CO2汽提法尿素生产工艺研究

介绍了CO2汽提尿素生产工艺的技术原理、工艺流程及技术特点,阐述了其技术进展,并与其它尿素工艺的技术指标进行了比较。结果表明,该法是目前极具竞争力的尿素生产技术。     

计时电位溶出法测定天麻中的痕量砷

以镀金玻碳电极为工作电极,计时电位溶出法测定天麻中的痕量砷。选择富集电位为-0.45V,溶出低液为3.0 mol/L的硝酸,在+0.14V电位处获得一灵敏的砷(Ⅲ)的二次微分电位溶出峰,且该溶出峰的峰高与砷的质量浓度在2.0～12.0μg/L范围内呈线性关系,方法的检出限(3S/N)为0.96μg/L。方法用于测定天麻中痕量砷的回收率为97.6%～102.4%,RSD为2.7%～3.1%。     

利用超声波阳极溶出伏安法测定痕量汞

以阳极溶出伏安法研究了超声波作用下汞在金电极上的电化学行为,建立了痕量汞的超声波-阳极溶出伏安法。采用超声波增加了汞的溶出峰电流,提高了方法的灵敏度,在优化实验条件下,汞离子浓度在0～25μg/L范围内,线性方程为I=1.08c+0.27,(μg/L,R=0.998),加入标准汞溶液为6μg/L时,测量值的重复性和精确度都在5%以内。常见金属离子一般不干扰,方法简便快速。     

A review of biodiesel production by integrated reactive separation technologies

Biodiesel is a biodegradable and renewable fuel, emerging as a viable alternative to petroleum diesel. Conventional biodiesel processes still suffer from problems associated with the use of homogeneous catalysts and the limitations imposed by the chemical reaction equilibrium, thus leading to severe economic and environmental penalties. This work provides a detailed review—illustrated with relevant examples—of novel reactive separation technologies used in biodiesel production: reactive distillation/absorption/extraction, and membrane reactors. Reactive separation offers new and exciting opportunities for manufacturing the fatty acid alkyl esters involved in the industrial production of biodiesel and specialty chemicals. The integration of reaction and separation into one operating unit overcomes equilibrium limitations and provides major benefits such as low capital investment and operating costs. These reactive separation processes can be further enhanced by heat‐integration and powered by heterogeneous catalysts, to eliminate all conventional catalyst related operations, using efficiently the raw materials and the reaction volume, while offering higher conversion and selectivity, as well as significant energy savings compared with conventional biodiesel processes. Remarkable, in spite of the high degree of integration, such integrated reactive‐separation processes are still very well controllable as illustrated by the included examples. Copyright © 2012 Society of Chemical Industry     

Study of nonionic surfactants on HVOCs removal from coacervate solutions using cocurrent vacuum stripping in a packed column

ABSTRACT

Cloud point extraction has been shown to be an effective technique to remove hydrophobic volatile organic compounds (HVOCs) from aqueous solution using nonionic surfactant. A cocurrent vacuum stripper is used to recover the surfactant in coacervate phase from extraction for economic viability. The solutions containing two series of aromatic and chlorinated HVOCs. Surfactants studied were alkyl phenol ethoxylates, secondary alcohol ethoxylates (AEs), and branched secondary AEs. From equilibrium measurements, the apparent Henry’s law constant (volatility) of the HVOCs in surfactant solution decreased with increasing HVOCs hydrophobicity due to solubilization of the HVOCs in micelles. The results showed that the mass transfer of HVOC decreases due to the solubilization enhancement of the HVOCs.     

PVC装置废水汽提系统运行总结

简要介绍了新建废水汽提系统的工艺,分析了该系统在处理含有氯乙烯、甲苯、PVC粉料等组分的废水过程中出现的问题及解决措施：①塔盘和塔底泵入口过滤器堵塞,其原因是加入废碱液所致;②进塔换热器堵塞和泛塔,改进措施是用带降液管的大孔筛板塔处理该废水时,降液管下沿至下层塔盘的间距不宜小于25mm。     

圆柱型电泳挂具挂点自动脱漆装置和低腐蚀快速脱漆剂的研究

对电泳挂具挂点自动脱漆装置和低腐蚀快速脱漆剂配方进行了研究,电泳挂具挂点自动脱漆装置可大幅度降低员工劳动生产强度、延长挂具的使用时间和降低生产成本,同时研究的低腐蚀性快速脱漆剂由于不含二氯甲烷、苯酚、甲苯和二甲苯等有害物质,对人身体和大气不造成污染,该脱漆剂使用复合式缓蚀剂,对钕铁硼磁性材料具有低腐蚀作用,磁体退漆后基体几乎没有损伤。     

Stripping and recycling of metal ions in aqueous nitric acid solutions: Experimental and molecular dynamics insights

Stripping of metal ions (i.e., Cs⁺ and Na⁺) in presence of ionophore such as dibenzo-18-crown-6, (DB18C6) from the ionic liquid phase to the aqueous nitric acid phase by molecular dynamics simulation is reported. The experimentally determined stripping percentages of Na⁺ (i.e., 43.4, 38.5, 34.4, and 31.9%) were found to be higher than the same for Cs⁺ (i.e., 32.6, 32.0, 31.3, and 30.2%). The nonbonded and the hydrogen bond energies between Na⁺ and water (i.e., −356.41 and −363.77 kcal/mol) were higher when compared with Cs⁺ (i.e., −212.43 and −221.04 kcal/mol). The spatial distribution functions further confirmed that the surfaces of Na⁺ were very closely distributed around the active sides of water whereas for Cs⁺, it was distributed very far from the water molecules. In the penultimate section, the effect of methanol to the aqueous phase was studied so as to enhance the extraction efficiency of the complex.     

混合溶剂法氯磺化聚乙烯橡胶湿法凝聚工艺研究

采用湿法凝聚工艺对氯磺化聚乙烯胶液进行凝聚,并将混合溶剂脱出回收重复利用,凝聚后的湿胶块经螺杆脱挥等干燥处理后即成氯磺化聚乙烯橡胶。研究了凝聚温度、搅拌桨、水胶比等、对湿胶块水含量、混合溶剂含量等的影响,并测其物化性能,根据螺杆脱挥的要求确定了湿法工艺条件。     

含锌高浓度氨氮废水治理研究

分析了高浓度氨氮废水的成份 ,将其含硫废水进行一定的调配调解后 ,使其中重金属污染物 Zn2 沉淀过滤出来 ,Zn2 的去除率达 99.99% ;其过滤液作为汽提原料 ,汽提可除去大部分硫化物与氨氮