Low-temperature VOCs oxidation performance of Pt/zeolites catalysts with hierarchical pore structure

Different zeolites supported Pt catalysts with micro-mesoporous structure were prepared by organic base tetrapropylammonium hydroxide (TPAOH) treatment and their catalytic oxidation activity for various volatile organic compounds (VOCs) were evaluated. The results reveal that the synergistic effect between Pt nanoparticles and surface acid sites plays an important role in VOCs low-temperature removal. The small size and high dispersion of Pt nanoparticles on the surface of the zeolites would promote the catalytic oxidation of aromatics and alkanes over the Pt/zeolite catalysts, while strong acidity and abundant acid sites of catalysts are in favour of the oxidation of the VOCs containing N and O heteroatoms. In addition, it was found that Pt/ZSM-5 catalyst exhibits the highest oxidation activity for various VOCs low-temperature removal amongst all the catalysts due to the balance of both Pt dispersion and abundant acid sites in the catalyst. This comprehensive consideration should be very helpful when designing and preparing novel catalysts for the low-temperature removal of VOCs.     

Exposure characteristics of phthalate metabolites among the Zunyi cohort of pregnant women in Southwest China

Environmental Science and Pollution Research - Reported evidence has increasingly indicated that exposure to phthalates can cause adverse pregnancy outcomes. However, phthalate exposure levels...     

液膜法处理含硝基酚废水试验研究

采用液膜法对含硝基酚废水进行了处理试验研究。对低浓度废水选取了适宜的工艺条件：油相中表面活性剂的质量分数为2％；内水相中NaOH的质量分数为2％；乳液中油相与内水相的质量比为2：1；外水相：pH为2；乳液与外水相的体积比为1：3。在进水总酚质量浓度分别为1050、6700mg／L的条件下，出水总硝基酚的去除率均高达99．9％以上，同时废水中的硝基苯和COD也有较好的去除效果。     

外源NO对Cu胁迫下番茄幼苗L-精氨酸代谢的影响

一氧化氮(nitric oxide,NO)作为生物活性分子,广泛参与各种生物和非生物胁迫。采用营养液培养,研究Cu胁迫下番茄体内L-精氨酸、NO、多胺代谢对外源NO的响应机制,以期为铜污染区域蔬菜种植提供科学依据和技术支持。结果表明,Cu胁迫下添加外源SNP(硝普钠,外源NO供体)能够调节番茄根系和叶片中精氨酸脱羧酶(Arginine Decarboxylase,ADC)、鸟氨酸脱羧酶(Ornithine Decarboxylase,ODC)及一氧化氮合酶(Nitric Oxide Synthase,NOS)活性。根系中,外源SNP能够上调NOS活性,L-精氨酸代谢向着NO合成方向进行;叶片中,外源SNP能够同时上调ADC、ODC、NOS活性,PA、NO的合成同时进行;此外,Cu胁迫下添加外源SNP能够增加根系和叶片L-精氨酸含量,而作为PA、NO的合成前体,精氨酸含量升高无疑会间接促进PA、NO的合成,从而提高番茄对Cu胁迫的抵抗能力。     

生态-人工渗滤技术在高速公路收费站生活污水处理中的应用

研究了生态-人工渗滤组合技术在高速公路收费站生活污水中的处理效果。结果表明:在水力负荷为1.5m3/(m2.d),湿干比为1∶3的条件下,系统对COD、SS、NH4+-N、TP均有较好的去除效果,进水中COD、SS、NH4+-N以及TP浓度分别由126~218、123~186、19.89~32.69、2.75~4.53 mg/L降到出水的8~56、7~28、0.45~1.95和0.12~0.40 mg/L,COD、SS去除率分别在80%、85%以上,NH4+-N、TP的去除率均在90%以上。此研究显示,生态-人工渗滤技术在工程应用良好,基建和运行成本较低,在处理远离城市的生活废水时具有巨大的优势。     

Sorption mechanisms of diphenylarsinic acid on natural magnetite and siderite: Evidence from sorption kinetics,sequential extraction and extended X-ray absorption fine-structure spectroscopy analysis

• DPAA sorption followed pseudo-secondary and intra-particle diffusion models. • Chemical bonding and intra-particle diffusion were dominant rate-limiting steps. • DPAA simultaneously formed inner- and outer-sphere complexes on siderite. • DPAA predominantly formed occluded inner-sphere complexes on magnetite. • Bidentate binuclear bond was identified for DPAA on siderite and magnetite. Diphenylarsinic acid (DPAA) is both the prime starting material and major metabolite of chemical weapons (CWs). Because of its toxicity and the widespread distribution of abandoned CWs in burial site, DPAA sorption by natural Fe minerals is of considerable interest. Here we report the first study on DPAA sorption by natural magnetite and siderite using macroscopic sorption kinetics, sequential extraction procedure (SEP) and microscopic extended X-ray absorption fine-structure spectroscopy (EXAFS). Our results show that the sorption pseudo-equilibrated in 60 minutes and that close to 50% and 20%–30% removal can be achieved for magnetite and siderite, respectively, at the initial DPAA concentrations of 4–100 mg/L. DPAA sorption followed pseudo-secondary and intra-particle diffusion kinetics models, and the whole process was mainly governed by intra-particle diffusion and chemical bonding. SEP and EXAFS results revealed that DPAA mainly formed inner-sphere complexes on magnetite (>80%), while on siderite it simultaneously resulted in outer-sphere and inner-sphere complexes. EXAFS analysis further confirmed the formation of inner-sphere bidentate binuclear corner-sharing complexes (²C) for DPAA. Comparison of these results with previous studies suggests that phenyl groups are likely to impact the sorption capacity and structure of DPAA by increasing steric hindrance or affecting the way the central arsenic (As) atom maintains charge balance. These results improve our knowledge of DPAA interactions with Fe minerals, which will help to develop remediation technology and predict the fate of DPAA in soil-water environments.     

铈改性Al2O3担载Pd催化剂的CO氧化性能研究

浸渍法制备了Al₂O₃+CeO₂为载体的Pd催化剂,对制备中各因素对催化剂效果的影响作了初步研究。考察了活性组分含量与催化剂性能的关系以及焙烧温度、水蒸气对催化剂活性的影响。结果表明,稀土Ce元素的存在使催化剂的性能得到明显改善。制备过程中焙烧步骤对催化剂的活性影响很大,催化剂制备必须高于600℃焙烧。     

Comparison of end-of-life tire treatment technologies: A Chinese case study

The aim of this paper is to compare different end-of-life tire (ELT) treatment technologies in China from an environmental and economic perspective. Four treatment technologies were evaluated: ambient grinding, devulcanization, pyrolysis and illegal tire oil extraction.Life cycle assessment (LCA) was applied to evaluate the potential environmental impact of each treatment based on the Eco-indicator 99 (Hierarchist approach) method provided by GaBi 4 software. The final result shows that pyrolysis represents the environmentally benign option while illegal tire oil extraction caused the worst damages. For the three legal treatments, although high credit was obtained when considering avoided impacts from recycled materials and energy, they have great impact as to respiratory effects (inorganic) dominantly contributed by energy production stage, which implies that the emphasis on environmental policies related to ELT treatment should shift from the control of emissions from treatment process to the reduction of energy consumption.A simplified comparison of net benefits and total impacts shows that the most eco-effective ELT treatment technology is pyrolysis, followed by dynamic devulcanization and ambient grinding. The illegal tire oil extraction, however, must be prohibited immediately because of its highest environmental pollution and lowest net benefit.     

提高页岩粉末中杀虫双释放率的研究(Ⅰ)--吸附特征

用动态法在不同的pH值与环境条件下,测定了页岩粉末对杀虫双的吸附量.在pH为5.00～8.50,温度在26～90℃时,60～80目的页岩粉末的弱吸附为1.15～1.86mg/g干样,可逆吸附为0.99～5.31mg/g干样,不可逆吸附为0.69～4.90mg/g干样.     

京津地区SF6示踪扩散实验

在北京北郊铁塔的100m高度释放六氟化硫(SF_6)气体(每小时排放30—40kg),在下风方向3、5km两条弧线上用一辆汽车往返穿行,在车上用塑料针筒取样,然后回到实验室分析浓度。在9、20km弧上和36、50、70km的弧上分别各用一辆汽车装载连续示踪物检测仪穿行,当时在记录器上记录浓度的空间分布。 根据实验资料并配合计算的100、50m和地面的水平轨迹及其它气象资料,分析了风速垂直切变、水平风摆动、大气稳定度和地表特征等因子对扩散的影响。风速垂直切变(特别是地形风和城市热岛引起的风速垂直切变)使浓度水平分布分裂为几段。而在切变较小的稳定和中性条件下,在36km距离的浓度仍呈现典型的正态分布。 计算了水平扩散参数σy,得到城区和郊区的两种稳定度下(中性和稍不稳定)几十公里距离的σy随距离的变化。其规律与用平衡球定位方法所得到的结果接近,并与国外同类实验结果进行了比较。