共查询到19条相似文献,搜索用时 125 毫秒
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采用同位素稀释、高分辨气相色谱/高分辨质谱(HRGC/HRMS)联用技术,分析了广州市某一地区两采样点大气悬浮颗粒物和大叶榕、龙眼树树叶中二噁英的含量。结果表明,两地点大气悬浮颗粒物中二噁英质量浓度(10.87 pg/Nm3和10.34 pg/Nm3)和毒性当量(0.119 pg/Nm3和0.121 pg/Nm3)接近,而大叶榕、龙眼树树叶中二噁英质量浓度分别为268.4 ng/kg.dry和972.5 ng/kg.dry,毒性当量为3.99 ng/kg.dry和15.11 ng/kg.dry。通过分析大气和树叶样品中17种有毒同系物的分布特征,可推断这两种植物树叶中的二噁英主要来源于大气干沉降。此外,龙眼、大叶榕树叶中六氯代以上的有毒PCDD/Fs质量分数较高,说明高氯代二噁英在树叶中较稳定,易累积到较高的水平。 相似文献
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以苯甲醇、苯酚为起始原料,在催化剂活性Al2O3存在下,通过克莱森(Claisen)重排反应得到关键中间体2-苄基苯酚,再经过醚化、胺化和酸化反应得到新型结构的二苯美仑类化合物。反应过程经优化使中间体2-苄基苯酚产率得到提高。合成的新化合物通过IR1、H-NMR及元素分析表征。 相似文献
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1,2-苯并异噻唑啉-3-酮(BIT)已广泛用于造纸、粘合剂、化学纤维、涂料(乳胶漆)、颜料、聚氨酯制品、油墨、乳胶制品、皮革制品中,也应用于化妆品、洗涤用品、药品、食品包装材料、水处理剂、油田注水、工业冷却循环水等各个工业生产领域。BIT的工业生产和合成工艺创新正越来越受到重视。本文主要阐述制取BIT的传统工艺路线、流程、操作要点和安全生产注意事项,介绍BIT合成工艺路线的进展,提供绿色环保的BIT工业生产方法。 相似文献
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Xue Zhang Chenxi Zhang Xiaomin Sun Lingyan Kang Yan Zhao 《International journal of molecular sciences》2015,16(4):8128-8141
As a widely used antimicrobial additive in daily consumption, attention has been paid to the degradation and conversion of triclosan for a long time. The quantum chemistry calculation and the canonical variational transition state theory are employed to investigate the mechanism and kinetic property. Besides addition and abstraction, oxidation pathways and further conversion pathways are also considered. The OH radicals could degrade triclosan to phenols, aldehydes, and other easily degradable substances. The conversion mechanisms of triclosan to the polychlorinated dibenzopdioxin and furan (PCDD/Fs) and polychlorinated biphenyls (PCBs) are clearly illustrated and the toxicity would be strengthened in such pathways. Single radical and diradical pathways are compared to study the conversion mechanism of dichlorodibenzo dioxin (DCDD). Furthermore, thermochemistry is discussed in detail. Kinetic property is calculated and the consequent ratio of kadd/ktotal and kabs/ktotal at 298.15 K are 0.955 and 0.045, respectively. Thus, the OH radical addition reactions are predominant, the substitute position of OH radical on triclosan is very important to generate PCDD and furan, and biradical is also a vital intermediate to produce dioxin. 相似文献
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以10mgw(Pd)=5%的Pd/C为催化剂,在35℃和1 01×105Pa下,ρ(三氯新)=4g/L的三氯新水/乙醇〔V(水)∶V(乙醇)=1∶1〕溶液20mL反应30min就100%脱氯。在乙醇中,三氯新加氢1h氯的去除率为68%。水的存在,改善了三氯新的反应环境,消除了NaCl在催化剂上的富集,使催化剂保持了较高的活性。在水溶液中,ρ(氯化物)=5g/L的碱金属或碱土金属氯化物的存在,对三氯新的加氢脱氯反应没有影响,这是因为这些无机氯化物在水中完全电离,离子化的无机氯化物不会堵塞反应孔道,也不会在催化剂表面吸附,因此不会阻碍三氯新的加氢脱氯。 相似文献
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《国际聚合物材料杂志》2012,61(10):497-508
This work aims at preparation of poly-L-lactide (PLLA)/triclosan nanoparticles as antibacterial products used in some specific medical applications. PLLA was synthesized by the reaction extrusion via the ring opening polymerization of L-lactide using a continuous single-stage process, which is a fast and easy method. The PLLA triclosan nanoparticles were prepared by the emulsification–diffusion process with few modifications. Chloroform was used for the surface reaction of triclosan without any chemical shifts. The resulting nanoparticles with various triclosan quantities were fully characterized. The release as well as its kinetics was studied using the UV-visible spectroscopy. All the results confirmed the high stability and process efficiency of molecular dispersion and attachment of triclosan to PLLA. The sample containing 30% triclosan showed the best form among the others with the highest encapsulation efficiency. The synthesized nanoparticles with the controlled antibacterial activity could be considered as an appropriate alternative for application as antibacterial agent in the implantable surgical products as well as the drug delivery and wound-dressing applications. 相似文献
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The effect of water on the formation of polychlorinated dibenzo-p-dioxins(PCDDs)and dibenzofurans(PCDFs)from precursor was investigated by the experiments with a fixed-bed reactor:the reactant mixture with different moisture of 123-TrCB and CuCl2 for metal-catalyzed formation,that of 123-TrCB and fly ash for surface-catalyzed formation. The experimental results show that the water has the following effects:first,suppressing the formation of PCDD/Fs as less its yield;second,inhibiting chlorination reaction as lower chlorination degree;third,having different effect on PCDDs and PCDFs as lower ratio of PCDFs/PCDDs.The explanations might be the competitive adsorption of water vapor with TrCB on active sites of the fly ash and the catalysis of copper was weakened chloride because of its oxidative conversion to copper oxide. 相似文献
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Hideyuki Inui Toshimasa Itoh Keiko Yamamoto Shin-Ichi Ikushiro Toshiyuki Sakaki 《International journal of molecular sciences》2014,15(8):14044-14057
Polychlorinated dibenzo-p-dioxins (PCDDs) and coplanar polychlorinated biphenyls (PCBs) contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP)-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high activities toward monoCDDs, diCDDs, and triCDDs but no detectable activity toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). Large amino acids located at putative substrate-recognition sites and the F-G loop in rat CYP1A1 contributed to the successful metabolism of 2,3,7,8-tetraCDD. Rat, but not human, CYP1A1 metabolized 3,3'',4,4'',5-pentachlorobiphenyl (CB126) to two hydroxylated metabolites. These metabolites are probably less toxic than is CB126, due to their higher solubility. Homology models of human and rat CYP1A1s and CB126 docking studies indicated that two amino acid differences in the CB126-binding cavity were important for CB126 metabolism. In this review, the importance of CYPs in the metabolism of dioxins and PCBs in mammals and the species-based differences between humans and rats are described. In addition, the authors reveal the molecular mechanism behind the binding modes of dioxins and PCBs in the heme pocket of CYPs. 相似文献
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液相色谱法测定化妆品中三氯生含量的不确定度评定 总被引:1,自引:0,他引:1
分析了液相色谱法测定化妆品中三氯生含量的检测过程,建立了该方法的定量数学模型并推导出不确定度计算公式,找出了该检测过程中的不确定度来源,并计算了公式中各个变量的不确定度,最后计算出了检测结果的合成不确定度和扩展不确定度。 相似文献
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三氯新在抗菌洗洁精中的应用研究 总被引:13,自引:1,他引:12
将三氯新与普通洗洁精复配 ,制得了w(三氯新 ) =0 3%的抗菌洗洁精。采用抑菌环法做抑菌实验 ,该抗菌洗洁精在稀释至质量分数为 0 2 %时 ,对金黄色葡萄球菌和大肠杆菌的抑菌环直径分别为 2 8 8mm和 11 5mm。在 5 4℃存放 14d和 37℃存放 90d ,该抗菌洗洁精的抑菌环直径没有变小 ,抑菌效果和稳定性均很满意。急性经口毒性实验表明 ,该抗菌洗洁精半致死量LD50 >5 0 0 0mg/kg ,属实际无毒级。用该抗菌洗洁精洗涤厨房抹布 ,证明抑菌除臭功能显著。该抗菌洗洁精具有较高的实用价值和良好的市场前景。 相似文献