钡盐共沉法处理酸性含铅废水

硫酸盐、氯化物复杂体系含铅酸性废水对环境的污染比较严重,并且不易处理.采用钡盐共沉法对含铅废水的处理进行研究,结果表明,钡盐共沉法可有效除去废水中的铅,但除铅效果受铅与废水中氯离子络合程度的影响,而受反应时间、温度、陈化时间的影响较小,容易实现工业化.采用钡盐共沉法处理硫酸盐氯化物复杂体系酸性废水.处理后的废水中含铅量远低于0.5 mg/L.     

钯/聚合物复合催化膜制备及催化还原对硝基苯酚

钯金属具有较高的催化加氢性能,钯催化还原降解水体中污染物的研究一直是国内外研究的热点。为了制备催化性能稳定、催化活性高且易于回收利用的Pd催化剂,实验以聚丙烯腈(PAN)聚合物分离膜作为基材,采用层层自组装方法将聚乙烯亚胺/钯配合物(PEI-Pd(II))和聚苯乙烯磺酸钠(PSS)交替组装在基膜表面,制备了(PEI-Pd(0)/PSS)n复合催化膜,并采用膜分离装置通过对硝基苯酚催化加氢反应来评价催化膜的催化性能。实验结果表明,荷电化处理时间、NaOH溶液浓度、PEI和Pd(II)摩尔比、自组装层数影响着膜的催化性能。当荷电化处理时间为1.5 h,NaOH溶液浓度为1.5 mol/L,PEI和Pd(II)摩尔比为60∶4,自组装层数为5层时,复合催化膜有最佳的催化性能,其对对硝基苯酚的去除率能达到90%以上。     

Trace elements in atmospheric particulate matter over a coal burning power production area of western Macedonia, Greece

Total suspended particle (TSP) concentrations were determined in the Eordea basin (western Macedonia, Greece), an area with intensive lignite burning for power generation. The study was conducted over a one-year period (November 2000–November 2001) at 10 sites located at variable distances from the power plants. Ambient TSP samples were analyzed for 27 major, minor and trace elements. Annual means of TSP concentrations ranged between 47 ± 33 μg m⁻³ and 110 ± 50 μg m⁻³ at 9 out of the 10 sites. Only the site closest to the power stations and the lignite conveyor belts exhibited annual TSP levels (210 ± 97 μg m⁻³) exceeding the European standard (150 μg m⁻³, 80/779/EEC). Concentrations of TSP and almost all elemental components exhibited significant spatial variations; however, the elemental profiles of TSP were quite similar among all sites suggesting that they are affected by similar source types. At all sites, statistical analysis indicated insignificant (P < 0.05) seasonal variation for TSP concentrations. Some elements (Cl, As, Pb, Br, Se, S, Cd) exhibited significantly higher concentrations at certain sites during the cold period suggesting more intense emissions from traffic, domestic heating and other combustion sources. On the contrary, concentrations significantly higher in the warm period were found at other sites mainly for crustal elements (Ti, Mn, K, P, Cr, etc.) suggesting stronger influence from soil resuspension and/or fly ash in the warm months. The most enriched elements against local soil or road dust were S, Cl, Cu, As, Se, Br, Cd and Pb, whereas negligible enrichment was found for Ti, Mn, Mg, Al, Si, P, Cr. At most sites, highest concentrations of TSP and elemental components were associated with low- to moderate-speed winds favoring accumulation of emissions from local sources. Influences from the power generation were likely at those sites located closest to the power plants and mining activities.     

Effect of natural organic matter and green microalga on carboxyl-polyethylene glycol coated CdSe/ZnS quantum dots stability and transformations under freshwater conditions

The influence of pH, ionic strength, presence of humic or alginic acids, extracellular polymeric substances (EPS), or freshwater microalga Chlorella kesslerii on the stability and transformation of carboxyl-PEG-CdSe/ZnS core/shell quantum dots (QDs) in terms of number, hydrodynamic size and fluorescence of individual particles, was studied by fluorescence correlation spectroscopy. Obtained results demonstrated that QDs form stable dispersions at nanomolar concentrations under conditions typical for freshwaters. The presence of 5 or 15 mg C L⁻¹ of humic acid or 50 mg C L⁻¹ EPS did not significantly affect these parameters. In contrast, 5 or 50 mg C L⁻¹ alginate at ionic strength of 10 mM shifted the hydrodynamic radius toward larger values, suggesting a possible capture of QDs by the linear alginate chains. The addition of microalga to the QD dispersions resulted in a slight reduction of the number of QDs and a significant decline in the fluorescence of individual QDs.     

Kinetic study of heterogeneous ozonolysis of alachlor, trifluralin and terbuthylazine adsorbed on silica particles under atmospheric conditions

To better understand the atmospheric behaviour of pesticides, heterogeneous ozonolysis of three herbicides (alachlor, terbuthylazine and trifluralin) adsorbed on silica particles were performed in a flow reactor. The experimental setup used in this study and previously validated (Pflieger et al., 2009) has been specially developed to investigate extremely slow reactivity. The pesticides were adsorbed on particles using a gas/solid adsorption equilibrium, in order to simulate atmospheric conditions. After exposure to ozone concentrations ranging from 5 to 41 ppm during 90 min to 6 h, the kinetics were calculated by comparing the initial and the remaining amounts of pesticides adsorbed on silica particles. This work offers the first results of heterogeneous ozonolysis of alachlor and trifluralin adsorbed on mineral particles. Although alachlor and terbuthylazine were expected to react with ozone, no degradation was observed which leads to a lifetime higher than 8 months towards ozonolysis (for 40 ppb of O₃). A significant degradation of trifluralin adsorbed on silica particles by heterogeneous ozonolysis was observed. The experimental data could be fit by both the Langmuir–Rideal and the Langmuir–Hinshelwood models resulting in atmospheric lifetimes (towards heterogeneous ozonolysis) of 40 and 32 days respectively (for 40 ppb of O₃). These results are discussed and compared to other studies.     

双极电袋复合除尘器的增效减阻效应

为提高现有电袋复合除尘器的除尘效率,降低压力损失,改进清灰效果,设计出一种线管式双极电袋复合除尘器,并对其增效减阻作用和单极电袋复合除尘器进行了对比研究。在硅微粉中位径1.74 μm、过滤风速3 m·min-1、入口粉尘浓度2 500 mg·m-3的实验条件下,双极电袋复合除尘器比单极电袋复合除尘器的粉尘透过率、压力损失分别降低25%、27%以上。为分析双极荷电粉尘的静电凝并增效作用,测定了滤料表面沉积粉尘层的粒度分布,发现单极荷电和双极荷电沉积尘的中位径分别为1.83 μm和1.92 μm,表明双极荷电粉尘具有较好的静电凝并作用,所形成的较粗团聚颗粒物不易透过滤料,使除尘效率提高。为阐明双极荷电粉尘的减阻作用,采用自然堆积法测出双极荷电粉尘的堆积密度小于单极荷电粉尘,证明粉尘双极荷电后会在滤料表面形成较蓬松的粉尘层,这将有助于降低压力损失、提高清灰效果。     

不同烟气流速下线板式电除尘器中磁场效应验证

为进一步提高线板式静电除尘器(ESP)的除尘效果、减少细微颗粒物随烟气的逃逸,将磁场引入其中,模拟了特征颗粒粒径2.5 μm、工作电压50 kV条件下的除尘效率,探究了不同烟气流速下磁场对细微颗粒物捕集性能的影响。结果表明：磁场能有效改变带电颗粒的运动轨迹,大幅度提高细微颗粒物的除尘性能;颗粒在低烟气流速条件下,偏向收尘板的趋势更明显,更有利于颗粒物的捕集;外加磁场在高烟气流速时对除尘效率提升作用更显著,且这一提升幅度随着磁感应强度的增大而不断增大并趋于平缓;随着磁感应强度不断减小,烟气流速降低除尘效率的幅度逐步增大,直至无磁场环境时达到最大。以上研究结果可为磁场在静电除尘器的应用提供参考,对改善ESP的除尘性能具有重要意义。     

含油废水异质结微通道分离机理及实验

石油炼制废水等石化行业含油废水普遍存在油分与悬浮物高度复合、油分乳化且水质剧烈波动等特征,其达标处理成为关乎企业绿色发展与产能拓展的关键因素。针对含油废水分离资源化需求,采用聚二甲基硅氧烷(PDMS)、四氢呋喃(THF)、聚甲基丙烯酸甲酯(PMMA)、固化剂等配制涂敷剂,通过喷涂石英砂制备了改性颗粒,并混合常规石英砂构建了异质结颗粒群,由此开发出异质结微通道沸腾床分离实验装置,考察了其对复合污染乳化废水中污染物的分离效果。结果表明：涂覆改性颗粒的接触角明显增加,且改性颗粒与油滴接触的微界面动态识别过程表明其较原始石英砂的疏油性显著增加;异质结颗粒群经过撕裂、剥离和聚并过程,将乳化液中10 μm以下的细小油滴有效聚结并确保废水油分去除率超过92%。针对油分和悬浮物质量浓度不超过50 000 mg·L⁻¹的实际石化废水,现场10 m³·h⁻¹规模的异质结微通道沸腾床侧线实验结果表明,在常规工况和波动工况条件下,其出水平均油分质量浓度分别为11.4 mg·L⁻¹和18.2 mg·L⁻¹,悬浮物质量浓度则分别降至21.3 mg·L⁻¹和29.1 mg·L⁻¹,且经过20 min反洗后沸腾床分离器满足长期稳定运行要求。     

杭州市城区冬季大雾频发的原因及防治对策

杭州市１９９８年冬季大雾频发,这是气象因素与环境共同作用的结果,加强环境管理,减少大气层中颗粒物的排放,降低大气中颗粒物的浓度,是控制冬季大雾频发的有效途径。     

载带苯并[a]芘的纳米碳／二氧化硅颗粒引起大鼠氧化应激作用的研究

通过人工制备载带B[a]P的纳米碳(C)和纳米二氧化硅(SiO2)颗粒,采用气管滴注染毒方式,以7.5mg·kg-1(以体重计)的染毒剂量急性染毒大鼠,观察染毒24小时后载带B[a]P的纳米C/SiO2颗粒对机体产生氧化应激损伤的联合毒性效应.结果表明,在急性染毒后大鼠外周血中反映机体脂质过氧化损伤程度指标的丙二醛(MDA)含量表现为染毒组较对照组显著增加(p<0.05),表明纳米颗粒诱发机体发生了氧化应激反应.在急性染毒后各组大鼠肺泡灌洗液中谷胱苷肽过氧化物酶(GSH-PX)和超氧化物岐化酶(T-SOD)活力与对照组相比显著增加(p<0.05)(载带B[a]P的纳米SiO2组除外);载带B[a]P的纳米SiO2组肺泡灌洗液中GSH-PX活力与对照组相比无显著差异,而与单纯纳米SiO2组和B[a]P组比较显著降低,推测与抗氧化酶的一过性增高有关;载带B[a]P的纳米C组肺泡灌洗液T-SOD活力与其单纯纳米C组和单纯B[a]P组比较显著增加(p<0.05),由此表明载带B[a]P的复合纳米C/SiO2颗粒在致机体氧化损伤效应方面二者存在一定的协同作用.