Pd/activated carbon sorbents for mid-temperature capture of mercury from coal-derived fuel gas

Higher concentrations of Hg can be emitted from coal pyrolysis or gasification than from coal combustion, especially elemental Hg. Highly efficient Hg removal technology from coal-derived fuel gas is thus of great importance. Based on the very excellent Hg removal ability of Pd and the high adsorption abilities of activated carbon（AC） for H2 S and Hg, a series of Pd/AC sorbents was prepared by using pore volume impregnation, and their performance in capturing Hg and H2 S from coal-derived fuel gas was investigated using a laboratory-scale fixed-bed reactor. The effects of loading amount, reaction temperature and reaction atmosphere on Hg removal from coal-derived fuel gas were studied. The sorbents were characterized by N2 adsorption, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The results indicated that the efficiency of Hg removal increased with the increasing of Pd loading amount, but the effective utilization rate of the active component Pd decreased significantly at the same time. High temperature had a negative influence on the Hg removal. The efficiency of Hg removal in the N2-H2S-H2-CO-Hg atmosphere（simulated coal gas） was higher than that in N2-H2S-Hg and N2-Hg atmospheres, which showed that H2 and CO, with their reducing capacity, could benefit promote the removal of Hg. The XPS results suggested that there were two different ways of capturing Hg over sorbents in N2-H2S-Hg and N2-Hg atmospheres.     

Characteristics of atmospheric particles and heavy metals in winter in Chang-Zhu-Tan city clusters, China

To understand the pollution characteristics of atmospheric particles and heavy metals in winter in Chang-Zhu-Tan city clusters, China, total suspended particulate(TSP) and PM10samples were collected in cities of Changsha, Zhuzhou and Xiangtan from December 2011 to January 2012, and heavy metals of Cd, Pb, Cr, and As were analyzed. It shows that the average TSP concentration in Changsha, Zhuzhou and Xiangtan were(183 ± 73),(201 ± 84) and(190 ± 66) μg/m3respectively, and the average PM10 were(171 ± 82),(178 ± 65) and(179 ± 55) μg/m3respectively. The lowest TSP and PM10concentrations occurred at the background Shaping site of Changsha. The average ratio of ρ(PM10)/ρ(TSP) was 91.9%, ranging from 81.3% to 98.9%. Concerning heavy metals, in TSP samples, the concentration of Cr, As, Cd and Pb were 28.8–56.5, 18.1–76.3, 3.9–26.1 and 148.0–460.9 ng/m3, respectively, while in PM10samples, were 16.4–42.1, 15.5–67.9, 3.3–22.2 and 127.9–389.3 ng/m3, respectively. The enrichment factor of Cd was the highest, followed by Pb and As, while that of Cr was the lowest.     

Evaluation of soil washing process with carboxymethyl-β-cyclodextrin and carboxymethyl chitosan for recovery of PAHs/heavy metals/fluorine from metallurgic plant site

Polycyclic aromatic hydrocarbons(PAHs)/heavy metals/fluorine(F) mixed-contaminated sites caused by abandoned metallurgic plants are receiving wide attention. To address the associated environmental problems,this study was initiated to investigate the feasibility of using carboxymethyl-β-cyclodextrin(CMCD) and carboxymethyl chitosan(CMC) solution to enhance ex situ soil washing for extracting mixed contaminants. Further,Tenax extraction method was combined with a first-three-compartment model to evaluate the environmental risk of residual PAHs in washed soil. In addition,the redistribution of heavy metals/F after decontamination was also estimated using a sequential extraction procedure. Three successive washing cycles using50 g/L CMCD and 5 g/L CMC solution were effective to remove 94.3% of total PAHs,93.2% of Pb,85.8% of Cd,93.4% of Cr,83.2% of Ni and 97.3% of F simultaneously. After the 3rd washing,the residual PAHs mainly existed as very slowly desorbing fractions,which were in the form of well-aged,well-sequestered compounds; while the remaining Pb,Cd,Cr,Ni and F mainly existed as Fe–Mn oxide and residual fractions,which were always present in stable mineral forms or bound to non-labile soil fractions. Therefore,this combined cleanup strategy proved to be effective and environmentally friendly.     

Acute and chronic toxic effects of Pb2+ on polychaete Perinereis aibuhitensis：Morphological changes and responses of the antioxidant system

Perinereis aibuhitensis was used to assess adverse biological effects caused by acute and chronic Pb2＋exposure in artificial seawater under controlled laboratory conditions. In 96-hr acute toxicity experiments,the morphological changes showed a positive time/dose-dependent tendency,and the 96-hr LC50 value of Pb2＋was 686.41 mg/L. The responses of enzymatic and non-enzymatic antioxidants in tissues including catalase（CAT）,peroxidase（POD）,superoxide dismutase（SOD）,glutathione peroxidase（GSH-PX）,malondialdehyde（MDA） and the content of total soluble protein（TSP）,were investigated on days 1,4,7 and 10 after Pb2＋exposure under chronic toxicity testing. Results showed that the activation of the antioxidant system in P. aibuhitensis depended on the Pb2＋concentration and the duration of exposure time.Specifically,POD and SOD activities were induced on the first day of the exposure and decreased to the control level on day 10 after exposure. Therefore,these two indexes could be used to indicate oxidative stress associated with P. aibuhitensis exposure to Pb2＋.     

Review of the progress in preparing nano Ti02： An important environmental engineering material

TiO2 nanomaterial is promising with its high potential and outstanding performance in photocatalytic environmental applications, such as CO2 conversion, water treatment, and air quality control. For many of these applications, the particle size, crystal structure and phase, porosity, and surface area influence the activity of TiO2 dramatically. TiO2 nanomaterials with special structures and morphologies, such as nanospheres, nanowires, nanotubes, nanorods, and nanoflowers are thus synthesized due to their desired characteristics. With an emphasis on the different morphologies of TiO2 and the influence factors in the synthesis, this review summarizes fourteen TiO2 preparation methods, such as the sol-gel method, solvothermal method, and reverse micelle method. The TiO2 formation mechanisms, the advantages and disadvantages of the preparation methods, and the photocatalytic environmental application examples are proposed as well.     

我国清洁生产审核现状分析

清洁生产是我国工业可持续发展的一项重要战略.但目前有些清洁生产审核机构的清洁生产审核工作还存在着“粗放”现象,不利于清洁生产可持续发展.本文结合清洁生产审核现状,针对清洁生产审核过程中存在的问题,进行了系统分析.作者认为,树立群体意识、加强领导的表率作用,对促进我国清洁生产审核工作持续、稳定、健康发展,推进环境污染防治工作具有重要意义.     

壳聚糖絮凝微藻的研究进展及展望

微藻作为一种卓越的生物资源已经受到全世界的关注。从藻液中采收微藻一直是个瓶颈。壳聚糖是目前被普遍认可的安全有效的微藻絮凝剂,通过对其进行适当的改性,可以更好地提高絮凝效率。文章综述了壳聚糖以及改性壳聚糖絮凝剂的絮凝机理和性能,并对壳聚糖絮凝微藻研究的发展趋势进行了展望。     

吸收法处理玉米深加工过程异味气体的实验研究

为解决玉米深加工过程中产生的异味气体造成的环境污染问题,采用吸收法对玉米深加工的废气中VOCs进行了处理实验,分别测定了不同吸收剂(清水、3%碱液、1.25%硫酸、森林之源除臭剂、烷基苯磺酸钠溶液、非离子型相转移试剂X溶液)对VOCs的去除效果,并和生物洗涤法进行比较分析,其中,0.03%非离子型相转移试剂溶液对玉米深加工废气中VOCs可以达到95%以上的去除效果,吸收液可送废水处理设施处理。     

低碳高氮污水处理应用技术研究

针对碳氮比小于7的污水,其碳源不能满足硝化与反硝化的要求这一问题,通过改变SBR工艺的运行方式、调解工艺参数等技术手段,使其能够达标处理此类工业废水,并通过某淀粉厂的工程实例进行了验证:采用改良的SBR工艺可以对低碳高氮污水进行有效的处理。     

上海某饮用水源地不同形态氮的时空分布研究

在2010~2012年进行的上海某水源地水质监测资料的基础上,应用纳氏试剂分光光度法等分析方法研究该水源地2011年1~10月总氮、氨氮、硝酸盐氮、亚硝酸盐氮等不同形态的氮素在水体中的空间分布规律及时间变化规律。并就其氮的来源、迁移转化机理和对氮的迁移转化有较大影响的因素进行研究和分析,得出该水库水体中各种形态氮以硝酸盐氮为主,平均占总氮的71.6%,氨氮及亚硝酸盐氮各占总氮的4.39%及0.95%;水体中的温度、光照条件、溶解氧、点位位置分布、水深等是影响各氮形态含量与分布的重要环境因子。