Promotional effect of cobalt doping on catalytic performance of cryptomelane-type manganese oxide in toluene oxidation

The cryptomelane-type manganese oxide (OMS-2)-supported Co (xCo/OMS-2; x = 5, 10, and 15 wt.%) catalysts were prepared via a pre-incorporation route. The as-prepared materials were used as catalysts for catalytic oxidation of toluene (2000 ppmV). Physical and chemical properties of the catalysts were measured using the X-ray diffraction (XRD), Fourier transform infrared spectroscopic (FT-IR), scanning electron microscopic (SEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H₂-TPR) techniques. Among all of the catalysts, 10Co/OMS-2 performed the best, with the T_90%, specific reaction rate at 245°C, and turnover frequency at 245°C (TOF_Co) being 245°C, 1.23 × 10⁻³ mol_toluene/(g_cat·sec), and 11.58 × 10⁻³ sec⁻¹ for toluene oxidation at a space velocity of 60,000 mL/(g·hr), respectively. The excellent catalytic performance of 10Co/OMS-2 were due to more oxygen vacancies, enhanced redox ability and oxygen mobility, and strong synergistic effect between Co species and OMS-2 support. Moreover, in the presence of poisoning gases CO₂, SO₂ or NH₃, the activity of 10Co/OMS-2 decreased for the carbonate, sulfate and ammonia species covered the active sites and oxygen vacancies, respectively. After the activation treatment, the catalytic activity was partly recovered. The good low-temperature reducibility of 10Co/OMS-2 could also facilitate the redox process accompanied by the consecutive electron transfer between the adsorbed O₂ and the cobalt or manganese ions. In the oxidation process of toluene, the benzoic and aldehydic intermediates were first generated, which were further oxidized to the benzoate intermediate that were eventually converted into H₂O and CO₂.     

多孔氧化铝层制备的研究

采用预腐蚀与交流腐蚀相结合的方法．研究了多孔氧化铝层的制备工艺．探讨了制备工艺中各步骤的作用以及影响因素。利用扫描电镜，研究了多孔氧化铝层制备工艺对铝箔微观形貌的影响。研究表明．交流腐蚀工艺对铝箔表面微观形貌的改变作用最明显。一次后处理后铝箔表面蚀孔变密．氧化膜的结构更加疏松细腻。二次后处理，调整和热处理等步骤对铝箔表面的微观形貌影响不大。     

Greenhouse impacts of anthropogenic CH4 and N2O emissions in Finland

The Finnish anthropogenic CH₄ emissions in 1990 are estimated to be about 250 Gg, with an uncertainty range extending from 160 to 440 Gg. The most important sources are landfills and animal husbandry. The N₂O emissions, which come mainly from agriculture and the nitric acid industry are about 20 Gg in 1990 (uncertainty range 10–30 Gg). The development of the emissions to the year 2010 is reviewed in two scenarios: the base and the reduction scenarios.According to the base scenario, the Finnish CH₄ emissions will decrease in the near future. Emissions from landfills, energy production, and transportation will decrease because of already decided and partly realized volume and technical changes in these sectors. The average reduction potential of 50%, as assumed in the reduction scenario, is considered achievable.N₂O emissions, on the other hand, are expected to increase as emissions from energy production and transportation will grow due to an increasing use of fluidized bed boilers and catalytic converters in cars. The average reduction potential of 50%, as assumed in the reduction scenario, is optimistic.Anthropogenic CH₄ and N₂O emissions presently cause about 30% of the direct radiative forcing due to Finnish anthropogenic greenhouse gas emissions. This share would be even larger if the indirect impacts of CH₄ were included. The contribution of CH₄ can be controlled due to its relatively short atmospheric lifetime and due to the existing emission reduction potential. Nitrous oxide has a long atmospheric lifetime and its emission control possiblities are limited consequently, the greenhouse impact of N₂O seems to be increasing even if the emissions were limited somehow.     

尿中氚水和总氚的分析测定

用蒸馏-液闪法和氧化蒸馏-液闪法分别测量了氚污染人员尿中的氚水浓度和总氚(氚水和有机氚)浓度。根据72个高于本底水平的尿中氚水和总氚浓度分析比较，认为在氚内污染工作人员的尿中，有机氚与氚水的浓度比值为(5.4 3.7)％。     

铁氧化物复合氧化铝催化臭氧化过程中溴酸盐的生成控制

以市售活性炭、硅藻土和氧化铝小球为载体，考察了负载铁基活性组分对催化臭氧化过程中溴酸盐的控制情况，其中，铁基复合氧化铝小球体现出更好的溴酸盐还原特性和催化剂稳定性，证实催化剂中铁氧化物是溴酸盐得到有效控制的主要活性组分。进一步考察了铁基复合氧化铝小球催化臭氧化处理实际原水过程中对溴酸盐的生成控制，以及反应过程中溶解性有机碳（DOC）的去除情况。结果表明，与单独臭氧化相比，该催化剂既能有效去除水中的溶解性有机物，又能明显抑制溴酸盐的生成，反应50h，其活性并没有明显下降。催化剂失活主要归因于吸附位点数量的下降，可以通过负载铁氧化物来实现催化剂的再生。     

钛基金属氧化物电极的制备及性能

采用聚合物前驱体法制备了Ti/SnO₂-Sb₂O₃电极，再通过恒电流电沉积法制备了 Ti/SnO₂-Sb₂O₃/PbO₂和Ti/SnO₂-Sb₂O₃/MnO₂电极。采用SEM技术对3种金属氧化物电极表面的形貌进行了表征，并分别以3种电极为阳极进行了苯酚的电催化氧化实验。实验结果表明：电解时间为2.5 h时，Ti/SnO₂-Sb₂O₃电极、Ti/SnO₂-Sb₂O₃/PbO₂电极和Ti/SnO₂-Sb₂O₃/MnO₂电极对苯酚的降解率分别为85.9%，83.2%，44.6%；苯酚在3种电极上的电催化氧化反应均遵循一级反应动力学方程；苯酚在Ti/SnO₂-Sb₂O₃ 电极和Ti/SnO₂-Sb₂O₃/PbO₂电极上的反应速率较快，并具有较高的析氧电位；Ti/SnO₂-Sb₂O₃/PbO₂电极具有更好的耐腐蚀性和更长的使用寿命。     

Biogenic palladium prepared by activated sludge microbes for the hexavalent chromium catalytic reduction: Impact of relative biomass

• Pd nanoparticles could be reduced and supported by activated sludge microbes. • The effect of biomass on Pd adsorption by microbes is greater than Pd reduction. • More biomass reduces Pd particle size, which is more dispersed on the cell surface. • When the biomass/Pd add to 6, the catalytic reduction rate of Cr(VI) reaches stable. Palladium, a kind of platinum group metal, owns catalytic capacity for a variety of hydrogenations. In this study, Pd nanoparticles (PdNPs) were generated through enzymatic recovery by microbes of activated sludge at various biomass/Pd, and further used for the Cr(VI) reduction. The results show that biomass had a strong adsorption capacity for Pd(II), which was 17.25 mg Pd/g sludge. The XRD and TEM-EDX results confirmed the existence of PdNPs associated with microbes (bio-Pd). The increase of biomass had little effect on the reduction rate of Pd(II), but it could cause decreasing particle size and shifting location of Pd(0) with the better dispersion degree on the cell surface. In the Cr(VI) reduction experiments, Cr(VI) was first adsorbed on bio-Pd with hydrogen and then reduced using active hydrogen as electron donor. Biomass improved the catalytic activity of PdNPs. When the biomass/Pd (w/w) ratio increased to six or higher, Cr(VI) reduction achieved maximum rate that 50 mg/L of Cr(VI) could be rapidly reduced in one minute.     

金属冶炼进口物料的固体废物鉴别方法

建立了金属冶炼进口物料的固体废物鉴别方法,并利用该方法对海关查扣的3种金属冶炼进口物料进行了固体废物鉴别。鉴别结果显示:物料1、2和3的自然属性分别为砷含量超标铜精矿、锰阳极泥、回转窑氧化锌,产生来源分别为有害物质超标的产品、污染控制设施产生的物质、有意识加工的目标产物;物料1和2属于我国禁止进口的固体废物,物料3不属于固体废物。本文建立的固体废物鉴别方法可行,可为金属冶炼进口物料的固体废物鉴别和监管提供参考。     

模拟阳光下Ag／I-TiO2光催化预处理山核桃加工废水

研究了在模拟太阳光下，采用银修饰的碘掺杂二氧化钛光催化剂（Ag／I—TiO2）对某食品厂山核桃加工废水进行光催化预处理的效果。结合x射线衍射（XRD）、比表面积分析（BET）、紫外-可见漫反射光谱（uV—Vis）的表征结果，来分析催化剂结构对于废水处理效果的影响。探讨了Ag含量、废水初始pH（pHi）和光照时间等因素对化学需氧量（COD）去除及水质可生化性（B／C）提高的影响。并得出适宜的反应参数为：3％Ag含量；pHi为6；光照时间为240min。在最佳条件下，COD去除率45％，废水B／C比由0．17上升到0．31。光催化氧化法能够有效降低山核桃加工废水的COD含量，并达到显著提高废水可生化性的目的。     

TiO2-Cu2O/蒙脱土复合光催化剂的制备与性能

以钠基蒙脱土（MMT）为载体，先采用溶胶-凝胶法将纳米TiO₂引入到MMT层间，再采用化学沉积法将纳米Cu₂O负载在TiO₂/MMT上，制备出TiO₂-Cu₂O/MMT纳米复合光催化剂。采用XRD、SEM、紫外-可见漫反射技术对催化剂进行了表征。以甲基橙为目标污染物，考察了催化剂的光催化性能。表征结果显示：TiO₂与Cu₂O均匀分布在MMT的表面与片层孔隙中;TiO₂-Cu₂O/MMT结合了TiO₂和Cu₂O的特性，拓宽了催化剂的光吸收范围。实验结果表明，在光源为可见光、初始甲基橙质量浓度为20 mg/L、光催化剂加入量为2 g/L的条件下，TiO₂-Cu₂O/MMT纳米复合光催化剂对甲基橙的光催化降解效果明显优于单一负载的Cu₂O/MMT和TiO₂/MMT，大幅提高了催化剂的光催化效率，反应300 min时TiO₂-Cu₂O/MMT对甲基橙溶液的脱色率达到93%。