Hazardous waste dechlorination reduces the potential of creating dioxins during the incineration process. To investigate the salt effect on waste dechlorination, molten hydroxides with a low melting temperature were u...Hazardous waste dechlorination reduces the potential of creating dioxins during the incineration process. To investigate the salt effect on waste dechlorination, molten hydroxides with a low melting temperature were utilized for the pre-dechlorination and decomposition of chlorine-containing organic wastes(COWs) including trichlorobenzene(TCB),perchloroethylene, hexachlorobenzene and chlordane. The results showed that a eutectic mixture of caustic sodium and potassium hydroxides(41 wt.% NaOH and 59 wt.% KOH) led to a low melting point below 300°C and a relatively high chlorine retention efficiency(CRE) with TCB as a representative COWs. The amounts of hydroxides, reaction time, and temperature all had notable influence on CRE. When the mass ratio of hydroxides to TCB reached 30:1,approximately 98.1% of the TCB was destroyed within 2.5 hr at 300°C with CRE of 71.6%.According to the residue analysis, the shapes of reaction residues were irregular with particles becoming swollen and porous. The benzene ring and C–Cl bonds disappeared, while carboxyl groups formed in the residues. The stripped chlorine was retained and condensed to form chloride salts, and the relative abundance of the chloride ions associated with the mass of TCB in residues increased from 0 to 75.0% within the 2.5 hr reaction time. The observed concentration of dioxins in residues was 5.6 ngTEQ/kg. A reaction pathway and possible additional reactions that occur in this dechlorination system were proposed. Oxidizing agents may attack TCB and facilitate hydrogenation/dechlorination reactions, making this process a promising and environmentally friendly approach for chlorine-containing organic waste treatment.展开更多
A novel method is proposed to enhance the gasification and removal of copper from molten steel by adding ammonium salts or urea into molten steel under normal pressure.The decopperization experiments were conducted in...A novel method is proposed to enhance the gasification and removal of copper from molten steel by adding ammonium salts or urea into molten steel under normal pressure.The decopperization experiments were conducted in a molybdenum-wire resistance furnace at 1 873 K.The copper content of about 400 g of a mild steel was reduced from 0.49%(mass fraction,the same below) and 0.51% to 0.31% and 0.38% using 0.7 g of NHC1 and 0.5 g of(NH)COrespectively,while the copper content of the molten steel was reduced from 0.61%to 0.56% using 2.00 g of NHCONH.展开更多
Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing...Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing atmosphere.The crystal structure and morphology of CeO_(2)abrasive s were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet—visible diffuse reflectance spectroscopy(UV-Vis DRS),and X-ray photoelectron spectroscopy(XPS).The CeO_(2)abrasives were obtained under different atmospheres(Air,Ar,and Ar/H_(2)).With the enhancement of the reducing atmosphere,the morphology of the abrasives transforms from spherical to octahedral,while more oxygen vacancies and Ce^(3+)are generated on the surface of CeO_(2)abrasives.The CMP experiments show that the MRRs of the CeO_(2)-Air,CeO_(2)-Ar,and CeO_(2)-Ar/H_(2)abrasives on SiO_(2)substrates are 337.60,578.74,and 691.28 nm/min,respectively.Moreover,as confirmed by atomic force microscopy(AFM),the substrate surfaces exhibit low roughness(20.5 nm)after being polished using all of the prepared samples.Especially,the MRR of CeO_(2)-Ar/H_(2)abrasives is increased by 104.76%compared with CeO_(2)-air abrasives.The improved CMP performance is attributed to the increased Ce^(3+)concentration and the octahedral morphology of the abrasives enhancing the chemical reaction and mechanical removal at the abrasive-substrate interface.展开更多
太阳能海水淡化是解决全球淡水短缺的最有前景方法之一.然而,传统的蒸发体在高盐度海水中遭遇了盐累积带来的蒸发速率下降甚至失效的瓶颈.受古代水车的启发,本文开发了一种自适应旋转蒸发器,其可以在任意浓度的盐水中实现长期高效的太...太阳能海水淡化是解决全球淡水短缺的最有前景方法之一.然而,传统的蒸发体在高盐度海水中遭遇了盐累积带来的蒸发速率下降甚至失效的瓶颈.受古代水车的启发,本文开发了一种自适应旋转蒸发器,其可以在任意浓度的盐水中实现长期高效的太阳能海水淡化.这种蒸发器是一种双硫化物负载的滚筒式生物质炭.借助了木材天然的水传输通道和分层结构,蒸发器具有杰出的水供应和热定位能力.实验和数值模拟表明,归因于其低密度及独特的亲疏水特性,这个蒸发器能够在盐结晶产生的重心偏移下周期性转动以实现自动盐移除.这使得这个蒸发体甚至可以在饱和盐水(26.47%)中,24 h内保持2.8 kg m^(-2)h^(-1)的高蒸发速率,这是过去一直无法实现的.因此,这项概念验证工作展示了一种不受浓度和运行时间限制的、自旋转诱导脱盐的蒸发器.展开更多
基金supported by the National Natural Science Foundation of China(No.21677112)the Science and Technology Program of Ministry of Housing and Urban–Rural Development(No.2015-K7-021)
文摘Hazardous waste dechlorination reduces the potential of creating dioxins during the incineration process. To investigate the salt effect on waste dechlorination, molten hydroxides with a low melting temperature were utilized for the pre-dechlorination and decomposition of chlorine-containing organic wastes(COWs) including trichlorobenzene(TCB),perchloroethylene, hexachlorobenzene and chlordane. The results showed that a eutectic mixture of caustic sodium and potassium hydroxides(41 wt.% NaOH and 59 wt.% KOH) led to a low melting point below 300°C and a relatively high chlorine retention efficiency(CRE) with TCB as a representative COWs. The amounts of hydroxides, reaction time, and temperature all had notable influence on CRE. When the mass ratio of hydroxides to TCB reached 30:1,approximately 98.1% of the TCB was destroyed within 2.5 hr at 300°C with CRE of 71.6%.According to the residue analysis, the shapes of reaction residues were irregular with particles becoming swollen and porous. The benzene ring and C–Cl bonds disappeared, while carboxyl groups formed in the residues. The stripped chlorine was retained and condensed to form chloride salts, and the relative abundance of the chloride ions associated with the mass of TCB in residues increased from 0 to 75.0% within the 2.5 hr reaction time. The observed concentration of dioxins in residues was 5.6 ngTEQ/kg. A reaction pathway and possible additional reactions that occur in this dechlorination system were proposed. Oxidizing agents may attack TCB and facilitate hydrogenation/dechlorination reactions, making this process a promising and environmentally friendly approach for chlorine-containing organic waste treatment.
基金supported by the National Foundation of Natural Science of China
文摘A novel method is proposed to enhance the gasification and removal of copper from molten steel by adding ammonium salts or urea into molten steel under normal pressure.The decopperization experiments were conducted in a molybdenum-wire resistance furnace at 1 873 K.The copper content of about 400 g of a mild steel was reduced from 0.49%(mass fraction,the same below) and 0.51% to 0.31% and 0.38% using 0.7 g of NHC1 and 0.5 g of(NH)COrespectively,while the copper content of the molten steel was reduced from 0.61%to 0.56% using 2.00 g of NHCONH.
基金the National Natural Science Foundation of China(51905324)the Scientific Research Program Funded by Shaanxi Provincial Education Department(20JK0545)the Doctoral Scientific Research Startup Foundation of Shaanxi University of Science and Technology(2018BJ-14)。
文摘Ce^(3+)as the active site on the CeO_(2)abrasive surface is the key to enhancing the material removal rate(MRR).The CeO_(2)abrasives with high chemical activity were prepared by the molten salt method under a reducing atmosphere.The crystal structure and morphology of CeO_(2)abrasive s were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),ultraviolet—visible diffuse reflectance spectroscopy(UV-Vis DRS),and X-ray photoelectron spectroscopy(XPS).The CeO_(2)abrasives were obtained under different atmospheres(Air,Ar,and Ar/H_(2)).With the enhancement of the reducing atmosphere,the morphology of the abrasives transforms from spherical to octahedral,while more oxygen vacancies and Ce^(3+)are generated on the surface of CeO_(2)abrasives.The CMP experiments show that the MRRs of the CeO_(2)-Air,CeO_(2)-Ar,and CeO_(2)-Ar/H_(2)abrasives on SiO_(2)substrates are 337.60,578.74,and 691.28 nm/min,respectively.Moreover,as confirmed by atomic force microscopy(AFM),the substrate surfaces exhibit low roughness(20.5 nm)after being polished using all of the prepared samples.Especially,the MRR of CeO_(2)-Ar/H_(2)abrasives is increased by 104.76%compared with CeO_(2)-air abrasives.The improved CMP performance is attributed to the increased Ce^(3+)concentration and the octahedral morphology of the abrasives enhancing the chemical reaction and mechanical removal at the abrasive-substrate interface.
基金supported by the National Natural Science Foundation of China(52272153 and 52032004)Open Project of Key Laboratory of Optical System Advanced Manufacturing Technology(2022KLOMT02-05)。
文摘太阳能海水淡化是解决全球淡水短缺的最有前景方法之一.然而,传统的蒸发体在高盐度海水中遭遇了盐累积带来的蒸发速率下降甚至失效的瓶颈.受古代水车的启发,本文开发了一种自适应旋转蒸发器,其可以在任意浓度的盐水中实现长期高效的太阳能海水淡化.这种蒸发器是一种双硫化物负载的滚筒式生物质炭.借助了木材天然的水传输通道和分层结构,蒸发器具有杰出的水供应和热定位能力.实验和数值模拟表明,归因于其低密度及独特的亲疏水特性,这个蒸发器能够在盐结晶产生的重心偏移下周期性转动以实现自动盐移除.这使得这个蒸发体甚至可以在饱和盐水(26.47%)中,24 h内保持2.8 kg m^(-2)h^(-1)的高蒸发速率,这是过去一直无法实现的.因此,这项概念验证工作展示了一种不受浓度和运行时间限制的、自旋转诱导脱盐的蒸发器.
