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Hexachlorobutadiene emissions from typical chemical plants

Minxiang Wang, Lili Yang, Xiaoyun Liu, Zheng Wang, Guorui Liu, Minghui Zheng

《环境科学与工程前沿（英文）》 2021年第15卷第4期 doi: 10.1007/s11783-020-1352-8

摘要： Abstract • Unintentional HCBD production in typical chemical plants was investigated. • The highest HCBD concentrations were found in the bottom residue. • Tri/tetrachloroethylene production processes were important HCBD sources. Hexachlorobutadiene (HCBD) was classed as a persistent organic pollutant under the Stockholm Convention in 2015. HCBD is mainly an unintentionally produced by-product of chlorinated hydrocarbon (e.g., trichloroethylene and tetrachloroethylene) synthesis. Few studies of HCBD formation during chemical production processes have been performed, so HCBD emissions from these potentially important sources are not understood. In this study, HCBD concentrations in raw materials, intermediate products, products, and bottom residues from chemical plants producing chlorobenzene, trichloroethylene, and tetrachloroethylene were determined. The results indicated that HCBD is unintentionally produced at much higher concentrations in trichloroethylene and tetrachloroethylene plants than chlorobenzene plants. The sum of the HCBD concentrations in the samples from all of the trichloroethylene and tetrachloroethylene production stages in plant PC was 247000 mg/mL, about three orders of magnitude higher than the concentrations in the tetrachloroethylene production samples (plant PB) and about six orders of magnitude higher than the concentrations in the chlorobenzene production samples (plant PA). The HCBD concentrations were highest in bottom residues from all of the plants. The concentrations in the bottom residue samples contributed 24%–99% of the total HCBD formed in the chemical production plants. The bottom residue, being hazardous waste, could be disposed of by incineration. The HCBD concentrations were much higher in intermediate products than raw materials, indicating that HCBD formed during production of the intended chemicals. The results indicate the concentrations of HCBD unintentionally produced in typical chemical plants and will be useful in developing protocols for controlling HCBD emissions to meet the Stockholm Convention requirements.

关键词： Hexachlorobutadiene Chemical plant Chlorobenzene Trichloroethylene Tetrachloroethylene

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Surface modification of titanium dioxide for electrophoretic particles

PENG Xuhui, LE Yuan, BIAN Shuguang, LI Woyuan, WU Wei, DAI Haitao, CHEN Jianfeng

《化学科学与工程前沿（英文）》 2007年第1卷第4期页码 338-342 doi: 10.1007/s11705-007-0061-1

摘要： To prepare stable electrophoretic ink (E Ink) needs color particles to be uniformly dispersed in the organic medium. Thus, t-he modification of inorganic particle surface is required. In this paper, Titanium dioxide modified by alumina has been studied. The surface composition and structures of modified particles have been characterized by X-ray photoelectron spectrometer (XPS), X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FT-IR). The dispersibility and electrophoretic mobility of these particles in tetrachloroethylene (TCE) have been investigated by laser particle size analyzer, static sedimentation and electrophoretic instrument. Effects of temperature, pH value and stirring rate on the dispersibility and the charge property of samples have been discussed. The results indicate the settle time of modified TiO can last 120 h with the response time of 35 s under the optimized modifying conditions, in which temperature is 85°C–90°C, pH is 8–9 and stirring rate is 800 r · min. The dispersibility and electrophoretic mobility have been significantly improved, which means that the modified TiO is suitable for electrophoretic ink particles.

关键词： inorganic particle temperature tetrachloroethylene transform optimized modifying