Binary Aqueous Solutions Research Articles

Probing the Molecular Dynamics of Aqueous Binary Solutions with THz Time-Domain Ellipsometry.

Using a customized time-domain ellipsometer operating in the THz range, the molecular dynamics of a liquid binary solution based on water and isopropyl alcohol (2-propanol) is investigated. The setup is capable of detecting small changes in the optical properties of the mixture within a single measurement. The complex dielectric response of samples with different concentrations is studied through the direct measurement of the ellipsometric parameters. The results are described using an effective Debye model, from which the relaxation parameters associated with different activation energies can be consistently extracted. Significant deviations between experimental data and the theoretical expectations at an intermediate volume percentage of 2-propanol in water are observed and interpreted as produced by competing effects: the creation/destruction of hydrogen bonding on the one hand, and the presence of cluster/aggregation between water and alcohol molecules on the other.

Application of chemometrics tools for removal of crystal violet and methylene blue in binary solution by eco-friendly magnetic adsorbent modified on Heracleum persicum waste

Synthetic dyes can be hazardous to the ecosystem, even at low concentrations in the effluent. In this research, the Heracleum persicum stems-Fe3O4 (MHPS) adsorbent performance for the removal of crystal violet (CV) and methylene blue (MB) from binary aqueous solutions was investigated in a batch method under the influence of different parameters. In addition, predictive models for the adsorption process were developed using machine learning techniques such as artificial neural networks and random forests. ANN and RF models achieved high R2 values of 0.9501 and 0.9797 for CV, 0.9471, and 09,834 for MB, respectively, and obtained low MSE values of 0.07107 and 0.03405 for CV, 0.09933, and 0.02908 for MB. The proposed adsorbent is cheap and eco-friendly and, on the other hand, is easily collected by the magnetic field. The adsorbent was characterized by applying FESEM-EDX, FESEM, BET, and FTIR. Various isotherm and kinetics models for the simultaneous adsorption of CV and MB were investigated in aqueous solutions. The adsorption isotherm and kinetics studies explain that the extended Langmuir model and pseudo-second-order models are best suited for CV and MB in the binary solution. The exothermic adsorption was achieved in the temperature range of 5–45 °C.

Study of the properties of binary systems: Selected derivatives of B-vitamins-cationic surfactant

Aqueous binary solutions consisting of CTAB and niacinamide or d-panthenol were tested using conductometric, spectroscopic and tensiometric methods in two concentration variants. Based on the conductometric tests, the CMC values were determined and the interaction parameter (β) was estimated. Slight antagonistic interactions were found in mixed micelle systems. Based on tensiometric measurements, the parameters of the adsorption at the interface were determined, the adsorption process was thermodynamically more preferred for the CTAB-niacinamide system. The Wilhelmy method was used to determine the effect of niacinamide and d-panthenol addition on the value of the contact angle and thus on the wetting properties of the binary systems tested. UV–vis analysis enabled the identification and understanding of structural changes and interactions occurring in the studied binary systems. Moreover free Radical Scavenging Capacity of investigated systems was evaluated using DPPH• assay. IC50 value indicated weak antioxidant activity of niacinamide. An increase in Free Radical Scavenging Capacity of CTAB-N system was observed compared to pure niacinamide.

Surface tension models for binary aqueous solutions: a review and intercomparison.

The liquid-air surface tension of aqueous solutions is a fundamental quantity in multi-phase thermodynamics and fluid dynamics and thus relevant in many scientific and engineering fields. Various models have been proposed for its quantitative description. This Perspective gives an overview of the most popular models and their ability to reproduce experimental data of ten binary aqueous solutions of electrolytes and organic molecules chosen to be representative of different solute types. In addition, we propose a new model which reproduces sigmoidal curve shapes (Sigmoid model) to empirically fit experimental surface tension data. The surface tension of weakly surface-active substances is well reproduced by all models. In contrast, only few models successfully model the surface tension of aqueous solutions with strongly surface-active substances. For substances with a solubility limit, usually no experimental data is available for the surface tension of supersaturated solutions and the pure liquid solute. We discuss ways in which these can be estimated and emphasize the need for further research. The newly developed Sigmoid model best reproduces the surface tension of all tested solutions and can be recommended as a model for a broad range of binary mixtures and over the entire concentration range.

Oscillations in Dynamic Surface Tension of Cationic-nonionic Binary Surfactant Aqueous Solutions.

In this work, the adsorption dynamics of mixed aqueous solutions of tetraethyleneglycol monoocthyl ether (C8E4) - dodecyltrimethylammonium bromide (DTAB) were studied using sessile bubble surface tensiometry. When C8E4 was added to the DTAB solution, the dynamic surface tension exhibited a unique oscillation decay pattern. In contrast, the addition of DTAB to the C8E4 solution resulted in a simple monotonic decay of the surface tension. The same trend was observed for mixtures of tetradecyltrimethylammonium bromide (TTAB) and DTAB. The occurrence of two distinguishable dynamic surface tension behaviors showed reasonable similarity with the theory of the adsorption kinetics of polymer solutions, where the surface tension oscillation was caused by the delayed desorption of polymers due to the conformational change at the solution surface. We compared the dynamic surface tension of binary surfactant systems and the polymer solution theory, and discussed the origin of surface tension oscillations based on the difference in the surface activity of the surfactants.

Selective Adsorption and Removal of Congo Red Based on Ethylenediamine Functionalized Mesoporous Silica

AbstractFive types of mesoporous silica‐based adsorbents were prepared by rationally implementing five diverse amine‐containing functional units into the mesoporous SBA‐15 structures. The prepared materials were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption−desorption isotherms and thermogravimetric analysis. Among the five adsorbents, the ethylenediamine functionalized SBA‐15, namely, AAPTMS‐SBA‐15, achieved the complete adsorption of Congo red (CR) at pH 6.0, with the maximum adsorption capacity of 4608 mg/g. The AAPTMS‐SBA‐15 material was used effectively for CR adsorption from the individual and binary dye aqueous solutions, indicating that AAPTMS‐SBA‐15 can selectively remove and separate CR from wastewater. The hydrogen bonding interactions between AAPTMS‐SBA‐15 and CR were beneficial to the high selectivity and excellent adsorption capacity of AAPTMS‐SBA‐15 toward CR. Moreover, the selective adsorption and efficient separation of CR realized the recovery and reusability of AAPTMS‐SBA‐15 and CR, which can not only avoid secondary environmental pollution, but also save economic costs.

Investigation on the Adsorption Properties of an Engineered Biochar (Fe2o3-Bc) Nano-Composite in Binary and Ternary Aqueous Solutions

The binary and ternary adsorptions of Pb (II), methyl orange (MO) and brilliant blue (BB) on engineered biochar (Fe2O3-BC) nano-composite using pyrolysis and microwave activation were investigated in this work. Batch experiments were conducted to investigate the capacity of Fe2O3BC to remove MO, Pb and BB in binary and ternary aqueous solutions. MO removal was higher in MO-Pb binary solution than in ternary MO solution. A large amount of adsorbent dosage, high concentration and longer time were witnessed to achieve maximum removals in ternary solutions as compared to binary solutions. The Langmuir plots indicated that the isotherm can be used to describe sorption studies of both MO dye and Pb2+, while Temkin isotherm was not in agreement with the results. The closeness of R2 value to 1 indicated that the data obtained fits Langmuir Isotherm model of monolayer adsorption kinetics. It was concluded that the Fe2O3-BC nano-composite has a series of distinct homogeneous sites available for binding the MO anions in solution. Therefore, the use of Fe2O3-BC nano-composite for small scale community water purification is a novel cause.

Viscosity of Binary Aqueous Solutions Involving Malonic, Maleic, Malic, Tartaric, and Citric Acids in the Temperature Range between 303 and 363 K: Experimental Data and Modeling

Kinematic viscosity is a key property for the design of flow systems. This transport property is directly dependent on temperature and concentration and indirectly dependent on molecular interactions that take place in a mixture. Carboxylic acids are a class of chemical compounds with employment in a large variety of processes and applications. The viscosity of carboxylic acid solutions changes due to the acid size and its concentration. The application of models can provide property prediction and generate information about molecular interactions in a mixture. This work studies the kinematic viscosity of binary aqueous solutions of carboxylic acids (malonic, maleic, malic, tartaric, and citric acids) at different temperatures (from 303.2 to 363.2 K with an increment of 10 K) and concentrations (from 0.5 to 3.0 mol·kg–1 with an increment of 0.5 mol·kg–1). The data were treated by the Eyring equation combined with the UNIFAC model. The experimental results and thermodynamic properties indicate that the kinematic viscosity is strongly influenced by the size of carboxylic acid and the molar mass of the binary solution. The suggested modeling showed capability of correlating the experimental data.

Thermodynamic Studies of Aqueous Binary and Ternary Solutions Involving Lysozyme and Urea at 298.15 K

Measurements for osmotic pressure and densities for lysozyme in aqueous and aqueous solutions containing urea have been reported at 298.15 K using a vapor pressure osmometer and vibrating tube digital density meter, respectively. The partial molar volumes and activity coefficients of both the components and the osmotic pressure of the solutions have been calculated. The molar mass and second virial coefficient of lysozyme have been obtained using the McMillan–Mayer theory of solutions and are compared with the values obtained in aqueous salt solutions. The Guggenheim–Stokes equation for osmotic coefficient has been used to obtain the protein molecular diameter in an aqueous medium. The estimated diameter of lysozyme is similar in magnitude to that in the pure state, confirming the retaining of the native state of the protein in aqueous solutions over the studied concentration region. These studies have been extended to aqueous–urea (∼2.0 mol·kg–1) solutions at 298.15 K. Data of water activity and activity coefficient of all the three components in ternary solutions as a function of lysozyme concentration have been determined by the methodology developed by us earlier. The data have been further analyzed to obtain Gibbs free energy changes of transfer of lysozyme as well as that urea from corresponding aqueous binary to aqueous ternary solutions through which information about the binding of denaturant to protein can be derived. The analysis further reveals that the binding of urea to the protein molecules occurs through the breakdown of protein–water H–bonds leading to the opening of a coiled structure of lysozyme. All these results are discussed in terms of protein hydration, protein–protein hydrophobic interactions, and protein denaturant binding equilibria for the solutions of lysozyme.

Calculation of water activity in electrolytic solutions using the Electrolattice and Q-Electrolattice equations of state

Water activity directly influences the deterioration, texture, pigmentation, and preservation of nutrients in food. This property quantifies the availability of water for the enzymatic, chemical, or microbiological activity that defines the shelf life of food. In this way, the food industry needs to measure, predict, and control this property. In this context, the present work aims to evaluate the performance of the Electrolattice and Q-Electrolattice equations of state in predicting and correlating the water activity of solutions containing electrolytes. Parameters available in the literature were used to compare the performance of the Electrolattice and Q-Electrolattice equations in predicting the water activity (in binary, ternary, and quaternary solutions of salts). The Q-Electrolattice model presented better performance than the Electrolattice equation, with a relative mean deviation (RMD) of 1.95%, 0.14%, and 0.06% for binary, ternary, and quaternary aqueous electrolytic solutions, respectively. Then, the Q-Electrolattice equation was used to correlate experimental data of systems containing water + NaCl + sugar (fructose, sucrose, glucose, and xylose) at 25°C and water + sugar (fructose, sucrose, glucose, and xylose) at 35°C in aqueous solutions of salts and sugar. The general weighted average of the RMD% was equal to 0.29%. Finally, the procedure was validated with solutions containing water, NaCl, and sugar (fructose, sucrose, glucose, and xylose) at 35°C, a condition that was not used in the parameter fitting process. The overall weighted average of the RMD for predicting the water activity of water + NaCl + sugar solutions at 35°C using the Q-Electrolattice equation was 0.57%, thus validating the parameters estimated in this work. The results obtained in this study showed the feasibility of using the Q-Electrolattice equation to predict water activity in aqueous solutions of salts and sugars used as a basis for the osmotic drying of food.

Dynamics and thermodynamics for competitive adsorptive removal of methylene blue and rhodamine B from binary aqueous solution onto durian rind.

Concurrent adsorptive removal of methylene blue (MB) and rhodamine B (RhB) onto durian rind (DR) agricultural waste, from an aqueous binary solution as a model of wastewater containing multiple synthetic dyes, was investigated. The concurrent adsorption of the dyes followed pseudo-second-order kinetics. The adsorption isotherm was well simulated by the Langmuir model, implying a monolayer adsorption to the surface with a homogeneous binding energy. The adsorption process was governed by external mass transfer through two-step intraparticle diffusion of the dyes onto the adsorbent surface. The adsorption efficiency of MB (96.4%) is much higher than that of RhB (56.3%). This is attributed to the higher rate constant for the adsorption of MB (0.348gmg-1min-1) as compared to that of RhB (0.151gmg-1min-1). The adsorption behavior suggested that the two cationic dyes in the binary solution diffused and adsorbed independently and randomly onto the DR surface. The adsorption capacity of MB and RhB in the binary solution (47.4mgg-1 and 32.9mgg-1, respectively) is lower than those of their single solute solutions (93.3mgg-1 and 62.8mgg-1, respectively), suggesting a competitive effect in their concurrent adsorption. This was confirmed based on the adsorption characteristics of the binary solution with different molar ratios. The competitive effect was attributed to either non-interactive or repulsive electrostatic interactions between the positively charged dyes in the binary system. The domination of MB is attributed to its smaller molecular size, higher planarity, and faster adsorption kinetics compared with RhB.

Insights into High-Performance and Selective Elimination of Cationic Dye from Multicomponent Systems by Using Fe-Based Metal-Organic Frameworks.

Metal-organic frameworks (MOFs), especially Fe-MOFs, have shown prospective application in eliminating organic dyes from wastewater due to their well-developed pores, water stability, easy preparation, and economy. Herein, we synthesized four types of Fe-MOFs (such as MIL-88A, MIL-88B, MIL-100, and MIL-101) using the hydrothermal method. The products were analyzed with several methods. By comparing the adsorption effect of those four types of Fe-MOFs on three kinds of dyes, it has been shown that MIL-100 owns the best adsorption efficiency on cationic organic dyes methylene blue (MB) and Rhodamine B (RhB) in 180 min, while all MOFs have slight removal capacity on methyl orange (MO). MIL-100, as an adsorbent, was studied under various research conditions, and the maximum removal efficiencies to MB, RhB, and MO were found to be up to 97.36%, 88.75%, and 13.00%, respectively. Furthermore, cationic dye MB's removal by MIL-100 was fitted with a pseudo-second-order model and Langmuir isotherm model (Qm = 411.041 mg/g) by adsorption kinetics and isotherms research, and MIL-100 could rapidly and selectively divide MB from a binary complex aqueous solution of MB and MO. The as-fabricated MIL-100 also exhibited excellent recyclability after four adsorption-desorption recycles and can be treated as a potential substance with high removal efficiency of cationic organic dye-containing industrial effluents.

Removal of methylene blue and crystal violet in binary aqueous solution by magnetic Terminalia catappa kernel shell biosorbent using Box–Behnken design

Removal of methylene blue and crystal violet in binary aqueous solution by magnetic Terminalia catappa kernel shell biosorbent using Box–Behnken design

Quantitative Analysis of Glassy State Relaxation and Ostwald Ripening during Annealing Using Freeze-Drying Microscopy.

Supercooling during the freezing of pharmaceutical solutions often leads to suboptimal freeze-drying results, such as long primary drying times or a collapse in the cake structure. Thermal treatment of the frozen solution, known as annealing, can improve those issues by influencing properties such as the pore size and collapse temperature of the lyophilisate. In this study we aimed to show that annealing causes a rearrangement of water molecules between ice crystals, as well as between the freeze-concentrated amorphous matrix and the crystalline ice phase in a frozen binary aqueous solution. Ice crystal sizes, as well as volume fractions of the crystalline and amorphous phases of 10% (w/w) sucrose and trehalose solutions, were quantified after annealing using freeze-drying microscopy and image labelling. Depending on the annealing time and temperature, the amorphous phase was shown to decrease its volume due to the crystallisation of vitreous water (i.e., glassy state relaxation) while the crystalline phase was undergoing coarsening (i.e., Ostwald ripening). These results allow, for the first time, a quantitative comparison of the two phenomena. It was demonstrated that glassy state relaxation and Ostwald ripening, although occurring simultaneously, are distinct processes that follow different kinetics.

Modeling dynamic viscosities of multi-component aqueous electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl−, SO42− and dissolved CO2 under conditions of CO2 sequestration

Two accurate models were developed by this study for dynamic viscosities of multi-component aqueous electrolyte solutions containing Li+, Na+, K+, Mg2+, Ca2+, Cl−, SO42− and dissolved CO2 under conditions of CO2 sequestration. The first model is constructed by extending the Mao–Duan model for viscosities of binary aqueous solutions (aqueous single electrolyte solutions) of alkali-chloride to binary solutions of alkaline-earth chlorides, common sulfate and CO2 and combining it with Hu's mixing rule to model viscosities of multi-component solutions. The second model is constructed by improving the Goldsack–Franchetto model based on the Eyring's absolute rate theory to account for the effect of temperature on viscosity. The forms of both models are simple.Comparisons of calculations of the two models with experimental viscosity data show that both models can well represent dynamic viscosities of aqueous single electrolyte solutions and aqueous CO2 solutions at temperatures from 273 K to temperatures higher than 473 K, and at pressures from 0.1 MPa to 100 MPa. Furthermore, the two models can predict viscosities of aqueous NaCl solutions with dissolved CO2, brine containing Li+, Na+, K+, Mg2+, Ca2+, Cl−, SO42− and seawater over a wide P-T range. The absolute average deviations of the two models from most of experimental data sets are less than 2%.

Acetamiprid in several binary aqueous solutions: Solubility, intermolecular interactions and solvation behavior

This study focused on the solubility profile, dissolving characteristics, computational methods, and solvation behavior of acetamiprid in aqueous solutions of isopropanol/acetone/methanol/EG (1). The quantitative analysis of molecular surface, as well as Hirshfeld surface analysis, were used herein to explain the electrostatic features of basicity of acetamiprid molecule. The primary and second electrophilic sites are the CN and N groups, respectively. All solubility tests were carried out in a shake-flask technique at p = 101.2 kPa and temperatures ranging from 278.15 to 318.15 K. The solubility parameter and dipolarity-polarizability of solutions played a significant role in solubility variation. To investigate solubility performance, the three-dimensional Hansen solubility parameter was used. Several common relationships, such as the modified van't Hoff Jouyban–Acree model, the mixture response surface model, and the Jouyban–Acree model, provided acceptable correlation results for the solubility magnitudes with relative average deviations of < 4.98 percent. The preferred solvation of acetamiprid was further investigated by quantification using the inverse Kirkwood–Buff integrals method. Positive preferential solvation values in isopropanol/ethanol/acetone/methanol-rich and -intermediate composition solutions suggest that isopropanol/ethanol/acetone/methanol preferentially solvates acetamiprid. Nonetheless, EG in the EG + water solution didn’t preferentially solvate acetamiprid. Moreover, the dissolution and transfer properties as well as enthalpy–entropy compensation were discussed.

Evaluation of the Adsorptive Potential of Zeolite Volcanic Tuff in Single and Binary Aqueous Solutions of the Basic Blue 41 Cationic Dye

AbstractA volcanic tuff of clinoptilolite type has been assessed in regards to its efficiency on Basic Blue 41 (BB‐41) cationic dye removal from aqueous solutions. Optimal working conditions were established by considering influences of the particle sizes, initial pH, dye concentration, contact time, and temperature. Tuff samples have been characterized by using SEM/EDX, FT‐IR, and N2 gas adsorption‐desorption techniques. Experimental data at equilibrium showed a better fitting of adsorption kinetics on pseudo‐second‐order and Langmuir models, whereas the thermodynamic parameters indicate an endothermic spontaneous process. Tuff particles of 47 μm medium sizes, which own the highest zeolite content, were found to be the most suitable for practical use as adsorbents, attaining a maximum adsorptive capacity of 123.5 mg g−1 pure dye at 323 K, equivalent to 303 mg g−1 commercial product containing 40 % dye. A potential interference involving the retention pattern was furthermore evaluated within binary systems with other two cationic dyes, Rhodamine B (RhB) and Methylene Blue (MB). The adsorbent shows a relevant selectivity towards BB‐41, influenced by commercial dye additives, structural configuration, molecular size, and contact time, with the 99.7 % dye removal efficiency at 24 hours only slightly depressed in binary systems with RhB ‐ 97.4 %, respective MB ‐ 90.2 %. This study confirmed the tuff particles as efficient adsorbents for the treatment of textile wastewater effluents.

Density, speed of sound, and surface tension of binary aqueous solutions containing ammonium based protic ionic liquids

Density, ρ, speed of sound, u, and surface tension γ, of binary mixtures containing ethanolammonium based protic ionic liquids (PILs) and water were measured to access the influence of PIL-water interactions on physicochemical properties. Volumetric properties of PILs were evaluated at ambient pressure but at temperatures from 298.15 K to 313.15 K. Apparent molar volume and apparent molar isentropic compressibility values of ethanolammonium acetate [EAAc], ethanolammonium butanoate [EABu], and ethanolammonium hexanoate [EAHx], were calculated and commuted to determine the infinite dilution partial molar volume using Redlich-Mayer type of equation. Further, excess molar volume was also determined as a function of mole fraction. The coefficients of Redlich-Kister equation also determined and presented. Overall, the hydrophilic interactions occur between PILs and water molecules and the strength of interactions weakens as anionic chain length increases. Low surface tension values were observed for PILs with longest alkyl chain. The results indicate that hydrophobicity of alkyl chain strongly influences the interfacial properties.

Sequestration of heavy metal ions from multi-metal simulated wastewater systems using processed agricultural biomass

Industrial effluents generally contain several metals, so during adsorptive treatment, they may influence the removal of each other. It is essential to explore the effect of co-cations on metal removal in multi-metal solutions. The present study examined the possibility of processed rice husk and saw dust to remove Cr6+, Ni2+, Cu2+, Cd2+ and Zn2+, from the single, binary and multi-component aqueous solutions. A substantial lesser removal of metal ions was observed in the presence of co-ions. This study revealed antagonistic effect on the removal of a particular metal ion, from the industrial effluent, even at optimum process parameters if other metal ions are present in the effluent. Although, a higher concentration of one metal ion than others in effluents increased its removal due to a greater number of ions as compared to other for the biosorption, yet presence of other ions influences the uptake of individual ions. In case of industrial effluents, maximum adsorption was obtained at pH 2.0 for Cr6+, 5.0 for Ni2+ and Cd2+ and 6.0 for Zn2+ and Cu2+. The study confirms the beneficial use of the studied biosorbents in water remediation.

Experimental Analysis of Heat Storage and Release of Binary Methanol Aqueous Solution Pulsating Heat Pipe Phase Change Accumulator

To improve the problems of energy shortage and low utilization rate, this paper designed a set of pulsating heat pipe (PHP) devices coupled with phase change energy storage material. Further, the binary methanol-water solution is proposed as a novel experimental filling medium to enhance the heat transfer performance of the device. The fluid flow model of the PHP was analyzed via experiment and simulation. Besides, the heat storage and release performances of the PHP at different flow rates, different heating temperatures, different filling mediums, and different filling ratios are investigated. The results show that when the filling medium (binary methanol-water solution) possesses the filling ratio of 0.6 (methanol and water are each 0.3), the heat source inlet flow is 0.60 m3/h, the heat source heating temperature is 120°C, and the PHP is at the best heat storage performance. During the exothermic process, the lower the initial temperature of cooling water, the higher the heat recovery rate. Thus, it can be concluded that the selection of an appropriate filling medium and the optimal parameters to enhance heat transfer can have a broader application prospect in the field of waste heat recovery.