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.     

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。     

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。     

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

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

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.     

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.     

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。     

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。     

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。     

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.     

Cure Kinetics and Sorption Characteristics of Neoprene-Based Rubber Ferrite Composites

Rubber ferrite composites were prepared by incorporating nickel ferrite in a neoprene rubber matrix. Kinetics of the cure reaction were determined from the rheometric torque values and found to follow first-order kinetics. Analysis of the swelling behavior of the rubber ferrite composites in toluene elucidates the mechanism of solvent penetration and sorption characteristics, and reveals the extent of the physical interaction of the ferrite particles with the neoprene rubber matrix. Mechanical properties of rubber ferrite composites were determined, which support the reinforcing nature of nickel ferrite to the neoprene rubber matrix. These results show that magnetic composites with the required processing safety can be prepared economically by incorporating higher amounts of nickel ferrite in the neoprene rubber matrix.     

Modeling of Sorption Isotherms of Various Kinds of Wood at Different Temperature Conditions

Adsorption and desorption isotherms of pine, spruce, birch, and willow Salix viminalis v. Orm (2-year stem) under three temperature conditions (20, 50, 75°C) in the range of water activity 0.0-0.9 were studied. In order to describe our experimental data, five models were implemented (GAB, Peleg, Chung-Pfost, Oswin, Halsey) and compared. It was found that GAB and Peleg models provide the best fit to the experimental data. On the basis of GAB modeling, the monolayer moisture content for each kind of wood was calculated. Moreover, the hysteresis phenomenon was investigated. The influence of temperature and wood variety on sorption isotherms was also tested.     

Sorption Behavior of Monosodium Titanate and Amorphous Peroxotitanate Materials Under Weakly Acidic Conditions

Inorganic, titanate-based sorbents are tested with respect to adsorption of a variety of sorbates under weakly acidic conditions (pH 3). Specifically, monosodium titanate (MST) and amorphous peroxotitanate (APT) sorption characteristics are initially probed through a screening process consisting of a pair of mixed metal solutions containing a total of 29 sorbates including alkali metals, alkaline earth metals, transition metals, metalloids and nonmetals. MST and APT sorption characteristics are further analyzed individually with chromium(III) and cadmium(II) using a batch method at ambient laboratory temperature, varying concentrations of the sorbents and sorbates and contact times. Maximum sorbate loadings are obtained from the respective adsorption isotherms.     

Sorption Characteristics of Whole Pistachio Nuts (Pistacia Vera L.)

ABSTRACT

Moisture sorption characteristics of whole pistachio nuts were investigated at 10, 20, and 30°C using the static method. The sorption isotherms exhibited hysteresis over the range of 0.10-0.80 water activity which was succesfully interpreted using BET, GAB, Oswin, Smith, Henderson, Chung-Pfost and Halsey mathematical models and from which the BET, GAB and Oswin models were found to give the best fit. Monolayer moisture content of pistachio nuts was determined from BET and GAB equations and the isosteric heat of sorption data were derived using Clausius-Clapeyron equation and presented in graphical form. The information generated can be utilized to optimize the packaging parameters for long term storage of pistachio nuts.     

Moisture Sorption Characteristics of Blanched and Osmotically Treated Apples and Papayas

ABSTRACT

The moisture adsorption and desorpcion characteristics of blanched and osmotically treated apples and papayas and the color of the equilibraced samples were evaluated at 25-C. The sorption isotherms were in agreement with the reported shape for high sugar foodstuffs. A two-way analysis of variance showed that there was not hysteresis for the blanched fruits; however, this phenomenon was present in the osmotically treated samples. Different equations proposed in the literature were used to fit sorption data. The best fit was obtained with GAB model (average mean relative deviation of 9.8%). The apples' white and the papayas' yellow indexes of the equilibrated fruits decreased as a, increased. Browning of the apples varied with the type of isotherm (adsorption or desorption) and with the initial sugar content.     

A Cheap,Fast and Simple Way to Measure Sorption Isotherms of Granular Materials

ABSTRACT

A set-up and a method are described with which sorption isotherms of granular materials can be measured. The set-up uses a recirculating air flow through a fluidized bed of granular materials. The measuring procedure starts with drying the granular material completely. A known amount of water is added to the fluidized bed. At equilibrium between the amount of water in the granular material and the circulating air the air humidity is measured. The method is demonstrated using silica gel.