A large-scale outdoor atmospheric simulation smog chamber for studying atmospheric photochemical processes: Characterization and preliminary application

Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China. Thus, a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences (the CRAES Chamber), which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment. The chamber consisted of a 56-m³ fluorinated ethylene propylene (FEP) Teflon film reactor, an electrically-driven stainless steel alloy shield, an auxiliary system, and multiple detection instrumentations. By performing a series of characterization experiments, we obtained basic parameters of the CRAES chamber, such as the mixing ability, the background reactivity, and the wall loss rates of gaseous compounds (propene, NO, NO₂, ozone) and aerosols (ammonium sulfate). Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol (SOA), including α-pinene ozonolysis, propene and 1,3,5-trimethylbenzene photooxidation. Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work: higher temperature and the presence of seed could reduce the vapor wall loss; SOA yield was found to depend inversely on temperature, and the presence of seed could increase SOA yield. The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls. The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.     

Influence of particle size on the aggregation behavior of nanoparticles: Role of structural hydration layer

More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and pH all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.     

氯化处理船舶压载水对外来生物存活的影响

初步研究了氯化处理船舶压载水对外业生物存活的影响。结果表明，氯化自理对杀灭中的细菌最为有效；对单细胞灌类则依种类需要不同浓度的有效氯，有的种类在４０ｍｇ／Ｌ有效氯作用下依然能存活。     

垃圾焚烧飞灰物理化学性质的实验研究

应用激光粒度粒形分析仪、灰熔融性测定仪、原子吸收光谱仪和XRD等仪器手段对国内2种垃圾焚烧飞灰的密度、颗粒特性、熔点、成分和晶相结构等物理化学性质进行了详细的研究。研究发现，2种灰样颗粒直径的数量积分分布非常接近，其中基本没有超过40 μm的颗粒。由于垃圾焚烧飞灰在化学成分上存在的差异导致了其熔点有很大的不同。此外，XRD结果显示不同来源的飞灰其晶相结构存在较大的差别，这可能与垃圾的来源和焚烧工艺以及烟气处理方法有关。实验结果为飞灰无害化低温烧结工艺的选择和运行参数的制定提供了依据。     

SBR工艺处理高盐度生活污水试验

针对海水冲厕产生的高含盐生活污水,试验采用SBR工艺分别研究了不同海水盐度的污水中有机物的降解及氨氮的去除情况。结果表明,在高盐度污水的生物处理系统中,污泥的驯化是关键的一步。有机物和氨氮的去除率总体上随着盐度的增大而降低,但在海水冲厕范围内(海水比例在30%内,盐度为10500mg/L,Cl-为5700mg/L),海水盐度对有机物及氨氮的去除影响不大。     

亚超临界水技术在废旧尼龙6解聚中的应用

研究了尼龙6在亚超临界水中的解聚反应,以期为废旧尼龙6的回收利用提供技术参数.实验分别利用气质联用仪和紫外分光光度计对解聚后的液相产物进行定性和定量分析,并考察了不同的反应温度、反应压力和反应时间对液相产物收率的影响.结果表明,液相产物绝大部分为己内酰胺;解聚的最佳条件为370 ℃、25 MPa、60 min;己内酰胺最大收率为96%.通过动力学分析和Arrhenius关系计算,得出尼龙6亚超临界水解聚的活化能为64.4 kJ/mol.     

淀山湖沉水植物死亡分解过程中营养物质的释放

测定了上海淀山湖5种常见沉水植物的营养成分含量及其死亡后在好氧(DO>3.5 mg/L)或低氧(DO<3.5 mg/L)状态下分解释放TN、TP和有机物(以高锰酸盐指数计,下同)等营养物质的动态过程,并对营养物质释放强度与营养成分含量的相关性进行了分析.结果表明, 5种沉水植物中,金鱼藻的TN和TP含量最高,质量分数分别为(4.07±0.22)%和(0.99±0.09)%;好氧状态下TN和有机物的释放强度大于低氧状态,两种状态下TP的释放强度没有显著差异;TP的释放比TN快,一般需10 d左右,而TN和有机物的释放分别需要29 d和20 d左右;在好氧状态下,NO-2-N、NO-3-N和可溶性总磷酸盐的平均释放强度与植物TN含量呈显著正相关(p<0.05),NH 4-N的平均释放强度与植物TP含量呈显著正相关(p<0.05);在低氧状态下,NO-2-N的平均释放强度与植物TN含量、NO-3-N的平均释放强度与植物TP含量分别呈显著正相关(p<0.05);有机物的平均释放强度与植物TP含量呈极显著负相关(p<0.01).     

钱塘江流域污染负荷及水环境容量研究

采用排污系数法计算了钱塘江流域不同污染源COD和氨氮的污染负荷,研究了整个流域90%、75%和so%水文保证率下的水环境容量.以流域水质目标为出发点,考虑污染负荷和流域社会经济发展需求相协调的原则,确定了钱塘江流域水污染总量控制阶段性目标.     

伞罩型除尘脱硫塔内除雾器性能研究

除雾器是湿法烟气脱硫(WFGD)系统内重要的设备之一,其性能对WFGD系统运行的可靠性有重要影响.利用Fluent6.2软件对新型伞罩型除尘脱硫塔内的三维两相流场进行数值模拟,气相采用RNG湍流模型,液相采用离散相模型,选择SIMPLE算法进行计算,分析塔内的折板除雾器和旋流板除雾器的速度场、压力场和液滴的分布情况.结果表明,烟气经过折板除雾器,产生了明显的压降,且在拐角区域湍流耗散强烈,是实现气液分离的关键区域;烟气经过旋流板除雾器,速度和压强分布具有良好的对称性,液滴被气流旋转抛向壁面实现气液分离.模拟结果对新型的WFGD除雾器的设计和运行具有一定的理论指导意义.     

稀土Ce掺杂SnSb复合涂层电极的实验研究

采用涂刷热分解氧化法,把无机盐SnCl4·5H2O、SbCl3和Ce(NO3)3·6H2O以一定的配比溶解在有机溶剂异丙醇中制备涂层液,以钛板为基体,制备多组分的涂层电极.考察了不同掺杂量下制备的电极对生活污水的处理效果,并对稀土Ce掺杂SnSb涂层进行了SEM表征,结果表明,在热处理温度为500℃、稀土掺杂量(原子质量比)为Sn∶Sb∶Ce=100∶10∶1的电极降解效果最好;稀土Ce的掺杂有利于锡锑金属氧化物涂层电极的电化学性能的提高.