Pressure effect on soot formation in turbulent diffusion flames

Soot formation in a methane air turbulent jet diffusion flame is investigated numerically using a semi-empirical model. The temperature, density and species (the soot precursor C2H2) fields are calculated using detailed chemical kinetic mechanism based on the flamelet library approach. The influence of pressure on the soot formation and the behavior of the semi-empirical model in different flame situations are investigated. It is found that the flame shape and the flame temperature can be well predicted by the flamelet library approach. The calculated soot yield is mostly sensitive to the soot surface growth rate and the increase of pressure. The increase of pressure leads to the increase of soot surface growth rate and therefore to the increase of soot volume fraction. By adjusting a model constant in the soot surface growth rate, the soot emissions in both pressure p = 1 atm and p = 3 atm are properly simulated by the current semi-empirical soot model.     

表面包覆聚合氯化铝吸附材料的制备与性能表征

在颗粒状黏土素瓷载体上 ,经灼烧制备具有共价结合的铝胶薄膜 ,并以此为载体 ,在聚合氯化铝形成过程中与氯化铝悬浊液共熟化 ,在铝胶薄膜表面生成聚合氯化铝 ,经灼烧进一步固化而制得表面包覆聚合氯化铝吸附材料。该吸附材料作为絮凝剂可循环使用约 17次。用于处理造纸污水 ,COD、BOD、悬浮物、硫化物、色度等指标可分别降低约 93%、77%、96 %、94 %和 80 %。     

无锡职教园区餐厨垃圾理化性质调查分析研究

为提高餐厨垃圾厌氧消化效率,应用理化方法分别测试了无锡职教园区大中餐、小中餐、西餐、汤锅和食堂餐厨垃圾的容重、含水率、pH值、有机干物质、含油率、盐分、氮磷含量等指标,此外,应用餐厨垃圾厌氧发酵模拟试验分析其产沼气效率.通过理化性质试验获得不同类型餐厨垃圾理化指标的异同点.通过产沼气试验可知,容积负荷由1 kgVS/m3·d逐渐提升到4 kgVS/m3·d时,日产气量从2.91 L提高到9.01 L,沼气中甲烷含量在65％以上.     

亚甲基蓝分光光度法测定硫化物校准曲线斜率、截距参考值研究

通过近三年实验室采用亚甲基蓝分光光度法测定硫化物校准曲线制作的一系列原始数据的收集,并通过数理统计方法对校准曲线、-余标准偏差、斜率扩展不确定度、截距扩展不确定度开展了详细讨论,得出亚甲基蓝分光光度法测定硫化物校准曲线斜率(b)参考范围为:0.019 1±0.00044,截距(a)参考值范围:0.003 3±0.005 0.此结果对实验室分析人员判定硫化物项目校准曲线制作是否合格具有一定的参考价值.     

某铀尾矿区及其周边水系中氟的含量特征与成因分析

矿山开采导致大量的氟元素得到释放,进入水体造成氟污染。选取某铀尾矿库区排放水、尾矿库渗滤水及其周边浅层地下水作为研究对象,研究和分析了该铀尾矿库及其周边水系中氟的含量特征与成因。结果表明:研究区尾矿库排放水、尾矿库渗滤水和浅层地下水中氟的浓度平均值分别为30.93、21.27和1.82 mg/L。尾矿库排放水氟的含量均未达到排放要求;周边浅层地下水氟污染严重,超标率达到85.7%。总体而言,尾矿区及其周边水系中氟的含量较高,整体污染严重。而影响水系中氟的含量除人为因素外,还包括p H值、TDS以及当地气候条件等重要因素;水系中的F~-与HCO_3~-、Ca~(2+)以及其它阴、阳离子都在一定程度上呈现正负相关,表明氟的含量也可能受这些阴、阳离子的影响。     

Characteristics of atmospheric single particles during haze periods in a typical urban area of Beijing: A case study in October, 2014

To investigate the composition and possible sources of particles, especially during heavy haze pollution, a single particle aerosol mass spectrometer (SPAMS) was deployed to measure the changes of single particle species and sizes during October of 2014, in Beijing. A total of 2,871,431 particles with both positive and negative spectra were collected and characterized in combination with the adaptive resonance theory neural network algorithm (ART-2a). Eight types of particles were classified: dust particles (dust, 8.1%), elemental carbon (EC, 29.0%), organic carbon (OC, 18.0%), EC and OC combined particles (ECOC, 9.5%), Na-K containing particles (NaK, 7.9%), K-containing particles (K, 21.8%), organic nitrogen and potassium containing particles (KCN, 2.3%), and metal-containing particles (metal, 3.6%). Three haze pollution events (P1, P2, P3) and one clean period (clean) were analyzed, based on the mass and number concentration of PM_2.5 and the back trajectory results from the hybrid single particle Lagrangian integrated trajectory model (Hysplit-4 model). Results showed that EC, OC and K were the major components of single particles during the three haze pollution periods, which showed clearly increased ratios compared with those in the clean period. Results from the mixing state of secondary species of different types of particles showed that sulfate and nitrate were more readily mixed with carbon-containing particles during haze pollution episodes than in clean periods.     

Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis

Polyethylene terephthalate mesh(PET) enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis(FO) mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2 μm. The performance of the optimal FO membrane was tested using 0.2 mol/L Na Cl as the feed solution and 1.5 mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47 L/(m2·hr) and salt rejection of95.48% in FO mode. While in pressure retarded osmosis(PRO) mode, the water flux was4.74 L/(m2·hr) and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.     

Insight into selective removal of copper from high-concentration nickel solutions with XPS and DFT: New technique to prepare 5N-nickel with chelating resin

An efficient and profitable separation process was proposed to prepare 5N(the purity of the metal solution reaches 99.999%) high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions,was explored quantitatively. The maximum adsorption capacity for copper was 2.286 mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing5N-level high-purity nickel solutions, which was further verified using the 800 BV(bed volume) effluent in the column dynamic process.According to the cost–benefit analysis, purification contributed to a profit of approximately 60,000 USD per cycle, and the investment return period was less than 1/3 years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms,implying a coordination ratio of approximately 1:1.     

Best Reviewer Awards (2016)

正On behalf of Dr.X.Chris Le,the Editor-in-Chief of Journal of Environmental Sciences,we congratulate the following reviewers for frequently providing high-quality and timely reviews for Journal of Environmental Sciences.These scientists are the most deserving recipients of the Best Reviewer Awards(2016).     

南京市环境应急处置体系现状分析与研究

在对南京市环境应急处置体系现状进行调研的基础上,从环境风险、环境应急管理机制、环境应急指挥体系运行、环境应急监测体系以及环境应急技术研究等方面进行深入的分析,针对存在的环境应急机制,环境应急预案、环境应急管理能力等方面的问题进行了分析和总结,并且提出了完善环境应急管理机制,建立完善的预案体系,加强应急处置能力、队伍建设及环境预警能力建设等对策建议,对于和南京拥有类似环境风险特征的城市环境安全预警及应急响应系统的构建也提供了借鉴.