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161.
162.
将十溴联苯醚(BDE-209)于400~600℃的温度范围内进行热降解,利用GC、GC/MS对产物种类及含量变化进行分析,讨论了温度、时间、碱性化合物和含硫化合物对BDE-209降解以及对溴代二噁英生成的影响.结果表明.温度和时间均是BDE-209热降解和生成溴代二噁英的重要影响因素;热降解40min时,450℃条件下溴代二噁英生成量最多;产物种类证实碱性化合物通过与BDE-209脱溴形成的HBr反应促进降解,且可抑制二噁英的生成;含硫化合物的添加同样促进BDE-209降解,抑制二噁英的形成,其详细的抑制机理有待进一步确定,BDE-209的降解反应有两种情况,即苯环上的脱溴反应和醚键的断裂反应. 相似文献
163.
采用乙二醇对聚2,6-萘二甲酸乙二醇酯(PEN)进行降解,表征了醇解产物,探讨了醇解原理。结果表明:醇解后PEN中的酯键断裂,PEN分子内的蟄合羟基变成2,6-萘二甲酸乙二醇酯(BHEN)上分子间缔合羟基和游离羟基;醇解后产物的O与C的原子比由醇解前的0.28增至0.38,醇解产物中C=O和C—O两种O结构的质量比为1∶2.18,C—C、C—O和O—C=O三种C结构的质量比为5.38∶2.22∶1,产物的平均分子量降为200左右;醇解产物主要为BHEN及其低聚物,BHEN单体纯度在90%以上,收率为25.95%。该醇解反应是酯基断裂又聚合,PEN长链变短的过程。 相似文献
164.
Xiaoyou Zhang Xianli Ruan Minchan Yan Yaxian Zhao Wuji Wei Yongjian Yang Haiming Xu Yan Li 《环境科学学报(英文版)》2011,23(7):1199-1204
Polybrominated diphenyl ethers (PBDEs) as ubiquitous persistent organic pollutants have attracted much attention in recent years.
Exposure to PBDEs could induce a high health risk for children. The aim of this study was to investigate the PBDEs exposure of
children (9–12 years) from Taizhou, China. Fifty-eight blood samples were collected in one school in a mountainous area in Taizhou.
The concentrations of Σ9PBDEs (sum of BDE-28, -47, -99, -100, -153, -154, -183, -197 and -209) ranged from 2.66 to 33.9 ng/g lipid
wet (lw) with a median of 7.22 ng/g lw. These concentrations were lower than those of children in USA, but close to European and
Asian general population levels. The results showed that children in Taizhou countryside were at a low level of PBDEs exposure. The
predominant congener was BDE-209, followed by BDE-28, -47, -197 and -153. High abundance of BDE-209 was consistent with the
pollution background of PBDEs in China characterized by high brominated congeners as main pollutants. 相似文献
165.
166.
Xiaofei Qin Xijuan Xi Zhongzhi Yang Shishuai Yan Yaxian Zhao Rongguo Wei Yan Li Mi Tian Xingru Zhao Zhanfen Qin Xiaobai Xu 《环境科学学报(英文版)》2010,22(5):744-751
Decabromodiphenyl ether (decaBDE), as a flame retardant, is widely produced and used. To study the thyroid disruption by technical
decaBDE at low concentrations, Xenopus laevis tadpoles were exposed to technical decaBDE mixture DE-83R (1–1000 ng/L) in
water from stage 46/47 (free swimming larvae, system of Nieuwkoop and Faber) to stage 62. DE-83R at concentration of 1000 ng/L
significantly delayed the time to metamorphosis (presented by forelimb emergence, FLE). Histological examination showed that DE-
83R at all tested concentrations caused histological alterations – multilayer follicular epithelial cell and markedly increased follicle size
accompanied by partial colloid depletion and increase in the peripheral colloid vacuolation, in thyroid glands. All tested concentrations
of DE-83R also induced a down-regulation of thyroid receptor mRNA expression. These results demonstrated that technical decaBDE
disrupted the thyroid system in X. laevis tadpoles. Analysis of polybrominated diphenyl ethers (PBDEs) (sum of 39 congeners) in X.
laevis indicated that mean concentrations of total PBDEs in X. laevis exposed to 1, 10, 100, 1000 ng/L were 11.0, 128.1, 412.1, 1400.2
ng/g wet weight, respectively. Considering that PBDEs burden of X. laevis tadpoles was close to PBDEs levels in amphibians as reported
in previous studies, our study has raised new concerns for thyroid disruption in amphibians of technical decaBDE at environmentally
relevant concentrations. 相似文献
167.
168.
以二甘醇单丁醚-二甘醇单乙醚-对二甲苯体系为萃取剂,0.1 mol/L的Na OH溶液为反萃取剂,采用三级萃取-反萃取法处理4,4’-二氨基二苯乙烯-2,2’-二磺酸氧化废水,考察了萃取和反萃取的影响因素,并对废水中的可用有机资源进行了回收。实验结果表明:在V(二甘醇单丁醚)∶V(二甘醇单乙醚)=1∶3、V(醇醚)∶V(废水)=2∶5、V(对二甲苯)∶V(废水)=1∶5的最佳萃取条件下,经三级萃取工艺处理后,平均COD去除率达92.0%、平均脱色率达96.4%、BOD5/COD0.3,可生化性明显增强;最佳反萃取条件为V(Na OH溶液)∶V(有机相)=13∶24、反萃取温度60℃;平均总硝基化合物回收率达88.9%,平均萃取剂回收率达96.7%,回收的萃取剂可循环使用。该工艺对废水处理的综合成本约为700~1 000元/t。 相似文献
169.
水中油的测定方法探讨 总被引:10,自引:0,他引:10
探讨了重量法,紫外光度法测定水中石油类的合适条件和动物油,植物油的干扰。按选定的操作方法测定,取得了满意结果。提供了一个处理石油醚的简单方法。 相似文献
170.
Subhasish K. Chakraborty Savitri Chakraborty Anjan Bhattacharyya Ashim Chowdhury 《Journal of environmental science and health. Part. B》2013,48(11):919-926
Photolysis of oxyfluorfen, an herbicide of the nitrodiphenyl ether class, was studied in aqueous methanol under UV and sunlight. UV irradiation was carried out in a borosilicate glass photoreactor (containing 250 ppm oxyfluorfen in 50% aqueous methanol) equipped with a quartz filter and 125 watt mercury lamp (maximum output 254 nm) at 25 ± 1°C. Sunlight irradiation was conducted at 28 ± 1°C in borosilicate Erlenmeyer flasks containing 250 ppm oxyfluorfen in 50% aqueous methanol. The samples from both the irradiated conditions were withdrawn at a definite time interval and extracted to measure oxyfluorfen content by gas chromatography-flame ionization detector for rate study. The half-life values were 20 hours and 2.7 days under UV and sunlight exposure, respectively. Photolysis of oxyfluorfen yielded 13 photoproducts of which three were characterized by infrared spectrophotometer and 1H NMR and 13C NMR spectroscopy. The rest of the photoproducts were identified by gas chromatography-mass spectrometry (GC-MS) and thin layer chromatography (TLC). An ionization potential 70 eV was used for electron impact-mass spectrometry (EI-MS) and methane was used as reagent gas for chemical ionization-mass spectrometry (CI-MS). Two of the photoproducts were also synthesized for comparison. The main phototransformation pathways of oxyfluorfen involved nitro reduction, dechlorination, and hydrolysis as well as nucleophiles displacement reaction. 相似文献