Affinity For Water Molecules Research Articles

Theoretical investigations on the nature of interactions in ions (Li+, Na+, Be2+, Mg2+)-water clusters in the gas phase

The nature of interaction that is present in ion-water ( M ( H 2 O ) n ) ( M = L i + , N a + , B e 2 + , M g 2 + ) (n = 1–10) clusters are highlighted in the present work. We have used theories of atoms in molecules, symmetry-adapted perturbation, and infrared spectroscopy in the gas phase. The inner structure where the M is surrounded by four H 2 O molecules represent the first shell, followed by the second shell, which is the most stable cluster when n ≥ 4 , for M ( H 2 O ) n ( M = L i + , N a + , B e 2 + ) clusters, and n ≥ 6 for M ( H 2 O ) n ( M = M g 2 + ) cluster. The successive binding energies of M ( H 2 O ) n clusters leads to the conclusion that the affinity for water molecules follows the trend: B e 2 + > M g 2 + > L i + > N a + . The SAPT study demonstrates that the total interaction energy of B e 2 + − water clusters are higher than the other clusters because of high attractive induction and electrostatic energy. The IR spectrum results conclude that in the presence of cations in ( H 2 O ) n clusters blue shifts occur for the hydrogen-bonded O − H stretching mode, and a red shift occurs for the free O − H stretching mode. This investigation contributes significantly to the scientific understanding of these clusters’ bonding interactions, total interaction energy, and successive interaction energy.

Ternary Holey Carbon Nanohorn/Potassium Chloride/Polyvinylpyrrolidone Nanohybrid as Sensing Film for Resistive Humidity Sensor

The study presents findings on the relative humidity (R.H.) sensing capabilities of a resistive sensor. This sensor utilizes sensing layers composed of a ternary nanohybrid, consisting of holey carbon nanohorn (CNHox), potassium chloride (KCl), and polyvinylpyrrolidone (PVP), with mass ratios of 7/1/2, 6.5/1.5/2, and 6/2/2 (w/w/w). The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensing film is deposited on the sensing structure via the drop-casting method. The sensing layers’ morphology and composition are investigated through Scanning Electron Microscopy (SEM) and RAMAN spectroscopy. The resistance of thin-film sensors based on ternary hybrids increased with exposure to a range of relative humidity (R.H.) levels, from 0% to 100%. The newly designed devices demonstrated a comparable response at room temperature to that of commercial capacitive R.H. sensors, boasting excellent linearity, swift response times, and heightened sensitivity. Notably, the studied sensors outperform others employing CNHox-based sensing layers in terms of sensitivity, as observed through manufacturing and testing processes. It elucidates the sensing mechanisms of each constituent within the ternary hybrid nanocomposites, delving into their chemical and physical properties, electronic characteristics, and affinity for water molecules. Various alternative sensing mechanisms are considered and discussed, including the reduction in holes within CNHox upon interaction with water molecules, proton conduction, and PVP swelling.

Low-cost ZnO incorporated carbonized nitrile butadiene rubber (NBR) as a relative humidity monitoring sensor

This paper presents the development and characterization of a sustainable humidity sensor that is both cost-effective and high performing. The sensor utilizes a composite material comprising conductive carbon derived from recycled Nitrile Butadiene Rubber (NBR) gloves and zinc oxide (ZnO). Among the various chemical compositions tested, the sensor with a carbon-to-zinc oxide (C:ZnO) ratio of 1:0 exhibited superior humidity-sensing performance. The study encompassed a broad spectrum of relative humidity levels, ranging from 5% to 95% at room temperature (25 °C) at an optimum frequency of 100 Hz. The sensor exhibited remarkable characteristics, including a minimal hysteresis of only 0.36%, indicating its ability to provide consistent and accurate readings. Moreover, the sensor demonstrated excellent long-term stability, ensuring reliable performance over extended periods. Additionally, the sensor showcased rapid and dependable sensing capabilities, with a response time of 18 s and a recovery time of 16 s. This indicates its ability to detect and recover from changes in humidity levels promptly. The composite material's high sensitivity to relative humidity variations can be attributed to the presence of zinc oxide nanoparticles (NPs), which have an affinity for water molecules and facilitate interaction. To assess its performance, the developed sensor was compared to most previous work in the literature and the results revealed that the proposed sensor exhibits comparable levels of accuracy and reliability. This work provides a simple, cost-effective strategy for fabricating high-performance humidity sensors by exploring waste materials like NBR.

High Proton Conductivity of Magnetically Ordered 2D Oxalate-Bridged [MnIICrIII] Coordination Polymers with Irregular Topology.

Two heterometallic coordination polymers {[NH(CH3)2(C2H5)]8[Mn4Cl4Cr4(C2O4)12]}n (1) and {[NH(CH3)-(C2H5)2]8[Mn4Cl4Cr4(C2O4)12]}n (2) were obtained by slow evaporation of an aqueous solution containing the building block [A]3[Cr(C2O4)3] [A = (CH3)2(C2H5)NH+ or (CH3)(C2H5)2NH+] and MnCl2·2H2O. The isostructural compounds comprise irregular two-dimensional (2D) oxalate-bridged anionic layers [Mn4Cl4Cr4(C2O4)12]n8n- with a Shubnikov plane net fes topology designated as (4·82), interleaved by the hydrogen-bonded templating cations (CH3)2(C2H5)NH+ (1) or (CH3)(C2H5)2NH+ (2). They exhibit remarkable humidity-sensing properties and very high proton conductivity at room temperature [1.60 × 10-3 (Ω·cm)-1 at 90% relative humidity (RH) of 1 and 9.6 × 10-4 (Ω·cm)-1 at 94% RH of 2]. The layered structure facilitates the uptake of water molecules, which contributes to the enhancement of proton conductivity at high RH. The better proton transport observed in 1 compared to that in 2 can be tentatively attributed to the higher hydrophilicity of the cations (CH3)2(C2H5)NH+, which is closely related to their affinity for water molecules. The original topology of the anionic networks in both compounds leads to the development of interesting magnetic phases upon cooling. The magnetically ordered ground state can be described as the coupling of ferromagnetic spin chains in which Mn2+ and Cr3+ ions are bridged by bis(bidentate) oxalate groups into antiferromagnetic planes through monodentate-bidentate oxalate bridges in the layers, which are triggered to long-range order below temperature 4.45 K via weaker interlayer interactions.

Ternary Holey Carbon Nanohorns/TiO2/PVP Nanohybrids as Sensing Films for Resistive Humidity Sensors

In this paper, we present the relative humidity (RH) sensing response of a chemiresistive sensor, employing sensing layers based on a ternary nanohybrids comprised of holey carbon nanohorns (CNHox), titanium (IV) oxide, and polyvinylpyrrolidone (PVP) at 1/1/1/(T1), 2/1/1/(T2), and with 3/1/1 (T3) mass ratios. The sensing device is comprised of a silicon-based substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensitive layer was deposited via the drop-casting method on the sensing structure, followed by a two-step annealing process. The structure and composition of the sensing films were investigated through scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). The resistance of the ternary nanohybrid-based sensing layer increases when H increases between 0% and 80%. A different behavior of the sensitive layers is registered when the humidity increases from 80% to 100%. Thus, the resistance of the T1 sensor slightly decreases with increasing humidity, while the resistance of sensors T2 and T3 register an increase in resistance with increasing humidity. The T2 and T3 sensors demonstrate a good linearity for the entire (0–100%) RH range, while for T1, the linear behavior is limited to the 0–80% range. Their overall room temperature response is comparable to a commercial humidity sensor, characterized by a good sensitivity, a rapid response, and fast recovery times. The functional role for each of the components of the ternary CNHox/TiO2/PVP nanohybrid is explained by considering issues such as their electronic properties, affinity for water molecules, and internal pore accessibility. The decreasing number of holes in the carbonaceous component at the interaction with water molecules, with the protonic conduction (Grotthus mechanism), and with swelling were analyzed to evaluate the sensing mechanism. The hard–soft acid-base (HSAB) theory also has proven to be a valuable tool for understanding the complex interaction of the ternary nanohybrid with moisture.

Bénard-Marangoni Dendrites upon Evaporation of a Reactive ZnO Nanofluid Droplet: Effect of Substrate Chemistry.

Evaporation of a particle laden sessile drop can lead to complex surface patterns with structural hierarchy. Most commonly, the dispersed particles are inert. We have recently reported that when the sessile drop contains reactive ZnO nanoparticles, solidified Bénard-Marangoni (BM) cells with dendritic micromorphology were formed in the residual surface pattern from in situ-generated nanoclusters. Here, we report the effect of substrate chemistry on the residual pattern from the evaporation of nanofluids containing ZnO particles dispersed in a mixture of cyclohexane and isobutylamine, by comparing three different substrates: glass, silicon, and hydrophilized silicon. In particular, we performed a quantitative analysis of the BM cell size, distribution, and the cell morphological characteristics via the fractal dimension analysis. We find that the size dimension λBM of the dendritic Bénard-Marangoni cells varied on the different substrates, attributed to their different hydrophilicity and affinity for water molecules, evident from the different polar components γP in their surface free energy from the Owens-Wendt analysis. The average BM cell size was the smallest for the glass substrate (λBM = 289 μm) and comparable for the unmodified and UV/ozone-treated silicon wafers (with λBM = 466 and 423 μm, respectively). The fractal dimension analysis provided a quantitative description of the BM cells with complex structural hierarchy, highlighting the differences in the geometric features of the surface patterns resulting from different substrate chemistry. We also found that the fractal dimensions depended on the BM cell size, attributing it to two different regimes: the growing fractals and the maturing fractals.

Recognition dynamics of trinuclear copper cluster and associated histidine residues through conserved or semi-conserved water molecules in human Ceruloplasmin: The involvement of aspartic and glutamic acid gates

Human Ceruloplasmin belongs to the family of multi-copper oxidases and it is involved in different physiological processes, copper ion transport, iron metabolism, iron homeostasis, and biogenic amine metabolism. MD-simulation studies have indicated the higher hydrophilic susceptibility of the trinuclear copper cluster in native CP compared to its oxygen bound form. The copper (T2/T3) atom Cu3047 of the cluster, which is close to T1 copper center Cu3052 (~13 Å) has a higher affinity for water molecules compared to other copper centers. The water molecules of W3, W4, W5, W9, and W12 conserved water sites are coordinated to Cu3047, where W3, W9, and W12 centers are found to play some crucial role in the stabilization of native trinuclear copper cluster. The hydrogen bonding interaction of Asp169, Glu112, Asp995, and Glu1032 residues with the copper-bound conserved water molecules (W3, W4, W5, W10, and W11) in native CP is observed to be unique. The conformational flexibility of Asp169 and Glu112 and their association with the copper-bound water molecules, but the absence of such interaction in O2-bound simulated structure of the enzyme is indicating some plausible rational on the role of these acidic residues in the gating of O2 molecule in the native trinuclear Cu cluster of CP. The simulation results may shade some new light on the biochemistry/chemistry of CP, specially on the hydration dynamics of the trinuclear copper cluster.

Tuning ionic liquids for natural gas dehydration using COSMO-RS methodology

The quantum chemical COSMO-RS (Conductor like Screening Model for Real Solvents) methodology was applied to evaluate the ability ionic liquids as alternative solvents for dehydration of natural gas. First, a general evaluation of COSMO-RS model to predict activity coefficients at infinite dilution of water in ionic liquids were performed by comparing the computed results with a set of experimentally measured activity coefficient of water in different ionic liquids over various temperatures. The mean prediction error (MPE) and linear correlation coefficient (R2) between the experimental and predicted activity coefficients are 29.9% and 0.968, respectively. Then, a detailed analysis of water and ionic liquids behaviors and the effects of possible structural variation of ionic liquids on the water-ionic liquids interactions were performed using the sigma-profile and sigma-potential generated by COSAMO-RS model. For which, a total of 31 cations and 43 anions resulting in 1333 possible combinations were screened via COSMO-RS model by calculating the activity coefficient of water in these ionic liquids at infinite dilution over temperature range of (298.15–368.15) K. It was found that ionic liquids the contain cations with longer alkyl chain show less affinity for water molecules. Moreover, ionic liquids with fluorinated and cyano anions shows lower affinity and selectivity for water molecules. However, ionic liquids containing carboxylate and amino acid based anions and cations with shorter alkyl side chain have strong affinity and more selectivity for water molecules.

The influence of corrosion inhibitors on hydrate formation temperature along the subsea natural gas pipelines

Pipeline industry annually invests millions of dollar on corrosion inhibitors in order to minimize corrosion׳s implication on flow assurance; however, attention has never been focused on the possibilities of these chemicals to promote hydrate formation along deepwater pipeline which is also a flow assurance problem. Five inhibitors were investigated in this study at different concentrations and pressures in a cryogenic sapphire cell at static condition. The changes in the formation temperature established that all the inhibitors promote hydrate but at different rates while their hydrate formation patterns also differ from one another. Their ability to promote hydrate could be attributed to their hydrogen bonding properties which is required for hydrate formation. Also, the difference in the promotion rate is attributed to their different sizes and structures, active functional groups and affinity for water molecules which determine the type of hydrogen bonding exhibited by each inhibitor while in solution. The structure and size of each inhibitor also affect its electronegativity and ionization energy since the active electrons of some of the inhibitors have direct exposure to the nucleus while for others; the active electrons at the outermost shell have been shielded from direct influence of the attractive force. Furthermore, the active functional groups obeys electronegativity trend of periodic table to determine whether the resulting bond type will be polar ionic, covalent or ionic with some covalent characteristic in nature. Though, all the inhibitors are foamy; dodecylpyridinium chloride (DPC) was however the foamiest. DPC also exhibited its highest promotion ability at 200 ppm and exhibited specific behaviour at 5000 ppm to suggest a change in the hydrate formation rate beyond the Critical Micelles Concentration (CMC). Again, increase in agitation rate prolonged the complete solidification time of the hydrates probably due to the gas solubility. Finally, the feasibility of using this chemical as an additive at high concentrations for natural gas transportation and storage in slurry form was observed due to some exhibited properties, this however requires further investigations.

Simulation of Water Molecules Inside Gold Nanotubes of Various Sizes and Temperatures

This study investigates the behavior of water molecules inside Au nanotubes by molecular dynamics. Different sizes of Au nanotubes under three temperatures for three levels of density of Au nanotube have been studied. The structure of each thermodynamic state is analyzed through the characterization of the hydrogen-bond network. An observation of the water molecule distribution reveals that the adsorption of water molecules creates shell-like formation of water near the Au nanotube wall, and such formations are found to be more pronounced within an Au nanotube. Au atoms of different sizes have an affinity for water molecules at different temperatures.

Effect of oxidation level on the dual modification of banana starch: The mechanical and barrier properties of its films

AbstractBanana starch was oxidized at three different levels and then acetylated. The double‐modified starch was used for film preparation. The physical, mechanical, and barrier properties were tested. The oxidation level increased the whiteness of the film, and the second modification (acetylation) did not affect this parameter. The solubility increased with temperature and oxidation level. However, acetylation decreased the solubility value. At the longest storage times, the solubility decreased because of starch reorganization inside the polymeric matrix. In general, oxidation increased the tensile strength of the films, and a slight increase was observed when the oxidized starch was acetylated. This effect was more noticeable at the longest storage time. The oxidation level decreased the percentage elongation at break, and a slight effect due to acetylation was observed. The film of oxidized–acetylated starch showed a higher elastic modulus value than its oxidized counterpart. The water vapor permeability increased with oxidation level, but the acetylation decreased this parameter. The oxidation increased the hydrophilic character of the starch because of the formation of carbonyl and carboxyl groups that showed more affinity for water molecules. When the oxidized banana starch was acetylated, a decrease in the water vapor permeability was found because the acetylation increased the hydrophobic character of the starch due to the ester group. Films prepared with the double‐modified banana starch had some improved physical, mechanical, and barrier properties, and they may be used in specific applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Probing the Dynamics of Matrix Hydration in the Presence of Electrolytes

The aim of our work was to probe the mechanisms associated with induced matrix stiffening via textural analysis as a consequence of in situ electrolyte interactions within hydroxypropylmethylcellulose (HPMC) and polyethylene oxide (PEO) matrices in relation to their role in controlling the release of highly soluble drugs such as diltiazem hydrochloride (>50% water soluble at 25°C). The dynamics of HPMC and PEO matrix swelling during hydration in the presence of appropriate electrolytes intended to induce constant drug release rates from simple monolithic systems are influenced by continuously shifting peripheral matrix stiffening toward the matrix core in a manner dependent on electrolyte content and hydration time. Matrix erosion for HPMC and PEO controls (i.e., without electrolyte) follow linear dissolution kinetics (r2 > 0.97), while formulations with electrolyte characteristically undergo a square root of time decline in weight. The swelling potential of the electrolyte-containing matrices, influenced by the boundary infiltration process, reflected considerable suppression during the first 2 hr of exposure to medium, while subsequent events differed in both polymers. In view of these differences, simultaneous measurements in textural transitions and electrolyte conductivity showed that PEO has a higher affinity for water molecules than does HPMC.

Effect of cellulase adsorption on the surface and interfacial properties of cellulose

The surface properties of several purified cellulose (Sigmacell 101, Sigmacell 20, Avicel pH 101, and Whatman CF 11) were characterised, before and after cellulase adsorption. The following techniques were used: thin-layer wicking (except for the cellulose Whatman), thermogravimetry, and differential scanning calorimetry (for all of the above celluloses). The results obtained from the calorimetric assays were consistent with those obtained from thin-layer wicking – Sigmacell 101, a more amorphous cellulose, was the least hydrophobic of the analysed celluloses, and had the highest specific heat of dehydration. The other celluloses showed less affinity for water molecules, as assessed by the two independent techniques. The adsorption of protein did not affect the amount of water adsorbed by Sigmacell 101. However, this water was more strongly adsorbed, since it had a higher specific heat of dehydration. The more crystalline celluloses adsorbed a greater amount of water, which was also more strongly bound after the treatment with cellulases. This effect was more significant for Whatman CF-11. Also, the more crystalline celluloses became slightly hydrophilic, following protein adsorption, as assessed by thin-layer wicking. However, this technique is not reliable when used with cellulase treated celluloses.

Mechanistic evaluation of mitigation of petroleum hydrocarbon contamination by soil medium

Present in situ chemical treatment technologies for mitigation of petroleum hydrocarbon contamination are in the developmental stage or being tested. To devise efficient strategies for restricting the movement of petroleum hydrocarbon (PHC) molecules in the contaminated soil, it is proposed to utilize the sorption–interaction relationships between the petroleum contaminants and the soil substrate. The basic questions addressed in this paper are as follows (i) What are the prominent chemical constituents of the various petroleum fractions that interact with the soil substrate? (ii) What are the functional groups of a soil that interact with the contaminants? (iii) What are the bonding mechanisms possible between the soil functional groups and the PHC contaminants? (iv) What are the consequent changes brought about the soil physical properties on interaction with PHC's? (v) What are the factors influencing the interactions between PHC molecules and clay particles of the soil substrate? (vi) What is the possibility of improving the soil's attenuation ability for PHC's? The development of answers to the basic questions reveal that petroleum hydrocarbons comprise a mixture of nonpolar alkanes and aromatic and polycyclic hydrocarbons, that have limited solubility in water. The bonding mechanism between the nonpolar PHC's and the clay surface is by way of van der Waals attraction. The adsorption of the nonpolar hydrocarbons by the clay surface occurs only when their (i.e., the hydrocarbon molecules) solubility in water is exceeded and the hydrocarbons exist in the micellar form. Dilute solutions of hydrocarbons in water, i.e., concentrations of hydrocarbons at or below the solubility limit, have no effect on the hydraulic conductivity of clay soils. Permeation with pure hydrocarbons invariably influences the clay hydraulic conductivity. To improve the attenuation ability of soils towards PHC's, it is proposed to coat the soil surface with "ultra" heavy organic polymers. Adsorption of organic polymers by the clay surface may change the surface properties of the soil from highly hydrophilic (having affinity for water molecules) to organophilic (having affinity for organic molecules). The organic polymers attached to the clay surface are expected to attenuate the PHC molecules by van der Waals attraction, by hydrogen bonding, and also by adsorption into interlayer space in the case of soils containing swelling clays. Key words: petroleum hydrocarbons (PHC's), bonding mechanisms, functional groups, PHC-soil interaction, permeation, hydraulic conductivity, attenuation, van der Waals, organic polymers, organophilic.