Sorption Properties of Nonwoven Materials

Varying the composition of fiber blends and the process parameters allows fabricating nonwoven materials with a set spectrum of mechanical and sorption properties. The sorption properties of nonwoven materials (especially from blends of polyester and polypropylene fibres) that have undergone the process stages of basic needle-punching and heat treatment were preserved and the strength properties increased significantly. The sorption capacity decreased after heat treatment of nonwovens which resulted in 30-35% shrinkage, and this was due to a change in the structure of the material.     

Water Sorption Isotherms of Some Building Materials

Abstract:

Moisture is one of the most deteriorating factors of buildings. The masonry moisture content depends on hygroscopic equilibrium between building materials and environment. Moisture sorption (adsorption and desorption) isotherms of 4 sandstones, 2 bricks, and 6 plasters were determined at 15, 25, and 35°C. A modified Oswin equation was used to predict experimental data for water activity in the range between 0.03 and 0.90. The hysteresis phenomenon between adsorption and desorption was observed for all the examined materials and classified at various isotherm types. A correlation of the hysteresis type with the microstructural characteristics of the materials was attempted.     

水泥基孔隙材料中水蒸气的等温吸附与脱附过程

分别采用水胶比为0.3、0.4和0.5的净浆和砂浆,结合文献模型对水泥基材料中水蒸气的等温吸附(脱附)平衡和动力学过程进行了拟合和参数分析。结果表明:多层吸附的Guggenheim-Andersen-de Boer(GAB)模型能够更好地描述水泥基材料中水蒸气的吸附(脱附)平衡以及吸附-脱附滞回,吸附过程的第1层吸附能常数大于脱附过程的,但单层吸附量小于脱附过程的,吸附-脱附滞回在相对湿度为65%~70%时最大;二阶模型最能够描述水泥基材料中水蒸气的吸附(脱附)动力学过程,二阶模型中的初始吸附速率要明显低于初始脱附速率,两者均随相对湿度的增大而显著增加;速率常数在吸附过程中随相对湿度减小而增大,在脱附过程中则随相对湿度减小而减小。     

脱硫废渣流态型填筑材料的研究与应用

采用脱硫石膏、干法脱硫灰、原状粉煤灰等固体废弃物作为主要原材料,掺加少量改性剂,开发出一种新型流态型填筑材料。研究其力学性能、耐久性能,并进行工程应用。结果表明:脱硫废渣流态型填筑材料7 d、28 d抗压强度分别达到0.54 MPa和1.75 MPa,掺入5%改性剂GX-I后,各龄期强度显著提高,且具有较好的水稳定性、抗冻性和抗干缩性能。     

Sorption and Drying Characteristics of Xylite

The wood from which xylite is formed in a long-term process undergoes numous changes while still retaining the character of a hygroscopic porous material. To plan the optimal drying schedule of xylite, the permeability coefficient, diffusion coefficient, and surface emission coefficient were determined. The porosity of xylite is low due to the demolished capillary structure; concurrently with the blocked pits, the permeability of xylite is very low, with a permeability coefficient not higher than 2.12 × 10^?10 m²/Pa s. The capillary flow of free water is insignificant, allowing the diffusion transport of water to prevail. The diffusion coefficient is considerably influenced by the xylite's density. We confirm a significant increase in the bound water diffusion coefficient as the temperature increased (from 5.5 × 10^?12 m²/s at 20°C to 46.3 × 10^?12 m²/s at 40°C), and we predict that the activation energy will increase as the moisture content of xylite decreases (approx. 0.63 to 1.05%/% MC changes). As a consequence of the low surface resistance, the surface emission coefficient barely influences the moisture transport below the fiber saturation point.With an appropriate drying schedule, quality dried xylite can be used for various products as an equivalent substitute for dark-colored, high-density woods like ebony.     

尾矿膏体胶结充填料的微观结构和力学性能研究

以低含硫量尾矿(含硫量约为0.49wt％)为主要成分,同时添加粘结剂(普通硅酸盐水泥)和絮凝剂(聚合氯化铝)制备尾矿膏体胶结充填料,并通过淋滤实验确定了粘结剂和絮凝剂配比.采用XRD、SEM-EDS、BET等分析方法,对膏体胶结充填料的微观结构和力学性能进行了深入研究.结果表明,絮凝剂的添加不仅大大地降低了粘结剂的添加量,而且改善了充填料的力学性能和耐水性.随着粘结剂和絮凝剂添加量的增加,尾矿膏体胶结充填料的比表面积逐渐增大,无侧限抗压强度也随之增大.养护龄期为28 d时,絮凝剂添加量为100 g/L的尾矿膏体胶结充填料的强度均达到2 MPa以上,能够达到满足矿山采空区回填要求.     

Water Vapor Sorption Mechanism and Hygroscopicity of Textile Materials

It is shown that the quasichemical model bears much more information on the supramolecular structure of polymers and the mechanism of sorption of water vapor than the equations borrowed from the theory of adsorption on "rigid" adsorbents. The physical meaning of the constants and limitations of the existing equations formally used for describing sorption in swollen systems are analyzed. The constants of the quasichemical model for sorption of water vapor by different classes of polymers are reported.     

Water Sorption Characteristics of Sugar Impregnated Strawberries

ABSTRACT

Sorption behaviour of fresh and sucrose or glucose impreqnated strawberries in the a, ranqe 0.11-0.90 was determined at 28°C. For both- fresh and osmosed strawberries, the sorption isotherms displaved hysteresis Osmotic treatment produced a complex influence on the fruit behaviour that might be explained in terms of the chemical complexity of the systems, sucrose hydrolysis, sugar supersaturation, kinetic impediment to solute dissolution and crystallization of sugar.     

Water Sorption Characteristics of Sugar Impregnated Strawberries

Sorption behaviour of fresh and sucrose or glucose impreqnated strawberries in the a, ranqe 0.11-0.90 was determined at 28°C. For both- fresh and osmosed strawberries, the sorption isotherms displaved hysteresis Osmotic treatment produced a complex influence on the fruit behaviour that might be explained in terms of the chemical complexity of the systems, sucrose hydrolysis, sugar supersaturation, kinetic impediment to solute dissolution and crystallization of sugar.     

不同类型减水剂对渣土基高流态回填材料性能的影响

相比传统回填材料,渣土基高流态回填材料具有高流态、自流平、自密实等优点,能够有效避免因压实不充分导致的工程问题。然而,渣土基高流态回填材料在使用中存在易沉陷、易泌水等问题,限制了其工程化应用空间。在本文中,选择了聚羧酸减水剂(PCE)、脂肪族减水剂(SAF)、萘系减水剂(FDN)、三聚氰胺减水剂(PMS)四种减水剂来调节渣土基高流态回填材料的用水量和流动度,同时比较了四种减水剂对渣土基高流态回填材料性能的影响。结果表明:在保持相同流动度下,四种减水剂的减水效果从高到低依次为PCE＞SAF＞PMS＞FDN;在经时流动度方面,FDN体系较其他减水剂体系在1 h内具有更好的流动性,四种减水剂体系的流动度保持性从优到劣依次为FDN＞PCE＞PMS＞SAF;四种减水剂均能降低渣土基高流态回填材料的泌水率,缩短渣土基高流态回填材料的凝结时间。     

萘系减水剂对不同种类尾砂充填材料性能的影响

根据焦家金矿现有充填工艺,采用全尾砂替代分级尾砂作为充填集料,对比两种尾砂配制成的尾砂充填材料性能的优异,并且研究不同掺量下萘系高效减水剂对尾砂胶结充填料浆沉降速率、泌水率、流动性及充填体强度的影响.结果表明,与粗尾砂相比,全尾砂作为充填集料制成的全尾砂充填料浆具有更优的流动性能和悬浮性能,不易在管道内发生堵塞,且形成的充填体强度较高.萘系减水剂的加入可以降低尾砂充填料浆的沉降速率,改善浆体悬浮性,明显的增加料浆的流动性能,并且提高硬化后充填体的强度.在萘系减水剂掺量为0.3％时,全尾砂充填材料的各项性能均达到最优值.     

Sorption of Uranium and other Metal Ions on Amine-Functionalized Silica Materials

Sorption of U(VI) and other metal ions on amine-functionalized silica was studied, including aminopropylsilica (APS), 3-(ethylenediamino)propyl silica (ENPS), and 3-[2-(2-aminoethylamino)ethylamino]propyl silica (DIENPS). DIENPS showed the strongest and fastest sorption for U(VI) that can be described by Langmuir isotherm, suggesting U(VI) was sorbed at well-defined and energetically identical sites independent from each other. The sorption efficiency of DIENPS follows the order: U(VI) > Fe(III) > Cu(II) > Pb(II) > Ni(II) > Mg(II) > Sr(II). Results demonstrate that the amine-functionalized silica materials could be used as efficient sorbents to remove uranium and hazardous metal ions in environmental remediation.     

Comparative Study of Sc(III) Sorption onto Carbon-based Materials

The sorption behavior of Sc(III) on different materials including activated carbon (AC), carbon nanotubes (CNTs), graphene oxide (GO), and the chelating resin Chelex 100 was investigated. In general, the sorption of scandium increases with increasing pH. For pH in the range from 2.5 to 5.5, the sorption of Sc(III) onto CNTs, GO, and Chelex 100 is quantitative, whereas a significantly lower amount of scandium ions was retained on AC. The specific amount of Sc(III) adsorbed at pH 2 attained 2.1, 2.9, 36.5, and 37.9 mg g^?1 for AC-COOH, Chelex 100, GO, and CNTs-COOH, respectively. At pH 4, a similar value was obtained for oxidized AC (2.2 mg g^?1), whereas the specific amount adsorbed significantly increased for Chelex (23.4 mg g^?1). The highest values were obtained for GO (39.7 mg g^?1) and oxidized CNTs (42.5 mg g^?1). Better kinetic retention was observed at pH 2 for CNTs and GO, whereas at pH 4 the kinetic behavior of Chelex 100, GO, and CNTs toward Sc(III) was comparable.     

泥浆固化充填材料的制备、微结构及其固化机理的研究

应用复合胶凝剂制备红壤土泥浆充填材料,利用正交实验方法研究了胶凝剂组分对充填体强度的影响,并运用扫描电镜和X射线衍射技术探讨了固化机理.泥浆固化体早期(3d和7d)强度高,后期(28 d)强度稳定增长.其中硫铝酸盐熟料、石灰和硬石膏的总加量对固化体各龄期强度的影响最为显著;水玻璃与烧碱的加量对固化体的早期强度增长有益,但对后期强度有一定的负面影响;矿渣和硅灰对固化体后期抗压强度有明显贡献.对粘土进行离子交换,并在水化过程不同阶段生成C-S-H凝胶与高结晶水含量的钙矾石是复合胶凝剂的固化机理.     

水蒸气等温吸附表征水泥基材料孔隙结构

采用水胶比0.45的净浆、砂浆和混凝土材料,以水蒸气等温吸附法和压汞法为试验方法,以GAB吸附模型为数据分析手段,通过等温吸附曲线、脱附曲线、滞回曲线和孔隙分布,研究使用水蒸气等温吸附法表征水泥基材料的孔隙结构。研究结果表明:骨料对水泥基材料的水蒸气等温吸附曲线几乎没有影响;水泥基材料吸附/脱附滞回曲线出现在整个湿度区域,并在湿度为80%达到最大值;考虑表面吸附层能够提高水蒸气等温吸附计算的孔隙分布精度;水蒸气等温吸附法得到的孔隙率和比表面积与压汞法得到的数值具有正相关性;微孔(r<3nm)中能量不稳定和显孔(r>3nm)中墨水瓶效应是水蒸气等温吸附过程滞回现象的主要原因。     

基于等温吸附的水泥基孔隙材料水分传输过程

讨论了水泥基孔隙材料水分传输的主要机理,建立了孔隙水分传输的多相和简化模型。测试了胶凝材料含有70%矿渣的净浆和砂浆材料的等温吸附与脱附曲线(WVSI),得到了孔隙材料的水分特征曲线。利用水分传输模型对等温吸附实验脱附过程的实验数据进行回归,得到材料的本征渗透率。结果表明:在相对湿度h=60%时,两个模型的回归结果相近;在相对湿度h=18%时,两个模型的回归结果相差较大;简化模型仅适用于中等湿度(h=60%)及以上环境中水分传输过程的描述;基于等温吸附曲线数据,利用模型回归水泥基材料本征渗透率的方法基本可行。     

粒状偕胺肟基蒙脱土纳米吸附材料的制备及铀吸附性能

采用PVC为粘合剂制备粒状偕胺肟基蒙脱土材料,选取粒径范围为0.8-1.7 mm颗粒进行铀吸附试验,考察了实验条件对铀吸附性能的影响,并对其吸附动力学进行了初步探讨。结果表明,当PVC、偕胺肟基蒙脱土、DMF、KCl的质量比为1.0:1.0:6.0:0.4时,粒状材料的成型效果较好。该材料对铀的吸附随时间的增加而增加,并在60 h后达到饱和。当铀初始浓度较大、吸附温度较高、振荡吸附方式时,其铀吸附速率较快;当铀溶液的pH=3时,该材料对铀的平衡吸附量最高。该材料铀的饱和吸附量达10.55 mg/g。动力学研究表明,该粒状吸附剂对铀的吸附控制步骤为液膜扩散控制,吸附速率常数为0.000 5 min-1;20℃下的吸附过程符合Freundlich吸附等温方程,qe=0.2137ce0.772 6。     

Experimental Determination and Modeling of Sorption Isotherms of Erythrina Fusca Lour Bark

The water sorption isotherms of the Erythrina fusca Lour bark at 30 and 40°C were determined over relative humidity ranging from 55 to 85%. The equilibrium moisture content was determined gravimetrically. The moisture sorption isotherms showed that the equilibrium moisture decreases with increase of temperature. Six models were used for to fit the experimental curves of equilibrium humidity. Parameters of each equation were determined by nonlinear regression analysis. The isosteric heat of moisture sorption was calculated using the Claussius-Clapeyron equation.     

Sorption of alkanes on sulfated zirconias—Modeling of TAP response curves

The transient TAP method was applied to investigate sorption phenomena of alkanes on differently prepared sulfated zirconias to provide further explanation of different catalytic performances in the n-butane isomerization. A modified “three-zone” model was developed to describe the experimental results of a single-pulse response experiment. It allowed the extraction of the ratios of adsorption and desorption rate constants. The introduction of a second sorption center in the model is proposed to reproduce the sorption behavior for larger alkanes quantitatively better, especially in the low-temperature region. Moreover, the new model is able to reflect the heterogeneous distribution of active centers, e.g., different acidic sites in combination with surface sulfate species. Temperature dependent measurements have been performed to calculate heats of adsorption for various alkanes. The impact of these values on the catalytic properties is discussed.