介质阻挡放电协同Ag/Al_2O_3对NO_x脱除的影响

为有效去除发电厂烟气中产生的NOx,利用介质阻挡放电(DBD)产生低温等离子体并结合催化剂Ag/Al2O3进行烟气脱硝实验,研究了在加入乙烯的条件下,平均负载量、催化温度和装置的布置方式对NOx脱除的影响。结果表明,随着负载的增多,NO脱除率呈现先增大后减小的趋势,5种负载量中最佳为1.76%;随着催化温度的升高,NO脱除率同样呈现先增大后减小的趋势,最佳的催化温度为150℃左右;3种不同布置方式对NO和NOx脱除有明显差别,单独催化剂在NO和NOx的脱除率都比较低;单独介质阻挡放电NO脱除率很高,但是NOx很却很低;而两者结合在NO和NOx都达到了很好的效果。     

Regulation (EC) No. 1107/2009 and upcoming challenges for exposure assessment of plant protection products--Harmonisation or national modelling approaches?

In the new European Pesticide Regulation (EC) No. 1107/2009, the harmonisation of approaches for estimation of the environmental exposure of pesticides is considered a major goal. Several member states currently require their own models for the calculation of predicted environmental concentrations (PEC) in surface water. The variety of methods makes risk evaluations rather time-consuming for both notifiers and evaluating authorities. In the present study we compare surface water concentrations of 19 compounds using EU and country-specific models and risk assessment approaches to evaluate to which extent the resulting estimated exposure concentrations differ. Our results show that EU and country specific approaches and the resulting surface water concentrations differ considerably regarding basic model assumptions and assessment methods. The results indicate that the aimed harmonisation of risk assessment approaches within the EU will be difficult based on current models. New scenarios may help to achieve a harmonisation taking country-specific features into account.     

壳聚糖的物理/化学改性及其对含酚废水的处理

将壳聚糖物理改性为球形颗粒,然后在微波辐射下,球形壳聚糖与柠檬醛接枝反应,再与NaBH4还原反应,制备一种新型环保材料--物化改性壳聚糖.采用红外光谱仪(IR)、X衍射仪(XRD)、电子显微镜(SEM)和比表面测定及孔径分析仪(BET)结构表征改性壳聚糖.通过含酚制药废水的动态小柱吸附实验,研究了时间、柱高和出水流速等...     

室内空气中颗粒物污染特征研究

为获得室内空气颗粒物污染特征,2009年8月18～24日在某单位工作及生活区选取4个室内点和1个室外点进行颗粒物采样和成分分析.结果表明,室内粗颗粒(PM10)符合<室内空气质量标准>(GB/T 18883-2002),而细粒子(PM2.5)的浓度水平较高,表明室内PM2.5的污染较重;室内与室外PM2.5比值显示,P...     

A national inventory to estimate release of polychlorinated dibenzo-p-dioxins and dibenzofurans in Portugal

Taking into account current environmental concerns, the main objective of this work focused a national inventory aiming to estimate the amount of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) released in Portugal in 2006. The methodology used was based on the Standardized Toolkit for Identification and Quantification of Dioxins and Furan Releases, developed by UNEP Chemicals, in 2005. The method allows the assessment of the amount of PCDD/PCDF released into the environment along five vectors involving air, water, land, products and residues. Facing some difficulties mainly regarding to the availability of data for some activities known to produce PCDD/PCDF, three scenarios (Sc1 to Sc3) corresponding to lower, central and upper estimates were established. The Sc1 scenario (lower estimate) includes the situations where in case of doubt or scarce information, reduced or none emission values were assumed, Sc2 refers to a central estimate, which is believed to be the most realistic for the Portuguese situation, while Sc3 corresponds to the worst case (upper estimate). The results obtained pointed out that the total amount of PCDD/PCDF emitted in Portugal during the period under analysis was in the range of 51.2-217.9 g TEQ year⁻¹, with the most likely value of 95.2 g TEQ year⁻¹ achieved under the Sc2 scenario. This study also showed that the methodology developed by UNEP Chemicals is a very simple one, and the main difficulty is the availability of data. The main indicators calculated in this study were 8.98 μg TEQ/(year person) by taking into account the total amount of PCDD/PCDF released, and 3.63 μg TEQ/(year person) when only air emissions were considered.     

质子化改性交联壳聚糖的制备及其吸附硫酸根离子的性能

以壳聚糖为原料,甲醛为氨基保护剂,戊二醛为交联剂,采用反相悬浮交联法制备交联壳聚糖,再对其进行质子化改性得到质子化改性交联壳聚糖吸附剂。通过正交实验对该吸附剂的制备条件进行优化,并对其吸附水中硫酸根（SO₄^2-）的吸附等温特性和动力学进行研究,最后对制备和吸附过程进行能谱分析（EDS）并对吸附剂进行了再生实验。实验结果表明,交联反应的优化条件为：反应温度50℃、反应时间6 h、甲醛：戊二醛：壳聚糖为4.5：0.5：3（质量比）;该吸附过程符合Langmuir吸附等温模型,在25℃（298 K）下,吸附容量最大可达133.87 mg/g;吸附过程较好地符合拟二级动力学模型;EDS分析表明了交联反应、质子化改性和吸附反应均已发生;该吸附剂的再生性能良好,可以重复使用。     

混凝-生物接触氧化处理合成橡胶碱洗废水

对化学合成橡胶碱洗废水进行了有机组分和可生化性分析,废水主要含有氯甲烷、六甲苯、异丁醇、甲醇等污染物质,生化降解实验中废水TOC可在6 d内从60.9 mg/L下降至0.0 mg/L,可生化降解性好,适于生化处理。选择混凝-生物接触氧化组合工艺对废水进行处理,采用优化条件(pH=8、PAC=40 mg/L、PAM=8 mg/L)进行混凝,碱洗废水COD去除率为9.95%~72.94%(平均31.51%);混凝后的碱洗废水与冲洗废水1∶5混合进行接触氧化处理,在HRT为36 h的情况下,COD去除率为65.6%~72.6%(平均70.4%),出水COD为134~331 mg/L,满足企业废水排放市政管网的要求;同时,实验发现COD去除率与COD容积负荷存在指数函数变化关系。     

Degradation of pentachlorobiphenyl by a sequential treatment using Pd coated iron and an aerobic bacterium (H1)

The reductive dechlorination and biodegradation of 2,2^′4,5,5^′-pentachlorobiphenyl (PCB#101) was investigated in a laboratory-scale. Palladium coated iron (Pd/Fe) was used as a catalytic reductant for the chemical degradation of 2,2^′4,5,5^′-pentachlorobiphenyl, and an aerobic bacteria was used for biodegradation following the chemical reaction in this study. Dechlorination was affected by several factors such as Pd loading, initial soil pH and the amount of Pd/Fe used. The results showed that higher Pd loading, higher dosage of Pd/Fe and slightly acid condition were beneficial to the catalytic dechlorination of 2,2^′,4,5,5^′-pentachlorobiphenyl. In laboratory batch experiments, 2,2^′4,5,5^′-pentachlorobiphenyl was reduced in the presence of Pd/Fe bimetal, which was not further degraded by aerobic bacteria. 2,2^′,4-trichlorobiphenyl (PCB#17), a reduction product from 2,2^′4,5,5^′-pentachlorobiphenyl, was readily biodegraded in the presence of a aerobic bacterial strain. It is suggested that an integrated Pd/Fe catalytic reduction-aerobic biodegradation process may be a feasible option for treating PCB-contaminated soil.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans and polychlorinated biphenyls levels in human breast milk from different regions of Turkey

Human breast milk offers the optimal nutrition for all infants and have been widely used in biomonitoring programs to assess human exposure to lipophylic environmental contaminants such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB). There are no previous reports from Turkey on chemically determined levels of PCDDs, PCDFs, and PCBs in human breast milk expressed as World Health Organization (WHO) toxic equivalents (TEQ). To get an overview of the levels of these contaminants in Turkish human milk, samples from 51 Turkish women living in the Ankara, İstanbul, Antalya, Kahramanmaraş, and Afyon provinces were analyzed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) throughout 2007. The mean concentrations of WHO_PCDD/F-TEQ and WHO_PCB-TEQ of all samples from the five regions were 7.5 and 3.1 pg g⁻¹ on a lipid basis, respectively. PCDD/F concentrations ranged between 0.78 and 29.3 pg WHO-TEQ g⁻¹ fat (1.7 and 36.2 pg WHO-TEQ g⁻¹ fat, respectively, including PCB). Of the five studied locations, the lowest levels of ∑TEQs (PCDD/F + PCB) were found in the Afyon (6.8 pg WHO-TEQ g⁻¹ fat) and the highest in the Antalya (15.6 pg WHO-TEQ g⁻¹ fat) province. The results have been discussed in terms of regions and PCDD/F and PCBs for which analyses had been made. The mean levels of PCDD/Fs and PCBs in Turkish human milk are comparable to that found in other countries.     

A new direct thermal desorption-GC/MS method: Organic speciation of ambient particulate matter collected in Golden, BC

Particulate matter having an aerodynamic diameter less than 2.5 μm (PM2.5) is thought to be implicated in a number of medical conditions, including cancer, rheumatoid arthritis, heart attack, and aging. However, very little chemical speciation data is available for the organic fraction of ambient aerosols. A new direct thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) method was developed for the analysis of the organic fraction of PM2.5. Samples were collected in Golden, British Columbia, over a 15-month period. n-Alkanes constituted 33–98% by mass of the organic compounds identified. PAHs accounted for 1–65% and biomarkers (hopanes and steranes) 1–8% of the organic mass. Annual mean concentrations were: n-alkanes (0.07–1.55 ng m⁻³), 16 PAHs (0.02–1.83 ng m⁻³), and biomarkers (0.02–0.18 ng m⁻³). Daily levels of these organics were 4.89–74.38 ng m⁻³, 0.27–100.24 ng m⁻³, 0.14–4.39 ng m⁻³, respectively. Ratios of organic carbon to elemental carbon (OC/EC) and trends over time were similar to those observed for PM2.5. There was no clear seasonal variation in the distribution of petroleum biomarkers, but elevated levels of other organic species were observed during the winter. Strong correlations between PAHs and EC, and between petroleum biomarkers and EC, suggest a common emission source – most likely motor vehicles and space heating.