Hydration Swelling Research Articles

ESTUDIO DE LA CINÉTICA DE BIOSORCIÓN DE IONES CADMIO (II) EN PECTINA RETICULADA PROVENIENTE DE CÁSCARAS DE NARANJA

Se ha estudiado la cinética de biosorción de cadmio a 20°C en pectina extraída de cáscaras de naranja obteniéndose una capacidad de adsorción en el equilibrio, q ,igual a 99,56 mg/g en el e rango de pH de 4,5-5,5. El material péctico fue extraído mediante hidrólisis ácida (pH: 1,5, temperatura: 90°C, tiempo: 30 min) y reticulado con formaldehído en medio ácido para disminuir su capacidad de hidratación e hinchamiento, así como impedir que se produzca la lixiviación del polisacárido al encontrarse en medio acuoso. Los datos experimentales de cinética de biosorción presentaron mayores coeficientes de correlación para el modelo matemático de pseudo segundo orden. Los parámetros fisicoquímicos: influencia de tamaño de partícula (125 µm - 500 µm y 0 µm - 125 µm) y concentraciones de biosorbente y metal en la solución, fueron evaluados en la cinética de biosorción. La constante de pseudo segundo -4 -1 -1 orden, k = 8,0x10 g.mg min , para el biosorbente con tamaño de partícula 125-500 µm, 2 aumentó en 13,7% cuando la granulometría disminuyó a 0-125 µm, mientras que la q se e incrementó de 140,7 a 148,4 mg/g a las mismas condiciones. La concentración residual de plomo (II) en las soluciones se determinó mediante espectroscopía de absorción atómica. Para el procesamiento de datos y tratamiento estadístico se empleó el programa informático Origin 6.0, ajustándolos mediante regresión no lineal a los modelos de pseudo primer orden y pseudo segundo orden.

Physical and cooking characteristics of some Indian kidney bean (Phaseolus vulgaris L.) cultivars

Pulses are an essential component of our diet especially in developing world, information on their physical properties is needed for designing the machines, while cooking quality is important for consumer acceptance. Four kidney bean cultivars were evaluated for their composition, physical, cooking and textural properties. Protein, ash and carbohydrate contents varied significantly (P⩽0.05) in the range of 22.3–26.7%, 3.5–3.8% and 62.1–65.9%, respectively. Physical properties determined at 10.0% moisture revealed that the length, breadth, thickness and equivalent diameter of seeds varied significantly in the range of 11.45–16.45mm, 6.65–7.00mm, 4.70–6.13mm and 7.31–9.24mm, respectively. Bulk density varied from 0.78 to 0.81g/mL and angle of repose from 15.20° to 18.67°. Hydration capacity and swelling capacity of the seeds varied significantly in the range of 0.12–0.42g/seed and 0.09–0.28mL/seed, respectively. Cooking time of unsoaked seeds differed significantly from 68.67 to 86.67min. Soaking of seeds reduced cooking time by 15.33–30.67min.

Inhibitive effect of potassium methylsiliconate on hydration swelling of montmorillonite

Herein we report on a study on the inhibition effect of potassium methylsiliconate on hydration swelling of montmorillonite. The results of linear swelling tests showed that potassium methylsiliconate exhibits a high performance as an effective shale inhibitor in drilling fluids. The inhibition mechanism was investigated by means of a variety of methods including Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and zeta potential measurements. The high degree of inhibition is a result of the synergy of action of potassium cations and methylsiliconate anions. Methylsiliconate anions form a hydrophobic shell around each montmorillonite particle through the adsorption on the edge sites, thus inhibiting the penetration of water into the interlayer. The potassium ions promote the formation of a less hydratable structure of montmorillonite through cation-exchange interaction.

Physicochemical and release kinetics of natural and retrograded starch of Indian palmyrah shoots

Starch was isolated from the shoots of Indian palmyrah (Borassus flabellifer L.) and it was subjected to the process of retrogradation. The influence of retrogradation on morphological, physicochemical and drug release properties was studied. Retrogradation of native starch changed its morphology from oval, elliptical to crystalline rods. Due to retrogradation there is an increase in amylose content and better hydration capacity, swelling and solubility power. The micromeritic properties of native and retrograded starch uncover its usage as excipients in tablet manufacturing. The retrograded starch showed better powder characteristics to that of native starch. The characteristic peaks for d-glucopyranosyl ring confirms the carbohydrate nature of starch. The TGA data reveals that the retrograded starch shows less bound water to that of native starch during the first decomposition step. In-vitro release study reveals that the retrograded starch attained a better release retardant property and was best explained by Hixson–Crowell model. The result showed that retrograded starches can be used for the preparation of sustained release tablets.

Synthesis of a Biglucoside and Its Application as Montmorillonite Hydration Inhibitor

A biglucoside (BG) was synthesized with glucose and epichlorohydrin as raw materials. The inhibition of BG against montmorillonite swelling was investigated by various methods including montmorillonite linear expansion test, mud ball immersing test, thermogravimetric analysis, and scanning electron microscopy. The results show that the BG has good inhibition ability to the hydration swelling and dispersion of montmorillonite. Under the same condition, the linear expansion ratio of montmorillonite in BG solution is much lower than that of MEG. The particle distribution measurement, thermogravimetric analysis, FT-IR, and scanning electron microscopy results all prove the efficient inhibition of BG.

Inhibitive Effect of Potassium Methylsiliconate on Hydration Swelling of Montmorillonite

Inhibitive Effect of Potassium Methylsiliconate on Hydration Swelling of Montmorillonite

Combined Salt and Temperature Impact on Montmorillonite Hydration

AbstractBentonite is to be used as a sealing material for long-term storage of radioactive waste. During permafrost periods the buffer may freeze, causing the following: montmorillonite dehydration, ice formation, and pressure build-up that may fracture the surrounding rock. No previous study has been done on freezing of bentonite in saline water. Using small and wide angle X-ray scattering, the present study aimed to increase understanding of the combined impact of salt and temperature on the hydration (swelling) of Wyoming montmorillonite. The basal spacing of the Na-montmorillonite was very dependent on the water content, while this was not the case for the Ca-montmorillonite (after reaching 19 Å). The basal spacing of the free-swelling Na-montmorillonite (34–280 Å) was estimated successfully using simple calculations. During freezing of Na-montmorillonite in NaCl solution, both ice and hydrohalite formed (at -50 and -100ºC). At starting concentrations ≥ 1.5 M the basal spacing was not affected by freezing. During freezing of Ca-montmorillonite in CaCl2 solution, ice formed; antarcticite formed only sporadically. The basal spacing of the Ca-montmorillonite at high NaCl concentrations (>1 M) was greater at -50 and -100ºC (18 Å) than at 20ºC (16 Å). The opposite was observed at low concentrations. This change was attributed to small amounts of salts introduced into the montmorillonite interlayer, hence changing the interlayer water properties. The montmorillonite hydration was also temperature dependent; decreasing temperature increased the hydration (as long as no ice was formed) and increasing the temperature decreased the hydration. This was attributed to the temperature impact on the entropy of the hydration reaction. This observation was also reproduced in an experiment up to 90ºC. A small amount of salt in the groundwater was noted to reduce significantly the potential problem of ice formation in bentonite sealings.

Constitutive unsaturated hydro-mechanical model based on modified mixture theory with consideration of hydration swelling

This paper has extended modified mixture theory with consideration of hydration swelling in unsaturated rock. By using non-equilibrium thermodynamics and Biot elasticity, a fully coupled formulation including hydration swelling term is derived. Standard arguments of non-equilibrium thermodynamics are used to derive the Darcy’s law for unsaturated flow. Helmholtz free energy has been used to give the relationship between the stress and pore pressure. The chemical potential of water in pore space and clay platelets has been included in the analysis of water sensitive materials such as shale. Finally, a simple numerical example has been presented for illustrative purpose, the results show that the swelling parameter has a strong influence on stress and strain.

Variability and correlation studies for nutritional and cooking quality traits in chickpea (Cicer arietinumL.)

Thirty genotypes of chickpea were studied to find out the variability for seed characters, nutritional components and seed yield. Interrelationships have also been found for these physico-chemical traits and seed yield to help breeders to find suitable strategy for quality improvement in chickpea. “Kabuli” types had highest mean of 100-seed weight (32.62 g), 100-seed volume (25.1 ml), solid dispersion after cooking (21.4%), hydration capacity (0.33 g/seed), hydration index (1.02), swelling capacity (0.32 ml/seed) over “desi” chickpea groups. However, highest seed yield (2038.9 kg/ha) and tryptophan (0.54 g/100 g protein) were recorded in “desi” medium bold group. “Desi” bold (23.7%) and “kabuli” types (23.3%) were on a par in protein content. Correlation analysis revealed that, irrespective of any group, an increase in 100-seed weight reduced cooking time and increased seed volume, hydration capacity, hydration index, swelling capacity and swelling index while an increase in hydration capacity and swelling capacity significantly decreased seed yield in kabuli chickpea. The study revealed significant variation for physico-chemical, nutritional and cooking quality attributes.

Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials

This study focuses on the impact of landfill high concentration solutions erosion on geosynthetic clay liner (GCL) materials permeability. The permeation tests on the GCL, submerged using different kinds of solutions with different concentrations, were carried out systematically by taking these chemical solutions as permeant liquids. Based on seasonal variations of ion concentrations in Chenjiachong landfill leachate (Wuhan Province), CaCl2, MgCl2, NaCl, and KCl were selected as chemical attack solutions to carry out experimental investigations under three concentrations (50 mM, 100 mM, 200 mM) and soak times (5, 10, and 20 days). The variation law of the GCL hydraulic conductivity under different operating conditions was analyzed. The relationship between GCL hydraulic conductivity, chemical solutions categories, concentrations, and soak times were further discussed. The GCL hydraulic conductivity, when soaked and permeated with high concentration chemical solutions, increases several times or exceeds two orders of magnitude, as compared with the permeation test under normal conditions that used water as the permeant liquid. This reveals that GCL is very susceptible to chemical attack. For four chemical solutions, the chemical attack effect on GCL hydraulic conductivity is CaCl2 > MgCl2 > KCl > NaCl. The impact of soak times on GCL hydraulic conductivity is the cooperative contribution of the liner chemical attack reaction and hydration swelling. A longer soak time results in a more advantageous hydration swelling effect. The chemical attack reaction restrains the hydration swelling of the GCL. Moreover, the GCL hydraulic conductivity exponentially decreases with the increased amplitude of thickness.

Genetic variability and interrelationships of phenological, physicochemical and cooking quality traits in chickpea

Eighty-six chickpea (Cicer arietinum L.) genotypes, including 44 Kabuli type and 42 Desi type, were evaluated for their phenological, physicochemical and cooking quality traits. There were significant differences among the genotypes for days to 50% flowering (34–81 d), days to maturity (85–122 d), number of pods per plant (13–66), number of seeds per plant (15–85), 100-seed weight (10.5–58.6 g), seed yield (561–1852 kg/ha), hydration capacity (0.11–0.68 g water/seed), hydration index (0.80–1.21), swelling capacity (0.11–0.7 ml/seed), seed volume (0.1–0.52 ml/seed) and cooking time (38–125 min). The Desi and Kabuli types of chickpea differed significantly from each other for all the traits except for hydration index, swelling index and cooking time. High heritability coupled with high genetic advance was recorded for 100-seed weight, hydration capacity, swelling capacity and seed volume in both Desi and Kabuli genotypes. Seed size (100-seed weight and seed volume) showed significant positive correlations with hydration capacity and swelling capacity. Cooking time did not show any significant positive or negative correlation with any of the traits studied, including seed size, indicating that other additional factors may be involved in controlling cooking time. The results of this study indicate that it is possible to develop cultivars with faster cooking time in both Kabuli and Desi types and in all seed size categories.

Decrease in Fruit Moisture Content Heralds and Might Launch the Onset of Ripening Processes

It is known that fruit ripening is a genetically programmed event but it is not entirely clear what metabolic cue(s) stimulate the onset of ripening, ethylene action notwithstanding. Here, we examined the conjecture that fruit ripening might be evoked by an autonomously induced decrease in tissue water status. We found decline in water content occurring at the onset of ripening in climacteric and nonclimacteric fruit, suggesting that this phenomenon might be universal. This decline in water content persisted throughout the ripening process in some fruit, whereas in others it reversed during the progression of the ripening process. Applied ethylene also induced a decrease in water content in potato (Solanum tuberosum) tubers. In ethylene-mutant tomato (Solanum lycopersicum) fruit (antisense to1-aminocyclopropane carboxylate synthase), cold-induced decline in water content stimulated onset of ripening processes apparently independently of ethylene action, suggesting cause-and-effect relationship between decreasing water content and onset of ripening. The decline in tissue water content, occurring naturally or induced by ethylene, was strongly correlated with a decrease in hydration (swelling) efficacy of cell wall preparations suggesting that hydration dynamics of cell walls might account for changes in tissue moisture content. Extent of cell wall swelling was, in turn, related to the degree of oxidative cross-linking of wall-bound phenolic acids, suggesting that oxidant-induced wall restructuring might mediate cell wall and, thus, fruit tissue hydration status. We propose that oxidant-induced cell wall remodeling and consequent wall dehydration might evoke stress signaling for the onset of ripening processes. This study suggests that decline in fruit water content is an early event in fruit ripening. This information may be used to gauge fruit maturity for appropriate harvest date and for processing. Control of fruit hydration state might be used to regulate the onset of fruit ripening.

Comparative Evaluation of Zea mays (L.) and Ipomoea batatas (L.) as a Pharmaceutical Excipient

This investigation aims at comparing starches from two grains: Maize (Zea mays) and Sweet potato (Ipomoea batatas) grains. These grains are used mainly as foods and they contain high amount of carbohydrate. The presence of starch in these grains varies and thus their use as pharmaceutical excipients will vary to the degree of their starch functionality. The powders obtained were characterized for their particle size, particle size distribution. The organoleptic and physicochemical characterization such as viscosity, hydration capacity, swelling capacity, moisture sorption capacity, pH, flow rate and porosity, Carr's index and Hausner's ratio were evaluated. Maize starch showed the least Carr's index, Hausner ratio, porosity, moisture sorption capacity and the greatest flow rate. Sweet potato starch showed the highest hydration capacity and swelling capacity. The results obtained showed that between the two starches in relation to their flowability, maize starch possesses the best flow property. Compatibility of Etoricoxib with maize and sweet potato starch was evaluated by IR spectra and found that both Etoricoxib is compatible along with maize and sweet potato starch. This knowledge of starch properties will help to explain the behavior of these starches when used as tablet excipients.

Mild Protein Oxidation Enhanced Hydration and Myofibril Swelling Capacity of Fresh Ground Pork Muscle Packaged in High Oxygen Atmosphere

This study investigated the influence of an oxygen-enriched modified atmosphere packaging (HiOx: 80% O₂/20% CO₂) in comparison with air-permeable polyvinylchloride (PVC) wrapping and partial vacuum (VP: 60%) packaging on the ability of myofibrils to imbibe water during retail display of fresh ground pork at 2 to 4 °C. Both HiOx and PVC muscles after 4 d showed maximum myofibril swelling and A-band dissolution when isolated myofibrils were subjected to a graded series of salt solutions (0.2→0.4 M NaCl with 10-mM sodium pyrophosphate, pH 6.2), while VP samples exhibited no remarkable change. Protein carbonyl content increased substantially from day 0 to 4 in all muscle samples. For HiOx, muscle hydration capacity increased linearly (P < 0.05) during storage up to 14 d, corresponding to protein carbonyl production. No significant changes in hydration properties were noted in VP muscle samples, which also maintained lower levels of protein oxidation, during storage up to 21 d. These results indicated that packaging in modified atmosphere with high levels of oxygen could result in increased protein oxidation but enhanced hydration capacity of fresh meat. Packaging of fresh meat, including ground pork, under an oxygen-enriched atmosphere condition is widely used in the industry to preserve red color of meat. Results from the present study indicate that high oxygen packaging has a discordant effect on fresh ground pork: it enhances hydration but decreases water-binding, and this seems to be caused by increased swelling of muscle fibers due to mild protein oxidation. Hence, it is advisable to employ a water-binding agent in this type of packaging system so as to retain the moisture in stored fresh pork products while maintaining the color stability.

Sustained Release of a Water-Soluble Drug from Directly Compressed Okra Gum Matrix Tablets

Okra gum was evaluated as a controlled-release agent in modified release matrices in comparison with sodium carboxymethylcellulose (NaCMC) using aspirin as the model drug. Tablets were produced by direct compression and the in vitro drug release was assessed under conditions similar to those in the gastrointestinal system for a period of 6 hours. The hydration (swelling) and erosion rates of the okra gum matrix tablets were also studied. Okra gum matrices provided a controlled-release of aspirin and the release rates followed time-independent kinetics. The addition of the tablet excipients, lactose and Avicel, altered the dissolution profile and release kinetics. Okra gum compared favourably with NaCMC and a combination of okra gum and NaCMC resulted in near zero-order release of aspirin from the matrix tablets. The results indicate that okra gum is suitable for the sustained release of water soluble drugs. Keywords: Okra gum, aspirin, matrix tablet, sustained-release The East and Central African Journal of Pharmaceutical Sciences Vol. 9 (2) 2006: pp. 46-51

Molecular Dynamics Simulation of the Energetics and Structure of Layered Double Hydroxides Intercalated with Carboxylic Acids

Molecular dynamics (MD) simulation of the Mg/Al (3:1) layered double hydroxide (LDH), hydrotalcite (HT), containing the monocarboxylic acids formate, acetate, and propanoate as the charge balancing interlayer anions provides new molecular-scale insight into the interlayer structure, hydrogen bonding, and energetics of hydration and consequent swelling of LDH compounds containing organic molecules and biomolecules with carboxylate functional groups. As for citrate−HT (Kumar, P. P.; Kalinichev, A. G.; Kirkpatrick, R. J. J. Phys. Chem. B 2006, 110, 3841), the hydration energy of these systems as a function of water content has no distinct minima, indicating the absence of energetically well-defined structural states with specific water contents. The hydration energies, however, approach the energy of bulk liquid water at lower water contents than for citrate−HT, suggesting that synthesis strategies involving delamination of the hydroxide layers in water are likely to be more successful using starting compoun...

Steeply Dipping Heaving Bedrock, Colorado: Part 3 Environmental Controls and Heaving Processes

This paper examines the environmental processes and mechanisms that govern differential heaving in steeply dipping claystone bedrock near Denver, Colorado. Three potential heave mechanisms and causal processes were evaluated: (1) rebound expansion, from reduced overburden stress; (2) expansive gypsum-crystal precipitation, from oxidation of pyrite; and (3) swelling of clay minerals, from increased ground moisture. First, we documented the effect of short-term changes in overburden stress, atmospheric exposure, and ground moisture on bedrock at various field sites and in laboratory samples. Second, we documented differential heaving episodes in outcrops and at construction and developed sites. We found that unloading and exposure of the bedrock in construction-cut areas are essentially one-time processes that result in drying and desiccation of the near-surface bedrock, with no visible heaving response. In contrast, wetting produces a distinct swelling response in the claystone strata, and it may occur repeatedly as natural precipitation or from lawn irrigation. We documented 2.5 to 7.5 cm (1 to 3 in.) of differential heaving in 24 hours triggered by sudden infiltration of water at the exposed ground surface in outcrops and at construction sites. From these results, we interpret that rebound and pyrite weathering, both of which figure strongly into the long-term geologic evolution of the geologic framework, do not appear to be major heave mechanisms at these excavation depths. Heaving of the claystone takes two forms: (1) hydration swelling of dipping bentonitic beds or zones, and (2) hydration swelling within bedrock blocks accommodated by lateral, thrust-shear movements along pre-existing bedding and fracture planes.

A laboratory study of the self sealing behaviour of a compacted sand–bentonite mixture

Bricks made of compacted sand–bentonite mixture are considered as a possible engineered barrier to isolate high-level radioactive waste at great depth. This work is aimed at investigating some specific effects related to the presence of discontinuities at the contact between the bricks and the excavation wall. In order to do this, an experimental device was developed in the laboratory. The model is made up of a specially designed infiltration cylinder which allows the precise definition of a planar discontinuity between the compacted specimen (a sand–bentonite mixture made up of sand and Kunigel clay from Japan) and a metal wall. During hydration and subsequent specimen swelling, the planar wall is filled, resulting in a healing process. Three total pressure gauges placed along the wall allow a detailed observation of the increase in total stress against the wall. After different periods of swelling, the maximum resistance of the specimen–wall interface to pressure was tested by imposing a pressure increase through a porous stone placed at one end of the cylinder. It was found that the maximum pressure supported by the interface is a function of the initial thickness of the discontinuity and the initial density of the specimen. It was also found that the maximum sustainable pressure depends linearly on the elapsed time. These results are of interest for optimizing water infiltration procedures in either mock-up tests or real disposal systems. If the maximum sustainable pressure at the interface is known, it is possible either to ensure homogeneous hydration of a mass of bricks by respecting the maximum injection pressure limit or to accelerate hydration by forcing water paths along the discontinuities.

Hydration, Swelling, Interlayer Structure, and Hydrogen Bonding in Organolayered Double Hydroxides: Insights from Molecular Dynamics Simulation of Citrate-Intercalated Hydrotalcite

Molecular dynamics (MD) simulation of the Mg/Al (3:1) layered double hydroxide (LDH), hydrotalcite (HT), containing citrate, C6H5O7(3-), as the charge balancing interlayer anion provides new molecular scale insight into the interlayer structure, hydrogen bonding, and energetics of the hydration and consequent swelling of LDH compounds containing organic and biomolecules. Citrate-HT exhibits affinity for water up to very high hydration levels, in contrast to the preferred low hydration states of most LDHs intercalated with small, inorganic anions. This result is consistent with the recent experimental observation of the delamination of lactate-HT. The high water affinity is rationalized in terms of the preference of citrate ion for hydrogen bonds (H-bonds) donated from water molecules rather than from the hydroxyl groups of the metal hydroxide layer and the need to develop an integrated interlayer H-bond network among the citrate ions, water, and -OH groups of the hydroxide layers. The changes in the orientation of citrate molecules with progressive hydration are also intimately related to its preference to accept hydrogen bonds from water.

Hydration Mechanisms and Swelling Behavior of Na-Magadiite

The hydration behavior of synthetic Na-magadiite was studied by combining thermal analyses, water adsorption gravimetry, X-ray diffraction, and infrared spectroscopy under controlled water pressure. Thermal analyses reveal, at least, two distinct water populations. The water adsorption isotherm exhibits two steps at low relative pressure. These steps correspond to three well-defined interlayer distances on the X-ray diffractograms. Infrared spectra recorded under various water pressures show distinct water populations. For relative pressures ≥ 0.20, some water molecules (1665 cm-1) are doubly hydrogen bonded, likely to surface sites, whereas other (1625 cm-1) exhibit a signal similar to that observed for hydrated clay minerals at low relative pressures, suggesting a strong influence of the interlayer cation. For lower relative pressures, a single water population at 1635 cm-1 is observed, suggesting a dual influence of both the interlayer cation and the surface sites.