镍基催化剂对污泥微波热解制生物气效能的影响

为实现污水污泥减量化、无害化及资源化的目标,在微波热解污水污泥基础上,进行了镍基催化剂对制取生物气效能影响的研究。采用元素分析对污泥元素进行检测,气/质联用分析(GC-MS)和气相色谱(GC)对热解生物气的组成和含量进行测定。实验结果表明,镍基催化剂的添加对微波热解污水污泥制取生物气有较大促进作用。5%添加量与800℃热解终温条件下具有最佳催化效果:生物气中H2、CO产量最大,H2产量由29 g/kg增加到35.8 g/kg,提升23.4%,CO产量由302.7 g/kg增加到383.3 g/kg,提升26.6%;同时催化剂还能提高热能利用效率,降低热解终温,即5%添加量在700℃热解终温时可达到空白800℃时的产气效果;镍基催化剂主要在500~600℃时发挥催化作用,加快了H2和CO的释放。微波热解污泥制取的生物气具有产量大、富含H2与CO等优点,可推动污水污泥的资源化进程。     

磷石膏水热法合成硫酸钙晶须

以磷石膏为原料,二水合硫酸钙、硫酸镁、甘油为添加剂,采用水热法合成硫酸钙晶须,考察了料浆含量、反应温度、反应时间、体系pH等因素对晶须的直径和长径比的影响;并采用SEM技术观察硫酸钙晶须的形貌。实验结果表明,当磷石膏含量2.5%（w）、反应温度130 ℃、反应时间4 h、体系pH 4时,制备得到的硫酸钙晶须长径比为56.24,平均直径为0.17 μm。SEM表征结果显示,硫酸钙晶须形貌规整、分散均匀、直径较小,达百纳米级。     

溴酸钾对二茂铁(Fc)非均相Fenton效能的影响

研究了KBrO3对二茂铁(Fc)非均相Fenton效能的影响,深入考察了KBrO3对体系中Fc溶解、H2O2分解和羟基自由基(·OH)生成的影响。结果表明,KBrO3的加入对不同反应阶段Fc/Fenton体系的效能均有明显的促进作用,初始阶段主要是由于KBrO3对·OH产生的促进作用所致,后期主要是由于KBrO3促进了体系中Fc的溶解,使得体系中溶解态的Fc催化的均相Fenton反应的比例增加,体系中H2O2的分解加快,·OH的表观生成率增加,进而促进了反应的进行。无KBrO3添加,pH=4,MB初始浓度为10 mg/L,Fc的量为1.6×10-3mol/L,[H2O2]/[MB]=3.14时,45 min时,MB的剩余率为9.1%,105 min时为0。当KBrO3的用量为3×10-4mol/L时,反应45 min后MB的去除率即可达到100%。随着KBrO3浓度的增加,其对Fc/Fenton效能的促进作用增强。     

Manganese concentrations in maternal–infant blood and birth weight

Manganese (Mn) is an essential mineral nutrient in mammals. The physiological role of Mn in animal models is well documented, but little is known about the adverse effects of Mn deficiency or overexposure in humans, including pregnancy outcomes such as birth weight. We examined the relationship of the maternal and cord blood Mn levels with birth weight in a cohort of 172 mother–infant pairs born in Shanghai, China. Non-linear spline and quadratic regression models were used to test the hypothesis of an inverted U-shaped association between the Mn levels and birth weight. The median (range) levels of Mn in the maternal and cord blood were 5.38 (2.34–30.37) μg/dL and 7.66 (2.57–34.23) μg/dL, respectively. An inverted U-shaped relationship was observed between maternal Mn and birth weight after adjusting for potential confounders. The birth weight increased with Mn levels up to 4.18 μg/dL, and a slight reduction in weight was observed at higher levels. The cord blood Mn levels were not found to be associated with birth weight. Both lower and higher Mn exposures are associated with lower birth weight, which may influence important developmental parameters; the association of higher Mn levels with lower weight was weak and imprecise.     

人工湿地基质对NH4＋-N吸附性能

为研究建筑废物红砖和工业废物煤渣用作人工湿地脱氮基质的可行性,分别通过静态吸附实验和动态NHf—N去除效果实验进行考察。结果表明,红砖和煤渣对NH4＋-N最大静态吸附量分别为0．2533mg／g和0．0533mg／g,其吸附等温曲线均符合Freundlich型吸附方程,吸附常数分别为0．0419和0．0091;红砖煤渣组合对污水中NH4＋-N平均动态脱除率达到41．18％,高于红砖的37．63％和煤渣的30．92％。     

Hexachlorocyclohexane (HCH) as new Stockholm Convention POPs��a global perspective on the management of Lindane and its waste isomers

Purpose

Hexachlorocyclohexane (HCH) isomers (??-, ??- and ??- (Lindane)) were recently included as new persistent organic pollutants (POPs) in the Stockholm Convention, and therefore, the legacy of HCH and Lindane production became a contemporary topic of global relevance. This article wants to briefly summarise the outcomes of the Stockholm Convention process and make an estimation of the amount of HCH waste generated and dumped in the former Lindane/HCH-producing countries.

Results

In a preliminary assessment, the countries and the respective amount of HCH residues stored and deposited from Lindane production are estimated. Between 4 and 7 million tonnes of wastes of toxic, persistent and bioaccumulative residues (largely consisting of alpha- (approx. 80%) and beta-HCH) are estimated to have been produced and discarded around the globe during 60 years of Lindane production. For approximately 1.9 million tonnes, information is available regarding deposition. Countries are: Austria, Brazil, China, Czech Republic, France, Germany, Hungary, India, Italy, Japan, Macedonia, Nigeria, Poland, Romania, Slovakia, South Africa, Spain, Switzerland, Turkey, The Netherlands, UK, USA, and former USSR. The paper highlights the environmental relevance of deposited HCH wastes and the related POPs?? contaminated sites and provides suggestions for further steps to address the challenge of the legacy of HCH/Lindane production.

Conclusion

It can be expected that most locations where HCH waste was discarded/stockpiled are not secured and that critical environmental impacts are resulting from leaching and volatilisation. As parties to the Stockholm Convention are legally required to take action to stop further POPs pollution, identification and evaluation of such sites are necessary.     

Chlorination of chlortoluron: kinetics, pathways and chloroform formation

Chlortoluron chlorination is studied in the pH range of 3-10 at 25 ± 1 °C. The chlorination kinetics can be well described by a second-order kinetics model, first-order in chlorine and first-order in chlortoluron. The apparent rate constants were determined and found to be minimum at pH 6, maximum at pH 3 and medium at alkaline conditions. The rate constant of each predominant elementary reactions (i.e., the acid-catalyzed reaction of chlortoluron with HOCl, the reaction of chlortoluron with HOCl and the reaction of chlortoluron with OCl⁻) was calculated as 3.12 (± 0.10) × 10⁷ M⁻² h⁻¹, 3.11 (±0.39) × 10² M⁻¹ h⁻¹ and 3.06 (±0.47) × 10³ M⁻¹ h⁻¹, respectively. The main chlortoluron chlorination by-products were identified by gas chromatography-mass spectrometry (GC-MS) with purge-and-trap pretreatment, ultra-performance liquid chromatography-electrospray ionization-MS and GC-electron capture detector. Six volatile disinfection by-products were identified including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone, dichloronitromethane and trichloronitromethane. Degradation pathways of chlortoluron chlorination were then proposed. High concentrations of CF were generated during chlortoluron chlorination, with maximum CF yield at circumneutral pH range in solution.     

高温烧结磷石膏钙渣制备轻质碳酸钙

以磷石膏钙渣为原料,通过高温煅烧,然后经消化、精制、碳化,制成轻质碳酸钙产品.研究结果表明:高温煅烧的最佳温度为 1 000 ℃,最佳煅烧时间为 1.0 h;沉淀反应的初始反应温度为 60 ℃,Ca(OH)2乳液质量浓度为 70 g/L,CO2流量为 1.8 L/h.制备的轻质碳酸钙产品各项指标均达到 HG/T2226...     

降低FCC再生烟气NOx排放助剂的实验室评价

通过采用ACE装置与烟气NOx分析仪器联用的实验室评价方法,可在更接近实际催化裂化反应-再生过程的条件下,评价助剂对再生烟气中NOx的催化转化性能,同时还可考察助剂的加入对催化裂化产品分布的影响。采用该方法对几种降NOx助剂的性能进行了评价,结果表明,在催化剂体系中含有Pt基CO助燃剂的情况下,加入4％的RDNO;助剂后,烟气NOx降低幅度约30％～40％,且催化裂化产品分布基本不受影响。     

A modeling assessment of association between East Asian summer monsoon and fate/outflow of α-HCH in Northeast Asia

Using a dynamic numerical atmospheric transport model for organochlorine pesticides (OCPs), the relationship between the East Asian summer monsoon and the fate of α-hexachlorocyclohexane (α-HCH), a banned OCP, in the atmosphere over Northeast Asia was investigated and assessed. The modeled temporal and spatial patterns and variability of α-HCH air concentrations during the summer months of 2005 revealed a strong link between this chemical in the atmosphere over Northeast Asia and the East Asian summer monsoon. At lower atmospheric levels, easterly and southeasterly winds blowing from relatively cold ocean surface convey α-HCH air concentration from southeast China to northeast China. A monsoon front extending from southeast China to Japan, characterized by a strong wind convergence, carried the air concentration to a high elevation of the atmosphere where it was delivered by southerly monsoon flow to northern China and North Pacific Ocean. This summer monsoon associated northward atmospheric transport caused a reversal of the soil/air exchange from outgassing to net deposition during spring–summer period. The modeled wet deposition fluxes of α-HCH agreed well with the changes in the typical summer monsoon rain bands, designated as Meiyu in China, Changma in Korea, and Baiu in Japan. The major wet deposition flux paralleled with the monsoon front as well as the monsoon rain bands. The temporal change in the fluxes exhibits abrupt northward advances, which is associated with a stepwise northward and northeastward advance of the East Asian summer monsoon. The modeled α-HCH outflow in the atmosphere from China occurs mostly in the summer months and through northeast China, featured strongly by the evolution of the summer month. This study suggests that the East Asian summer monsoon provides a major atmospheric pathway and summer outflows to α-HCH over East Asia.