Phase Volume Ratio Research Articles

Magnetization performance of hard/soft Nd9.6Fe80.3Zr3.7B6.4/α-Fe magnetic nanocomposites produced by surfactant-assisted high-energy ball milling

Neodymium iron boron (NdFeB) magnets are sintered anisotropic materials. They were commercially introduced in the early 1980s, and since have been used in different applications owing to their superior properties. Herein, we investigated the influence of 0.5 to 8 h of milling time on the morphological, structural, and magnetic performance of Nd9.6Fe80.3Zr3.7B6.4 powders produced using surfactant-assisted high-energy ball milling (SA-HEBM). The results revealed that the relationship between coercivity (H ci ) and milling time had a non-monotonous character reaching a maximum value of H ci = 8.92 kOe after 1 h of milling. The effect of the volume ratio of various magnetic phases (Nd2Fe14B and α-Fe) on microstructure and magnetic properties was also reported. The highest specific saturation magnetization (σ s = 120 emu g−1) was attained after 8 h of milling for powders with volume fraction: Nd2Fe14B–81 ± 2% and α-Fe–12 ± 2%. The expected value of Nd2Fe14B specific saturation magnetization was estimated (σ N = 108 ± 2.5 emu g−1) using the experimental value of σ s and magnetic phase volume fractions. The ratio of remanence to saturation magnetization of the Nd2Fe14B with milling time was also determined and analyzed.

Synthesis of Polymer Janus Particles with Tunable Wettability Profiles as Potent Solid Surfactants to Promote Gas Delivery in Aqueous Reaction Media.

Janus particles exhibit a strong tendency to directionally assemble and segregate to interfaces and thus offer advantages as colloidal analogues of molecular surfactants to improve the stability of multiphasic mixtures. Investigation and application of the unique adsorption properties require synthetic procedures that enable careful design and reliable control over the particles’ asymmetric chemistry and wettability profiles with high morphological uniformity across a sample. Herein, we report on a novel one-step synthetic approach for the generation of amphiphilic polymer Janus particles with highly uniform and tunable wettability contrasts, which is based on using reconfigurable bi-phasic Janus emulsions as versatile particle scaffolds. Two phase-separated acrylate oils were used as the constituent droplet phases and transformed into their solidified Janus particle replicas via UV-induced radical polymerization. Using Janus emulsions as particle precursors offers the advantage that their internal droplet geometry can be fine-tuned by changing the force balance of surface tensions acting at the individual interfaces via surfactants or the volume ratio of the constituent phases. In addition, preassembled functional surfactants at the droplet interfaces can be locked in position upon polymerization, which enables both access toward postfunctionalization reaction schemes and the generation of highly uniform Janus particles with adjustable wettability profiles. Depending on the particle morphology and wettability, their interfacial position can be adjusted, which allows us to stabilize either air bubbles-in-water or water droplets-in-air (liquid marbles). Motivated by the interfacial activity of the particles and particularly the longevity of the resulting particle-stabilized air-in-water bubbles, we explored their ability to promote the delivery of oxygen inside a liquid-phase reaction medium, namely, for the heterogeneous Au-NP-mediated catalytic oxidation of d-glucose. We observed a 2.2-fold increase in the reaction rate attributed to the increase of the local concentration of oxygen around catalysts, thus showcasing a new strategy to overcome the limited solubility of gases in aqueous reaction media.

Conversion of waste cooking oil into value-added emulsion liquid membrane for enhanced extraction of lead: Performance evaluation and optimization

This research study investigated the synthesis of environmentally benign green emulsion liquid membrane (GELM) employing waste cooking oil (WCO) as diluent. The emulsion was prepared using D2EHPA as the carrier, Span 80 as surfactant, and sulphuric acid as internal/stripping agent. The influence of nine operating variables namely, Span 80 concentration, D2EHPA concentration, shaking time, shaking speed, pH of the feed, treat ratio (TR), H2SO4 concentration, lead concentration in feed, and volume ratio of organic phase to aqueous phase (O/A) on the performance of lead extraction was studied. Plackett Burman design (PBD), was employed for the screening of variables. The Pareto analysis shows that six variables were the most significant variables at the confidence level of 95%. The selected variables were then screened applying Box-Behnken design (BBD). The optimum values of the variables were: D2EHPA concentration – 4.6 (v/v%), Span 80 concentration – 2.14 (v/v%), pH of the feed – 4.4, internal phase (H2SO4) concentration – 2 M, initial lead concentration – 173 ppm, phase ratio (O/A) – 1.3. At these optimum conditions, a maximum lead extraction of 97.39% was obtained. The mechanism for the extraction of lead was analyzed. Reuse and recycling of membrane phase show that the GELM can be recycled for 7 cycles without reduction in lead extraction efficiency. Kinetic analysis of lead extraction was performed using zero, first, and second-order model at optimum condition. The experimental data fitted well with first-order (R2 – 0.9653). Thermodynamic studies indicated that the extraction procedure is endothermic, spontaneous in nature.

Neodymium naphthenate-loaded organic phase stripping using sodium oxalate

Neodymium naphthenate-loaded organic phase stripping using sodium oxalate solution was studied to explore the feasibility of synchronous rare earth-loaded organic phase stripping, rare earth precipitation, and blank organic phase saponification. Experimental results show that loaded organic phase stripping, rare earth precipitation, and blank organic phase saponification can be realized simultaneously. When using 20% excess of sodium oxalate over the stoichiometry with the volume ratio of organic phase to aqueous phase of 1:1 at 25 °C for 40 min, the single stage stripping rate and saponification value are about 40% and 0.29 mol/L, respectively. After 16 stages of countercurrent continuous stripping, the stripping rate of neodymium can reach 99%, the saponification value is 0.42 mol/L, the Nd3+ concentration in saponified organic phase is less than 0.0020 mol/L, and the main phase in precipitation is Nd2(C2O4)3·10H2O. Afterwards, this saponified organic phase can be used in the extraction of NdCl3 solution, and then the loaded organic phases (neodymium naphthenate) with 0.16 mol/L Nd3+ can be retrieved. The morphology, particle size distribution, and composition of the Nd2(C2O4)3·10H2O products are similar to those of the current direct precipitation products. The neodymium oxide prepared by continuous calcination of neodymium oxalate meets the national standard of China (GB/T 5240−2015). These results prove the feasibility of stripping neodymium naphthenate-loaded organic phase by using sodium oxalate solution. Sodium oxalate can serve as a stripping agent, a saponifier, and a precipitator, thereby simplifying rare earth extraction and separation. This study provides theoretical and technical support for the development of a novel method for rare earth extraction and separation.

Removal of zinc by emulsion liquid membrane using lecithin as biosurfactant

The present investigation deals with zinc extraction using emulsion liquid membrane (ELM) method with the help of lecithin as biosurfactant. The emulsion liquid membrane system consists of paraffin as organic phase, lecithin as biosurfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractant, and sulfuric acid as stripping agent. In this study, five parameters affecting the extraction performance, i.e., lecithin concentration, pH of feed solution, treatment ratio, internal phase to organic phase volume ratio, and D2EHPA concentration were investigated. The stability of emulsion was determined by specifying breakage and swelling of the emulsion. The experiments were performed under ambient conditions to extract zinc with the initial concentration of 250 mg/L. The extraction step was completed after 10 minutes by stirring at 500 rpm. Optimal conditions were obtained at the biosurfactant concentration of 3% (v/v), pH 3, treatment ratio 0.3, internal phase to organic phase volume ratio 0.1, and D2EHPA concentration 6% (v/v). Under optimal conditions, zinc extraction was 98.38%. In these conditions, the breakage and swelling of the emulsion were 6.29% and 8.56%, respectively.

A Doubly Green Separation Process: Merging Aqueous Two-Phase Extraction and Supercritical Fluid Extraction

Aqueous two-phase extraction (ATPE) is a green separation technique which uses mixtures of water and environmentally benign polymers such as polyethylene glycol (PEG) as solvents. One of the challenges in implementing this extraction on an industrial scale is finding a suitable method for the isolation of target compounds from water-polymer solutions after the extraction, without diminishing ecological benefits of the method. In this paper, we propose using another green separation technique, supercritical fluid extraction (SFE), for the back-extraction of low molecular weight medium polarity compounds from ATPE solutions. Experiments with two model compounds, caffeine and benzoic acid, showed principal applicability of SFE for this task. Pressure (100–300 bar) and temperature (35–75 °C) of supercritical carbon dioxide play a major role in defining extraction capability. Extraction ratios of 35% for caffeine and 42% for benzoic acid were obtained at high fluid pressure and moderate temperature at 1:6 volume phase ratio. That gives an estimation of 10–20 theoretical steps required for complete exhaustive extraction from the ATPE solution, which is readily achievable in standard counter-current column SFE. Combining these two green methods together not only serves as an environmentally friendly method for the isolation of valuable low molecular weight compounds from diluted water solutions, but also allows for simple, energy effective recuperation of ATPE solvents.

Development of a gel-in-oil emulsion as a transdermal drug delivery system for successful delivery of growth factors

Growth factors (GFs) are indispensable in regenerative medicine because of their high effectiveness. However, as GFs degenerate easily, the development of a suitable carrier with improved stability for GFs is necessary. In this study, we developed a gel-in-oil (G/O) emulsion technology for the transdermal delivery of growth factors. Nanogel particles prepared with heparin-immobilized gelatin that can bind growth factors were dispersed in isopropyl myristate. The particle size of the G/O emulsion could be controlled by changing the surfactant concentration, volume ratio of the water phase to the oil phase, and gelatin concentration. Invitro skin penetration studies showed better penetration through the stratum corneum of fluorescent proteins containing G/O emulsions than of the aqueous solution of GF. Similarly, an invivo study showed an angiogenesis-inducing effect after transdermal application of GF-immobilized G/O emulsion. Angiogenesis in mice was confirmed owing to both an increased blood vessel network and higher hemoglobin content in the blood. Therefore, the G/O emulsion could be a promising carrier for GFs with better stability and can effectively deliver GFs at the target site.

Development of a green emulsion liquid membrane using waste cooking oil as diluent for the extraction of arsenic from aqueous solution – Screening, optimization, kinetics and thermodynamics studies

Environmental friendly treatment technology was adopted in the present work by employing green emulsion liquid membrane (GELM) for the extraction of arsenic from an aqueous solution. The GELM was composed of used waste cooking oil as a diluent, aliquat 366 as a carrier, span 80 as a surfactant and NaOH as a stripping agent. Waste cooking oil, a nontoxic organic solvent was used as a diluent. Initially, nine parameters, namely, surfactant concentration, carrier concentration, agitation time, agitation speed, pH of the external phase, treat ratio, internal phase concentration, arsenic concentration and volume ratio of organic to aqueous phase were selected and screened by Plackett-Burman design (PBD) for arsenic extraction. Then Box-Behnken design (BBD) was applied using the selected parameters to achieve the optimal condition for the arsenic extraction. The optimum conditions for the maximum removal of arsenic were: Surfactant concentration – 2.3 (v/v %), Carrier concentration – 5.6 (v/v%), Treat ratio – 12, internal phase concentration – 0.92 M, initial arsenic concentration – 100 ppm, O/A ratio – 1. The mechanism of arsenic extraction was also presented. The study on stripping and reuse of the GELM was discussed and recommended that membrane phase might be reused for 6 times. For the optimized factors the maximum extraction of arsenic was estimated as 99.0 %. Kinetic analysis shows that the arsenic extraction by GELM follows first-order reaction. In addition, thermodynamic analysis reveals that the extraction process was an endothermic, and spontaneous in nature.

Comparison of the mixed flow and heat transfer characteristics in the evaporator of a vapor compression heat pump in normal gravity and microgravity

As a thermal control system for space applications, the vapor compression heat pump is crucial for the future development of aerospace technology. The evaporator in the heat pump is significantly affected by the space environment. Lubricant is present in the system during the operation, and the gas-liquid separation is difficult to achieve in a microgravity environment. The oil-containing refrigerant may form an oil film on the evaporator wall, and deposition may occur. A mixed flow and heat transfer model of the refrigerant and lubricating oil in the evaporator of the vapor compression heat pump was established to investigate the gas-liquid separation and lubricating oil deposition of the vapor compression heat pump in microgravity. The heat flux effects on the flow and heat transfer characteristics were simulated in normal gravity and microgravity using FLUENT. The simulation and experimental results of the evaporator outlet temperature in normal gravity were compared, and the simulation results of the heat transfer coefficient of the refrigerant R134a were compared with experimental data obtained from the literature. The results demonstrate that the velocity field exhibits a large gradient and an asymmetric distribution in normal gravity and an asymmetric distribution with lower values in the lower and upper right positions in microgravity. The heat transfer performance of the evaporator is lower in microgravity than in normal gravity for the same heat flux. For the same heat flux (100000 W/m2), the vapor phase volume ratio of the evaporator outlet is 0.95-1 in normal gravity and 0.6-0.7 in microgravity. After the phase change of the refrigerant and lubricant mixture in the evaporator, the lubricant deposition is not affected by the heat flux in normal gravity and microgravity, and normal oil return occurs. A maximum deviation of 14.9% is observed between the simulated and experimental values of the evaporator outlet temperature in normal gravity. The heat transfer coefficient of the R134a obtained from the simulation is within the range of the experimental values in the literature. This work expands our understanding of microgravity two-phase flow heat transfer and provides theoretical guidance for the development of the evaporator in vapor compression heat pumps for aerospace applications.

Liquid-liquid extraction of phosphorus from sulfuric acid solution using benzyl dimethyl amine

This study addresses the liquid-liquid extraction behavior of phosphorus from a sulfuric acid solution using benzyl dimethyl amine (BDMA) in kerosene. The extraction equilibria investigated with varied BDMA concentrations could reveal the formation of $$\overline {3[{\rm MA }] \cdot [{{\rm{H}}_3}{\rm{P}}{{\rm{O}}_4}]} $$ complex in the organic phase. The thermodynamic properties determined at various temperatures indicated that the process was exothermic with a calculated enthalpy (ΔH⊖) of −24.0 kJ·mol−1. The organic-to-aqueous phase (O/A) volume ratio was varied to elucidate the quantitative extraction of phosphorus. The McCabe-Thiele diagram plotted for the extraction isotherm was validated for the requirement of three counter-current stages in the extraction at an O/A volume ratio of 2.0/3.5. The back-extraction of phosphorus from the loaded organic phase was quantitatively achieved by contacting 4.0 mol·L−1 H2SO4 solution in three stages of counter-current contact at an O/A volume ratio of 3/2. This study can be applied to remove phosphorus from the sulfuric acid leach solutions of monazite processing, and many other solutions.

Kinetics of simultaneous stripping of U(VI) and nitric acid from tri-n-butyl phosphate

The study of kinetics of simultaneous stripping of uranium U(VI) and nitric acid (HNO3) from the loaded tri-n-butyl phosphate (TBP) in n-dodecane (n-DD) phase was carried out using dilute nitric acid in a constant interfacial area stirred cell (Lewis Cell). The influence of various parameters like rotational speed of impeller, temperature and aqueous to organic phase volume ratio on the kinetics of stripping was investigated. The objective of the present work was to identify the location of reaction and regime of reaction for the simultaneous stripping of U(VI) and nitric acid based on the systematic experimental investigations. A comprehensive kinetic model has been developed and validated with the experimental data to determine the rate constants and the mass transfer coefficients. From the present study, it was concluded that the location of reaction is at the interface between aqueous and organic phases and the reaction regime was found to be kinetic controlled regime for the stripping of U(VI) and diffusion controlled regime for the stripping of nitric acid.

Selective separation of the homologues of baicalin and baicalein from Scutellaria baicalensis Georgi using a recyclable ionic liquid-based liquid-liquid extraction system

To explore convenient and efficient techniques for the extraction and separation of the active ingredients in medicinal plants is still ongoing. As a new class of molten salt, ionic liquids (ILs) are widely used in the extraction of bioactive compounds from plant resources. In this work, the IL-based biphasic system was developed for the extraction and separation of the homologues of baicalin and baicalein from Scutellaria baicalensis Georgi. The IL-water biphasic system is superior to the other organic solvents-water systems for the extraction and separation of baicalin and baicalein. The phase volume ratio of the IL-water biphasic system was studied, and the other influencing parameters of solid–liquid ratio, extraction temperature, extraction time, and ultrasonic time were optimized through the single factor experiments. The results revealed that the extraction yields were 43.3 mg/g and 14.3 mg/g for baicalin (aqueous phase) and baicalein (IL phase), respectively; and the distribution coefficients were 23.8 and 13.7 for baicalin and baicalein, respectively under the optimized conditions. Finally, the IL can be easily recycled and reused by means of its temperature-responsive characteristic. This study provides a green and efficient method for the selective separation of the homologues in natural plant resources.

The Feasibility of Emulsion Liquid Membrane for the Extraction of Organic Acids from Wastewater

The separation of hazardous organic acid pollutants such as phenol and carboxylic acids from aqueous waste streams released from industries is important and essential for environmental pollution. Acetic acid, benzoic acid, and phenol individually extracted from their aqueous solutions using emulsion liquid membranes prepared with kerosene as a membrane phase, Span 80 as a surfactant and NaOH as a stripping agent in the inner phase of W/O emulsions. Experiments have been performed to study the effect of volume ratio of membrane phase to internal phase (VM/VI), stripping phase concentration in the internal phase, agitation speed of feed solution, and volume ratio of emulsion phase to feed phase (VE/VF) on the organic acid extraction rates. More than 98% of benzoic acid and phenol can be extracted in less than 5 minutes, acetic can also be extracted but at much slower rates. Comparison of the extraction rates of organic acid indicates that benzoic acid and phenol are extracted more rapidly than that of acetic acid because the distribution coefficient (m) of benzoic acid and phenol is much larger than that of acetic acid due to their ability to dissolve in the membrane phase. The effective diffusivities indicate that the mobility of these compounds in the membrane phase obeys the following order: benzoic acid > acetic acid > phenol.

Experimental and numerical studies of non-equilibrium solvent exsolution behavior and foamy oil stability under quiescent and convective conditions in a visualized porous media

Non-equilibrium solvent exsolution and foamy oil stability in a visualized porous-media have been investigated. Two flow conditions were applied, namely, Static Constant Composition Expansion (SCCE) and Continuously Convective Flowing (CCF) schemes. The two schemes were aimed to study foamy oil non-equilibrium phase behavior deviating from the vapor–liquid-equilibrium under quiescent and convective condition, respectively. Two SCCE schemes, by both continuous and step-wise pressure depletion, were conducted. The non-equilibrium vapor phase volume ratio of the system was recorded, quantified and compared with the equilibrium state. Certain percentages from 5 to 35% of vapor-phase-ratio deviation from the equilibrium state were consistently found at multiple differentials from live oil saturation pressure. CCF tests up to 20 differentials from live oil saturation pressure were conducted to study non-equilibrium exsolution behavior under convection. Vapor phase volume ratio in CCF tests was always found to be 5–40% lower than that of the SCCE tests at the same operating pressure. Numerically, a MATLAB optimization module was developed to couple with CMG STARS reservoir simulator to study the non-equilibrium solvent exsolution behavior. Pseudo-chemical reaction kinetics representing non-equilibrium interphase mass transfer were applied. Gassy-liquid (compressible dispersed phase in a pseudo-single phase flow) and non-gassy-liquid (two-phase flow) schemes were implemented to history match the vapor phase volume ratio. The simulation results verified the phase-volume-ratio deviation from the equilibrium state in both SCCE and CCF schemes. Consistent to the experimental findings, the optimized kinetic reaction rate frequency factors indicated higher foamy oil stability under convective condition than that of quiescent condition.

Effects of secondary emulsification of ASP flooding produced fluid during surface processes on its oil/water separation performances

Effects of secondary emulsification of field ASP flooding produced fluid by centrifugal pumps and electrostatic field on its oil/water separation performances were evaluated. Secondary emulsification of certain ASP flooding produced fluid with high surfactant content by centrifugal pumps drastically downgraded its oil/water separation performances, increasing the residual water-cuts after 24h static settling at 60 °C respectively by 70% for original o/w emulsion and 1080% for w/o emulsion. Certain w/o emulsion produced by ASP flooding with high surfactant content was susceptible to secondary emulsification in high strength electrostatic field with up to 660% increase of residual water-cut after 24h static settling at 60 °C. Mechanisms governing the effects of secondary emulsification on the oil/water separation performances of ASP flooding produced fluid were discussed. In comparison with produced fluid by water flooding and polymer flooding, the oil/water interfacial tension in ASP flooding produced fluid is much lower, making oil droplets in water and water droplets in oil significantly more sensitive to shear and high strength electrostatic field. Energy dissipation rate, surfactant content and the volume ratio of dispersed phase in the emulsion were identified to be the most important factors affecting the secondary emulsification of ASP flooding produced fluid in turbulent flow. Water in oil emulsion extracted from high water-cut o/w or w/o/w ASP flooding produced fluid was found to have significantly higher water phase surfactant content than the original crude oil emulsion and is much more susceptible to secondary emulsification in turbulent flow than the original reverse emulsion. Surfactant content, content of dual wettability micron and submicron sized particles and the strength of electrostatic field were found to be major factors affecting the secondary emulsification of ASP flooding produced w/o emulsion in AC electrostatic field. As interfacial tension between oil and water in w/o emulsion produced by ASP flooding can be 1 to 2 orders lower than that in the w/o emulsion produced by water flooding and polymer flooding, strength of electrostatic field in electrostatic treaters has to be optimized as per the surfactant content in the ASP flooding produced w/o crude oil emulsion they treat.

New parameters for charactering the gas-bearing properties of shale gas

The hydrocarbons contained in shale pores are mainly free gas and adsorbed gas. Accurately evaluating the reservoir free phase density/hydrogen index and adsorbed phase density/hydrogen index can reflect the reservoir properties and assist in evaluating the reservoir parameters. We propose a method for calculating the free phase density/hydrogen index and adsorbed phase density/hydrogen index by using logging curves and choose the rock density and total organic carbon (TOC) content to evaluate the above parameters with high precision. Finally, we propose qualitative and quantitative application methods for the above parameters. Based on the parameters calculated by the free phase density/hydrogen index and adsorbed phase density/hydrogen index, when the free phase porosity and saturation are high, the adsorbed phase porosity and saturation are low, and the adsorbed phase -free phase volume ratio is low, the reservoir has the highest quality. The results show that the free phase density/hydrogen index and adsorbed phase density/hydrogen index can be accurately determined and evaluated, and the applications of this method are very meaningful. This study combines the advantages of predicting the physical characteristics of free gas and adsorbed gas and the gas-bearing properties of shale gas reservoirs.

Synthesis and characterization of ZEin-based Low Density Porous Absorbent (ZELDA) for oil spill recovery

Removal of spilled petroleum oil from water bodies using hydrophobic porous absorbent has garnered considerable attention due to the simplicity, large-scale adaptability and robustness of the process. However, the use of nonbiodegradable synthetic oil absorbent during cleanup has raised a secondary concern such as generating plastic pollutants that can accumulate in marine and other ecosystems. To encounter this potential hazard, there is a need to find new biocompatible alternatives to currently used non-degradable porous materials. Here we present ZEin-based Low Density porous Absorbent (ZELDA) synthesized from an emulsion templating method as a new class of naturally derived porous material with tunable hydrophobicity for oil spill recovery. Corn-derived zein nanoparticles are first used to form oil-in-water Pickering emulsion. The addition of polymeric zein into the continuous aqueous phase of the emulsion, and its gradual phase separation enables the formation of a porous matrix. The pore diameter, surface wettability, and oil uptake capacity of ZELDA can be programmed by tuning oil-to-water phase volume ratio of the Pickering emulsion and its selective surface functionalization using flaxseed oil. The synthesis of ZELDA can be further modified with iron oxide nanoparticles to induce magnetic response, which enables its contactless maneuverability and removal from spilled site. The study outlines a new method of synthesis of zein-based porous materials and introduces synthetic routes for controlled surface functionalization, wettability, and stimuli responsiveness of the porous material. The synthesized plant-based material provides an ecofriendly alternative to commercially used nonbiodegradable oil sorbents for spilled oil remediation.

Evaluation of mean diameter and drop size distribution of an emulsion liquid membrane system in a horizontal mixer-settler

A W/O emulsion consisting of distillated water, kerosene and Span 80 was prepared to be employed in a horizontal mixer settler. The effect of stirring speed, flow ratio, total flow, Span 80 concentration and the internal to membrane phase volume ratio on the Sauter mean diameter (D32) of emulsion, drop size distribution and also the holdup were investigated without mass transfer effect. The results revealed that, with increasing the stirring speed, the D32 decreased and the emulsion holdup increased. However, the emulsion globules breakage incremented due to producing high shear forces. For the ELM system with the surfactant concentration higher than 3wt.%, the D32 increased due to the emulsion swelling and the holdup reduced. In addition, raising the flow ratio and the total flow increased the drop size which led to the reduction in the holdup. Besides, for the internal to membrane phase volume ratio higher than 0.4, the drop size increased. Empirical correlation was presented to predict the D32 with average absolute relative errors (AAREs) of 3.9%. The drop size distribution was conformed to normal distribution, and α and β parameters have been correlated with AAREs of 3.4% and 3.7%, respectively.

Investigation on the equilibrium distribution of methanol in transformer oil-immersed cellulosic insulation

Methanol in oil was used to indirectly evaluate the aging status of cellulosic paper insulation for oil-immersed transformers. However, the distribution of methanol in oil is affected by many factors, not only related to the oil–paper adsorption equilibrium, but also may be affected by the vapor–liquid phase transition. In this study, the adsorption experiments of mineral oil and standard cellulosic Kraft paper for methanol were designed to explore the adsorption equilibrium process at different oil–paper mass ratios under room temperature. The vapor–liquid equilibrium experiments of methanol between oil and gas were carried out to explore the effects of temperature and phase volume ratios. It turned out that: firstly, compared with mineral oil, the Kraft paper has a stronger adsorption capacity for methanol, which makes most of methanol adsorbed in paper when equilibrium at room temperature. Secondly, the increase of oil–paper mass ratios reduces the adsorption of Kraft paper for methanol and makes the equilibrium time longer. Particularly, at a higher oil–paper mass ratio, due to the less paper mass, methanol would “reverse diffusion” from paper to oil standard solution in the early stage of equilibrium. Finally, the presence of methanol in gas phase cannot be ignored. The increase of temperature makes more liquid methanol in oil transferred to the gas phase by the phase transition process, while increasing the oil–gas phase volume ratios in constant volume system can inhibit this process.

Validation of aqueous two-phase extraction method

Nowadays, consumer interest in food with natural ingredients has increased. This need has led to the research of new sources and green extraction methods. Betalains are compounds responsible for giving color to cacti fruits. The aim is to obtain low-sugar betacyanins extracts from jiotilla Escontria chiotilla using aqueous two-phase systems (ATPS) to color food with the extract. The effect of principal parameters of ATPS (Ethyl alcohol- KH2PO4/K2HPO4) as tie-line length (TL;40,50 and 70), phase volume ratios (Vr; 1 and 3) on the partitioning of betacyanins, betaxanthins, total sugars, reducing sugars, and antioxidant activity in the extract was evaluated. The yields were determined from the top and bottom phases of the aforementioned parameters. Multivariate analysis of variance (MANOVA, α = 0.05) showed that TLL and Vr were statistically significant (P < 0.05). The lowest bottom sugar yield (25.78 ± 3.14%) corresponds to TLL = 40, Vr = 3. Under these conditions, the corresponding value for betacyanins yield is 62.98±4.52%. For the first time, the ATPS was used to extract betacyanins from cactus fruit.•Escontria chiotilla, as a biological source, contained a high percent of betalains•Aqueous two-phase systems (ATPS) was statistically optimized•The developed method enriches the valorization of environmentally related plants waste materials