZ method. Pyridines and Cl° are held together by a (2c--3e) bond and the intermolecular distances range from 2.313 to 2.343 Å. The existence of a N…Cl bond is confirmed by the atom-in-molecule analysis of the systems. The binding energies of the adducts, ranging from ?42.08 to ?53.96 kJ mol^?1, are linearly correlated to the proton affinity of the pyridines. The charge transfer from pyridine to Cl° varies between 0.222 and 0.277 e. The spin density analysis shows that the strongest complex has the highest (2c–3e) character. The CH bonds are contracted and the ν(CH) vibrations are blueshifted owing to the decrease in σ*(CH) occupation. This decrease results not only from the classical anomeric effect but also from the σ(CC) and σ(CN) → σ*(CH) delocalisation in the heteroaromatic ring.     

氯化烷基咪唑:一种氯气吸收及氯化反应的媒介

依据离子液体1-甲基-3-正己基咪唑氯盐([HeMIM]Cl)和1-甲基-3-正辛基咪唑氯盐([OcMIM]Cl)在常温下呈液态,且能与氯气反应生成三氯离子的特性,将其作为吸收氯气的反应媒介,并将所形成的含三氯离子的离子液体作为氯代试剂用于一些有机化合物,如烯烃、酮、芳香化合物的氯代反应之中,取得了令人满意的结果.这两种离子液体的最大吸收氯气含量分别达到25.9%和23.1%(质量分数),而且这些含有氯离子或三氯离子的离子液体作为吸收媒介或氯代试剂可以重复利用.     

微波解离氯分子及其解离率的研究

通过微波解离Cl2与Ar的混合气来获得Cl原子,并对Cl2解离率进行了测量。反应池内压力在200～253Pa范围变化时,可得到较多的Cl原子。当压力为256Pa时,Cl2 的解离率可达8%以上。但随着反应池内压力的增加,Cl2解离率反而下降,这可能是Cl原子发生复合的几率增大所致。     

两个丁二肟有机锡配合物的合成、结构及抗癌活性

合成了 2 个丁二酮肟有机锡化合物：双(三(2-甲基-2-苯基丙基)锡)丁二酮肟配合物(C₆H₅C(CH₃)₂CH₂)₃Sn(ON=C(CH₃)C(CH₃)=NO)Sn(CH₂C(CH₃)₂C₆H₅)₃ (1)和二苄基锡氧氯丁二酮肟多核配合物[μ₃-O-((C₆H₅CH₂)₂Sn)₂(ON=C(CH₃)C(CH₃)=NOH)(O)Cl]₂(2)。通过元素分析、红外光谱、核磁共振(¹H、¹³C、¹¹⁹Sn)、差热分析和单晶X射线衍射对配合物进行了结构表征,对其结构进行量子化学从头计算,并进行了体外抗癌活性研究。结果显示：配合物1为通过配体丁二酮肟桥联的双锡核中心对称分子,锡原子均为四配位的畸变四面体构型;配合物2为通过氧原子和丁二酮肟配体桥联的四锡核中心对称多环聚合结构,锡原子分别为五配位的畸变三角双锥构型和六配位的畸变八面体构型。配合物对人肝癌细胞(HUH7)、人肺癌细胞(A549)、人表皮癌细胞(A431)、人结肠癌细胞(HCT-116)和人乳腺癌细胞(MDA-MB-231)均有较强的抑制活性。     

氧碘化学激光器废气排放污染评价

氧碘化学激光器运行过程中会将氯气、碘蒸气等有毒有害物质排入大气,对工作场所空气质量和人员健康存在安全隐患。采用点源扩散的高斯模式,建立了小风条件下氧碘化学激光器废气的扩散模型,结合工作场地人员分布情况,计算得到激光器废气排放后15 min内,距地面1.5 m高度、距排放点500 m范围内废气中有毒成分氯气和碘的质量浓度空间分布。根据质量浓度空间分布情况,选取采样点,以Na2SO3溶液作为吸收液对氯气和碘进行了同时采样,并采取离子色谱测量了吸收液中氯离子和碘离子的质量浓度。结果表明：氧碘化学激光器废气排入大气后,氯气质量浓度最高为0.200 mg/m3,碘蒸气质量浓度小于检测方法的检出限0.030 mg/m3,低于国家职业卫生标准规定的最高容许质量浓度限值1 mg/m3。     

Comment on Pyrrolizidine Alkaloids and Terpenes from Senecio (Asteraceae): Chemistry and Research Gaps in Africa

The genus Senecio is one of the largest in Asteraceae. There are thousands of species across the globe, either confirmed or awaiting taxonomic delimitation. While the species are best known for the toxic pyrrolizidine alkaloids that contaminate honeys (as bees select pollen from the species) and teas via lateral transfer and accumulation from adjacent roots of Senecio in the rhizosphere, they are also associated with more serious cases leading to fatality of grazing ruminants or people by contamination or accidental harvesting for medicine. Surprisingly, there are significantly more sesquiterpenoid than pyrrolizidine alkaloid-containing species. The main chemical classes, aside from alkaloids, are flavonoids, cacalols, eremophilanes, and bisabolols, often in the form of furan derivatives or free acids. The chemistry of the species across the globe generally overlaps with the 469 confirmed species of Africa. A small number of species express multiple classes of compounds, meaning the presence of sesquiterpenes does not exclude alkaloids. It is possible that there are many species that express the pyrrolizidine alkaloids, in addition to the cacalols, eremophilanes, and bisabolols. The aim of the current communication is, thus, to identify the research gaps related to the chemistry of African species of Senecio and reveal the possible chemical groups in unexplored taxa by way of example, thereby creating a summary of references that could be used to guide chemical assignment in future studies.     

环境空气中含氯化合物监测装置的研制

利用火焰光度原理研制了环境空气中含氯化合物的监测装置,介绍装置的组成、工作原理、系统结构和工作参数。利用该装置监测环境空气中含氯化合物,具有精度高、快速、简便等优点。