Electric conduction of ceramic membranes modified with nanoparticles of an inorganic ion exchanger

The article has investigated electric conduction of systems including composite ceramic membranes whose macropores are filled with an ion-exchange component—hydrated with zirconium dioxide and the solution of 1,1-charged electrolyte HCl. It was found that experimental values of electric conduction of membranes are the values of the same order as the electric conduction of an equilibrium solution. Based on potentiometric transport numbers of counterions we computed electric conduction of the ion-exchanger-solution system with the account of not only electrolyte, which is in intraporous solution, but also of counterions localized in the phase of the ion-exchanger. We have proposed a model equation linking electrical conduction of the membrane, the ion-exchanger, and the solution. An assumption was made about the presence in the pores of nano-dimensional channels being formed when introducing the ion-exchanger to the matrix.     

Mobility of Cr(VI) anions in the phase of the amphoteric inorganic ion exchanger

The method of impedance spectroscopy has been used to investigate hydrogel and xerogel of hydrated zirconium dioxide containing Cr(VI) obtained from cation-and anion-substituted forms of an ion exchanger. It is shown that a complex composition of the amphoteric inorganic ion exchanger as well as protonization of its functional groups producing a substantial impact on the value of its electrical conductivity do not make it possible to assess mobility of sorbed ions. Nonetheless, the effective values of internal diffusion mobility of Cr(VI) may be obtained by the kinetic method: diffusion coefficients corresponding to the Cr(VI) → OH constitute 8.57 × 10^?12?6.85 × 10^?11 m²/s or hydrogel and 3.33 × 10^?13?5.45 × 10^?12 m²/s for xerogel depending on the sorbate concentration.     

Performance of porous inorganic membranes in non-osmotic desalination

The supply security of fresh drinking water is decreasing and raising a critical situation for communities worldwide. Inorganic membranes such as alumina and molecular sieve silica have in the past been shown to be highly effective at separating gases and could offer promise as liquid separators due to their high flux and stability. In this work, we develop a range of inorganic membranes with pore size ranging from 0.3 to 500nm and relate this to separation and transport performance. Best separation results were achieved for the silica membrane pressurised to only 7bar, exhibiting a flux of around 1.8kgm(-2)h(-1) and NaCl rejection of 98% with 3.5wt% (seawater-like) feed. Potable water from seawater-like feed was achieved from the membrane in a single stage after regeneration. Conditions such as pressure and temperature were also modified showing performance characteristics and diffusion mechanisms. The non-osmotic set-up for inorganic membranes is therefore a viable technology for desalination.     

Water purification of hydroxocomlexes of heavy metals by electromicrofiltration using inorganic membranes

we have developed the highly effective reagentless method of water purification of hydroxocomplexes of heavy metals by electromicrofiltration on a tubular titanium membrane acting as a cathode. It has been shown that given the location of the anode outside the tube, the current density 37.3–74.6 A/m², pressure 0.1 MPa and the pH of the permeate 11–12, the retention factor of these compounds reaches 99.7% at the specific capacity ～0.15 m³/(m² h).     

Defluorination of water by modified ceramic membranes from clayey minerals

Investigated are main regularities of the process of defluorination of water by nation-made ceramic membranes from clayey minerals, modified by a dynamic layer from aluminum hydroxycompounds and demonstrated its high efficiency. It was proposed to use specified membranes for defluorination of water to MAC standards in drinking water at the initial concentration F^– up to 22.0, Al³⁺—4.0–6.0 mg/dm³ in the additive forming the dynamics, pH_ini 6.5–7, P—1.0 MPa.     

The formation of nanodimensional conducting channels in inorganic composite membranes

By the use of the potentiometric method we determined the dimensions of conducting channels in inorganic membranes modified by nanolayers of the ion-exchange component—hydrated zirconium dioxide (HZD). The dimensions of the channels are within the interval 26–50 nm depending on the degree of filling the pores with the ion-exchanger. Effectively complete absence of the diffusion double electric layer in the pores is shown, therefore composite membranes should be considered as analogues of polymer ion-exchange membranes.     

氯离子对钢筋混凝土结构的侵蚀分析

氯离子侵蚀引起钢筋锈蚀破坏十分突出,是造成钢筋混凝土结构过早破坏的主要原因之一.分析氯离子进入混凝土中的途径、存在形式和氯离子在混凝土中的扩散模式,考虑温度变化、时间变化、湿度变化以及混凝土内部缺陷特征不同对扩散系数的影响,基于Fick第二扩散定律建立了氯离子在混凝土中的扩散模型,并分析了氯离子表面浓度、氯离子临界浓度和有效氯离子扩散系数的影响因素和确定方法,由此建立的模型可供寿命预测参考使用.     

Separation characteristics and the state of water in ultrafiltration charged membranes modified by anionic SAS

We have investigated separation characteristics of experimental charged ultrafiltration membranes based on aromatic polyamide PA-100⁽⁺⁾, PA-100^(?), and membrane PA-10 modified by the solutions of sodium dodecylsulfate of various concentrations. The method of differential scanning calorimetry was used to study the state of the water in initial and modified membranes. It has been found that the treatment of the membranes PA-100⁽⁺⁾ and PA-100^(?) with the solutions of sodium dodecylsulfate results in an increase of their hydrophilicity. Concurrently one can observe minor variations of separation characteristics of the PA-100^(?) membrane. In the case of the PA-10 membrane there occurs hydrophobization of the surface and the porous space, which substantially affects its separation characteristics.     

RCM法测试混凝土氯离子渗透扩散性

本文主要介绍一种新型的混凝土氯离子扩散系数快速测定方法——RCM法。对其工作原理及测试方法进行了评述。并测定了氰离子在一系列不同水灰比的混凝土中的扩散系数，结果表明，混凝土的抗氯离子渗透扩散能力随水灰比的减小而提高。     

Chromate ion adsorption by agricultural by-products modified with dimethyloldihydroxyethylene urea and choline chloride

The use of cellulose-containing agricultural by-products modified with the cross-linking reagent dimethyloldihydroxyethylene urea (DMDHEU) and the quaternary amine, choline chloride, as anion exchange resins, has not been reported. The objective of the present study was to convert the readily available by-products, soybean hulls, sugarcane bagasse and corn stover to functional anion exchange resins using DMDHEU and choline chloride. Optimization of the modification method was achieved using soybean hulls as a substrate. The optimized method was additionally used to modify sugarcane bagasse and corn stover. Adsorption efficiency results with chromate ion showed that modification with both DMDHEU and choline chloride was required for the highest efficiencies. Adsorption capacities of the modified by-products were determined using chromate ion and found to be 1.97, 1.61 and 1.12 mmol/g for sugarcane bagasse, corn stover and soybean hulls, respectively. Competitive adsorption studies were conducted at 10 and 50 times US Environmental Protection Agency (US EPA) limits for arsenic, chromium and selenium in a simulated wastewater at pH 7. The results showed preferential adsorption of chromate ion over arsenate or selenate ion. Estimated product costs for the three resins ranged from $0.88/kg to $0.99/kg, which was considerably lower than the market costs for the two commercial anion exchange resins QA-52 and IRA-400 also used in this study. DMDHEU/choline chloride modification of the three by-products produced an anion exchange resin with a high capacity to adsorb chromate ion singly or competitively in the presence of other anions from aqueous solutions.     

Comparison of the filtration characteristics of organic and inorganic membranes in a membrane-coupled anaerobic bioreactor

Comparison of filtration characteristics of organic and inorganic membranes was made in terms of physicochemical properties of the membrane materials, cake layer formation, backflushing and backfeeding effects in a membrane-coupled anaerobic bioreactor. For the inorganic membrane, struvite (MgNH4PO4 x 6H2O) was found to have accumulated inside the membrane pore and plays a key role in flux decline. For the organic, however, a thick cake layer composed of biomass and struvite formed on the membrane surface, thus causing a major hydraulic resistance. In order to mitigate flux decline for both membranes, backflushing and backfeeding modes were examined. With acidic (pH 2.0) backflushing, the flux was approximately doubled for the organic membrane. However, unexpectedly a negative effect was observed for the inorganic membrane. An alkaline backflushing instead of acidic backflushing gave rise to a flux improvement by a factor of two without any negative effect, even for the inorganic membrane. The backfeeding mode gave rise to a much higher flux compared with the normal mode in both types of membrane, although the flux returned to the same level as that with the normal mode after 6 days for the inorganic membrane. The differences between the two types of membranes were explained by membrane morphology, a ligand exchange reaction as well as a surface charge effect.     

APP改性沥青屋面卷材现场功能调研综述

如今，改性沥青防水卷材已经处于成熟阶段。这种材料可用于各种屋面结构和在极其高温和低温气候条件下使用，因而老化性能是此类材料最重要的性能指标之一。加速老化试验的方法在世界各国不尽相同，试样在加速老化试验箱内的时间可以从4至24个星期不等，温度变化在70～80℃之间。有些采用QUV(石英紫外光)，有些则倾向暴露于氙气中。     

Dechlorination of trichloroethylene by Ni/Fe nanoparticles immobilized in PEG/PVDF and PEG/nylon 66 membranes

The highly reactive bimetallic Fe/Ni nanoparticles immobilized in nylon 66 and PVDF membranes were synthesized and characterized for dechlorination of trichloroethylene (TCE) under anoxic conditions. Scanning electron microscopy (SEM) images and electron probe microanalysis (EPMA) elemental maps showed that the distribution of Fe in nylon 66 membrane was uniform and the intensity of Ni layer was higher than that in PVDF membrane. The particle sizes of bimetallic Fe/Ni in PVDF and nylon 66 membranes were 81 ± 12 and 55 ± 14 nm with the Ni layers of 12 ± 3 and 15 ± 2 nm, respectively. Low agglomeration of immobilized Fe/Ni nanoparticles in nylon 66 membrane was observed, presumably attributed to the more multifunctional chelating groups in membrane. A rapid hydrodechlorination of TCE with ethane as the main end product was observed by the immobilized Fe/Ni nanoparticles. The pseudo-first-order rate constants for TCE dechlorination were 6.44 ± 0.32 and 1.66 ± 0.08 h⁻¹ for nylon 66 and PVDF membranes, respectively. In addition, the efficiency and rate of TCE dechlorination increased upon increasing the mass loading of Ni, ranging between 2.5 and 20 wt%, and then decreased when further increased the Ni loading to 25 wt%. In addition, the stability and longevity of the immobilized Fe/Ni nanoparticles was evaluated by repeatedly injecting TCE into the solutions. A rapid and complete dechlorination of TCE by trace amounts of Fe/Ni nanoparticles was observed after 16 cycles of injection within 10 days, indicating that the immobilization of Fe/Ni nanoparticles in the hydrophilic nylon 66 membrane can retain the longevity and high reactivity of nanoparticles towards TCE dechlorination.     

为提高我国改性沥青卷材的质量建言献策

分析了我国改性沥青防水卷材生产与应用中存在的问题以及与国外相比存在的差距；提出提高我国改性沥青卷材质量的几个建议，涉及胎体、改性材料、粘接方法、质量保证等诸多方面。     

SBS与APP改性沥青防水卷材新国标纵横谈

介绍了SBS与APP改性沥青防水卷材两个新国标GB18242和GB 18243修订的原由,阐述了相关标准从1994版行标到2000版国标再到2008版国标修订版的内容演变过程,并将新国标与欧美标准作了对比,最后提出了贯彻实施新国标的建议.     

奥米无机纤维混凝土性能及工程应用

通过对比实验介绍了两种奥米无机纤维的主要功能,并结合某实际道路工程对纤维的施工工艺等做了详细的说明,为奥米无机纤维的推广应用提供了指导。     

硫酸根离子对带裂缝混凝土中氯离子扩散性能的影响研究

通过单一氯盐溶液、氯盐-硫酸盐混合盐溶液中带裂缝混凝土的浸泡试验,研究了裂缝、硫酸根离子的存在对氯离子在混凝土中扩散性能的影响。试验中先测定混凝土中的总氯离子含量的分布规律,再使用电通量法来评价氯离子扩散性能,然后运用XRD测试方法对混凝土试验前后微观组成的变化进行了分析。结果表明,裂缝能够扩大氯离子扩散系数,离裂缝越近,总氯离子含量越高;硫酸根离子能够降低氯离子在混凝土的扩散性能;XRD图谱所反映的混凝土内部固相组成演变规律同样验证了上述裂缝与硫酸根离子对氯离子扩散系数的影响。     

杂散电流与硫酸盐耦合作用下混凝土氯离子扩散性能研究

配制了两种配合比的混凝土试件,开展了杂散电流单独作用以及杂散电流与硫酸盐耦合作用下的氯离子侵蚀试验。测试了混凝土中水溶性氯离子含量,计算了不同试验条件下的氯离子扩散系数及其时变规律,分析了杂散电流、硫酸盐以及矿物掺合料对混凝土氯离子扩散性能的影响,并通过微观分析进一步阐述了杂散电流与硫酸盐耦合作用对混凝土氯离子扩散性能的影响机理。试验结果表明:杂散电流会通过电场作用促进氯离子向混凝土内部扩散;复掺粉煤灰和矿粉可降低混凝土孔隙率,显著降低氯离子扩散性能;硫酸盐会与水泥水化产物生成钙矾石,短期内对氯离子扩散起抑制作用,长期将增大氯离子扩散性能;杂散电流与硫酸盐长期耦合作用将增大氯离子扩散性能。