Aqueous Isopropanol Solution Research Articles

Investigation on Solutal Marangoni Convection around a Bubble under Different Gravities

The Marangoni convection during isopropanol volatilization to a single nitrogen bubble with the deformable interface is investigated by combining the Volume of Fluid model and the Level Set method. Both the deformation of the bubble and the thermal effect accompanying with the mass transfer are taken into account. The Marangoni convection is investigated under non-gravity and gravity conditions respectively. The flow, temperature and concentration field information are acquired, and the influence of the Marangoni convection on the mass transfer is distinguished. The mass transfer process of a single rising bubble with different diameters in the stationary isopropanol aqueous solution is investigated under different gravities, and occurrence of the Marangoni convection is discriminated.

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.

CONSTANTS OF ELECTROLYTIC DISSOCIATION OF THE LITHIUM, SODIUM AND POTASSIUM SULFATES IN AQUEOUS ISOPROPANOL SOLUTIONS

At introduction of isopropyl alcohol in saturated aqueous solutions of sulfates of lithium, sodium and potassium at 25 °C physico-chemical properties of the studied systems Li2SO4-H2O-C3H7OH, Na2SO4-H2O-C3H7OH and K2SO4-H2O-C3H7OH are changed. This reduces the density of solutions and salt content in aqueous isopropanol solutions due to a decrease in solubility of salts. It is shown that the variation of the volume content of alcohol from 0% to 90% results in the decrease of Li2SO4 solubility 1280 times, Na2SO4 – 548 times, K2SO4 – in 278 times. Alcohol additives also affect the degree of electrolytic dissociation of salt in aqueous isopropanol solutions. To study the electrochemical properties of salts we used conductometric method based on the measurement of the molar conductivity of solutions depending on salt concentration. In aqueous solutions, alkali metal sulfates exhibit the properties of strong electrolytes and almost completely dissociate into ions. When the volume content of isopropanol in the solution is more than 30%, alkali metal sulfates begin to show the properties of weak electrolytes, as evidenced by the correlation of the molar conductivity of the diluted solution with the salt concentration under the equation describing the state of weak electrolytes. From the transformations of experimental data in the coordinates of this equation, the values of the electrolytic dissociation constants of the studied salts were determined, which vary (8.30 ± 0.01)·10-5 to (4,35 ± 0,01)·10-8 (mol/l)2 when varying the alcohol content from 30 to 90% volume. It is shown that isopropanol additives reduce the constant (and hence the degree) of electrolytic dissociation of alkali metal sulfates: the higher the alcohol concentration in the solution, the weaker the salt becomes as an electrolyte. The value of the electrolytic dissociation constant depends on the nature of the salt: with an increase in the size of the sulfate cation, the electrolytic dissociation constant decreases.

Equilibrium solubility, solvent effect and preferential solvation of 5-nitrofurazone (form γ) in aqueous co-solvent mixtures of isopropanol, N-methyl pyrrolidone, ethanol and dimethyl sulfoxide

Solubilities of 5-nitrofurazone (form γ) in aqueous co-solvents mixtures of isopropanol, N-methyl pyrrolidone (NMP), ethanol and dimethyl sulfoxide (DMSO) were experimentally investigated via the saturation shake-flask technique at temperatures from 278.15 K to 323.15 K under ambient pressure of p = 101.2 kPa. The solubility of 5-nitrofurazone increased to a maximum value with 100% mass fractions of NMP and DMSO in aqueous solutions of NMP and DMSO, while with 80% mass fractions of isopropanol and ethanol in aqueous solutions of isopropanol and ethanol. The solids equilibrated with liquor were characterized by X-ray power diffraction, indicating that no solvate formation or polymorphic transformation occurred. The Jouyban-Acree model was accepted to correlate the obtained solubility. The acquired highest relative average deviation and root-mean-square deviation values were, respectively, 5.62 × 10−2 and 11.18 × 10−4. Quantitative values for local mole fractions of NMP (ethanol, DMSO, DMF or isopropanol) and water nearby 5-nitrofurazone were obtained by the method of Inverse Kirkwood–Buff integrals. The parameters of preferential solvation were positive for isopropanol/ethanol in the isopropanol/ethanol mixtures in intermediate compositions, and for NMP/DMF/DMSO in the NMP/DMF/DMSO mixtures in intermediate and NMP/DMF/DMSO-rich compositions, which indicated that 5-nitrofurazone was preferentially solvated by the co-solvents. Linear solvation energy relationships were used to model the solvent effect through the analysis of correlations between solubility data and solvent polarity quantified by suitable descriptors.

Investigation on Preferential Solvation, Transfer Properties and Solvent Effect of Sulfachloropyridazine in Aqueous Co-solvent Solutions of Some Alcohols

The effect of solvent on the solubility of sulfachloropyridazine was studied by making a correlation between the solubility values and solvent’s descriptors for solvent–solute and solvent–solvent interactions with the help of linear solvation energy relationships concept. From analysis of the molecular structure of sulfachloropyridazine, the variation of solubility was well explained in terms of the change in hydrogen bond basicity of mixtures when the mole fraction of methanol (or ethanol or isopropanol) increased in all aqueous binary solvent mixtures. The preferential solvation analysis of sulfachloropyridazine in the three aqueous co-solvent solutions of isopropanol, ethanol and methanol was carried out from solubility values through the method of inverse Kirkwood–Buff integrals. In water-rich compositions of the aqueous co-solvent solutions, the δx1,3 values are negative, indicating that the sulfachloropyridazine was solvated preferentially by the solvent water. In intermediate and alcohol-rich compositions, sulfachloropyridazine was preferentially solvated by the isopropanol, ethanol or methanol. The magnitude of preferential solvation of sulfachloropyridazine is greater in isopropanol solutions than in the other two co-solvent solutions. Analysis results of the KAT-LSER and IKBI methods indicate that the solute mainly acts as a Lewis acid through its –NH2 and > NH functionalities. In addition, the enthalpy, Gibbs energy and entropy of transfer were obtained, which demonstrated that the solubilization ability was more favorable in intermediate composition of the alcohols.

Baicalin solubility in aqueous co-solvent mixtures of methanol, ethanol, isopropanol and n-propanol revisited: solvent–solvent and solvent–solute interactions and IKBI preferential solvation analysis

ABSTRACT The effect of solvent on the baicalin solubility was studied by making a correlation between the solubility values and solvent’s descriptors for solute–solvent and solvent–solvent interactions with the help of linear solvation energy relationship concept. The preferential solvation analysis of baicalin in the four aqueous co-solvent solutions of isopropanol, n-propanol, ethanol and methanol was carried out from solubility values through the method of inverse Kirkwood–Buff integrals. In intermediate and alcohol-rich compositions, the solvation of baicalin was preferred by the isopropanol, n-propanol, ethanol or methanol.

Graphene oxide modified porous P84 co-polyimide membranes for boron recovery by bipolar membrane electrodialysis process

Composite anion-exchange membranes with porous structures have been successfully prepared by incorporating quaternized graphene oxide (QGO) into P84 co-polyimide, and then undergoing the phase inversion, amination and quaternization processes. The membranes’ porous structures can be readily adjusted by the category of non-solvent during the phase inversion process. Large finger-like voids are present in the lower parts of the membrane cross sections by using water or 50% isopropanol aqueous solution, which facilitate the entrance of polyethylenimine chains into the membrane matrix, leading to higher degree of amination and quaternization. The incorporation of QGO does not influence the membrane morphology obviously, but can further enhance the ion exchange capacity (1.23–1.65 mmol/g) and decrease the membrane area resistance (1.6–1.9 Ω cm2).The QGO-P84 composite membranes are used in bipolar membrane electrodialysis (BMED) for the removal of boron from synthetic model solutions (Na2B4O7·10H2O, 1000 mg B/L). The finger-like pores decrease the steric resistance of boron transport, while the incorporation of QGO improves the membrane electro-chemical properties and thus the BMED performances. The separation efficiency is 76.6% after running 3 h under 30 V, the current efficiency is 94.9% and the energy consumption is 26.16 kW h/kg by using the optimal composite membrane. The BMED performances are better than those of commercial membrane CJMA-3 (separation efficiency of 51.6%, current efficiency of 81.2%, and energy consumption of 30.56 kWh/kg). Hence, the QGO-P84 composite membranes are effective for removal and recovery of boron from aqueous solution through BMED method.

Graphene oxide functionalized with zwitterionic copolymers as selective layers in hybrid membranes with high pervaporation performance

Zwitterionic copolymers, poly(glycidyl methacrylate-sulfobetaine methacrylate) [poly(GMA-SBMA)], was incorporated into graphene oxide (GO) to form a GO–poly(GMA-SBMA) framework. This compound was then deposited onto a polysulfone support through pressure-assisted filtration to fabricate hybrid membranes. Optimum fabrication conditions were determined by varying the poly(GMA-SBMA) loading. Attenuated total reflectance-Fourier transform infrared and X-ray photoelectron spectroscopy confirmed the covalent bonding between poly(GMA-SBMA) and GO. On account of loading incremental amounts of poly(GMA-SBMA), the membrane thickness was increased (illustrated by field emission scanning electron microscopic images), the interlayer spacing between GO sheets was expanded (shown by X-ray diffraction patterns), and the membrane hydrophilic properties were enhanced (indicated by water contact angle data). Relative to the pristine GO membrane, hybrid membranes fabricated at optimum conditions exhibited superior separation performance (99.60 wt% water concentration in permeate and 1102 g m−2⋅h−1 permeation flux) on dehydrating a 70 wt% aqueous isopropanol solution by pervaporation. This present study explored the potential of poly(GMA-SBMA) for developing hybrid membranes with excellent pervaporation performance.

Separation of non-sulfonated oil from industrial petroleum sulfonate

The non-sulfonated oil in industrial petroleum sulfonate was separated by centrifugal method and extraction method, respectively. The oil separation rates of each method were compared, and the effects of oil separation rates under different conditions on the purity of non-sulfonated oil were investigated. The purity information of non-sulfonated oil separated by different methods was analyzed by infrared spectroscopy. The experimental results showed that the oil separation rate of centrifugation was low, and the oil extraction rate was higher. The purity of non-sulfonated oil separated with alcohol–water solution as extractant was lower, while the purity of non-sulfonated oil separated by water extraction method was the highest, and the extractant was nontoxic and environmentally friendly. Water was preferred as extractant. Solvent ratio, temperature and pressure all had great influence on oil separation rate. The optimum conditions for SL petroleum sulfonate were: solvent ratio 1.5:1, 90 °C, atmospheric pressure, which the oil separation rate was 78.51%; and for DQ petroleum sulfonate, the optimum conditions were: solvent ratio 2:1, 90 °C, atmospheric pressure, which the oil separation rate was 79.86%. Non-sulfonated oil separated by water extraction had the least petroleum sulfonate, followed by ethanol single solvent extraction. Although the extraction efficiency of isopropanol aqueous solution and n-pentane was the highest, the content of petroleum sulfonate in non-sulfonated oil was the highest, which affected the product performance and should not be used.

Solubility Determination, Modeling, and Preferential Solvation of Terephthalaldehydic Acid Dissolvend in Aqueous Solvent Mixtures of Methanol, Ethanol, Isopropanol, and N-Methyl-2-pyrrolidone

The present work mainly reports the terephthalaldehydic acid solubility in aqueous solutions of methanol, ethanol, isopropanol, and NMP, which was achieved through a steady-state method covering a ...

Titanate nanotubes–incorporated poly(vinyl alcohol) mixed matrix membranes for pervaporation separation of water-isopropanol mixtures

Mixed matrix membranes (MMMs) base on poly(vinyl alcohol) (PVA) incorporated with titanate nanotubes (TNTs), cross-linked with glutaraldehyde, were prepared. The hydrothermally synthesized TNTs and the membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), Thermogravimetric analysis (TGA), Field emission scanning electron microscope (FESEM), and tensile strength analyses. The prepared nanocomposite membranes were used for dehydration of isopropanol by pervaporation process. The effects of the weight fraction of TNTs, feed temperature, and concentration on the performance of the membranes were investigated. The results indicated that incorporation of hydrophilic TNTs could effectively improve the separation performance of PVA membranes in terms of both permeability and separation factor. Based on the results, the separation factor of all nanocomposite membranes was increased. Moreover, the membrane containing 4 wt% of TNTs exhibited the highest separation factor value of 5520, while the maximum value of flux was about 0.126 kg/m2h for the membrane containing 10 wt% TNTs. So, there was about 794% and 741% enhancement in separation factor and flux respectively, compared to the pristine PVA membranes. Consequently, the results confirm incorporating TNTs in the PVA matrix could improve the separation of water from isopropanol aqueous solutions effectively due to the intrinsic hydrophilicity and special structure of TNTs.

Lignin as an effective agent for increasing the separation performance of crosslinked polybenzoxazine based membranes in pervaporation dehydration application

This work reports the utilization of lignin, a renewable and biomass-based material, as an effective modifying agent for thermally stable and hydrophobic membranes based on crosslinked polybenzoxazine (CRPBz) to significantly enhance their permeation fluxes in pervaporation dehydration tests. Lignin could involve in the crosslinking reaction of polybenzoxazine so as to be chemically embedded in the polymer networks. In addition to the inherent hydrophilicity of lignin, lignin could release the hydrophilic groups (phenol and tertiary amine) of crosslinked polybenzoxazine with formation of hydrogen bonding with crosslinked polybenzoxazine, consequently to significantly enhance the hydrophilicity and water permeation fluxes of the studied membranes. With feeding a 70 wt% tetrahydrofuran aqueous solution at 25 °C, lignin modification increases the permeation flux of the CRPBz based membrane from 237 g m−2 h−1 to 490 g m−2 h−1 and separation factor from 11,920 to 19,440. Lignin modification significantly enhances the water permeation flux of the membrane without scarifying separation ability. A 3.4-folds of pervaporation separation index (PSI, the product of permeation flux and separation factor) has been demonstrated with the lignin modification. Similar performance has also been recorded on the tests on a 70 wt% isopropanol aqueous solution. The effect of lignin has been attributed to increase the membrane hydrophilicity for facilitating water permeation. The results demonstrate the wide application scopes of the lignin-modified CRPBz based membranes in pervaporation dehydration based on their high stability and hydrophilicity.

Poly(vinyl alcohol)/ZSM-5 zeolite mixed matrix membranes for pervaporation dehydration of isopropanol/water solution through response surface methodology

Mixed matrix membranes (MMMs) of poly(vinyl alcohol) (PVA) containing certain amounts of ZSM-5 zeolite were evaluated for pervaporation dehydration of highly concentrated isopropanol aqueous solution. The effects of zeolite content, feed composition and feed temperature on the membrane separation performance are in detail examined by using a preliminarily one-factor-each time method and a systematically response surface methodology (RSM). Preliminarily results show the dehydration separation factor/selectivity have been greatly boosted but without the cost of pervaporation flux/permeance after adding zeolite ZSM-5, and it is consistent very well with the Arrhenius activation energy estimations where water molecules require much less energy whereas ethanol molecules need much more energy to transport through the membrane, probably because of the favorable hydrophilic and porous features of zeolite ZSM-5 as revealed by swelling and water contact angle results. High feed isopropanol concentration and low feed temperature are both observed to lead to very low pervaporation flux/permeance but very relatively high separation factor/selectivity. The RSM results suggest that zeolite content, feed composition and feed temperature all have highly significant impacts on total pervaporation flux and separation factor. The interaction effect of zeolite content and feed temperature on separation factor is for the first time found to be also significant. The polynomial models established according to the RSM analysis can fit very well against the experimental data with a very high coefficient of determination and the predictions given for optimized conditions have been experimentally confirmed by the validation results with a deviation of less than 2.0%.

Modification of Nafion membrane by polyaniline providing uniform polymer distribution throughout the membrane

Oxidative polymerization of aniline in the presence of Nafion membranes has been carried out in a water–isopropanol mixture after preliminary impregnation of the membrane with the monomer (aniline) in aqueous isopropanol. Uniform distribution of polyaniline (PANI) throughout whole membrane volume has been found. On the contrary, aniline polymerization in water, even after preliminary impregnation of the membrane with the monomer, has resulted in the formation of PANI thin layer only on the membrane surfaces but not inside the membrane. The polymerization in water–isopropanol mixture has not led to the change in the membrane surface properties but has induced the structural reorganization of Nafion membrane accompanied by the increase in the membrane ionic cluster size and the distance between the fluorocarbon crystallites. Modification by PANI carried out either in water or in aqueous isopropanol solution has resulted in the decrease in the membrane proton conductivity by 5–10 times.

Enhanced pervaporation performance of polyamide membrane with synergistic effect of porous nanofibrous support and trace graphene oxide lamellae

Electrospun nanofibrous membrane as a supporting layer has attracted great interests in fabricating high performance composite membranes due to its interconnected porous structure. However, it’s still a challenge to prepare an ultrathin and integrated skin layer on porous and undulating nanofibrous support, thereby restricting its application in pervaporation. Here, graphene oxide (GO) was introduced into amine aqueous phase to form an integrated and compact polyamide (PA) layer on nanofibrous substrate via interfacial polymerization (IP). Under the synergistic effect of high permeability of the nanofibrous scaffold and flexibility of GO lamellae, tiled GO lamellae acting as a skeleton got involved in the initial reaction for the construction of selective PA layer. By loading trace amount of GO in aqueous phase during IP, the selectivity of PA layer was enhanced significantly compared with that of pristine PA layer on nanofibrous scaffold. High permeate flux of 6593 g/m2h with a desirable separation factor of 1491 was achieved using the hybrid membrane with just 0.001 wt% of GO loading for pervaporation dehydrating 90 wt% isopropanol aqueous solution at 70 °C. These results indicated the feasibility of constructing a single homogeneous selective layer on nanofibrous support for high-performance pervaporation process.

High efficient hydrogen evolution over self-reproducible platinum photocatalyst

Abstract The current artificial photocatalysts often suffer from photocorrosion-induced irreversible damage and low efficiency. Here we report that under the UV irradiation of aqueous isopropanol solution, which photolysis to produce acetone and consume photoelectron in time and be oxidized to form acetone. And then the platinum nanoparticles can coordinate with product acetone on their surfaces to create a unique photocatalysis system for high efficient hydrogen evolution. In this system, the inherent close bonding between photoactive surface complexes and metallic platinum sites creates an efficient donor-acceptor system for charge transfer and leads to high efficiency, with hydrogen generation rate of 8.01 mmol⋅ h−1. Furthermore, in the presence of isopropanol the photoactive acetonyl-platinum complexes are generated reproducibly via a continuous isopropanol-to-acetone conversion and thus work sustainably. This finding indicates the possibility of artificially creating self-reproducible systems to drive photocatalytic reactions efficiently and robustly.

Pervaporation Performance of Submerged Type Membrane for the Separation of Water from Aqueous Isopropanol Solution

Pervaporation Performance of Submerged Type Membrane for the Separation of Water from Aqueous Isopropanol Solution

Preparation of inexpensive NaA zeolite membrane on pozzolan support at low temperature for dehydration of alcohol solutions

In this paper, inexpensive NaA zeolite membrane was hydrothermally prepared by in situ crystallization on flat pozzolan support at low temperature, and applied for dehydration of ethanol and isopropanol solutions through pervaporation process. The thin zeolite layer was grown on seeded support via secondary growth method using molar composition of synthesis batch of Al2O3: 2 SiO2: 15 Na2O: 800 H2O.The effect of operating parameters such as synthesis temperature and crystallization time on NaA zeolite membrane was investigated. X ray diffraction and scanning electron microscope analysis have confirmed, on the one hand, that zeolite synthesized at 60 °C is pure and has the typical NaA zeolite morphology (cubic form), and have shown on the other hand that the zeolite membrane is homogeneous and free from defects. Optimized membrane (prepared at 60 °C during 24 h) was studied in dewatering of ethanol and isopropanol aqueous solutions varying water content from 10 to 50 wt.% by pervaporation 75 °C. At 10 wt.% of water content, experimental results showed that separation performance of the membrane is excellent in terms of separation factor (11,100 and 14,400 respectively for ethanol and isopropanol) and permeate flux (9.5 and 10.1 kg/h.m2 respectively for ethanol and isopropanol). The findings of this research suggest that the prepared NaA zeolite membrane could be useful for high separation performance of alcohol/water mixtures at low cost (using cheaper pozzolan support as well as NaA zeolite crystallization at low temperature).

Graphene nanosheets obtained through graphite powder exfoliation in pulsed underwater electrical discharge

Graphene nanosheets were produced by graphite exfoliation through underwater electrical discharge, also known as plasma underwater. Graphite particles were dispersed in different solvents with different ratios between polar and dispersive surface tension components (pure water and an aqueous solution of isopropyl alcohol (IPA) at different concentrations (1:1 and 7:3 IPA:Water)) under constant stirring and low voltage pulses (about 1.5 kV). Even under relative low voltage, the production of graphene was observed in all solvents with the most of the graphene sheets containing less than 10 monolayers. Results show that further affinity between the surface tensions of the graphite and the solvents influenced in the characteristic of the graphene obtained. The 7:3 IPA/water solution has a similar ratio between polar and dispersive surface tension components to the graphite and the mixture. Exfoliation product obtained with this mixture presented an intense peak at ∼284.3 eV, which is corresponding to sp2 binding, characteristic of the graphene. However, in this solution, it was observed further break of C-C bonds and a significant reduction of its surface area. Smaller graphene flakes sizes present more C-O contents due to the carboxyl groups be more likely to form at graphene edges than at defect sites within the basal plane.

High permselectivity of networked PVA/GA/CS-Ag+-membrane for dehydration of Isopropanol

Using glutaraldehyde (GA) as the crosslinking agent, the polyvinyl alcohol (PVA)/GA/chitosan (CS)-Ag+ networked membrane having high mechanical strength could be readily obtained via blending the Ag+-chelated CS precursor with PVA, performing excellent permeability and selectivity for the dehydration of aqueous isopropanol (IPA) solution. The introduction of the silver ion for the PVA/GA/CS-Ag+ membrane could effectively facilitate the water flux without loss its selectivity and particularly show its importance for the dehydration of water/isopropanol system under lower water percentage in feed, which is more favorable for high degree of propanol purification applications. Based on the membrane prepared under the Ag+ content of 1.17 × 10−2 mol., we demonstrated that the highest flux of 1.97 kg/m2 h accompanied with a separation factor up to 89991 could be achieved for the pervaporation dehydration of an isopropanol solution with the concentration of 90 wt% under a temperature of 30 °C. X-ray diffraction (XRD) was used to examine the existence of the sliver ion and its compatibility with polymeric matrix, and Fourier transform infrared spectroscopy (FTIR) enables the formation of networked structure to be detected, which can also reflect in the cross section morphology of the membranes observed using scanning electron microscopy (SEM). Effect of GA and the silver ion on the thermal-resistance of the resultant membrane was evaluated using thermogravimetric analysis (TGA). Membranes prepared using different compositions in response to hydrophilicity and mechanical strength were respectively evaluated by means of contact angle measurements and tensile strength tests.