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 Properties of Vacuum-Dried Strawberries

This work demonstrates the influence of changes in parameters of vacuum drying (temperature and pressure) on the sorption properties of dried strawberries. Fruits were dried at 50 and 70°C under pressures of 4 and 16 kPa. Vacuum drying was also conducted during the first 4 h at 70°C and then the temperature was decreased to 50°C at a pressure of 4 kPa. The other combination included increasing the pressure after the first 4 h from 4 to 16 kPa at a drying temperature of 70°C. Sorption isotherms were determined in the dried strawberries. It was shown that with increasing drying temperatures, there was a notable deterioration in the capacity for absorbing water vapor by the vacuum-dried fruit. On the other hand, the pressure at which vacuum drying proceeded did not significantly affect water vapor absorption. Changing the parameters of vacuum drying—that is, temperature in the range of 50–70°C and pressure in the range of 4–16 kPa—affected the shape and structure of the resultant dried strawberries. The combination of vacuum drying with convective drying also influenced the shape and structure of the dried fruit.     

溶剂浸渍树脂吸着螺旋霉素的动力学模型研究

本文根据颗粒扩散控制机制,认为溶剂萃取过程和固体内表面的吸附同时发生,建立了有限浴条件下溶剂浸溃树脂吸着螺旋霉素的动力学模型.浸渍树脂静态吸附螺旋霉素的计算值与实验值接近,得到螺旋霉素在浸渍树脂内的有效扩散系数为3.7×10~(-12)～29.4×10~(-12)m~2/s.线性吸附等温线条件下的分析解与非线性条件下的数值解比较,表明线性假设能较好地反映实际过程.     

Sorption of Hydrogen Cyanide onto Activated Carbon Cloth Impregnated with Metallo-organic Compounds

Abstract

Activated carbon cloth (ACC) was impregnated with metallo-organic compounds consisting of the following cations: copper, silver, iron, magnesium, and aluminum, and the following anions: acetate, oxalate, tartrate, stearate, and citrate. Impregnation was performed in order to increase the chemisorptive capacity of the cloth for bonding hydrogen cyanide. Characterization of all carbon samples by determining the cation and anion contents of impregnants on the cloth was performed by atomic absorption spectrometry and ion and gas chromatography. The image of the surface composition and morphology of the materials were made by scanning electronic microscopy (SEM) with simultaneous local energy-dispersive analysis (EDS). The surface analysis was also performed by ESCA and XPS techniques. Another purpose of the investigation was to find an optimal mechanism for metallo-organic salts impregnation of ACC. Sorption properties of ACC were examined for hydrogen cyanide and benzene in the gas phase by a standard gravimetric procedure with the use of a Cahn RG electrobalance. It was concluded that samples impregnated with copper(II) tartrate, silver(I) citrate, and iron(III) citrate have an optimal sorption capacity from the point of view of both physical adsorption and chemisorption. The salts of magnesium and aluminum which were used have no affinity for HCN bonding.     

Sorption Properties of Wood Impregnated with Boron Compounds,Sodium Chloride and Glucose

Chemical protection is one of the possible treatment processes that influence the sorption characteristics of wood. In the present research we have investigated the influence of biocides (boric acid, borax) and their concentrations on the sorption characteristic of impregnated wood. For comparison, two other chemicals were included in the research as well (NaCl and glucose). The equilibrium moisture content during the adsorption and desorption process at five levels of relative humidity (?₁ = 20%, ?₂ = 33%, ?₃ = 65%, ?₄ = 88%, and ?₅ = 98%) was monitored. The results showed that impregnation does not influence the wood moisture content of specimens conditioned at low relative air humidity. In the upper hygroscopic region, moisture content is significantly influenced by the concentration and properties of impregnation chemicals. The Guggenheim-Andersen-deBoer (GAB) and Dent models of sorption isotherms was fitted to experimental data to explain the sorption mechanisms in detail.     

The Sorption of Arsenic onto Activated Carbon Impregnated with Metallic Silver and Copper

Abstract

The adsorption of arsenic species in aqueous solutions onto activated carbon with and without chemical impregnation has been studied. The ability of activated carbon to adsorb arsenic depends on the arsenic oxidation state, the pH of the water, and the activity of the metal used for the activated carbon impregnation. The results of the investigations have shown that physical adsorption is effective only for the arsenic(V) species in water. Activated carbon adsorbs arsenic(V) with a saturation adsorption capacity of 0.27 mmol/g. The chemisorption process is effective for both arsenic species. By impregnation of activated carbon by copper, the sorption process for the arsenic(III) species is significantly improved. The saturation adsorption capacity of the activated carbon impregnated by copper is 0.41 and 0.23 mmol/g for the arsenic(III) and arsenic(V) species, respectively. The pH values of the water are important for both sorption processes because of the change in the ionic forms of both arsenic species. The optimal pH range is between 4 and 9, which is a consequence of the apparent affinity between the carbon surface and arsenic species H₃AsO₃ and H₂AsO₄ ^? that are predominant at this pH in water. Equilibrium isotherm analyses were undertaken using Langmuir and Freundlich equations.     

Sorption Of Salicylic And 5-Sulfosalicylic Acids On Silica Gel Impregnated With Aliquat 336

Abstract

Silica gel coated with Aliquat 336 was used as a sorbent for salicylic and sulfosalicylic acid or anions of these acids. It was found that both acids were extracted almost quantitatively if their concentrations in aqueous solutions did not exceed the theoretical capacity of the sorbent. Aliquat 336 extracts a large excess of salicylic acid and only a very small excess of sulfosalicylic acid relative to the amount of quaternary alkylammonium chloride in the sorbent in the form of undissociated molecules of acid. Although the main sorption process of both acids or their anions is an anion-exchange reaction, a physical partition of acids or anions between the two polar phases occurs to a lesser degree.     

Defluoridation of Water Using Zirconium Impregnated Coconut Fiber Carbon

Abstract

In this study the applicability of Zirconium ion impregnated coconut fiber carbon (ZICFC) as an adsorbent for fluoride removal from water was investigated. The dependence of fluoride adsorption on the physicochemical properties includes pH, agitation time, adsorbent dosage, temperature, and the initial concentration of the adsorbate. Maximum defluoridation was obtained at an original pH value of 4.0 with a rapid 93% adsorption being achieved within 10 min of contact with ZICFC. Adsorption data for fluoride onto ZICFC were better correlated to the Langmuir isotherm and pseudo-second order chemical reaction provided the best fit for the experimental data as obtained from kinetic studies. A combination of chemisorption and physisorption processes in hand with intraparticle diffusion, account for the high defluoridation ability of ZICFC, with the thermodynamic parameters indicating an endothermic phenomenon. The fluoride adsorption capacity of ZICFC when compared with those of other commonly used fluoride adsorbents highlights the substantial improvement in fluoride adsorption capacity of coconut fiber carbon on zirconium impregnation.     

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.     

CR型吸附剂对蔗糖和还原糖的吸附特性

本文提出液相色谱技术测定吸附相平衡常数和传质系数参数的估值模型，测定蔗糖还原糖在碱土金属型的ＣＲ型吸附剂上的吸附相平衡常数和总传质系数。结果表明：吸附相平衡常数随温度的升高而下降，吸附剂的选择性也随之下降；液固相间的总传质系数随温度的升高而增大，并随流速的增大而增大。在三种ＣＲ型吸附剂中，ＣＲ－２型吸附剂有较好的传质动力学性能和对还原糖吸附有较大的选择性。     

Sorption of Water Vapors by Armos Fibre

The extremely slow kinetics of absorption of water vapors by Armos fibre can be explained by notions concerning its cross-linked structure, which consists of units of the crystallite type and liquid-crystalline or amorphous crosslinks and has a relatively high density. Sorption of water vapors by the initial Armos fibre not treated with heat is much higher than for the heat-treated fibre. Sorption of water vapors by finished Armos fibres after storage in air for two years varies similar to the change in sorption under the effect of water for two weeks.     

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.     

石墨基浸金属多孔材料微观孔隙结构及其分形特征

为定量描述石墨基浸渍金属材料的孔隙结构特征并研究其对浸渍过程的影响规律,在石墨基多孔材料孔隙形成机理研究的基础上,分析形成浸不透孔洞的原因,并运用分形理论对孔隙结构特征进行了描述. 研究表明,石墨基浸渍金属多孔材料的孔隙结构具有典型的分形特征,其基体、孔隙、浸渍金属分形维数分别为1.80~1.85, 1.55~1.65, 1.50~1.55,未浸渍区域的分形维数为1.42~1.60,孔隙率为17.25%~24.85%. 分形维数反映了孔隙结构的非均质性,与采用压汞实验获得的孔隙率变化规律有较好的一致性,证明可用分形维数表征石墨基浸金属材料的孔隙率.     

Modeling of Sorption Characteristics of Backfill Materials

ABSTRACT

Sorption data analysis was carried out using the Freundlich, Langmuir, and Modified Freundlich isotherms for the uptake of sodium and potassium in an initial concentration range of 10–100 mg/L on backfill materials, viz., bentonite, vermiculite, and soil samples. The soil samples were collected from a shallow land disposal facility at Kalpakkam. The Freundlich isotherm equation is validated as a preferred general mathematical tool for representing the sorption of K⁺ by all the selected backfill materials. The Modified Freundlich isotherm equation is validated as a preferred mathematical tool for representing the sorption of Na⁺ by the soil samples. Since a negative sorption was observed for the uptake of Na⁺ by commercial clay minerals (vermiculite and bentonite clay in the laboratory experiments), sorption analysis could not be carried out using the above-mentioned isotherm equations. Hill plots of the sorption data suggest that in the region of low saturation (10–40 mg/L), sorption of K⁺ by vermiculite is impeded by interaction among sorption sites whereas sorption by soil and bentonite clay is enhanced by interaction among sorption sites. In the region of higher saturation (60–100 mg/L), sorption of K⁺ by all three backfill materials is enhanced by interaction among sorption sites. The Hill plot of the sorption data for Na⁺ by soil suggests that irrespective of Na⁺ concentration, sorption of Na⁺at one exchange site enhances sorption at other exchange sites.     

Effect of Cracks on Water Sorption of Glass

Water sorption on glass surfaces was measured by recording the weight gain of specimens exposed to a controlled-humidity environment. The difference between water sorption on glass surfaces with and without cracks introduced by controlled loading of a disk cutter is described. The increased sorption is explained in terms of condensation within the cracks.     

烟草中水溶性总糖与还原糖的分析研究进展

烟草中的水溶性总糖和还原糖对烟气的香吃味都有良好的作用,并能减少烟气的刺激性,对烟叶品质影响巨大,是决定烟叶品质的重要化学成分,是烟草化学常规分析中的重要项目.就烟草中水溶性总糖与还原糖的几种分析方法,如铜还原-滴定法、比色法、近红外光谱法、连续流动法等进行了综述,铜还原-滴定法是经典的方法,DNS定糖法建立了批量连续测定烟草样品中还原糖、水溶性总糖的方法,该方法具有快速省时、操作简便、试剂消耗少等优点,近红外光谱法是一种方便、高效、无污染、非破坏性、低成本的绿色分析技术,准确度高、操作方便,最新的烟草行业标准采用连续流动仪测定水溶性糖.以期对烟草中水溶性总糖与还原糖的研究具有一定的指导作用.     

Sorption and Desorption of Water Vapour on Starch

Adsorption-desorption isotherms for water vapour on starch have been obtained by the use of quartz fibre spring technique. The specific surface area of starch has been calculated by the BET and HJ methods and the values are in close agreement with each other.     

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。     

单分散氧化硅浓缩悬浮液浸渍Kevlar复合材料的防刺性能

以St(O)ber和离心交换法制备了不同浓度的单分散SiO_2/PEG浓缩悬浮液,并研究了其流变性能和用其浸渍Kevlar编织布所得复合材料的防刺性能.研究发现,所制备浓缩悬浮液在质量浓度低于50%时,具有微弱的剪切增稠效应,增稠所能达到的粘度值随浓度增加缓慢升高,而临界剪切速率降低;当浓度在55%左右时,先是剪切增稠,随后出现轻微的剪切减稀现象;当浓度达到65%时,出现较为显著的剪切增稠效应.所制备复合材料的防刺性能比纯Kevlar编织布有一定的提高,当SiO_2质量百分比浓度在40%～45%区间时,抗刺力可提高到1.66倍左右.