Weight Fraction Of Water Research Articles

Catastrophic Emulsion Inversion Process of Highly Viscous Isosorbide Biobased Polyester Monitoredin situ by Torque and Light Backscattering.

Highly viscous hydrophobic isosorbide biobased polyester O/W emulsions are prepared through catastrophic phase inversion. The process is followed in situ with two different methods: torque and light backscattering (LBS). Considering high viscosity of the system, only discontinuous conductivity monitoring is performed for comparison. Torque and LBS allow to highlight the emulsion inversion point (EIP) with relatively close water weight fraction values (fw≈0.20). The torque and LBS signals are rather noisy before inversion (evolution of different structures) and more smooth after phase inversion (continuous aqueous phase). Torque gives a more macroscopic information, representative of the global state of the dispersion. Consistent conductivity and torque measurements suggest indeed an inversion pathway through multiple o/W/O emulsions leading to multiple complex structures before getting continuous aqueous final emulsion. This hypothesis is confirmed with continuous LBS monitoring and microscopic observations. LBS signal seems more complete because it combines the information of conductivity and torque and allows to clearly follow in situ the inversion from the beginning to the end of the process.

Water absorption in recycled sand: New experimental methods to estimate the water saturation degree and kinetic filling during mortar mixing

Use of recycled concrete aggregates (RCA) as construction and building materials has not yet spread out. One of the reasons lies in porosity: a given RCA is more porous than its natural aggregate because of the presence of the attached old cement paste. This higher porosity causes inadequate mixing due to increase in both RCA water absorption and water exchange between RCA and new cement paste. It is thus necessary to quantify the weight fraction of in-pore water, which is usually done through the so-called water absorption coefficient (WAC), and to decrease this potential water exchange by pre-saturating the RCA. This paper aims to investigate mortar mixes made of RCA that is 1–4 mm in diameter called recycled sand (RS). It puts forward a new vacuum-based method combined with an evaporation method to measure the WAC, which permits saturating the RS fully and confirming that the standard method (NF EN 1097-6) largely underestimates the WAC (as already pointed out by other works). The evaporation method is also used to measure the water content of the pre-saturated RS, in order to evaluate the proportion of the pores that remain accessible to water even after pre-saturation, which was not done in other works. This paper then puts forward a new experimental approach to follow the absorption kinetics of the RS by immersing them into a limestone filler, which allows better reproduction of mixing mortar since aggregates are added into cement paste and not into water. Last, it is shown that adequately pre-saturating the RS can improve the mortar consistency.

Surface structure and water adsorption behavior of waxy/amylose extender (wx/ae) double‐mutant rice starch

We studied the surface structure and water adsorption behavior of waxy/amylose extender (wx/ae) double‐mutant rice starch using scanning electron microscopy, nitrogen gas adsorption, and water adsorption capacity analysis under various relative humidity conditions, and the nature of the bound water in the starch by differential scanning calorimetry. The wx/ae starch sample had a specific surface area of 3.26 m2/g and pores on its surface with diameters ranging from 6 to 60 nm. Its water adsorption capacity was 0.278 of the weight fraction of water and its weight fraction of bound water molecules was 0.233, both of which are larger than those of wx and wild‐type (WT) starches. We suggest that the starch–water interaction is primarily determined by the morphology and nanostructure of the starch, such as the granule shape and size, specific surface area, porosity, and crystal structure, and that wx/ae starch has a greater capacity to interact with water molecules because of its unique structure.

Hydrogen Production by γ-Ray Irradiation from Different Types of Zeolites in Aqueous Solution

Dihydrogen (H2) production via irradiation of zeolite–water mixtures was studied to investigate the effect of zeolites on the reaction process for H2 production. Four types of zeolites were comparatively examined under anoxic and aerated conditions. High yields of H2 were observed for the zeolites with high aluminum contents, A-type and X-type zeolites, compared to the Y-type and mordenite-type zeolites. The difference in the H2 yields was considerable at weight fractions of water below 50 wt % under anoxic conditions. The experimental results demonstrated a reaction pathway for H2 production that has different yields between the four zeolites. The H2 yields were compared with chemical analyses of the zeolites, and the comparison suggested that the extraframework aluminum species in the zeolites are involved in the reaction pathway for H2 production. On the other hand, under aerated conditions, the H2 yields from the zeolites were lower than under anoxic conditions probably due to the H2O2 that was produc...

Assessing pre-adsorption time impact on ultrafiltration performance for surface water treatment

Abstract This study was to assess the effect of powdered activated carbon (PAC) pre-adsorption time on ultrafiltration performance for surface water treatment. Experimental results demonstrated that membrane fouling could be mitigated by extending the pre-adsorption time. The molecular weight (MW) distribution of water samples was determined by liquid chromatography – organic carbon detector (LC-OCD) and results showed that the mechanism of PAC controlling fouling was attributed to a decrease in the low molecular weight (LMW) fraction of raw water via extending the pre-adsorption time. Fouling indexes (FIs) were used to evaluate membrane fouling potential and the results showed that polysaccharides (PS) and proteins (PN) were greatly responsible for membrane fouling. Therefore, prolonging the PAC pre-adsorption time and decreasing the PS and PN content in raw water are the main measurement for the alleviation of membrane fouling when PAC is used as the pretreatment in waterworks.

Emulsification of viscous alkyd resin by catastrophic phase inversion with nonionic surfactant

The addition of water to hydrophobic alkyd resin containing a hydrophilic nonionic surfactant (polyethoxylated-20-oleyl alcohol) was used to produce the emulsion morphology change from W/O to O/W in a small thermostated reactor (50mL). The so-called catastrophic phase inversion of the water/alkyd resin system was detected by monitoring both, the viscosity by torque measurement and the electrical conductivity, until an equal weight fraction of water and resin is attained (fw=0.5). The two methods provide similar values of the phase inversion point (PIP). Although the determination of the PIP exhibits a small inaccuracy, it is clear that different torque profiles and PIP are observed depending on the resin neutralization level, the surfactant concentration and the water addition rate. For the non-neutralized resin, both, PIP and emulsion drop size, decrease with surfactant concentration increase. The completely neutralized resin could be emulsified using a minimum of 2wt% of surfactant in the final emulsion. In such a case the water fraction at which inversion occurs (fw,Inv=0.36) is independent of the surfactant concentration and a small resin drop diameter (<200nm) can be obtained. A more precise study of the reached drop size of the emulsion versus resin neutralization (0, 25, 50, 75, 100 and 125%) indicates that a minimum diameter is obtained around 90–100% neutralization, with no effect of over-neutralization. For non-neutralized resin a maximum fw,Inv (0.25) can be obtained by reducing water addition rate allowing the production of 0.5μm droplets in a longer process.

Multiscaling wavelet analysis of infrared and Raman data on polyethylene glycol 1000 aqueous solutions

ABSTRACTInfrared and Raman scattering spectra of aqueous solutions of poly(ethylene glycol) with nominal weight 1000 Da have been collected and analyzed as a function of the water content both in terms of a two-state physical model and in terms of an innovative multiscale wavelet cross-correlation approach. Both the analysis procedures allow to highlight the spectral shape changes occurring when water is added to pure polymer, showing the effectiveness of the wavelet analysis. It is shown that, provided that the pure polymer spectral contribution is subtracted from the aqueous solutions spectra, the shape of the intramolecular O–H stretching band can be reproduced by a superposition of the spectrum of bulk water and of the spectrum of hydration water, i.e., the spectrum relative to the water molecules bonded to the polymer chain. The weight of the bonded-water spectrum changes with concentration furnishing a polymer hydration number value which well agrees with hydration number data, reported in literature, obtained with other techniques. On the other hand, the intramolecular infrared O–H stretching band and the low-frequency Raman spectra, for all the investigated polymeric aqueous solutions, when analyzed through a multiscale wavelet cross-correlation approach reveal that significant spectral changes are registered in the 0.00–0.46 water weight fraction range. Such complementary experimental and analytic findings suggest the picture that when the water content increases, the water molecules saturate the two lone pairs of each oxygen atom of the polymer furnishing a hydration number which agrees with previous determinations and hence supporting the validity of the wavelet approach.

Effect of additives on interfacial interactions for viscosity reduction of carbonaceous solid–water slurries

The interfacial interactions in carbonaceous solid–water slurries (CSWS) influence slurry viscosity. Additives impact the slurry viscosities by modifying the surface chemistry of the carbonaceous solids, thereby affecting the interfacial interactions in CSWS. The focus of this study was to determine the effect of the additives on the interfacial interactions which results in viscosity reduction in CSWS. Since additives are extremely specific to surface chemistry of solids in the slurry, this understanding would help in the selection of appropriate additive for viscosity reduction for specific carbonaceous water slurries. The study was conducted using three carbonaceous solids with different O/C ratios and two additives-one anionic and the other non-ionic. The adsorption of the additives on the carbonaceous solids, the change in the zeta potential and hydrophobicity/hydrophilicity of the solids and the change in the free water content of the slurries were experimentally determined. It was observed that adsorption of the additives increased with an increase in the mineral matter content of the carbonaceous solids. There was also an increase in the zeta potential of the carbonaceous solids in water upon addition of the anionic additive. However, the calculated resultant electrostatic repulsion energy upon the addition of the anionic additive was 5–6 orders of magnitude lower than the polar interaction energy of the carbonaceous solids in water. Contact angle measurements indicated that both additives changed the hydrophobicity/hydrophilicity of the solid surface. This resulted in the release of bound water into the bulk slurries, resulting in greater fluidity. The increase in free water content of the slurries with additives was confirmed by thermogravimetric analysis (TGA). A correlation predicting slurry viscosity on the basis of weight fraction of free water in the slurries was developed.

Strategy for Obtaining Bimodal Bubble Size Distribution in Water Blown Polyurethane Foams

Polyurethane foams with multimodal cell distribution exhibit superior mechanical and thermal properties. A technique for generating bimodal bubble size distribution exists in the literature, but it uses supercritical conditions. In the present work, an alternative based on milder operating conditions is proposed. It is a modification of reaction injection molding (RIM), using reactants already seeded with bubbles. The number density of the seeds determines if two nucleating events can occur. A bimodal bubble size distribution is obtained when this happens. A mathematical model is used to test this hypothesis by simulating water blown free rise polyurethane foams. The effects of initial concentration of bubbles, temperature of the reactants, and the weight fraction of water are studied. The study reveals that for certain concentrations of initial number of bubbles, when initial temperature and weight fraction of water are high, it is possible to obtain a second nucleation event, leading to bimodal bubble s...

Supramolecular Networks of Hyperbranched Poly(ether amine) (hPEA) Nanogel/Chitosan (CS) for the Selective Adsorption and Separation of Guest Molecules

Supramolecular networks with selective adsorption for guest molecules were formed via dynamic hydrogen-bonding interactions between the carboxyl group-containing hyperbranched poly(ether amine) nanogels (hPEA-NG) and chitosan (CS). The hPEA-NG/CS supramolecular networks were physically cross-linked and were composed of hPEA-NGs dispersed within a crystallized CS matrix. An increasing CS content enhanced the mechanical properties of the hPEA-NG/CS supramolecular networks. The transparent hPEA-NG supramolecular networks did not disassemble in aqueous solutions with different pH values and organic solvents and were swollen with high weight fractions of water (WH2O = 0.95) in less than 30 s. The adsorptive behavior of seven fluorescein dyes and five azobenzene (azo) dyes onto the hPEA-NG/CS supramolecular networks was investigated. These hPEA-NG/CS supramolecular networks showed rapid adsorption for Rose Bengal (RB), Erythrosin B (ETB), Eosin B (EB), 4′,5′-dibromofluorescein (DBF), Ponceau S (PS) and Evans blue (EVB) dyes with high adsorption capacities (Qeq). The networks showed very low adsorption for calcein (Cal), fluorescein (FR), 4,5,6,7-tetrachlorofluorescein (TCF), and Bismarck brown (BBY) dyes. The adsorption process was found to follow pseudo-second-order kinetics. The different adsorptive behaviors for different dyes indicated the selective adsorption of the hPEA-NG/CS supramolecular networks for the azo and fluorescein dyes despite similar backbone structures and charge states. On the basis of the unique selective adsorption, the separation of mixtures of fluorescein dyes, such as RB/Cal, RB/FR, and PS/MR, was achieved using the hPEA-NG/CS supramolecular network as an adsorbent.

Development of a Single-Sided Nuclear Magnetic Resonance Scanner for the In Vivo Quantification of Live Cattle Marbling.

Non-invasive in vivo marbling quantification helps owners to choose the optimum nutritional management for growing cattle and buyers to more precisely evaluate grown cattle at auctions. When using time-domain proton nuclear magnetic resonance (NMR) relaxometry, it is possible to quantify muscle and fat separately by taking advantage of the difference in the spin–spin relaxation time (T2) between water molecules in muscles and fat molecules, which would contribute to the non-invasive and objective determination of marbling scores. With this in mind, we developed a prototype NMR scanner (4.1 MHz for protons) using an original single-sided magnetic circuit and a plane radio frequency (RF) coil for use in the non-invasive quantification of water and fat in live cattle. The sensed region of the developed scanner is compact and almost cubical (19 × 19 × 16 mm3) while the investigation depth (the distance from the RF coil to the center of the sensed region) has been lengthened to 30 mm, which is sufficient for the in vivo trapezius muscle measurement of live cattle. Measurements of 17 samples of beef meat blocks kept at 39 °C were taken in a laboratory to successfully obtain the calibration lines used to convert the NMR signals into water and fat weight fractions at correlation coefficients in excess of 0.9. We also showed that each meat sample could be measured in about 10 s with a measurement error as small as approximately 10 wt%. Accordingly, we believe that our prototype scanner would be useful for in vivo marbling measurements of live cattle trapezius muscles.Electronic supplementary materialThe online version of this article (doi:10.1007/s00723-015-0657-4) contains supplementary material, which is available to authorized users.

Preparation and characterisation of gelatin–gum arabic aldehyde nanogels via inverse miniemulsion technique

Gelatin–gum arabic aldehyde nanogels designed by a nanoreactor concept using inverse miniemulsion technique were reported. Stable separate miniemulsions were prepared from gelatin (Gel) and gum arabic aldehyde (GAA). These emulsions were intermixed under sonication to obtain cross-linked nanogels. During fusion, cross-linking occurred between aldehyde groups of GAA and amino groups of gelatin. The concentration of the surfactant and weight fraction of water in the inverse miniemulsion was optimised so as to yield nanogels with controlled particle size. Properties of the nanogels were studied by FT-IR spectroscopy, particle size analysis and XRD. Surface morphology of the nanogels was established by Scanning Electron Microscopy (SEM). SEM and particle size analysis confirmed that nanogels possess spherical morphology with an average diameter of 151±6nm. Hemolysis property of the nanogels was examined and the results indicated that the nanogels were hemocompatible. The in vitro cytotoxicity of the nanogels towards MCF-7 cells was evaluated by MTT assay and the nanogels showed nontoxic behaviour towards the cells. All these studies confirm that these nanogels are potential candidates in applications such as drug and gene delivery.

A GMDH-type neural network for prediction of water activity in glycol and Poly(ethylene glycol) solutions

The objective of current work is to predict the activities of water in aqueous solution of glycols and polyethylene glycols (PEGs) by means of a group method of data handling (GMDH). The proposed model considers temperature, molecular weight of the polymer as well as weight fraction of water for input variables. A 387 experimental data set of activities of water in aqueous binary solution of different glycols and polyethylene glycols is used. Mean absolute error percent (MAE %) of the training and testing obtained were 2.45 and 2.46 respectively; the results when compared to those of an artificial neural network (ANN) model show a weaker correlation. However, a noticeably reduced runtime and more importantly an explicit general correlation function, typical of GMDH networks, offer superior advantages over an ANN model.

Tough stimuli-responsive supramolecular hydrogels with hydrogen-bonding network junctions.

Hydrogels were prepared with physical cross-links comprising 2-ureido-4[1H]-pyrimidinone (UPy) hydrogen-bonding units within the backbone of segmented amphiphilic macromolecules having hydrophilic poly(ethylene glycol) (PEG). The bulk materials adopt nanoscopic physical cross-links composed of UPy-UPy dimers embedded in segregated hydrophobic domains dispersed within the PEG matrix as comfirmed by cryo-electron microscopy. The amphiphilic network was swollen with high weight fractions of water (w(H2O) ≈ 0.8) owing to the high PEG weight fraction within the pristine polymers (w(PEG) ≈ 0.9). Two different PEG chain lengths were investigated and illustrate the corresponding consequences of cross-link density on mechanical properties. The resulting hydrogels exhibited high strength and resilience upon deformation, consistent with a microphase separated network, in which the UPy-UPy interactions were adequately shielded within hydrophobic nanoscale pockets that maintain the network despite extensive water content. The cumulative result is a series of tough hydrogels with tunable mechanical properties and tractable synthetic preparation and processing. Furthermore, the melting transition of PEG in the dry polymer was shown to be an effective stimulus for shape memory behavior.

Aggregation and phase separation of hydrophilically modified poly(dimethylsiloxane) in methanol–water mixtures

Hydrophilically modified poly(dimethylsiloxane) (HPM-PDMS) bearing quaternized amino groups on the side chains was dissolved in mixtures of methanol (MeOH) and water with a water weight fraction w H 2 O from 0 to 1 and with 0.1 M sodium acetate added. The degree of substitution and the degree of polymerization of this ionomer sample were 16 mol% and 1050, respectively, and the polymer concentrations were mostly <1%. Although the solutions were almost transparent, they were in the two-phase region at w H 2 O ≥ 0.5 , and HPM-PDMS formed random aggregates at w H 2 O < 0.5 . In the two-phase region, the coexisting concentrated phases formed colloidal particles with radii of gyration ranging from 100 to 300 nm just after dispersion. The colloidal particles, however, gradually coagulated, and the solutions became turbid when they were left standing for several days. The multiplet structure in the melt sample of HPM-PDMS may be responsible for the tentative dispersion of HPM-PDMS even in the two-phase region.

Influence of temperature on the phase inversion of chlorinated polypropylene

ABSTRACTIn this study, the maleic anhydride modified chlorinated polypropylene (MCPP) resin was emulsified by mixed ionic surfactants comprising sodium dodecyl sulfate (SDS) and sulfonated castor oil (SCO). The influence of temperature on the morphology of emulsion was studied through transitional and catastrophic inversion methods. The transitional inversion of emulsion from water‐in‐oil (W/O) to oil‐in‐water (O/W) was triggered by decreasing the temperature and the catastrophic inversion was achieved by increasing the weight fraction of water. The results of transitional and catastrophic inversion both indicated that the phase inversion of “ionic surfactant–MCPP–water” system is easier to trigger at low temperatures than at high temperatures, which could be interpreted by the thermodynamic and hydrodynamic theory. Incomplete phase inversion occurred at low temperatures when the volume of water phase was small and emulsions with small particle size and narrow particle size distribution could only be obtained at an intermediate temperature. These results are of great importance for the preparation of stable polymer emulsions in food, cosmetics and paints industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40325.

Mechanical properties of PGA at different water fractions – a molecular dynamics study

The mechanical properties of polyglycolic acid (PGA) of different water weight fractions (1.7%, 2.9%, and 5%) were investigated by molecular dynamics (MD) simulation through a tensile test.

Gibbs energies, enthalpies, and entropies of water and lysozyme at the inner edge of excess hydration

The aim of this study is to simultaneously monitor the excess partial Gibbs energies, enthalpies, and entropies of water and white egg lysozyme and demonstrate how these quantities correlate with the coverage of the protein macromolecules by water molecules. Isothermal calorimetry and water sorption measurements were applied to characterize the hydration dependencies of the excess thermodynamic functions. The excess partial quantities are found to be sensitive to changes in the water and protein states. At the lowest water weight fractions (w1), changes in the excess functions are primarily attributable to the addition of water. The transition of lysozyme from a glassy (rigid) to a flexible (elastic) state is accompanied by significant changes in the excess partial quantities. When the charged groups on the protein are covered, this transition occurs at w1 = 0.05; when the coverage of both polar and weakly interacting surface elements is complete, the excess partial quantities become hydrated at w1 > 0.5. At the highest water content, water addition has no significant effect on the excess quantities. At w1 > 0.5, changes in the excess functions solely reflect changes in the state of the protein.

Supercritical water gasification of manure: A thermodynamic equilibrium modeling approach

This study aims to investigate for the first time the equilibrium partitioning of elements on the basis of compounds and phases in the supercritical water gasification of mixed pig–cow manure for a temperature interval of 100–580 °C and at a pressure of 24 MPa. The software programs FactSage 5.4.1 and SimuSage 1.12 with user-defined databases have been used for thermodynamic equilibrium calculations. The temperature interval and the weight fraction of water have been chosen as 100 °C–580 °C and 80%, respectively. The effects of pressure and water fraction on main product gases have also been investigated. The results show that three phases are formed for the subcritical region: gas, liquid and solid. In addition to water vapor, CO2, CH4, N2 and H2 are the main gas products of the gas. The liquid phase is composed of an aqueous solution composed of stable ionic compounds such as HCO3−, K+, Na+ and Cl− and dissolved CH4 and N2. The solid phase compounds are mainly composed of C, Ca, Mg and P. Aqueous hydrates exist in the supercritical region but start precipitation at high temperatures. The results show that working above 340 °C would result in good carbon gasification efficiency under equilibrium conditions as the solid carbon completely disappears. In the supercritical region, backward methanation reaction takes place and CH4 decomposes and forms H2. While the water fraction has a significant effect on the amount of main product gases, pressure was found to be less significant.

Transport Properties Investigation of Aqueous Protic Ionic Liquid Solutions through Conductivity, Viscosity, and NMR Self-Diffusion Measurements

We present a study on the transport properties through conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], η, σ, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K.