Isopropanol Solution Research Articles

Experimental and numerical investigation on bubble behaviors and pool boiling heat transfer of semi-modified copper square pillar arrays

In the present study, bubble growth on the boiling surfaces and pool boiling heat transfer characteristics of semi-modified pillar arrays are experimentally investigated at atmospheric pressure, while the bubble behaviors inside pillar gaps are numerically revealed in different contact angles by lattice Boltzmann method based on the pseudopotential LB model. The hybrid and hierarchical pillars are fabricated by semi-silver-deposition and wire-electrode-cutting respectively. The effects of wettability, surface morphology and surfactant concentration are considered. Deionized water, aqueous isopropanol and n-heptanol solutions with concentrations of 100 ppm, 200 ppm, and 800 ppm are used as the working liquids. The experimental results show that contact angles of isopropanol and n-heptanol solutions on copper plate are changed considerably by silver-deposition. Semi-silver-deposition and additions of isopropanol and n-heptanol considerably affect pool boiling heat transfer and bubble behaviors of straight and hierarchical copper square pillars. The numerical results show that vapor films generate at most gap bottoms at the contact angle of 131.8° which impede liquid supplement process toward the gaps compared with the contact angle of 98.7° on the straight pillar array surface.

Synthesis and Characterization of Hydroxyethyl Starch from Chips Wastes Under Microwave Irradiation

This article focuses on the synthesis of hydroxyethyl potato starch (HEPS) for liquid hand soap by evaluating waste potato starch (WPS), a byproduct in potato chips production. It is a cheap, biodegradable, non-toxic and renewable natural polymer, available in great quantities on a global level. In a factory producing potato chips, WPS, which remained in the aqueous medium during peeling, slicing, and washing the potatoes, was purified at the desired temperature with H2O2 and NaOH. HEPSs with the molar substitution (MS) in the range from 0.298 to 0.670, were synthesized under microwave irradiation in isopropanol (IPA) and NaOH solution by adding ethylene oxide (EO) to WPS. The selected reaction parameters were the concentration of NaOH, the proportion of EO, and reaction time in an attempt to understand their effects on the reaction. Considering all the studied conditions, the highest viscosity was reached at 250 cP for the highest MS in the sample of HEPS-4 when 15 g EO was used in 20 mL solution of 40% NaOH at 40 °C for 40 min under microwave irradiation. The structure of synthesized HEPSs has been characterized by FT-IR, XRD, 1H(13C)-NMR spectroscopic methods, and the degree of molar substitution was calculated from 1H-NMR spectra. In addition, thermal stability and surface morphology of characterized HEPSs were studied by DTG-TG and SEM, respectively. The thickener effect of hydroxyethyl starch in liquid hand soap was investigated. In this way, it has been understood that in the production of liquid hand soaps, hydroxyethyl potato starch can be used instead of coco diethanolamide (CDEA).

High-performance polyamide composite membranes via double-interfacial polymerizations on a nanofibrous substrate for pervaporation dehydration

A novel double-interfacial polymerizations (double-IP) strategy was demonstrated for the maneuverable fabrication of high-performance polyamide (PA) composite membranes based on nanofibrous substrates for efficient isopropanol dehydration by pervaporation. Firstly, an ultra-thin auxiliary polyamide layer (A-PA) was synthesized on a highly porous polyacrylonitrile (PAN) nanofibrous substrate by using low concentration ethylenediamine (EDA) and trimesoyl chloride (TMC) solution, which decreased the reaction rate and prolonged polymerization time to achieve a smooth, relatively loose but intact A-PA layer. Secondly, a more compact PA selective layer (S-PA) was fabricated with relatively high concentration EDA and TMC solution on A-PA surface. Benefiting from the A-PA layer, the amount and diffusion rate of adsorbed EDA solution through the layer to contact TMC solution were effectively controlled in second IP process. S-PA layers tended to be more uniform, and there was no marked void or detachment observed between two PA layers. Significantly, the pervaporation performance of as-prepared membranes were tuned by changing the structure of S-PA layers with the assistant of different A-PA layers. The optimized two-tier polyamide (Bi-PA) thin-film nanofibrous composite (TFNC) pervaporation membranes exhibited high permeate flux (6075 g/(m2 h)) and enhanced separation factor (1314) for dehydrating 90 wt% aqueous isopropanol solution at 70 °C. This work may suggest an efficient and facile approach to fabricate high performance pervaporation membranes.

Per‐6‐Thiol‐Cyclodextrin Engineered [FeFe]‐Hydrogenase Mimic/CdSe Quantum Dot Assembly for Photocatalytic Hydrogen Production

[FeFe]‐hydrogenase ([FeFe]‐H2ase) mimics, inspired by hydrogenases in nature, have emerged as an important class of molecular catalysts toward hydrogen (H2) evolution. Herein, a per‐6‐thiol‐cyclodextrin (CDSH) engineered [FeFe]‐H2ase mimic/CdSe quantum dot (QD) assembly is established for effective photocatalytic H2 evolution. In the assembly, CDSH is first anchored on CdSe QDs via the strong multidentate Cd‐thiol coordination. Then, [FeFe]‐H2ase mimic is assembled on the QD surface via the host–guest supramolecular interaction between the hydrophobic cavity of cyclodextrin (CD) and the adamantyl (AD) group of [FeFe]‐H2ase mimic. In neutral aqueous solution of isopropanol, the Fe2S2‐AD/CDSH/CdSe assembly exhibits a turnover number (TON) of 1.12 × 105 (based on Fe2S2‐AD) under visible light, which is about 12‐fold to the corresponding system without CDSH. Mechanistic insights indicate that the CDSH can not only prevent the aggregation of QDs in acidic conditions, but also balance the interfacial charge (electron and hole) transfer to avoid the photocorrosion of QDs, thereby giving the highest TON of H2 photogeneration based on [FeFe]‐H2ase mimics up to date.

The Effect of Shape on the Motion and Stability of Marangoni Surfers

AbstractThe Marangoni propulsion of spheres and elliptical disks floating on the air–water interface were studied to understand the effect of particle shape on its motion and its stability at moderate Reynolds numbers. Self-propulsion of the Marangoni surfer was achieved by coating half of the spheres and the elliptical disks with either a solution of soap or isopropyl alcohol (IPA). The presence of the soap or IPA resulted in a surface tension gradient across the particles which propelled the particles in the direction of increasing surface tension. Beyond a critical velocity, a transition was observed from a straight-line motion to a rotational motion. These vortices were observed to shed above a critical Reynolds number resulting in an unbalanced torque that caused the particles to rotate. Increasing the aspect ratio between the major and minor axes of the elliptical disks was found to decrease their stability and greatly enhance their rate of rotation. This was especially true for elliptical disks traveling in a direction parallel to their major axis. The interactions between the particles and the wall of a Petri dish were also studied. Repulsive, concave curvature was found to decrease stability and enhance rotational motion, while attractive, convex curvature was shown to stabilize the straight-line motion of the spheres. For the neutrally buoyant elliptical disks, the presence of the bounding wall was found to greatly stabilize the straight-line motion of the elliptical disks when they were traveling in a direction parallel to their minor axis.

Problems Arising from Using KOH–IPA Etchant to Texture Silicon Wafers

Wet chemical processing of single-crystal silicon wafers, including their texturing, is a key process step in the fabrication of high-efficiency solar cells. Methods of texturing single-crystal silicon wafers used in solar cell technology have been studied. Optimal texturing parameters have been determined for test samples, and the most effective etchant for texturing, a KOH–isopropanol solution, has been found.

Equilibrium solubility of 7-amino-4-methylcoumarin in several aqueous co-solvent mixtures revisited: Transfer property, solute-solvent and solvent-solvent interactions and preferential solvation

The preferential solvation analysis was carried out by the inverse Kirkwood–Buff integrals method on available solubility data of 7-amino-4-methylcoumarin in four aqueous co-solvent mixtures of ethylene glycol (EG, 1) + water (2), isopropanol (1) + water (2), ethanol (1) + water (2) and DMF (1) + water (2). Results show that the drug is preferentially surrounded by water in water-rich regions, and by organic solvents in other composition ranges. Among these binary mixtures, the highest preferential solvation magnitude was recorded for isopropanol solutions. Selective solvation of the drug by organic solvents may be owing to the higher basicity of solvents that facilitates interactions with the Lewis acidic groups of 7-amino-4-methylcoumarin. A solvent effect analysis was performed by using the linear solvation energy relationships to unravel the relative importance of solute-solvent and solvent-solvent interactions on the solubility variation. In addition, the transfer properties, e.g. transfer Gibbs free energy (ΔtrGo), transfer enthalpy (ΔtrHo) and transfer entropy (ΔtrSo) were derived in terms of the accessible solubility data, indicating more favorable solubilization ability in the intermediate compositions of co-solvents.

5-Ammonium Valeric Acid Iodide to Stabilize MAPbI3 via a Mixed-Cation Perovskite with Reduced Dimension.

5-Ammonium valeric acid iodide (AVAI) has been widely known as a stabilizer to enhance the stability of MAPbI3 perovskite, but its role and function is still under exploration. The typical 2D perovskites of AVA2PbI4 have been proposed as the capping layer for stabilization. Here, a novel AVA-MA mixed-cation perovskite of AVAMAPbI4 is found to show a more even and compact coverage than the typical 2D perovskite of AVA2PbI4. A simple post-treatment on MAPbI3 films by using AVAI isopropanol solution can fabricate such a mixed-cation 2D perovskite capping layer on the MAPbI3 sample. This AVAMAPbI4 capping layer effectively passivates surface defects of MAPbI3 perovskite films and reduces the charge-carrier recombination, enabling AVAI-MAPbI3 perovskite films to exhibit improved stability against thermal and moisture stress. Finally, the AVAI-MAPbI3-based perovskite solar cells also show an enhanced photovoltaic performance with a champion PCE up to 20.05% with enhanced stability.

Highly crystalline MAPbI3 perovskite grain formation by irreversible poor-solvent diffusion aggregation, for efficient solar cell fabrication

Energy efficient synthesis providing high quality crystalline thin films are highly desired in many applications. Here we devise a non-toxic solvent approach for production of highly crystalline MAPbI 3 perovskite by exploiting diffusion aggregation processes. Isopropanol solution based methylammonium lead triiodide (MAPbI 3 ) is used in this context, where the crystal growth initiation starts in an unstable suspension far from equilibrium and the subsequent crystallization is driven by the solubility parameters. The crystal formation is monitored by scanning transmission electron microscope (STEM), observing small crystallization centers growing as time evolves to large grains with high crystal purity. Energy dispersive X-ray spectroscopy (EDS) in STEM mode revealed a Pb rich core-shell structure in newly formed grains. Nano-beam Electron Diffraction (NBED) scan defined PbI 2 crystallites in the Pb rich shell with a single crystal MAPbI 3 core in newly formed grains. After a week stirring, the same aggregated suspension exhibited grains with only single crystal MAPbI 3 structure. The NBED analysis shows a kinetically slow transition from a core shell structure to a single crystal grain. This research presents an impactful insight on the factors that may cause sub-stoichiometric grain boundary effects which can influence the solar cell performance. In addition, the structure, morphology and optical properties of the perovskite grains have been presented. A powder of highly crystalline particles was subsequently prepared by evaporation of the solvent in a low-vacuum oven. Thin film MAPbI 3 solar cells were fabricated by dissolving the powder and applying it in a classical fabrication route. The MAPbI 3 solar cells gave a champion efficiency of 20% (19.9%) and an average efficiency at approximately 17% with low hysteresis effects. Here a strategy to manufacture the material structure without toxic solvents is highlighted. The single-crystal growth devised here opens both for shelf storage of materials as well as a more flexible manufacturing of devices. The process can likely be extended to other fields, where the intermediate porous framework and large surface area would be beneficial for battery or super capacitor materials. • A non-toxic solvent approach for production of high quality MAPbI 3 perovskite grains. • Nano-beam electron diffraction scan on PbI 2 crystallites and single crystal MAPbI 3 grains. • The porous framework of grains and large surface area would be beneficial for energy storage. • Low hysteresis effects and high efficiency for the perovskite solar cells.

Development of Reference Materials with the Composition of Propyl and Isopropyl Alcohol Solutions

Development of Reference Materials with the Composition of Propyl and Isopropyl Alcohol Solutions

Method Development for Quantitative Determination of Diosgenin from the Seeds of Fenugreek, <i>Trigonella foenum-graecum</i> L.

Introduction . Modern pharmacognostic research is aimed at searching for plant biologically active individual compounds (RBAIS) isolated from plant extracts. Aim . Study of the content of the steroid sapogenin diosgenin in fenugreek seeds in plant extracts by HPLC-UV method. Materials and methods . The object of study was raw materials-fenugreek seeds produced as medicinal plant raw materials by LLC «Sage» (Irkutsk). Series of extraction and chromatographic separation by HPLC-UV method were performed. Results and discussion . In this work, the method of diosgenin extraction was successfully optimized (after acid hydrolysis of dioscin with a 5 % aqueous solution of hydrochloric acid when heated for at least 4 hours in a sand bath at a power of 150 W) from raw fenugreek seeds using a 50 % aqueous solution of isopropanol, h.h. A simplified technique for chromatographic separation of diosgenin from fenugreek seed extracts using an isocratic mode of 99.9 % acetonitrile elution (h.h.) was proposed. Conclusion . The average content of diosgenin (after acid hydrolysis of dioscin) in fenugreek seeds, taking into account the humidity of raw materials, is (M ± σ ) 5,3 ± 0,05 mg/g (95 % CI: 5,1-5,4 mg/g; n = 6).

Does skin preparation alter suture strength characteristics? Assessing the effect of chlorhexidine and isopropyl alcohol on common skin closure suture material.

Sutures are essential to approximate tissues and enable healing by first intention until a wound regains its original tensile strength. The mechanical properties of sutures are well documented, but the effects of exposing sutures to skin preparation solutions used in surgery are not. This study was performed to investigate whether 2% chlorhexidine and 70% isopropyl alcohol skin preparation, commonly used prior to incision and prior to closure, has any effect on the mechanical properties of several commonly used surgical suture types. Four suture types were soaked in either 2% chlorhexidine and 70% isopropyl alcohol or Hartmann's solution for 5 minutes. All sutures were left to dry for 11 days before being tested to failure using an Instron 3367 tensile testing machine. Testing revealed significant differences in failure load, ultimate tensile stress, and Young's modulus between suture types (P < .05). No significant differences in failure load (P = .98), ultimate tensile stress (P = .21), or Young's modulus (P = .22) were observed between the test group and the control group when comparing sutures of the same type. This study demonstrates that chlorhexidine/isopropyl skin preparation solutions do not significantly change the mechanical properties of suture materials exposed to them.

Capturing Lacunary Iron-Oxo Keggin Clusters and Insight Into the Keggin-Fe13 Cluster Rotational Isomerization.

The formation mechanism of ferrihydrite is the key to understand its treatment of pollutants in waste water and purification of surface water and groundwater. Although emerging evidence suggests that formation of the ferrihydrite occurs through the aggregation of prenucleation clusters, rather than classical atom-by-atom growth, its formation mechanism remains unclear. Herein, an iron-oxo anionic cluster of [Fe22 (μ4 -O)8 (μ3 -OH)20 (μ2 -OH)18 (CH3 COO)16 (H2 O)2 ]4- viewed as a dimer of bivacant β-Keggin-Fe13 clusters was for the first time obtained by using lanthanide ions as stabilizers. Upon dissolution in a mixed solution of isopropanol and water, the lacunary β-Keggin-Fe13 cluster can transform into an α-Keggin-Fe13 cluster, distinctly demonstrating that the Keggin-Fe13 cluster rotational isomerization can be realized through the vacant Keggin-Fe13 cluster.

Concomitant polymorphic forms of 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole.

The dipharmacophore compound 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole, C10H11N5O, was studied on the assumption of its potential biological activity. Two concomitant polymorphs were obtained on crystallization from isopropanol solution and these were thoroughly studied. Identical conformations of the molecules are found in both structures despite the low difference in energy between the four possible conformers. The two polymorphs differ crucially with respect to their crystal structures. A centrosymmetric dimer formed due to both stacking interactions of the `head-to-tail' type and N-H...N(π) hydrogen bonds is the building unit in the triclinic structure. The dimeric building units form an isotropic packing. In the orthorhombic polymorphic structure, the molecules form stacking interactions of the `head-to-head' type, which results in their organization in a column as the primary basic structural motif. The formation of N-H...N(lone pair) hydrogen bonds between two neighbouring columns allows the formation of a double column as the main structural motif. The correct packing motifs in the two polymorphs could not be identified without calculations of the pairwise interaction energies. The triclinic structure has a higher density and a lower (by 0.60 kcal mol-1) lattice energy according to periodic calculations compared to the orthorhombic structure. This allows us to presume that the triclinic form of 3-cyclopropyl-5-(2-hydrazinylpyridin-3-yl)-1,2,4-oxadiazole is the more stable.

Rutaecarpine dissolved in binary aqueous solutions of methanol, ethanol, isopropanol and acetone: Solubility determination, solute-solvent and solvent-solvent interactions and preferential solvation study

The main objective of this work was to report the mole fraction solubility of rutaecarpine in four binary solutions of methanol (1) + water (2), isopropanol (1) + water (2), acetone (1) + water (2) and ethanol (1) + water (2) acquired through the saturation shake-flask technique. All experiments were conducted at temperatures from 283.15 K to 323.15 K. The maximum solubility was observed in the pure solvent of methanol/ethanol/isopropanol/acetone for each solution. The achieved rutaecarpine solubility in mole fraction was mathematically described by two common co-solvency models, namely Jouyban-Acree model and van’t Hoff-Jouyban-Acree model. The calculated relative average deviations were no more than 6.78%; and root-mean-square deviations, no more than 23.69 × 10−6. The linear solvation energy relationships suggested by Kamlet and Taft was used to examine the effect of solvent descriptors on the behaviour of rutaecarpine solubility. The Hildebrand solubility parameter and dipolarity-polarizability were predominant contributors to solvent effect for the four mixtures studied. The local mole fractions of methanol (acetone, isopropanol or ethanol) and water nearby the solute rutaecarpine were quantitatively analyzed through an Inverse Kirkwood–Buff integrals method. For these mixtures within intermediate and methanol/ethanol/isopropanol/acetone-rich compositions, rutaecarpine was preferentially solvated by the methanol/ethanol/isopropanol/acetone; while within water-rich compositions, by the water.

Precipitation and Transformation of Vaterite Calcium Carbonate in the Presence of Some Organic Solvents.

In this paper, the production of CaCO3 particles via the carbonation route in the reaction of CaCl2 and CO2, using NH3 as a promoter of CO2 absorption, was studied. The solvents used as the reaction media for CaCO3 precipitation were aqueous solutions of methanol, isopropanol and dimethyl sulfoxide (DMSO), in a concentration range of 0–20% (v/v). It was found that the presence of an organic additive influenced the precipitation rate, the content of vaterite in the obtained product, the morphology and the size of the precipitated CaCO3 particles, as well as the rate of its transformation into calcite. The presence of all added organic solvents reduced the vaterite concentration in the produced CaCO3 both at the end of the reaction and after incubation in the reaction medium for 1 h. However, the transformation of vaterite particles into calcite in the tested solutions was slower when the 4 h and 24 h procedures were compared. The interactions of solvents with calcite and vaterite were compared using HPLC tests. DMSO molecules interacted with vaterite particles the most strongly, while the interaction of isopropanol with this polymorph was the weakest. The opposite effect was observed for interactions with calcite particles, and the affinity decreased in the series: isopropanol, methanol, DMSO.

Forces between silica particles in isopropanol solutions of 1:1 electrolytes

Interactions between silica surfaces across isopropanol solutions are measured with colloidal probe technique based on atomic force microscope. In particular, the influence of 1:1 electrolytes on the interactions between silica particles is investigated. A plethora of different forces are found in these systems. Namely, van der Waals, double-layer, attractive non-DLVO, repulsive solvation, and damped oscillatory interactions are observed. The measured decay length of the double-layer repulsion is substantially larger than Debye lengths calculated from nominal salt concentrations. These deviations are caused by pronounced ion pairing in alcohol solutions. At separation below 10 nm, additional attractive and repulsive non-DLVO forces are observed. The former are possibly caused by charge heterogeneities induced by strong ion adsorption, whereas the latter originate from structuring of isopropanol molecules close to the surface. Finally, at increased concentrations the transition from monotonic to damped oscillatory interactions is uncovered.

Bezafibrate in several aqueous mixtures of low alcohols: Solubility, solvent effect and preferential solvation

By using the saturation shake-flask method, the saturated solubility of bezafibrate in neat water, methanol, ethanol, n-propanol and isopropanol and aqueous co-solvent mixtures of methanol (1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and n-propanol (1) + water (2) was experimentally acquired at temperatures from 283.15 Kto 323.15 K and local atmospheric pressure. The maximum solubility magnitudes in mole fraction were recorded in the neat solvents of methanol/ethanol/n-propanol/isopropanol for corresponding solutions. The mole fraction solubility was described mathematically by using the van’t Hoff-Jouyban-Acree and Jouyban-Acree models. The largest value of relative average deviations was 6.23%; and, root-mean-square deviations, 8.92 × 10−5. The local mole fractions of water and co-solvent (methanol, ethanol, n-propanol or isopropanol) around the drug bezafibrate were quantitatively investigated by the use of Inverse Kirkwood–Buff integrals method. Results indicated that the bezafibrate was preferentially solvated by methanol (ethanol, n-propanol or isopropanol) in alcohol-rich and intermediate compositions in the alcohol mixtures; while in water-rich compositions, bezafibrate was preferentially solvated by water. The main factors relating to solvent effect were inspected through Kamlet and Taft linear solvation energy relationships, demonstrating that the cavity formation energy and dipolarity-polarizability in methanol solutions, cavity formation energy and basicity in ethanol solutions, and cavity formation energy in n-propanol (isopropanol) solutions played the principal role upon the bezafibrate solubility variation.

Peculiar and full debromination of tetrabromodiphenyl ether on Pd/TiO2: A competing route through hydro-debromination and coupling-debromination

The use of palladium deposited TiO2 (Pd/TiO2) as catalysts yielded complete debromination of 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) in isopropanol solution containing NaOH at 40 °C within 60 min. The final organic products were diphenyl ether and dibenzofuran. It was disclosed that two competing reduction paths (hydro-debromination and coupling-debromination) occurred over Pd nanoparticles. The hydro-debromination was dependent on the participation of active H atom species generated by catalytic transfer hydrogenation on metallic Pd. The coupling-debromination proceeded via the oxidative addition of Pd(0) to Br2C12H8OBr2′, leading to an transition state of Br2PdIIC12H8OBr2′, the reductive dissociation of which resulted in the elimination of Br− ions, producing a new transition state Pd0C12H8OBr2′−. A further oxidative addition of Pd0C12H8OBr2′− generated Br2′PdIIC12H8O−, and its final reductive elimination provided dibenzofuran, leading to the regeneration of Pd(0). The integration of the catalytic coupling and hydrogenation reaction on Pd nanoparticles greatly accelerated the removal of the halogenated organic pollutants.

Structural configurations and Raman spectra of carbon nanoscrolls

Three types of carbon nanoscroll (CNS) structures that are formed when scrolling up graphene sheets are investigated using Raman spectroscopy and atomic force microscopy (AFM). The CNSs were produced from exfoliated monolayer graphene deposited on a Si chip by applying a droplet of isopropyl alcohol (IPA) solution. The three types of CNS are classified as single-elliptical-core, double-elliptical-core (both with large internal volumes) and collapsed ribbon-like, based on AFM surface profile measurements. We discuss the structure and formation of CNS with much larger hollow cores than is commonly assumed and relate this to the large effective 2D bending stiffness of graphene in the IPA solution. The large elliptical core structures show Raman spectra similar to those previously reported for CNS and indicate little interaction between the scrolled layers. The Raman spectra from ribbon-like structures show additional features that are similar to that of folded graphene. These new features can be related to layer breathing modes combined with some resonance enhancement at specific regions of the ribbon-like CNSs that are due to specific twist angles produced when the structure folds/collapses.