Stability of titania nanoparticles in soil suspensions and transport in saturated homogeneous soil columns

The stability of TiO₂ nanoparticles in soil suspensions and their transport behavior through saturated homogeneous soil columns were studied. The results showed that TiO₂ could remain suspended in soil suspensions even after settling for 10 days. The suspended TiO₂ contents in soil suspensions after 24 h were positively correlated with the dissolved organic carbon and clay content of the soils, but were negatively correlated with ionic strength, pH and zeta potential. In soils containing soil particles of relatively large diameters and lower solution ionic strengths, a significant portion of the TiO₂ (18.8-83.0%) readily passed through the soils columns, while TiO₂ was significantly retained by soils with higher clay contents and salinity. TiO₂ aggregate sizes in the column outflow significantly increased after passing through the soil columns. The estimated transport distances of TiO₂ in some soils ranged from 41.3 to 370 cm, indicating potential environmental risk of TiO₂ nanoparticles to deep soil layers.     

活性炭纤维负载TiO2光催化降解甲醛的影响因素

利用自制光催化气体反应器体系,以活性炭纤维负载TiO2作催化剂,在紫外光照射下模拟降解室内污染气体甲醛,测试了活性炭纤维负载TiO2催化剂的催化活性,探讨了紫外光光强、催化剂的酸度、反应器内湿度及反应时间等控制反应的主要因素对甲醛降解率的影响。结果表明,活性炭纤维与TiO2的协同作用大大提高了对甲醛的降解效果;紫外光强增倍对甲醛降解率有一定提高,但提高幅度仅为11.71%;活性炭纤维用pH=5的TiO2溶胶浸泡做催化剂对甲醛的降解效果最好,60 min内降解率达到68.37%;反应器内的湿度为81%甲醛降解率最高,反应60 min后达82.2%;随着反应时间的延长,甲醛降解率的上升幅度不断减小,最高只能达到94.59%。     

燃油锅炉燃烧过程SO2的生成与排放特征

燃料燃烧过程是大气污染物的重要来源之一，对人体健康、空气质量和气候变化产生非常重要的影响。以62台燃油锅炉（≤10.5 MW）的燃料特性分析数据和SO₂排放实测数据为基础，通过统计分析方法，研究了燃油燃烧过程中燃油硫含量S和过量空气系数α对硫的转化率、SO₂排放因子和排放浓度的影响，获得了基于燃料消耗量、燃料发热量的SO₂排放因子EF_C、EF_H以及SO₂标态折算浓度C′_SO2与硫含量S间的关联式。结果表明，在过量空气系数α＞1的燃油燃烧过程中，EF_C、EF_H、C′_SO2与燃油硫含量S呈现出显著的线性正相关性，而与过量空气系数α无关，其关系式分别为：EF_C=18.86602×S，EF_H=443.78751×S ，C′_SO2＝1 509.28337×S；硫转化率η和基于燃料硫含量的SO₂排放因子EF_S则与燃油硫含量S和过量空气系数α无关，其平均值分别为96.3％和1.93 kg/kg。     

The relationship between economic and carbon footprint changes in EU: The achievements of the EU sustainable consumption and production policy implementation

The Sustainable Consumption and Production policy is a key objective in the renewed European Union (EU) Sustainable Development Strategy (SDS). EU countries implement the targets of Sustainable Consumption and Production policy at different a level. Nevertheless, SDS targets are concerned more with production than consumption side. In addition, analysis of the carbon footprint data, which was supplied by the Global Footprint Network, showed that in all EU countries consumption-based carbon footprint caught-up and exceeded the level of production-based carbon (except Denmark and Estonia) during 1993–2010 period. The significant absolute decoupling in terms of carbon footprint from production-based perspective was observed in Belgium, Denmark, Sweden, Slovakia, Poland, United Kingdom and Germany, meanwhile from consumption-based perspective only in Denmark, Estonia and Germany. Moreover in Spain, Portugal, Italy and Croatia the consumption-based carbon footprint grew faster than economy in general. Results imply that EU should put more focus on consumption side in terms of Sustainable Consumption and Production policy and measures taken. A commitment to reduce the environmental impact from consumption-based perspective should be more addressed covering values and lifestyles.     

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L⁻¹ added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment.     

二氧化氯深度处理垃圾渗滤液研究

利用二氧化氯对生物处理后的垃圾渗滤液进行深度处理，根据废水中有效氯浓度、COD、氨氮及细菌数等参数的分析，初步探讨了不同浓度的二氧化氯在不同处理时间内对垃圾渗滤液的处理效果。结果表明，对于COD初始浓度为450 mg/L左右的水样，二氧化氯的投加浓度达100 mg/L（有效氯），反应时间在50 min时，处理水样可达到同类废水的国家二级排放标准；对于同样条件下的水样，当加入约25 mg/L的二氧化氯时可以杀灭水样中的大肠杆菌，加入浓度达到90 mg/L的二氧化氯时，可以杀灭水样中几乎所有的细菌。     

Carbon accounting of material substitution with biomass: Case studies for Austria investigated with IPCC default and alternative approaches

There is evidence that the replacement of carbon-intensive products with bio-based substitutes (‘material substitution with biomass’) can be highly efficient in reducing greenhouse gas (GHG) emissions. Based on two case studies (CS1/2) for Austria, potential benefits of material substitution in comparison to fuel substitution are analysed. GHG savings are calculated according to default IPCC approaches (Tier 2 method assuming first-order decay) and with more realistic approaches based on distribution functions. In CS1, high savings are achieved by using wood residues for the production of insulating boards instead of energy. The superiority of material substitution is due to the establishment of a long-term carbon storage, the high emission factor of wood in comparison to natural gas and higher efficiencies of gas-fired facilities.The biomass feedstock in CS2 is lignocellulosic ethanol being used for bio-ethylene production (material substitution) or replacing gasoline (fuel substitution). GHG savings are mainly due to lower production emissions of bio-ethylene in comparison to conventional ethylene and significantly lower than in CS1 (per unit of biomass consumed). While CS1 is highly robust to parameter variation, the long-term projections in CS2 are quite speculative.To create adequate incentives for including material substitution in national climate strategies, shortcomings of current default accounting methods must be addressed. Under current methods the GHG savings in both case studies would not (fully) materialize in the national GHG inventory. The main reason is that accounting of wood products is confined to the proportion derived from domestic harvest, whereas imported biomass used for energy is treated as carbon-neutral. Further inadequacies of IPCC default accounting methods include the assumption of exponential decay and the disregard of advanced bio-based products.     

用外加热回转窑生产高纯活性氧化镁回收二氧化碳新工艺

针对当前镁制品生产过程中存在的严重资源浪费和环境污染严重的问题，提出以废弃菱镁矿渣为原料，利用新型外加热回转窑生产高纯氧化镁，并从生产废气中回收食品级液态二氧化碳的新工艺。     

Analysis of Long-term Measurements of Airborne Concentrations of Sulphur Dioxide and SO42- in the Rural United Kingdom

During the last two decades, the importance of sulphur dioxide as a pollutant has moved away from its association with suspended particulate matter, to it being a precursor of SO ₄ ^2- aerosol (acidic e.g. sulphuric acid, or neutralised e.g. ammonium sulphate). Co-located concentration data of sulphur dioxide and SO ₄ ^2- , at nine monitoring sites situated in predominantly rural areas in the United Kingdom, collected over the time period 1979–1995, have been analysed. The time series for both species are discussed for the sites. Further analysis has shown that there is a degree of correlation between sulphur dioxide and SO ₄ ^2- for most of the sites considered. This correlation is of approximately the same level for most of the sites taken independently and together, and in most cases the slopes and intercepts associated with the simple empirical model equations arising from the correlation analysis, are of the same order of magnitude. The implementation of these site-dependent model equations within dispersion models for the prediction of the concentration of airborne sulphate aerosol from knowledge of sulphur dioxide concentration is discussed. Furthermore, the correlation analysis revealed the influence of transported sulphate aerosol on the local concentration, especially during high concentration episodes.     

Single walled carbon nanotube reactivity and cytotoxicity following extended aqueous exposure

Globally carbon nanoparticles are increasingly utilized, yet it is not known if these nanoparticles pose a threat to the environment or human health. This investigation examined ‘as-prepared’, and acid cleaned carbon nanoparticle physicochemical characteristics (by FTIR, TEM, FESEM, UV-VIS and X-ray microanalysis), and whether these characteristics changed following 2.5-7 yr exposure to pH neutral saline or fresh water. To determine if these aqueous aged nanotubes were cytotoxic, these nanotubes were incubated with human epithelial monolayers and analyzed for cell viability (vital staining) and ultrastructural nanoparticle binding/localization (TEM, FESEM). The presence of Ni and Y catalyst, was less damaging to cells than CNT lattice surface oxidation. Extended fresh water storage of oxidized CNTs did not reduce surface reactive groups, nor lessen cell membrane destruction or cell death. However storing oxidized CNTs in saline or NOM significantly reduced CNT-induced cell membrane damage and increased cell survival to control levels.