ENVIRONMENTAL AUDITING: The Functional Unit in the Life Cycle Inventory Analysis of Degreasing Processes in the Metal-Processing Industry

1 and C₂ hydrocarbons (trichloroethane, trichloroethene, tetrachloroethene, dichloromethane). Measures aiming at the reduction of toxic emissions and ozone depletion potential (ODP) may possibly lead to a shift of environmental impacts towards higher energy consumption, emission of waste water, and volatile organic compounds (VOC) with photochemical oxidant creation potential (POCP). The present article concerns itself with a life cycle assessment of the three main degreasing processes in order to compare their integral environmental impacts with one another. This is supplemented by presenting the methodology of the life cycle inventory life cycle inventory analysis (LCI). Generally, the applicability of the established LCI method can be shown quite clearly. However, some difficulties arise, especially at the stage of the goal definition, as the use of the process and the functional unit cannot be pinned down as easily and neatly as for most other products. The definition of the use of the process and the functional unit is not as straightforward as for most products. Among the potential functional units identified are the mass of removed impurities, cleaning time, cleaning work, percentage of purity, throughput of parts, loads, mass or surface and virtual coefficients. The mass of removed impurities turned out to be the most suitable parameter for measuring the technical performance of degreasing processes. The article discusses background, purpose, scope, system boundaries, target group, process tree and representativeness of the present study.     

Deflagration suppression using expanded metal mesh and polymer foams

Expanded metal mesh and polymer foams of appropriate pore or cell size and sufficient surface area per unit volume can suppress deflagrations of gas/vapor–air mixtures. This paper reviews the requirements that have been established for use of these materials in military aircraft fuel tanks. Extensions and generalizations of these requirements for other applications have been developed and incorporated into the 2008 edition of the NFPA 69 Standard for Explosion Prevention. The new NFPA 69 requirements for testing, evaluating, and installing these materials are summarized here along with an explanation of the basis and rationale for these requirements.     

重金属污染水体的高效环保处理技术及研究进展

重金属污染作为影响环境的严重问题之一,不仅因其毒性大、易积累,而且处理后难以回收,对于重金属污染水体的处理技术,大部分仍存在成本高,易造成二次污染等问题。本文综述目前在处理工业废水中重金属离子的多种工艺技术,从环境保护、经济效益角度分析碳黑泥、矿物材料、树脂等的优缺点,提出发展高效环保型的处理技术,包括天然处理剂的应用,如竹炭,壳聚糖,微生物等,为去除重金属、净化水质提供新思路。     

吉林大安油田开发对周边农田土壤影响的研究

按照土壤环境质量标准及背景值对吉林大安油田周边农田土壤进行评价,油田区内土壤中Cu、Pb、As、Cd、Cr＋6等污染物均在二级标准限值内,土壤环境质量良好。油田区内土壤除石油类、硫化物、挥发酚外的其它污染物含量与背景土壤相比有一定差异,但差异不明显,高低相差1倍以内。各监测点各类土壤中石油类、硫化物均比背景土壤偏高,挥发酚差异不明显;钻井井场土壤石油类比背景土壤高76倍,采油井场高4倍,旱田和草地土壤石油类与背景土壤基本相当。     

乌鲁木齐城市道路地面径流中重金属的污染特征分析

采用原子吸收光谱法,对乌鲁木齐市城区3个采样点的两次降雨过程中采集的路面径流进行了重金属Zn、Pb、Cd、Cu和Ni的含量分析.结果表明,道路径流中Zn、Pb、Cd污染较严重,但随着时间的推移,它们在雨水径流中的含量逐渐减少,符合"浓度初期冲刷"规律.     

Biosorption of Cu(II), Zn(II), Ni(II) and Pb(II) ions by cross-linked metal-imprinted chitosans with epichlorohydrin

Cross-linked metal-imprinted chitosan microparticles were prepared from chitosan, using four metals (Cu(II), Zn(II), Ni(II), and Pb(II)) as templates, and epichlorohydrin as the cross-linker. The microparticles were characterized by Fourier transform infrared spectroscopy, solid state (13)C nuclear magnetic resonance spectroscopy, and energy-dispersive X-ray spectroscopy. They were used for comparative biosorption of Cu(II), Zn(II), Ni(II) and Pb(II) ions in an aqueous solution. The results showed that the sorption capacities of Cu(II), Zn(II), Ni(II), and Pb(II) on the templated microparticles increased from 25 to 74%, 13 to 46%, 41 to 57%, and 12 to 43%, respectively, as compared to the microparticles without metal ion templates. The dynamic study showed that the sorption process followed the second-order kinetic equation. Three sorption models, Langmuir, Freundlich, and Dubinin-Radushkevich, were applied to the equilibrium isotherm data. The result showed that the Langmuir isotherm equation best fitted for monolayer sorption processes. Furthermore, the microparticles can be regenerated and reused for the metal removal.     

A barrier to metal movement: Synchrotron study of iron plaque on roots of wetland plants

正A wetland with attractive plants hosting birds and other wildlife is an esthetically pleasing prospect that is gaining popularity as a way of stabilizing or remediating metalcontaminated soils and sediment(Weber and Gagnon,2014;     

Levels of PCDD/Fs and trace elements in superficial soils of Pavia Province (Italy)

Trace elements and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in soils from rural and light-industrialized sites (n=168) of Province of Pavia (Northern Italy). Most of the trace element values fit in typical ranges of concentrations in soils and are similar to the ones reported for rural sites in Italy or sites with no direct anthropogenic impact. Total concentrations of 2,3,7,8 chlorine substituted PCDD/Fs in superficial soils ranged between 24.4 and 1287 pg g(-1) dw (0.5-28.9 pg WHO(98)-TEQ g(-1) dw). The North Eastern part of the Province presented significantly higher levels (p<0.001) than the rest of the Province for As, Cd, Hg, Pb, Zn and PCDD/Fs. While the existence of a defined heavy metal polluting source for this specific site has been suggested, in the case of PCDD/Fs, profiles were not linked to any specific emission source fingerprint. In the whole extension of Pavia Province, OCDD/F dominated the 2,3,7,8 chlorine substituted congener soil pattern, followed by the 1,2,3,4,6,7,8 hepta-CDD/F congener. Principal Component Analysis (PCA) showed that this profile could not be associated to any described PCDD/F emission source fingerprint and was relatively similar to the baseline deposition of sites with no direct impact of PCDD/F emission sources independently of land use.     

Friction spark generation and incendivity of several metal alloys

When metal alloys are used as mechanical equipment or tools in explosive atmospheres, the occurrence and incendivity of mechanically generated sparks as ignition sources should be taken into consideration. The formation of mechanically generated sparks was investigated for seven metals, including Q235 steel, 304 stainless steel, TC4 titanium alloy, 6061 aluminum alloy, H62 bronze alloy, AMAK3 zinc alloy, and AZ31B magnesium alloy. The relationship between the physical-chemical properties and generation and incendivity of friction sparks was evaluated. For 6061 aluminum alloy, H62 bronze alloy, AMAK3 zinc alloy, and AZ31B magnesium alloy, no bright friction sparks were observed in the maximum friction velocity of 12 m/s and maximum surface pressure of 3.75 N/mm², because of low hardness, high thermal conductivity, low melting point, and the absence of carbon content. Ignition testing indicated that nano titanium dust layers with MIEL (minimum ignition energy of dust layer) of 1 mJ were not ignited by friction particles from the four metal alloys. However, bright particles were clearly observed for 304 stainless steel, Q235 steel, and TC4 titanium alloy. Friction sparks at the maximum power densities showed incendivity with micro titanium layers having an MIEL of 17.5–25 mJ but not with PMMA, corn starch, and wood dust having MIELs greater than 1 J. Two different particle burning behaviors with different fragmentation mechanisms during the friction process were determined, namely the micro explosion phenomenon for TC4 titanium alloy and particle burst for Q235 steel. Results indicate that the physical-chemical properties of friction metal rods are useful for preliminary evaluation of spark generation. Powder layers with known MIEL can be considered as indicator testing materials to evaluate spark incendivity.     

High phosphate removal using La(OH)3 loaded chitosan based composites and mechanistic study

Our present study was to prepare a biomass-supported adsorbents with high adsorptive capacity and high selectivity to prevent the accelerated eutrophication in water body. To this end, different metal hydroxide (La, Zr and Fe) first was successfully loaded on chitosan microspheres. Then the quaternary ammonium group with different content was introduced into the adsorbent by polymerization. By comparison of adsorption properties, chitosan-La(OH)₃-quaternary ammonium-20% (CS-La-N-20%) has strong adsorption to phosphate (160 mg/g) by immobilizing nano-sized La(OH)₃ within a quaternary-aminated chitosan and it maintain high adsorption in the presence of salt ions. The pH results indicated that the CS-La-N-20% would effectively sequestrate phosphate over a wide pH range between 3 and 7 without significant La³⁺ leaching. What's more, adsorption capacity on the introduce of positively charged quanternary-aminated groups was significantly higher than that of the unmodified adsorbents at alkaline conditions. The column adsorption capacity reached 1300 bed volumes (BV) when phosphate concentration decreased until 0.5 mg/L at 6 BV/hr. The column adsorption/desorption reveals that no significant capacity loss is observed, indicating excellent stability and repeated use property. Characterizations revealed that phosphate adsorption on CS-La-N-20% through ligand exchange (impregnated nano-La(OH)₃) and electrostatic attraction (positively charged quanternary-aminated groups). All the results suggested that CS-La-N-20% can serve as a promising adsorbent for preferable phosphate removal in realistic application.