Modeling of residual chlorine in water distribution system

Water quality within water distribution system may vary with both location and time.Water quality models are used to predict the spatial and temporal variation of water quality throughout water system.A model of residual chlorine decay in water pipe has been developed, given the consumption of chlorine in reactions with chemicals in bulk water,bio-films on pipe wall, in corrosion process, and the mass transport of chlorine from bulk water to pipe wall.Analytical methods of the flow path from water sources to the observed point and the water age of every observed node were proposed .Model is used to predict the decay of residual chlorine in an actual distribution system.Good agreement between calculated and measured values was obtained.     

包覆型纳米铁的制备及其去除三氯乙烯的研究

采用微乳聚合法成功的用聚甲基丙烯酸甲脂(PMMA)包覆了纳米铁粒子.透射电镜、红外光谱和热重分析证明,PMMA包覆层存在于铁表面,包覆型纳米铁在空气中的稳定性明显提高.批次实验结果表明,该纳米材料能有效降解环境污染物三氯乙烯(TCE),包覆型纳米铁对TCE的还原反应符合准一级反应动力学.     

Mini-Review： Green sustainable processes using supercritical fluid carbon dioxide

Environmentally benign carbon dioxide offers significant potential in its supercritical fluid phase to replace current reliance on a range of hazardous,relatively expensive and environmentally damaging organic solvents that are used on an extensive global basis.The unique combination of the physical properties of supercritical fluids are being exploited and further researched to continue the development and establishment of high efficiency,compact plant to provide energy and water efficient manufacturing processes.This mini-review is focused on the use and potential applications of supercritical fluid carbon dioxide for a selected range of key and emerging industrial processes as a sustainable alternative to totally eliminate or greatly reduce the requirement of numerous conventional organic solvents.Examples of the industries include:chemical extraction and purification,synthetic chemical reactions including polymerization and inorganic catalytic processes.Biochemical reactions involving enzymes,particle size engineering,textile dyeing and advanced material manufacture provide further illustrations of vital industrial activities where supercritical fluid technology processes are being implemented or developed.Some aspects relating to the economics of sustainable supercritical fluid carbon dioxide processes are also considered.     

反相微乳液聚合PAM在悬浮介质中的絮凝过程研究

研究了Span80-Tween80/异辛烷/H2O反相微乳液聚合丙烯酰胺反相微乳液聚合所得到的PAM的微观结构及其在1%高岭土悬浮液的模拟废水中的絮凝过程与机理。采用电子显微镜、激光纳米粒度仪、分光光度计等测试手段,测定了PAM粒子以及与悬浮介质结合的絮体形态、粒径和粒径分布等微观结构及其絮凝性能。试验结果表明:反相微乳液聚合所制备的PAM为单分散、球形的纳米材料,粒径(D)在145～175nm之间;AMPS改性PAM与高岭土结合后,高岭土与高分子团状结构包埋在一起,透过率较大,絮凝范围宽,可以理解为高分子絮凝剂的"架桥-吸附-网捕"机理。     

两步法制备导电聚吡咯薄膜研究

在陶瓷基底上,先用化学方法,再用电化学方法两步聚合制备导电聚吡咯（PPy）薄膜。研究了施加电流和聚合时间对PPy导电薄膜电导率的影响,对比分析了两步聚合法和化学方法对PPy导电薄膜组织的影响,并对两步法在陶瓷和Al2O3基底上制备PPy导电薄膜的微观形貌进行了观察分析。结果表明,两步聚合方法制备的PPy导电薄膜的电导率随着施加电流的增大和聚合时间的增长而逐渐提高;两步法制备PPy导电薄膜的组织较仅用化学方法制备PPy导电薄膜的组织要致密连续;陶瓷基底上PPy薄膜较均匀,而Al2O3基底上PPy薄膜较疏松且不连续。     

Probe into effect of the initiator on the thermal runaway hazards of methyl methacrylate bulk polymerization

The bulk polymerization of methyl methacrylate (MMA) is of great importance in chemical industry, but the polymerization process is highly hazardous, and few reports have focused on the effect of initiators on its thermal hazards. In this work, to thoroughly explore the thermal hazard characteristics, the runaway behavior of MMA bulk polymerization is investigated by a combination of thermodynamics experimental and kinetics theoretical methods. The results indicate that the presence of initiator exhibits an undesirable thermal hazard to the MMA bulk polymerization, and its exothermic behavior is also greatly influenced by the type and concentration of initiator. For azobisisoheptanenitrile (ABVN), azodiisobutyronitrile (AIBN) and dibenzoyl peroxide (BPO) initiators as examples, the AIBN-initiated reaction has the shortest adiabatic induction period (39.51 min), whereas the BPO-initiated polymerization exhibits the strongest maximum temperature-rising rate and maximum pressure-rising rate. Under adiabatic runaway, the temperature and pressure change significantly with increasing AIBN concentration, revealing a great potential risk of thermal runaway. Kinetic parameters are calculated to further understand the thermal runaway mechanisms, showing a strong agreement with the adiabatic experimental data. Finally, based on the cooling failure scenario, severity grading is determined by the evaluation criteria. The current work provides extensive data as a reference and guidance for the process design and optimization of MMA bulk polymerization from the perspective of safety.     

聚丙烯酸酯反相破乳剂制备条件优化及性能评价

以甲基丙烯酸(MAA)和丙烯酸乙酯(EA)为原料,通过乳液聚合制备了聚丙烯酸酯类反相破乳剂P(EA-MAA)。通过单因素实验考察了各因素对产物分子量、乳液粒径中值、聚合物凝胶残渣以及产物除油性能的影响,实验结果表明：在单体总质量分数为10%、单体配比(EA﹕MAA)为1:1,单体加入顺序为先EA后MAA,反应温度70℃,引发剂用量为1‰(占单体总质量分数),反应时间为6h的条件下,制备的P(EA-MAA)分子量大,粒径中值小,聚合物凝胶残渣少,除油率达到94.7%。     

双模板分子印迹微球的制备及其在海水溶液中的分子识别行为研究

以萘和蒽为双模板分子,以甲基丙烯酸为功能单体、二甲基丙烯酸乙二醇酯为交联剂、聚乙烯醇（PVA）为分散剂,通过悬浮聚合制备了双模板分子印迹微球.采用紫外光谱法分析了双模板分子印迹效应产生的机制,用静态吸附实验考察了印迹微球对海水中2—3环多环芳烃的吸附选择性,并以分子印迹-分散固相微萃取法分析了海水中2—3环的多环芳烃.结果表明,双模板-功能单体分子间的多位点协同作用,优化了分子印迹材料的印迹孔穴,提高了双模板分子印迹微球的分子识别能力;所制备的双模板分子印迹材料使用3次后其选择识别性能未显著降低,显示出其富集与分离海水样品中2—3环多环芳烃的良好前景.     

被动采样法表征降水离子浓度和通量的局限性

降水(湿沉降)是大气污染物进入地表环境的主要途径,由于传统的被动采样法易受到颗粒物和气体干沉降的干扰,而采集到的混合沉降样品不能科学表征降水化学组成,也不能准确量化湿沉降通量,因此目前正逐步被主动采样法所取代. 采用主动和被动2种采样法同步采集了降水样品,以考察被动采样法表征降水离子浓度和通量的适用性. 结果表明:被动采样法采集的降水样品中离子浓度明显偏高,其中ρ(NO₃-)、ρ(Mg2+)、ρ(Ca2+)、ρ(K+)、ρ(Cl-)、ρ(SO₄2-)、ρ(Na+)和ρ(NH₄+)分别比主动采样法高65%、58%、43%、41%、35%、26%、10%和9%. 受大气污染物干沉降影响,被动采样法获得的NO₃-、NH₄+和SO₄2-混合沉降通量分别比主动采样法获得的湿沉降通量高79%、18%和35%,差异最显著的是NO₃-. 被动采样法可以收集氮和硫的湿沉降,但不能有效捕获二者以颗粒物和气体形式发生的干沉降,对二者沉降总通量(干沉降通量+湿沉降通量)低估达39%〔23 kg/(hm2·a)〕和40%〔20 kg/(hm2·a)〕. 因此,鉴于大气污染形势日趋严重,污染物的干沉降作用凸显,被动采样法已难以准确测算污染物从大气向地表的沉降总通量,需要全面考虑细颗粒物(粒径≤2.5 μm)和气态物种(如HNO₃)的贡献.      

膜表面光接枝改性的研究现状及展望

本文介绍了利用紫外光将单体接枝到聚合物表面的技术原理与条件 ,并介绍了分离膜表面进行光接枝聚合的研究进展及发展趋势