Impact of carbon nanomaterials on the behaviour of 14C-phenanthrene and 14C-benzo-[a] pyrene in soil

The impact of fullerene soot (FS), single-walled (SWCNTs) and multi-walled (MWCNTs) carbon nanotubes on the behaviour of two ¹⁴C-PAHs in sterile soil was investigated. Different concentrations of carbon nanomaterials (0, 0.05, 0.1 and 0.5%) were added to soil, and ¹⁴C-phenanthrene and ¹⁴C-benzo[a]pyrene extractability assessed over 80 d through dichloromethane (DCM) and hydroxypropyl-β-cyclodextrin (HPCD) shake extractions. Total ¹⁴C-PAH activity in soils was determined by combustion, and mineralisation of ¹⁴C-phenanthrene was monitored over 14 d, using a catabolically active pseudomonad inoculum. No significant loss of ¹⁴C-PAH-associated activity from CNM-amended soils was observed over the ‘aging’ period. CNMs had a significant impact on HPCD-extractability of ¹⁴C-PAHS; extractability decreased with increasing CNM concentration. Additionally, ¹⁴C-phenanthrene mineralisation was inhibited by the presence of CNMs at concentrations of ≥0.05%. Differences in overall extents of ¹⁴C-mineralisation were also apparent between CNM types. It is suggested the addition of CNMs to soil can reduce PAH extractability and bioaccessibility, with PAH sorption to CNMs influenced by CNM type and concentration.     

Exposure to moderate concentrations of tropospheric ozone impairs tree stomatal response to carbon dioxide

With rising concentrations of both atmospheric carbon dioxide (CO₂) and tropospheric ozone (O₃), it is important to better understand the interacting effects of these two trace gases on plant physiology affecting land-atmosphere gas exchange. We investigated the effect of growth under elevated CO₂ and O₃, singly and in combination, on the primary short-term stomatal response to CO₂ concentration in paper birch at the Aspen FACE experiment. Leaves from trees grown in elevated CO₂ and/or O₃ exhibited weaker short-term responses of stomatal conductance to both an increase and a decrease in CO₂ concentration from current ambient level. The impairement of the stomatal CO₂ response by O₃ most likely developed progressively over the growing season as assessed by sap flux measurements. Our results suggest that expectations of plant water-savings and reduced stomatal air pollution uptake under rising atmospheric CO₂ may not hold for northern hardwood forests under concurrently rising tropospheric O₃.     

Carbon nanotubes as sorbents in the analysis of pesticides

With increasing public concerns for agrochemicals and their potential movement in the ecosystem, very sensitive, selective and precise methods for the analysis of pesticides are needed. Because these substances are present usually at trace levels, the extraction and preconcentration steps are so far essential for their detection. Discoveries of novel nanomaterials with unique properties have significant impact on their use also in extraction techniques. This overview reports the recent application of carbon nanotubes in the analysis of pesticides. The largest numbers of reported applications of carbon nanotubes concern their role as a sorbent materials in solid-phase extraction and microextraction techniques.     

Modelling the impact of nitrogen deposition, climate change and nutrient limitations on tree carbon sequestration in Europe for the period 1900-2050

We modelled the combined effects of past and expected future changes in climate and nitrogen deposition on tree carbon sequestration by European forests for the period 1900-2050. Two scenarios for deposition (current legislation and maximum technically feasible reductions) and two climate scenarios (no change and SRES A1 scenario) were used. Furthermore, the possible limitation of forest growth by calcium, magnesium, potassium and phosphorus is investigated. The area and age structure of the forests was assumed to stay constant to observations during the period 1970-1990. Under these assumptions, the simulations show that the change in forest growth and carbon sequestration in the past is dominated by changes in nitrogen deposition, while climate change is the major driver for future carbon sequestration. However, its impact is reduced by nitrogen availability. Furthermore, limitations in base cations, especially magnesium, and in phosphorus may significantly affect predicted growth in the future.     

拜耳法赤泥粒径分级预处理的研究

赤泥是从铝土矿中提取氧化铝的过程中产生的工业废渣.分析了拜耳法赤泥的粒径分布,以及主要化学组成和矿物组成在不同粒径赤泥中的变化规律.在此基础上,提出先将赤泥粒径分级预处理,然后根据粗细粒径赤泥的差异分别进行回收利用的思路.研究结果表明,赤泥中粒径大于0.075 mm的粗颗粒以铁、硅、钙为主,实践证明可以通过磁选或重选工...     

有机化纳米粘土基絮凝吸附材料对马铃薯淀粉加工废水的资源化处理

采用物理化学提纯方法制备了有机化纳米粘土基絮凝吸附材料,经过以聚乙二醇2000(PEG-2000)、十六烷基三甲基溴化氨(CTAB)、四丁基氢氧化铵(TBAOH,质量分数25％)和溴化四苯基磷(TPPB)4种表面活性剂对絮凝吸附材料进行有机化修饰,并将其应用于马铃薯淀粉加工废水的资源化处理.实验结果表明,有机化纳米粘土...     

纳米氧化物对钙基材料在高温燃煤中除砷脱硫的促进机理研究

将纳米MgO、Al2O3和ZnO分别添加于CaCO3中制备出钙基纳米氧化物复合吸附剂,进行了燃煤过程中除砷脱硫的实验研究;对燃煤灰渣进行了比表面积及孔隙度分析、X-射线衍射分析和扫描电镜观察,探讨了纳米MgO对CaCO3除砷脱硫的促进机理。结果表明,添加了纳米MgO的复合吸附剂除砷脱硫性能最好,比单一的CaCO3除砷率和脱硫率分别高出了28．73％和37．21％,表现出同时除砷脱硫的良好性能;其促进机理是纳米MgO的加入改变了灰样的微观结构促进了气相间的流动使得灰渣孔隙明显扩大,提高了CaO与As2O3和SO2反应的能力;在除砷的反应中生成了新的物质Ca3Mg2（AsO4）2,在一定程度上抑制了除砷产物的分解。     

Recycling of organic materials and solder from waste printed circuit boards by vacuum pyrolysis-centrifugation coupling technology

Here, we focused on the recycling of waste printed circuit boards (WPCBs) using vacuum pyrolysis-centrifugation coupling technology (VPCT) aiming to obtain valuable feedstock and resolve environmental pollution. The two types of WPCBs were pyrolysed at 600°C for 30 min under vacuum condition. During the pyrolysis process, the solder of WPCBs was separated and recovered when the temperature range was 400-600°C, and the rotating drum was rotated at 1000 rpm for 10 min. The type-A of WPCBs pyrolysed to form an average of 67.91 wt.% residue, 27.84 wt.% oil, and 4.25 wt.% gas; and pyrolysis of the type-B of WPCBs led to an average mass balance of 72.22 wt.% residue, 21.57 wt.% oil, and 6.21 wt.% gas. The GC-MS and FT-IR analyses showed that the two pyrolysis oils consisted mainly of phenols and substituted phenols. The pyrolysis oil can be used for fuel or chemical feedstock for further processing. The recovered solder can be recycled directly and it can also be a good resource of lead and tin for refining. The pyrolysis residues contained various metals, glass fibers and other inorganic materials, which could be recovered after further treatment. The pyrolysis gases consisted mainly of CO, CO(2), CH(4), and H(2), which could be collected and recycled.     

火电厂CO2捕集与封存技术探讨

火电厂CO2减排技术主要包括燃烧前处理、燃烧中减排及燃烧后捕集三类。介绍了IGCC、富氧燃烧、胺吸收法、生物法等CO2捕集与封存技术,分析其存在问题及应用前景。     

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。