太湖淤泥用作片状模塑料填料的探讨

为了将太湖淤泥用作片状模塑料复合材料的填料,从淤泥物化性能和结构特征对太湖淤泥进行了表征和分析.对太湖淤泥分别采用XRF分析化学成分,XRD分析矿物成分,颗粒分析仪分析粒径分布,SEM观察淤泥的微观形貌,IR和NMR分析淤泥的结构特征,并分析淤泥的吸油值.结果表明,淤泥的化学成分和矿物组成适合于成为片状模塑料硅酸盐类填料,淤泥的中位径(D50)与片状模塑料的碳酸钙填料近似,淤泥含有有机基团的特征更适宜与片状模塑料树脂均匀结合,并导致其吸油值高于碳酸钙填料.太湖淤泥作为再生资源可用于片状模塑料填料.     

滑石粉对环氧改性有机硅耐高温涂层性能的影响

以滑石粉和玻璃粉为主要填料,以环氧改性有机硅树脂为基料,制备了环氧有机硅耐高温涂层,研究了涂层附着力、冲击强度及耐急热性能,讨论了滑石粉质量分数对涂料性能的影响及影响机理。结果表明:随着滑石粉质量分数的增加,涂层的耐高温性能和力学性能都是先增强后减弱,以35%为最佳;涂层能够经受600、700和800℃的急热冲击;室温冲击强度为5 J;600℃高温处理后附着力由室温的9 MPa增大至32.8 MPa。当滑石粉质量分数过低,玻璃粉质量分数过高时,涂层在高温下发泡膨胀不稳定;当滑石粉质量分数过高,玻璃粉质量分数过低时,涂层在高温下没有足够的玻璃相,不能形成具有一定粘结强度的涂层。     

Sugar-beet pulp pectin gels as biosorbent for heavy metals: Preparation and determination of biosorption and desorption characteristics

The present work reports the feasibility of using sugar-beet pectin gels for the removal of heavy metals from aqueous solutions. Sugar-beet pectin hydro- and xerogels were tested in the batch biosorption and desorption of cadmium, lead and copper. Pectins were successfully extracted and demethylated from the sugar-beet pulp, an agricultural residue, and gelled in the presence of CaCl₂. The stability of the hydro- and xerogel pectin beads made them suitable for biosorption of heavy metals in different conditions. Biosorption data were fitted to the pseudo-second order kinetic model and the Langmuir isotherm model, obtaining the corresponding parameters. Treated and untreated beads were characterized using FTIR and SEM to determine possible binding mechanisms. The main mechanisms involved were ion exchange with calcium of gel structure and chelation or complexation with carboxyl groups. After biosorption, calcium in the gels was substituted by metal cations reorganizing the structure of the gel matrix in a way that was visible using scanning electron microscopy. HNO₃ 0.1 M was the best eluant for the reutilization of the gels and recovered all the adsorbed metal unlike HCl and H₂SO₄. Sugar-beet pectins could be used as an efficient biosorbent for the treatment and recovery of Cu, Pb and Cd from wastewater.     

Influence of treated sewage sludge applications on temporal variations of plant nutrients and heavy metals in a Typic Xerofluvent soil

The objective of this study is to determine influence of Treated Sewage Sludge (TSS) rates as organic matter and nutrient resource on temporal variations of some macronutrients and micronutrients and heavy metals concentrations in a Typic Xerofluvent soil. The experiment was conducted in Menemen Plain, in the Western Anatolia Region of Turkey in 2003–2005. Moist TSS was added to the soil at the rates of 0, 30, 60 and 90 Mg ha⁻¹ on May 1, 2003. Peanut (Arachis hypogaea) was planted as the first crop. On the other hand, mixture of green barley (Hordeum vulgare) and common vetch (Vicia sativa L.) was planted as the second crop. During the experiment, soil samples were taken five times. Increasing TSS applications to this soil resulted in significantly increased concentrations of total N, Cu, Pb and Ni, and available P, K, Ca, Fe, Cu, Zn, Mn concentrations in soil. However, concentrations of available Mg and Na, total Fe, Zn, Mn, Cd, Co and Cr in soil did not significantly change. Micronutrients and heavy metals concentrations in soil were found under threshold values in all sampling periods in this study. Available nutrient concentrations in the soil decreased particularly in the last sampling periods because of plant uptake of nutrients from the applied TSS. It is recommended that 90 Mg ha⁻¹ moist TSS can be added once in a 2-year period for improving nutrient concentrations in Typic Xerofluvent soil.     

Viscoelastic properties of fly ash‐filled natural rubber compounds: Effect of fly ash loading

Fly ash (FA) as a by‐product of power station plants is known to consist of silicon dioxide similar to precipitated silica. The use of FA as filler in natural rubber (NR) was of interest to reinforce and/or reduce product cost. In this article, viscoelastic properties of FA‐filled NR composites with various FA loadings were investigated with the utilization of two different modes of shear flow, namely, oscillatory and steady shear flow. It is found that the addition of FA to NR increases storage modulus (G′) and shear viscosity under both oscillatory and steady shear flow. Moreover, the oscillatory test results exhibit the unexpected increase in magnitude of viscous response with increasing FA loading in FA‐filled NR compounds. The explanation is proposed in terms of the ball‐bearing effect of FA with spherical shape associated with the occurrence of molecular degradation induced by inorganic constituents particularly manganese, iron, and copper in nonrubber component of NR as well as the small amount of heavy metals including iron, copper in FA. An isoprene rubber (IR) containing no nonrubber component was used to validate the proposed explanation. In addition, with the use of Cox‐Merz concept, the results of both complex viscosity under oscillatory shear flow and apparent shear viscosity under steady shear flow can effectively be superimposed in the case of FA‐filled compounds, supporting the promotion of viscous response by FA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

膜生物反应器在污水深度处理中的技术研究

试验研究了以膜生物反应器(MBR)为核心的单元式再生水处理装置(处理能力为30m3/d)在设置成A/O型MBR和A2/O型MBR两种工艺组合和不同运行条件下(如安装BS填料、投加PAC、改变原水条件和增减膜组件数量等)对城市污水的深度处理效果。试验结果表明单元式再生水处理装置具有较高的污泥浓度(MLSS=10000～12000mg/L)和较强的抗冲击负荷(温度、水质变化等)能力。在不同工况下CODcr、BOD5、NH3-N、TN、SS、浊度、色度和粪大肠菌群数等指标均达到或优于国家一级A标准。优化的A2/O型MBR工艺的各项出水指标达到或优于国家一级A标准。BS填料可明显提高生物脱氮效率。     

碱性填料对沥青胶浆性能影响研究

分别进行了消石灰、普硅水泥、活化改性矿粉与普通石灰岩石粉对90#道路石油沥青的性能改善试验,分析填料粉对沥青胶浆流变性能的改善机理,提出适宜于工程应用的填料选用要求。     

Adsorption behaviour of Cu and Cd onto natural bentonite

The adsorption behaviour of Cu²⁺ and Cd²⁺ onto bentonite was studied as a function of temperature under optimized conditions of amount of adsorbent, particle size, pH, concentration of metals, and shaking time. The adsorption patterns of metal ions onto followed the Langmuir, Freundlich and Dubinin-Radushkevich isotherms. This included adsorption isotherms of single-metal solutions at 298-333 K by batch experiments. The thermodynamic parameters such as variation of enthalpy ΔH, variation of entropy ΔS and variation of Gibbs free energy ΔG were calculated from the slope and intercept of lnK_o vs. 1 / T plots. The adsorptions were endothermic reactions. The results suggested that natural bentonite was suitable as sorbent material for the recovery and adsorption of metal ions from aqueous solutions.     

框架结构空心砌块填充墙裂缝的成因与防治措施

针对框架结构中底层空心砌块填充墙严重开裂现象,采用ANSYS程序建立三维有限元模型、进行了墙体荷载作用下结构有限元分析,通过墙体应力分布与墙体裂缝形态的对比,分析了框架结构中底层空心砌块填充墙中裂缝的成因,最后提出了相应的裂缝防治建议。     

Heavy metal mobility in intertidal sediments of the Scheldt estuary: Field monitoring

The current paper aims to check whether the factors affecting metal mobility in intertidal sediments and floodplain soils of the river Scheldt, as identified under controlled greenhouse conditions in previous studies, also play a similar role under variable field conditions. Moreover, we aimed to assess the importance of these factors as a function of sampling time and depth, with respect to the natural variations in water table levels. This field monitoring revealed that the mobility of metals in intertidal sediments of the Scheldt estuary indeed are affected by factors which were identified to affect the metal fate in the upper sediment layer in previous greenhouse experiments. However, the effects were often less pronounced under field conditions. This can be attributed to the lower sampling resolution, the occurrence of interactions between factors, the disturbance of microbial communities during setup of greenhouse experiments and the more moderate environmental conditions in the field, affecting microbial and enzymatic activities. At most of the sampled wetlands, the level of the water table fluctuated only slightly during fall, winter and spring, whereas it decreased substantially during summer, especially at the sites with more sandy sediments. The highest sulphide concentrations were found at the sites where the water table level never decreased considerably. These sulphides primarily suppress the availability of Cd, Cu, Ni and Zn. Organic complexation resulted in the mobilisation of Cu, Ni and Cr. The concentrations of Cd, Ni and Zn in the pore water were affected by Fe/Mn oxide reduction, whereas Cd and Zn concentrations appeared to be also affected by the salinity.