Growth mechanisms of multilayered anodic-titanium-oxide nanotube membranes

Anodic titanium oxide TiO₂ nanotube membranes with one, two and three layers have been prepared by the anodic oxidation method via adjusting applied bias during the oxidation process in glycol electrolytes containing 0.25 wt% or 0.50 wt% NH₄F. The morphologies of the as-prepared samples were presented in detail using scanning and transmission electron microscopy. The results indicated that the glycol electrolyte containing 0.25 wt% NH₄F yielded smooth double-walled nanotubes, and their tubes remained open in multilayers; while the glycol electrolyte containing 0.50 wt% NH₄F yielded single-wall nanotubes with ripples, and most of the nanotubes have closed bottoms. In the case of nanotubes with closed bottoms, it was proposed that the newly grown nanotubes on the succeeding layer formed in the gap between the nanotubes of the previous layer. In order to keep track of the growth of the nanotubes, samples were anodized for different periods of time from 1 to 90 min to study their formation process. Growth mechanisms were proposed for different morphologies.     

Kinetics and equilibrium of Cu(II) adsorption onto chemically modified orange peel cellulose biosorbents

A series of orange peel cellulose biosorbents has been specifically prepared by different chemical modifications to understand the mechanism of copper adsorption from chloride solutions. The different biosorbents and raw orange peels were characterized using elemental analysis and Fourier transform infrared spectroscopy (FTIR). The acidic and basic sites and pH of zero charge were also determined. The influences of pH, contact time, initial copper concentration and solid/liquid ratio on copper removal were examined. The maximum adsorption capacity of copper was 1.22 mol/kg, using orange peel esterified by 0.6 mol/L citric acid at 80 °C after 0.1 mol/L NaOH saponification. A comparison of different isotherm models revealed that the combination of Langmuir and Freundlich (L–F) isotherm model fitted the experimental data best. Results indicate that the chemically modified orange peel cellulose can provide an efficient and cost-effective technology for eliminating copper from aqueous solution.     

Enhanced dewatering of waste sludge with microbial flocculant TJ-F1 as a novel conditioner

Microbial flocculant (MBF) TJ-F1 with high flocculating activity was investigated to be used as a novel conditioner for the enhanced dewaterability of the waste sludge from wastewater treatment plant (WWTP). The experimental results showed that TJ-F1 was better than poly(acrylamide [2-(Methacryloyloxy)ethyl]trimethylammonium chloride) (P(AM-DMC)), the most commonly used conditioner in China, in improving the dewaterability of the waste sludge in terms of both the specific resistance in filtration (SRF) and the time to filter (TTF). The key parameters influencing the dewaterability of the waste sludge conditioned by TJ-F1, including the system pH, CaCl₂ concentration and TJ-F1 concentration, were systematically investigated. The favorite pH for the conditioning process was around the neutral. CaCl₂ was found to be a good conditioning aid to TJ-F1. A right dosage of TJ-F1 was decisive for the conditioning process. The optimized conditioning process is that about 0.17% (w/w) TJ-F1 and 1.3% (w/w) CaCl₂ are added into the sludge, and then the system pH was adjusted to 7.5. The compound use of TJ-F1 and P(AM-DMC) was also testified to be feasible in improving the dewaterability of the waste sludge.     

Thermal optimization and supercapacitive application of electrodeposited Fe2O3 thin films

In the present work, thin films of Fe₂O₃ were deposited onto stainless steel substrates by electrodeposition method. All deposited electrodes were annealed for 1 h within the temperature range of 423–673 K with an interval of 50 K. These were further characterized for their structural and morphological measurements by means of X-ray diffraction and scanning electron microscopy techniques, respectively. The supercapacitive characteristics of as-deposited and annealed electrodes were carried out in 1 M KOH electrolyte to confirm the variation in specific capacitance, specific energy, specific power and columbic efficiency, etc., with annealing temperatures.     

Effects of pH on ex-situ biomethanation with hydrogenotrophic methanogens under thermophilic and extreme-thermophilic conditions

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A new slurry-based shaping process for fabricating ceramic green part by selective laser scanning the gelled layer

This paper proposes a new slurry-based shaping process for fabricating ceramic green parts. Slurry was composed of SiO₂ powders (without polymer coating) as a structural element, silica sol and polyvinyl alcohol (PVA) as binders. The new process derived gelling effect from vaporization to generate a uniform gelled layer. By selective laser scanning, an alkali-insoluble 2D pattern was formed on the gelled layer. A green part was built by sequentially layer casting, drying, selective scanning and self-supporting removing. Because gelling occurs uniformly in the whole fresh layer, distortion is minimized. Therefore, this process not only can cast thinner layers to improve the staircase effect but also achieve a better surface by preventing surface pitting induced by laser ablation. No additional design for supports is required since overhangs and undercuts are supported by an inherent gelled support. Compared to other slurry-based processes, the process possesses time-efficiency in slurry preparation and support removal.     

Carbon footprint evaluation at industrial park level: A hybrid life cycle assessment approach

Industrial parks have become the effective strategies for government to promote sustainable economic development due to the following advantages: shared infrastructure and concentrated industrial activities within planned areas. However, due to intensive energy consumption and dependence on fossil fuels, industrial parks have become the main areas for greenhouse gas emissions. Therefore, it is critical to quantify their carbon footprints so that appropriate emission reduction policies can be raised. The objective of this paper is to seek an appropriate method on evaluating the carbon footprint of one industrial park. The tiered hybrid LCA method was selected due to its advantages over other methods. Shenyang Economic and Technological Development Zone (SETDZ), a typical comprehensive industrial park in China, was chosen as a case study park. The results show that the total life cycle carbon footprint of SETDZ was 15.29 Mt, including 6.81 Mt onsite (direct) carbon footprint, 8.47 Mt upstream carbon footprint, and only 3201 t downstream carbon footprint. Analysis from industrial sector perspectives shows that chemical industry and manufacture of general purpose machinery and special purposes machinery sector were the two largest sectors for life cycle carbon footprint. Such a sector analysis may be useful for investigation of appropriate emission reduction policies.     

混凝-粉末活性炭吸附-超滤工艺去除砂滤池反洗水溶解性有机物

通过混凝-粉末活性炭(PAC)吸附-浸没式超滤膜(UF)组合工艺去除砂滤池反洗水(FBWW)中溶解性有机物(DOM),以降低后续回用过程中消毒副产物(DBPs)生成量。试验对3种混凝药剂——聚合硫酸铁(PFS)、三氯化铁(FeCl3)、聚合氯化铝(PACl)处理FBWW的效果进行了比较,探讨其对UV254和水溶性有机物(DOC)的去除效果。结果表明,PFS对有机物去除效果优于PACl和FeCl3;PFS与粉末活性炭混合投加可增加有机物去除率,粉末活性炭为20mg/L,PFS为8mg/L时出水浊度为0.85NTU,UV254和DOC去除率分别为43%和31%;采用混凝-PAC吸附-超滤膜(UF)处理FBWW对UV254和DOC去除率分别达到51%和41%,出水浊度为0.19NTU,UV254为0.031cm-1,DOC为2.76mg/L.此工艺可有效降低反冲洗水中DOM含量,达到重新利用净水厂废水的目标.     

部分苯酚化合物对梨型四膜虫毒性的三维定量构效关系

采用比较分子力场分析描述子表征了133个苯酚类化合物对梨型四膜虫的毒性,从133个化合物中随机选取113个作为训练集建立CoMFA模型,其余的20个化合物作为检验集用于评价模型的预测能力,毒性与立体场和静电场的相互关系用三维等高线图直观显示,结果表明苯环上取代基给电子能力的大小和取代基团体积的大小对化合物的毒性均有直接影响.模型的交互验证相关系数(q2)为0.660,相关系数(R2)和标准偏差分别为0.924和0.215,最佳主成分数PC为8,F统计值为158.960,具有较好的预测能力.     

非分裂完全匹配层边界存储时间域全波形反演

正演波场的储存或重建是制约时间域全波形反演的关键问题,以计算代替存储的常规分裂完全匹配层（PML）边界存储策略可有效减少存储量。但常规分裂PML边界条件所需变量个数多、计算存储量大以及编程复杂。为此,采用非分裂复频移完全匹配层（CFS-NPML）有效边界存储策略重建正演波场实现时间域全波形反演。研究表明：CFS-NPML所需变量个数少,在边界吸收层网格点较少时吸收效果优于常规PML边界条件,波场重建过程中所需存储量少于常规PML边界条件。数值试验表明,该存储策略得到的重建波场与正向传播波场几乎无差别,其全波形反演结果与常规保存波场反演法一致;正演过程中引入并行计算技术未显著增加波场重建导致的额外正演时间。