Academic literature on the topic 'Capillary water adsorption'

Moisture-harvesting lizards, such as the Australian thorny devil Moloch horridus , have remarkable adaptations for inhabiting arid regions. Their microstructured skin surface, with channels in between overlapping scales, enables them to collect water by capillarity and passively transport it to the mouth for ingestion. We characterized this capillary water transport for live thorny devils using high-speed video analyses. Comparison with preserved specimens showed that live lizards are required for detailed studies of skin water transport. For thorny devils, there was no directionality in cutaneous water transport (unlike Phrynosoma ) as 7 µl water droplets applied to the skin were transported radially over more than 9.2 mm. We calculated the total capillary volume as 5.76 µl cm −2 (dorsal) and 4.45 µl cm −2 (ventral), which is reduced to 50% filling by the time transportation ceases. Using micro-computed tomography and scanning electron microscopy of shed skin to investigate capillary morphology, we found that the channels are hierarchically structured as a large channel between the scales that is sub-divided by protrusions into smaller sub-capillaries. The large channel quickly absorbs water whereas the sub-capillary structure extends the transport distance by about 39% and potentially reduces the water volume required for drinking. An adapted dynamics function, which closely reflects the channel morphology, includes that ecological role.

Summary Significant mass transfer between the steam and water phases makes it difficult to measure steam/water capillary pressure using routine methods. Because of the difficulties, few experimental data are available. A formula was derived on the basis of the Kelvin equation to calculate steam/water capillary pressure. The water-phase temperatures and pressures measured with a steady-state flow method were used to perform the calculations. The preliminary results of both drainage and imbibition steam/water capillary pressure were obtained. It was confirmed that the lowering of vapor pressure was small, but the capillary pressure was significant for the system studied. This experimental observation is consistent with thermodynamic analysis. Introduction It has often been assumed in steam numerical simulators that steam/water flow in porous media can be represented as gas (air or nitrogen)/water flow. In recent years, attention has been paid to the measurements of steam/water relative permeability.1–6 Horne et al.2 found that there were significant differences between nitrogen/water and steam/water relative permeabilities. Accordingly, there may also be significant differences between nitrogen/water and steam/water capillary pressures. To compare the two, reliable experimental data for steam/water capillary pressure are required. However, there have been few direct measurements of steam/water capillary pressure from steam/water flow experiments. Less attention has been paid to the measurements of steam/water capillary pressure, even though capillary pressure is of equal significance to relative permeability and plays an important role in controlling fluid distributions and recoveries in petroleum and geothermal reservoirs. Tsypkin and Calore7 developed a mathematical model of steam/water phase transition. They found that steam/water capillary pressure could play a stabilizing role for the vaporization front, causing a sharp zone to develop. Urmeneta et al.8 also studied the role of capillary forces in fractured reservoirs and found that capillary pressure tended to keep the vapor phase in the fracture and the liquid phase in the matrix. Using the adsorption data of Horne et al.9 for rock samples from The Geysers geothermal field, Sta. Maria and Pingol10 inferred the values of steam/water capillary pressure. They found that the steam/water capillary pressure ranged from 0 to 86,000 psi. Persoff and Hulen11 also inferred the capillary pressure from adsorption data of The Geysers rock samples and found that the steam/water capillary pressure ranged from 0 to approximately 28,000 psi. The graywacke core samples used by Persoff and Hulen11 were similar to those used by Sta. Maria and Pingol.10 The porosity was approximately 2%, and the permeability was in the nanodarcy (nd) range. The adsorption/desorption tests that have been used to infer steam/water capillary pressure are static processes in which there is no steam/water flow. In actual petroleum and geothermal reservoirs, however, capillary pressure plays an important role while steam and water flow simultaneously through the rocks. Hence, the process governing an adsorption test may not represent the mechanisms under actual fluid-flow conditions in those reservoirs. The steam/water capillary pressures from adsorption data may or may not be the same as those measured with a dynamic method in which steam and water are flowing. Very strict sealing requirements must be achieved for long periods of time during the adsorption tests, which is very difficult, especially at high temperatures. These disadvantages may be overcome by using a steady-state flow method. The main purpose of this paper was to develop a method to calculate steam/water capillary pressure using data from the experiments of steady-state steam/water flow. An X-ray computerized tomography (CT) technique was used to measure the water saturation and its distribution in the core sample. The effect of temperature on CT values used to calculate the water saturations was studied experimentally. Method Capillary Pressure. Using the Kelvin equation, steam/water capillary pressure can be calculated from the experimental data of liquid-phase pressure, temperature, and related parameters. The procedure is described in this section. The relative pressure (pv/p0) is used to characterize the capillary condensation on curved surfaces. Kelvin established the relationship between the relative pressure and the curvature of the interface, along with other properties of the fluid and the substrate. In a circular capillary tube with a radius of r, the relative pressure can be calculated using the Kelvin equation as follows:Equation 1 where p0=the vapor pressure when the vapor/liquid interface is flat; pv=the vapor pressure in a capillary tube of radius r when the vapor/liquid interface is curved; s=the interfacial tension and ?=the contact angle measured through the liquid phase; R=the gas constant; T=the absolute temperature; Mw=the molecular weight of liquid; and ?w=the density of liquid. The Kelvin equation assumes that (1) all adsorption is caused only by capillary condensation, (2) adsorbate density is equal to bulk liquid density, and (3) the validity is unimpaired at low values of r. The capillary pressure, Pc, in a circular capillary tube is also determined by the interface curvature and fluid and substrate properties and can be calculated asEquation 2 Combining Eqs. 1 and 2,Equation 3 Capillary pressure is defined as the pressure difference between the nonwetting and the wetting phases and is expressed as follows:Equation 4

Unfrozen water retention curve (UWRC) defines the relationship between temperature and unfrozen water content in frozen soils. Although many models have been proposed for the UWRC, these existing models cannot predict UWRC well over a wide temperatures range. In this study, a new UWRC model is proposed with explicit considerations of both capillarity and adsorption. In this model, capillarity is considered dominating when the freezing of soil pore water at higher temperatures (above -2oC), whereas the effects of adsorption pronounce at temperatures below -2oC. Moreover, effects of void ratio on the freezing of capillary water are incorporated. The proposed model was applied to predict UWRCs of silt and clay at different initial void ratios over a wide temperature range (from -50 to 0oC). Predicted results by this new model are compared with predictions by three well-known existing models. The new model can capture the density effects on UWRC. Moreover, the new model can predict better UWRC over a wide temperature range since it explicitly considers both effects of capillarity and adsorption.

AbstractSoil sorptivity is considered a key parameter describing early stages of water (rain) infiltration into a relatively dry soil and it is related to build-up complexity of the capillary system and soil wettability (contact angles of soil pore walls). During the last decade an increasing water repellency of sandy soils under pine forest and grassland vegetation has been frequently observed at Mlaky II location in SW Slovakia. The dry seasons result in uneven wetting of soil and up to hundredfold decrease in soil sorptivity in these vegetated soil as compared to reference sandy material, which was out of the reach of ambient vegetation and therefore readily wettable. As far as water binding to low moisture soils is governed by adsorption processes, we hypothesized that soil water repellency detected by water drop penetration test and by index of water repellency should also influence the water vapour adsorption parameters (monolayer water content, Wm, specific surface area, A, maximum adsorption water, Wa, maximum hygroscopic water MH, fractal dimension, DS and adsorption energies, Ea) derived from BET model of adsorption isotherms. We found however, that the connection of these parameters to water repellency level is difficult to interpret; nevertheless the centres with higher adsorption energy prevailed evidently in wettable materials. The water repellent forest and grassland soils reached less than 80% of the adsorption energy measured on wettable reference material. To get more conclusive results, which would not be influenced by small but still present variability of field materials, commercially available homogeneous siliceous sand was artificially hydrophobized and studied in the same way, as were the field materials. This extremely water repellent material had two-times lower surface area, very low fractal dimension (close to 2) and substantially lower adsorption energy as compared to the same siliceous sand when not hydrophobized.

Differential heats of adsorption have been measured calorimetrically for benzene and n-hexane on AlPO4-5. Adsorption isotherms have been determined for benzene, n-hexane and H2O. The heat of adsorption for benzene on AlPO4-5 was found to be less than the heat of adsorption for n-hexane. Isotherms of all adsorbates investigated exhibited hysteresis loops. The hydrophilicity of AlPO4-5 is explained by capillary condensation and/or coordinately bonded water.

Environmental contextAmmonium ion, an inorganic pollutant in agricultural land, can induce eutrophication, impacting on water quality. We investigate the adsorption of ammonium ion on surfactant-modified alumina and demonstrate highly efficient removal of ammonium ions by the alumina from two agricultural water samples. Adsorption mechanisms are also proposed based on adsorption isotherms, surface modification and the change in surface charge. AbstractThe adsorptive removal of ammonium ions (NH4+) from aqueous solution using surfactant-modified alumina (SMA) was investigated. The optimum NH4+ adsorption removal conditions on SMA were systematically studied and found to be pH 4, contact time 180min, adsorbent dosage 30mgmL–1 and ionic strength 1mM NaCl. The equilibrium concentration of NH4+ was measured by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) and spectrophotometry. Surface modification of α-Al2O3 with the anionic surfactant sodium dodecyl sulfate (SDS) at high salt concentration induced a significant increase of removal efficiency. The change in surface charge and surface modification of α-Al2O3 by pre-adsorption of SDS and subsequent adsorption of NH4+ were evaluated by zeta potential measurements and Fourier-transform infrared spectroscopy. Under optimum adsorption conditions, NH4+ removal from two agricultural water samples achieved very high removal efficiencies of 99.5 and 96.5%. The adsorption of NH4+ onto SMA increases with decreasing NaCl concentration because desorption of SDS from the α-Al2O3 surface is minimised. Experimental results of NH4+–SMA adsorption isotherms at different ionic strengths can be represented well by a two-step adsorption model. Based on adsorption isotherms, surface charge effect and surface modification, we suggest that the adsorption mechanism of NH4+ onto SMA was mainly electrostatic attraction between cationic NH4+ and the negatively charged SMA surface.

Hydrotalcite was synthesized using the co-precipitation method with the Mg/Al molar ratio of 3.0 and then calcined at 450 °C, for 5 h. The obtained solid was characterized by XRD, BET. As seen from results of physical characterization, the synthesized Hydrotalcite material owns large surface area of 309.3 m²/g, mean capillary diameter of 11.52 nm. Hydrotalcite application as adsorbent of heavy metal ions. The results of adsorption experiment for Pb²⁺ in water showed that the absorption equilibrium was attained after 90 minutes at pH = 5 with maximum adsorption loading capacity of 144.93 mg/g. The synthesized adsorbent could be regenerated with HNO₃ (1M) solution

The aim of this thesis work was to gain understanding of the interactions between talc mineral and surfaces, liquids and chemicals relevant for industrial applications, such as pulp and paper. Talc is used in the pulp and paper industry as a filler pigment, in control of pitch (lipophilic extractives) deposits and as a coating pigment. A deeper understanding of talc interactions will be beneficial in optimizing its use. Long-range attractive interactions between talc and hydrophobic model probes, as well as pitch probes, have been measured using the atomic force microscope (AFM) colloidal probe method. Two procedures for preparation of pitch colloidal probes were developed to allow these studies. Model hydrophobic, nanorough surfaces with surface energy characteristics similar to talc have also been prepared and their interactions with hydrophobic model probes compared to interactions between hydrophobic model probes and talc. It is demonstrated that talc mineral interacts with model hydrophobic particles, as well as with pitch, by long-range attractive forces, considerably stronger than the expected van der Waals force. The possible origin of the measured interaction forces is discussed, and the conclusion is that the main cause is an attractive capillary force due to formation of a gas/vapor capillary between the surfaces. Force measurements using model hydrophobic, nanorough surfaces show that a large-scale waviness does not significantly influence the range and magnitude of the capillary attraction, but large local variations in these quantities are found. It is demonstrated that a large variation in adhesion force corresponds to a small variation in local contact angle of the capillaries at the surfaces. The nature of the surface topographical features influences the capillary attraction by affecting the local contact angle and by pinning of the three-phase contact line. The effect is clearly dependent on the size of the surface features and whether they exist in the form of crevices or as extending ridges. Entrapment of air also affects the imbibition of water in pressed talc tablets. The effects of wetting and dispersion agents on the interactions between talc and hydrophobic probes have also been investigated. It is demonstrated that a common dispersing agent used for talc, poly(acrylic acid), does not affect the capillary attraction between talc and non-polar probes. In fact, the results strongly suggest that poly(acrylic acid) does not adsorb on the basal plane of talc. From this finding it is inferred that the stabilizing effect of this additive most likely is due to adsorption to the edges of talc. In contrast, a wetting agent (the non-ionic triblock copolymer Pluronic PE6400) removes the long-range capillary attraction. It is suggested that such an ability to replace air at the talc surface is of great importance for an efficient wetting agent. The Hamaker constant for talc has also been estimated by using optical data obtained from spectroscopic ellipsometry. It is demonstrated that a nanocrystalline talc mineral, cut in different directions displays very small differences in Hamaker constant between the different crystallographic orientations, whereas a microcrystalline sample displays a significantly higher value. The estimated Hamaker constants are discussed for different material combinations of relevance for the pulp- and paper industry, such as cellulose and calcium carbonate.
Målet med detta avhandlingsarbete var att öka förståelsen för interaktioner mellan talkmineral och ytor, vätskor och kemikalier relevanta för industriella applikationer, såsom papper och massa. Talk används i pappers- och massaindustrin som fyllmedel, för kontroll av hartsrika (lipofila extraktivämnen) avsättningar och som bestrykningspigment. En djupare förståelse för talkinteraktioner kommer att vara användbart för att optimera dess användning. Långväga attraktiva interaktioner mellan talk och hydrofoba modellpartiklar, såväl som mellan talk och hartspartiklar, har uppmätts med hjälp av atomkraftsmikroskopi (AFM) genom att fästa kolloidala partiklar på kraftsensorn. Två metoder för att framställa partiklar gjorda av harts har utvecklats för att möjliggöra dessa studier. Hydrofoba, nanostrukturerade modellytor med ytenergier liknande de för talk har också tillverkats och deras växelverkan med hydrofoba modellpartiklar har jämförts med dem mellan talk och hydrofoba modellpartiklar. Studierna visar att talkmineral växelverkar med hydrofoba modellpartiklar, såväl som med harts, genom långväga attraktiva krafter som är betydligt starkare än den förväntade van der Waals kraften. Möjliga orsaker till de uppmätta växelverkanskrafterna diskuteras och slutsatsen blir att huvudorsaken är en attraktiv kapillärkraft som uppkommer genom att en gas-/ångkapillär bildas mellan ytorna. Kraftmätningar gjorda med hydrofoba nanostrukturerade modellytor visar att en storskalig vågighet inte nämnvärt påverkar storleken av kapillärattraktionen, men stora lokala variationer existerar. Det demonstreras att en stor variation i adhesionskraft motsvaras av en liten variation i lokal kontaktvinkel för kapillärerna på ytorna. Ytornas topografi påverkar kapillärattraktionen genom att påverka den lokala kontaktvinkeln samt genom att trefaskontaktlinjen inte kan röra sig fritt över ytan. Effekten är tydligt beroende av huruvida ytojämnheterna existerar i form av nedsänkningar eller upphöjningar. Instängd luft påverkar också pressade talktabletters uppsugningsförmåga av vatten. Vätnings- och dispergeringsmedels inverkan på växelverkan mellan talk och hydrofoba partiklar har undersökts. Resultaten visar att ett vanligt dispergeringsmedel för talk, polyakrylsyra, inte påverkar kapillärattraktionen. I själva verket tyder data på att polyakrylsyra inte adsorberas på talks basalplan. Utifrån dessa resultat dras slutsatsen att polyakrylsyra stabiliserar talkdispersioner genom att adsorbera på talkkanterna. Ett vanligt vätmedel (nonjonisk triblock sampolymer Pluronic PE6400) tar å andra sidan bort långväga kapillärattraktion. Detta antyder att egenskapen att ersätta luft på talkytan är av stor betydelse för effektiva vätmedel. Hamakerkonstanten för talk har uppskattats genom att utnyttja optiska data från ellipsometrimätningar. Det demonstreras att ett nanokristallint talkmineral kapat i olika riktningar uppvisar mycket små skillnader i Hamakerkonstant mellan de olika kristallografiska orienteringarna, medan ett mikrokristallint prov uppvisar ett betydligt högre värde. De beräknade Hamakerkonstanterna diskuteras för olika materialkombinationer relevanta för pappersindustrin, såsom cellulosa och kalciumkarbonat.
QC 20100813

Die bei Textilbetonen überwiegend zum Einsatz kommenden Bewehrungen aus AR-Glas weisen infolge der Glaskorrosion einen signifikanten Tragfähigkeitsverlust auf. Im Rahmen des Teilprojektes D5 des SFB 532 wurden die Faktoren, die die Dauerhaftigkeit des Werkstoffes beeinflussen, evaluiert und in einen Modellansatz umgesetzt. Anhand dieser Untersuchungen konnten Möglichkeiten zur Reduktion des langfristigen Festigkeitsverlustes aufgezeigt werden. Eine dieser Möglichkeiten ist die Polymermodifikation des Betons, die im Wesentlichen einen Einfluss auf den Wassertransport innerhalb des Betonquerschnitts hat. Im Rahmen des Teilprojektes B4 des SFB 532 wurden polymermodifizierte Betone entwickelt und hinsichtlich ihres Wasseraufnahmeverhaltens untersucht. Im Anschluss wird die Wirkungsweise polymermodifizierter Betone hinsichtlich der Einflüsse auf die Dauerhaftigkeit von TRC beschrieben.

碩士
國立屏東科技大學
環境工程與科學系
92
Abstract The paper capillary permeation adsorption（PCPA）separation of 4-chlorophenol（4-CP）， 2,4,6-trichlorophenol（2,4,6-TPC），and pentachlorophenol（PCP）from water in the presence of cetytrimethylammonium bromide （CTAB） war studied . The pres effect of pH ,CTAB concentration， and salts on separatability has been investigated . A nearly 98% ，96% ，and 92% optimum sepaiatability was obtained for 4-CP， 2,4,6─TCP，and PCP，at pH 11 and 500 ppm CTAB，respectively . At constant pH 9 the separatability is greater than that without any addition of CTAB .It was confirmed that the investigated chlorophenols are adsorbed as ion pairs or by combination with the CTA+ on the fibet surface that contaims ion pairs CTA+ COO- formed by the combination of the CTA+ cations with the carboxyl grups bonded in the fiber surface . Desorption techniques for the fiber surface adsorbed chlorophenols was offered. The optimum desorption rate is nearly 82% for PCP，66% for 4-CP，and 100% for 2,4,6-TCP.

Water is a prerequisite for vine growth. It is essential for photosynthesis and to maintain the hydrated conditions and cell turgor necessary for a host of other bio­chemical processes in the plant. As we saw in chapter 4, diffusion of nutrient ions to the root, and their movement by mass flow into the vine’s “transpiration stream,” both depend on water. The volumetric water content θ, defined as the volume of water per unit vol­ume of soil (section 3.3.2), indicates how much water the soil can hold. How­ever, to understand what drives water movement in the soil, we must understand the forces acting on the water because they affect its potential energy. The energy status of soil water also influences its availability to plants. There is no absolute scale of potential energy. But we can measure changes in potential energy when useful work is done on a measured quantity of water or when the water itself does useful work. These changes are observed as changes in the free energy of water, which gives rise to the concept of soil water potential. The derivation of the soil water potential ψ (psi) is given in appendix 7. Historically, the energy status of soil water has been described by a number of terms related to soil water potential, such as pressure, suction, or hydraulic head. These terms ψ and their units are explained in box 6.1. The terms and head will be used in this book. Several forces act on soil water to decrease its free energy and give rise to compo­nent potentials. These are adsorption forces, capillary forces, osmotic forces, and gravity. Adsorption Forces. In very dry soils (relative humidity, RH, of the soil air <20%), water is adsorbed onto the clay and silt particles as a monolayer in which the molecules are hydrogen bonded to each other and the surface. With an in­crease in RH, more water molecules are adsorbed by hydrogen bonding to those on the surface. The charged surfaces of clay minerals also attract cations, and the electric field of the cation orients the polar water molecules around the ion to form a hydration shell, containing 6–12 water molecules.

Abstract Deliquescent salts have high water vapor adsorption capacity, but they dissolve in water by forming crystalline hydrates. That restricts their use in different water vapor adsorption applications. However, this limitation can be overcome by incorporating deliquescent salts within a polymer matrix which will keep the salt solution in place. Furthermore, if the polymer matrix used is also capable of adsorbing water vapor, it will further improve the overall performance of desiccant system. Therefore, in this work, we are proposing the synthesis and use of a highly effective new solid polymer desiccant material, i.e. superporous hydrogel (SPHs) of poly(sodium acrylate-co-acrylic acid (P(SA-co-AA)), and subsequently its composite with deliquescent salt, i.e. calcium chloride (CaCl2), to adsorb water vapors from humid air without the dissolution of the salt in the adsorbed water. Parental PAA-SPHs matrix alone exhibited an adsorption capacity of 1.02 gw/gads which increased to 3.35 gw/gads after incorporating CaCl2 salt in the polymer matrix. Both materials exhibited type-III adsorption isotherm and the experimental isotherm data fitted to the Guggenheim, Anderson and Boer (GAB) isotherm model. However, the adsorption kinetics followed linear driving force model which suggested that this extremely high adsorption capacity was due to the diffusion of water molecules into the interconnected pores of SPHs via capillary channels followed by the attachment of adsorbed water molecules to the CaCl2 salt present in the polymer matrix. Furthermore, the adsorbents were used successively for six cycles of adsorption with a very little loss in adsorption capacity. Therefore, the proposed polymer desiccant material overcomes the problem of dissolution of deliquescent salts and opens the doors for a new class of highly effective solid desiccant material.

Grand canonical Monte Carlo (GCMC) and canonical ensemble molecular dynamics (NVT-MD) simulations were performed to investigate water adsorption properties in mesoporous silica thin films. The effect of pore radius on the adsorption properties was assessed using two models of mesoporous silica thin films having different pore radius and film thickness (1.38 and 5.66 nm in Model 1, respectively, and 1.81 and 7.30 nm in Model 2, respectively). In the simulations, a water adsorption layer or water menisci were formed in a mesopore accompanying the growth or shrinkage of stable adsorption layers on the upper and lower surfaces. The stable two water adsorption layers were formed on the pore surface in both models. The curvature radius of a water meniscus decreased monotonically and approached a constant value. In addition, NVT-MD simulations were performed to investigate the kinetics of water uptake into a model of mesoporous silica thin film having a radius and thickness of 1.38 and 7.93 nm (Model 3). The calculation results showed that the kinetics of water uptake depended on the number of water molecules and there were two different transport mechanisms in the pore. One was diffusion of water along the pore surface, and the other was capillary rise of liquid water.

As the use of polymeric materials is increasing in microelectronics industry, the failure issues related to moisture are getting more popular. Moisture absorbed into the electronic package causes interfacial delamination through the synergetic effects of hygro-thermo-mechanical stresses and degradation of adhesion strength. It also results in catastrophic crack propagation during reflow process, called pop-coming. Vapor pressure inside preexisting voids at material interfaces is known to be a dominant driving force of this phenomenon. In order to explain vapor pressure generation at high reflow temperature, researchers so far have been presuming two mechanisms: liquid water boiling and quick moisture diffusion. In spite of the importance as a basis of the failure analysis, there has been little focus on the mechanism of liquid water accumulation, more exactly, high vapor pressure generation inside voids. In this study various known mechanisms of liquid water formation inside a void at polymer interface are reviewed. They include condensation, adsorption, capillary, and microfogging. As an alternative possibility, moisture diffusion around the void for a short reflow period is also assessed through numerical analysis.

In a recent study we have shown that when small particles, e.g., flour, pollen, glass, etc., contact an air-liquid interface, they disperse rapidly as if they were in an explosion. The rapid dispersion is due to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. The vertical motion of a particle during its adsorption causes a radially-outward lateral (secondary) flow on the interface that causes nearby particles to move away. We present direct numerical simulation results for the adsorption of particles and show that the inertia of a particle plays an important role in its motion in the direction normal to a fluid-liquid interface. Although the importance of inertia diminishes with decreasing particle size, on an air-water interface the inertia continues to be important even when the size is as small as a few nanometers.

This paper proposes non-fragile compliant humidity sensors that can be fabricated inexpensively on various types of nano-porous polymer membranes such as polycarbonate, cellulose acetate, and nylon membranes. The sensor contains a pair of interdigitated electrodes deposited on the nano-porous polymer membranes. The resistance and/or capacitance between these electrodes vary at different humidity levels with a very high sensitivity due to the water adsorption (capillary condensation) inside the nano-pores. The proposed sensors are low-cost in both material and fabrication. Due to its compliance, the sensors can be suitable for certain applications such as in-situ water leakage detection on roofs, where people can walk on top of them. Testing results demonstrated that the sensor changes resistance within large range of humidity values. For most sensors, the resistance changes from 0.1 GΩ to 2000 GΩ when the relative humidity changes from 39% to 100% at room temperature. It takes about 4–8 minutes for the resistance to reach steady state when the sensor was taken from 100% to 39% relative humidity at the room temperature.

When small particles like, flour, pollen, etc., contact an air-liquid interface, they disperse rapidly in the lateral direction. Using direct numerical simulation (DNS) we showed that the rapid dispersion is due to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. The vertical motion of a particle during its adsorption causes a radially-outward lateral flow on the interface that causes nearby particles to move away. The goal of this study is to experimentally analyze the reasons for the rapid dispersion of particles when they are simultaneously adsorbed at a two-fluid interface. Specifically, we will analyze the effect of particle size on the oscillatory behavior of a single particle, as it is being trapped at an air-water interface. The diameter of a particle will be varied between 300–850 μm. Our experimental setup consists of a high speed camera with a resolution of 512×512 pixel and the recording speed up to 3000 frames per second which is connected to a 12X microscope. The camera outputs are analyzed to determine the frequency and amplitude of oscillation during adsorption. The measured amplitudes and frequencies for the micro glass spheres used in the experiment were found to be in qualitative match with the DNS results.

Development of intelligent and ecological energy absorption systems (EAS) is important to various fields such as automotive (vehicle suspensions, bumpers, engine mounts), construction (protections against seismic and wind-induced vibrations), and defense (parachuted objects, armors). Usual EAS use composites, shape-memory alloys and foams. Recently, liquid adsorption/desorption in/from nanoporous solids was employed to develop high-performance nano-EAS. Energy loss is based on the well-known capillary phenomenon: external work must be done to spread a non-wetting liquid on a solid surface. Nano-EAS provide considerably higher dissipated energies, about 1–10J/g at deformability of 30–70%, compared with the energy absorption of Ti-Ni alloys, about 0.01–0.05J/g at deformability of 5–8%. For water against hydrophobic nanoporous silica gel (artificial sand), the nano-EAS become ecological; they can be also made intelligent by thermo-electrical control. Relative to thermal effects, Qiao et al. have investigated, for nanoporous silica gel with insufficient coverage of the alkyl-based hydrophobic coating, the problem of hysteresis recovery by increasing the temperature in the range 20∼80°C. Energy loss capacity reduced severely after the first loading-unloading cycle, so, the hysteresis was found as irreversible. Shape of the first hysteresis, the accessible specific pore volume and the desorption pressure were almost unaffected by the temperature change. At temperature augmentation the second hysteresis was partially recovered and when the temperature exceeded 50°C the system became almost fully reusable. Water inflow was found as governed by Laplace-Washburn equation but the outflow process was perceived as thermally aided. On the other hand, Eroshenko et al. have contradictorily obtained for nanoporous silica gel with full coverage of the alkyl-based hydrophobic coating, a stable hysteresis at repeated working cycles. Adsorption pressure decreased and desorption pressure increased at temperature augmentation, this producing a reduction of the hysteresis area and damping. However, the accessible specific pore volume was found as thermally unaffected. Oppositely, both the in- and out-flows were found as governed by Laplace-Washburn equation. In this work, for nanoporous silica gels with partial and full coverage of the alkyl and fluorocarbon based hydrophobic coatings, the thermal effects on the hysteresis and damping performances are studied. Test rig used is a compression-decompression chamber introduced inside of an incubator that allows temperature adjustment in the range of −10∼50°C. Results reveal that, depending on the hydrophobic coating coverage, findings reported by Qiao et al. and Eroshenko et al. are in fact not contradictory but complementary. However, as expected, the accessible specific pore volume was found to decrease at temperature reduction. In order to explain all these apparently opposite experimental findings, a model based on the water cluster size distribution versus temperature, the pore size distribution of silica gel and the ability of water molecules to form hydrogen bonds with the uncovered hydroxyl groups on the solid surface is proposed.

Abstract There are three types of oil production energy operations, primary recovery, secondary recovery and enhanced oil recovery (EOR). EOR consider as the last period for production operations. Where the EOR classify into many types such as thermal injection, gas injection, microbial EOR and chemical flooding. Chemical flooding classified into many types such as polymer, surfactant, alkaline and nanoparticles (NP). NP can be classified into many types such as Iron Oxide (Fe2O3), Aluminum Oxide (Al2O3) and Magnesium Oxide (MgO) etc. In this study NP Aluminum oxide (Al2O3) were used to enhance the oil recovery. The main objective of this study is to use the Nanoparticles EOR (Al2O3) and know it is effect on increasing the extraction of oil from cores. The big motivation of using Al2O3 that it is easy to extract it from raw clay. However, the raw clay is available in Libya and using it will be more economic than using other method of chemical EOR. Nanoparticles EOR Aluminum oxide (Al2O3) used as a spontaneous imbibition test for sandstone core samples after saturated by crude oil. A spontaneous imbibition test consisting of two scenarios of nanoparticle solution (Al2O3) with change temperature and compared with one scenario of distilled water. The spontaneous imbibition test was performed in this study at room temperature to oven temperature (30C°, 40C°, 50C°, 60C°, 70C°). The results shown that the oil recovery increases with the increase of the concentration of nanoparticle (Al2O3) and increase the temperature. The higher oil recovery was 76.04% at NP (Al2O3) concentration 1%. Finally, oil swelling and adsorption (NP (Al2O3) with oil drops) have been noticed during the extraction of oil. Thus, the gravity force will be higher than the capillary force.

While particles smaller than the thickness of the diffusion film have been known to enhance rates of interfacial mass transfer [1], a relatively new result is the discovery that nanoparticles in suspension show enhancements that far exceed the earlier reported enhancements, and without any apparent adsorptive or reactive effects[2]. Different mechanisms for the enhancements have been speculated upon, but there is a paucity of data on different nanoparticulate materials, collected in a systematic way on model contactors so that rational comparisons may be made. In this work, enhancement in Carbon dioxide absorption in water has been studied using SiO2 and TiO2 nanoparticles using the same capillary tube apparatus for which previous results of Fe3O4 were reported. For 0.4% silica particles and 0.0118% TiO2 nanoparticles, 165% and 155% enhancement was observed respectively. A phenomenological convective diffusion model has been proposed to explain the observed effects of particle size, holdup and material density. The model accounts for the overall effect of the Brownian (and any diffusiophoretic) motion of the nanoparticles on the surrounding fluid in terms of an ‘effective’ convective velocity, which is determined from the experimental data and correlated to the modified Sherwood Number proposed earlier [2], volume fraction of Nanoparticles and a solid Reynolds number Rp. This model provides a good fit to the data from wetted wall column and capillary tube experiment for iron oxide from the previous literature, as well as for the data on silica and Titanium dioxide nanoparticles from this work, the average error being 8.3%.