Initial Volume Ratio Research Articles

Interaction between vapor bubbles during flow boiling heat transfer in microchannels

Microchannel flow boiling is an efficient cooling solution for high-power-density miniaturized systems. Many studies on microchannel flow boiling focused on the dynamics of single vapor bubbles, while neglecting the interaction between bubbles, which is important in relevant applications. Here, numerical simulations are carried out to study the interaction between multiple vapor bubbles in microchannel flow boiling. The results show that for different numbers of bubbles in the microchannels with the same initial size and position of leading bubbles, the bubble size in a single-bubble microchannel is larger compared to the leading bubble of multiple-bubble cases because of heat absorption by the vaporization at the rear bubbles. As the initial volume ratio between the leading bubble and the rear bubble decreases, the leading bubble size in the downstream becomes smaller because of the reduced contact with the superheated thermal boundary layer. With increasing the Reynolds number, both the leading and the trailing bubbles increase slightly in size in the upstream of the heated region, because the bubbles at higher Reynolds number move faster and firstly get in contact with the superheated fluid. The increase in the bottom wall thickness increases the growth rate of the multiple bubble sizes with earlier bubble coalescence because of the higher upstream wall temperature by heat conduction in the solid wall.

An emerging route for efficient conversion of monopotassium phosphate via a pilot-scale electrodialysis metathesis

This study explores energy-efficient KH₂PO₄ (KDP) preparation, examining its implications for sustainability, and offers insights on enhancement and benefits. For the first time, electrodialysis metathesis (EDM) process was considered as a potential technique for efficient conversion and cleaner production of KDP in this study. The effects of key operational parameters including applied voltage, initial feed concentration, concentration ratio, and volume ratio on the conversion performance of EDM were systematically investigated. The promising conditions were established with an applied voltage of 2.3 V per repeating unit, a concentration ratio of 0.5 M NH4Cl to 0.6 M KCl, and a critical 1.43-fold volume ratio, yielding a high-purity KDP solution of 96.65 % at 78.52 g/L with an energy consumption rate of 0.52 KWh/kg. An economic evaluation indicates a 15.4 % cost reduction compared to the market price, presenting the EDM process as a viable and leading technology for the production of high-purity KDP.

Recovery of ammonia nitrogen from simulated reject water by bipolar membrane electrodialysis

ABSTRACT Ammonia monohydrate (NH3·H2O) is an important chemical widely used in industrial, agricultural, and pharmaceutical fields. Reject water is used as the raw material in self-built bipolar membrane electrodialysis (BMED) to produce NH3·H2O. The effects of electrode materials, membrane stack structure, and operating conditions (current density, initial concentrations of the reject water, and initial volume ratio) on the BMED process were investigated, and the economic costs were analyzed. The results showed that compared with graphite electrodes, ruthenium-iridium-titanium electrodes as electrode plates for BMED could increase current efficiency (25%) and reduce energy consumption (26%). Compared with two-compartment BMED, three-compartment BMED had a higher ammonia nitrogen conversion rate (86.6%) and lower energy consumption (3.5 kW· h/kg). Higher current density (15 mA/cm2) could achieve better current efficiency (79%). The BMED performances were improved when the initial NH 4 + concentrations of the reject water increased from 500 mg NH 4 + /L to 1000 mg NH 4 + /L, but the performance decreased as the concentration increased from 1000 mg NH 4 + /L to 1500 mg NH 4 + /L. High initial volume ratio of the salt compartment and product compartment was beneficial for reducing energy consumption. Under the optimal operating conditions, only 0.13 $/kg reject water was needed to eliminate the environmental impact of reject water accumulation. This work indicates that BMED can not only achieve desalination of reject water, but also generate products that alleviate the operational pressure of factories.

Technical Feasibility of Extraction of Freshwater from Produced Water with Combined Forward Osmosis and Nanofiltration.

This study assesses the technical feasibility of a forward-osmosis-based system for concentrating produced water and extracting freshwater. Forward osmosis was combined with nanofiltration, the latter system used to restore the initial osmotic pressure of the diluted draw solutions while concurrently obtaining the final freshwater product. Three draw solutions, namely, MgCl2, NaCl, and C3H5NaO2, were initially tested against a synthetic water mimicking a pretreated produced water effluent having an osmotic pressure equal to 16.3 bar. MgCl2 was thus selected for high-recovery experiments. Different combinations of draw solution osmotic pressure (30, 40, 60, 80, and 120) and draw-to-feed initial volume ratios (1, 1.6, and 2.2) were tested at the laboratory scale, achieving recovery rates between roughly 35% and 70% and water fluxes between 4 and 8 L m-2h-1. One-dimensional, system-wide simulations deploying the analytical FO water flux equation were utilized to validate the experiments, investigate co-current and counter-current configurations, and understand the system potential. The diluted draw solutions were then transferred to nanofiltration to regenerate their original osmotic pressure. There, the highest observed rejection was 96.6% with an average flux of 21 L m-2h-1, when running the system to achieve 100% relative recovery.

Process for Producing Lithium Iodide Cleanly through Electrodialysis Metathesis.

Lithium iodide is commonly used in the production of batteries and drugs. Currently, the neutralization method is the primary means of producing lithium iodide. This method involves using hydriodic acid as a raw material, adding lithium carbonate or lithium hydroxide, and obtaining lithium iodide through evaporation and concentration. However, hydriodic acid is chemically unstable. Its preparation can lead to explosive accidents and encountering high temperatures generates toxic iodine vapors. These limitations restrict its industrial production. The study evaluates the impact of membrane stack configuration, operating voltage, and initial concentrations and volume ratios of reactants on the production process. Electrodialysis metathesis, characterized by a simpler process flow, lower energy consumption, and environmental benefits, emerges as an effective technique for electrically driven membrane separation in lithium salt production and purification. Under the specific conditions of a C-C-A-C-A-C membrane stack configuration, operating voltage at 25 V, initial potassium iodide concentration at 0.4 mol/L, initial lithium sulfate concentration at 0.2 mol/L, and a 1:1 volume ratio of product liquid to raw material liquid, the method achieves a lithium iodide purity of 98.9% with a production cost of approximately 0.502 $/kg LiI.

Innovative sodium acrylate wastewater resource recovery through electrodialysis with integrated bipolar membranes

With the process of industrialization, many production fields produce high-salt organic wastewater. In this work, we have employed an electrodialysis (ED)-resin-bipolar membrane electrodialysis (BMED) mixed process to address sodium acrylate wastewater, achieving resource recovery. The influences of the initial volume ratio and applied voltage were investigated. In the ED-resin, the separation of organic compounds and pigments such as sodium acrylate and phenol was realized. The desalting rate could reach 93.1%, the energy consumption is 0.6 kWh/kg C3H3O2Na, and the chroma removal rate can reach 99%. In the subsequent BMED phase, we attain notable acrylic acid and base concentrations, reaching levels of 1.59 mol/L and 3.12 mol/L, with a current efficiency of 58.14% and an energy consumption of 3.28 kWh/kg NaOH. In addition, economic and environmental evaluations verify the feasibility of this process, which is indicative of its prospect of industrial application.

In-situ micro-CT damage analysis of carbon and carbon/glass hybrid laminates under tensile loading by image reconstruction and DVC technology

Carbon/ glass fibre-reinforced plastic (C/GFRP) offers advantages in engineering applications due to its low cost. However, the mechanism underlying the evolution of damage in C/GFRP under tension remains unclear. Advanced in-situ micro X-ray computed tomography (µCT) is a useful method for investigating the damage evolution of fibre composites. In this study, two tensile specimens, carbon fibre reinforced plastic (CFRP) and C/GFRP, were prepared, and in-situ µCT scanning was performed at different points during the tensile process. To quantify the voids, examine the fracture morphology, and investigate the void volume fractions, three-dimensional (3D) models were constructed while employing an image reconstruction algorithm. Finally, digital volume correlation (DVC) was employed to study the 3D strain fields. The results suggest that C/GFRP exhibits a higher initial void volume ratio and a faster rate of damage evolution. The 3D strain field and stress concentration area can be used to predict the precise location where the specimen would fracture.

Effect of formation of the maltodextrin/gelatin emulsion on gel properties of gelatin

This work investigated the influence of formation of the maltodextrin/gelatin emulsion on gel properties of gelatin. When the maltodextrin/gelatin emulsion was formed, adding maltodextrin increased the gelling temperature (Tg) but decreased the hardness of the gelatin gel. However, adding sucrose increased both the Tg and hardness, since no emulsion was formed. Thus, this work further investigated effects of the initial volume ratio of the gelatin and maltodextrin solutions (VGE/VMD), the dextrose equivalent (DE) of maltodextrin and the biopolymer concentrations on microstructure and properties of the emulsion gel. When the VGE/VMD was 3:7, 5:5, and 7:3, the Tg was 21.6, 24.6, and 23.8 °C, respectively, while the hardness was 365.2, 570.1, and 708.7 g, respectively. The droplet size decreased, as the VGE/VMD increased. These results suggested that smaller droplets induced a stronger emulsion gel. Similarly, maltodextrin of higher DE induced smaller droplets, lower Tg and larger hardness. Moreover, the gelatin concentration was positively correlated with the Tg and hardness but had no linear correlation with the droplet size, which suggested that more gelatin improved the gelling ability, and the emulsion gel strength depended on the gelling ability rather than the microstructure. Similarly, more maltodextrin induced higher Tg and hardness but bigger droplets.

Serial lung mass volume ratios as prognostic indicators of neonatal respiratory morbidity in fetal pulmonary malformations

Several studies have shown that the congenital pulmonary airway malformation volume ratio is a useful prognosticator of neonatal outcome in prenatally diagnosed lung lesions. However, there remains a lack of consensus on which congenital pulmonary airway malformation volume ratio values have the best predictive value because of operator dependence, inherent changes in lung lesion size throughout gestation, and the widespread use of maternal steroids. This study sought to determine the association between serial congenital pulmonary airway malformation volume ratio measurements and neonatal outcomes among fetuses with lung malformations. This was a retrospective cohort study of fetuses with a prenatally diagnosed lung malformation managed at 2 major fetal centers from January 2010 to December 2021. Prenatal variables, including prospectively measured congenital pulmonary airway malformation volume ratio measurements (initial, maximum, and final), were analyzed. The results were correlated with 3 outcome measures, namely surgical resection before 30 days of life, a need for supplemental O2 at birth, and endotracheal intubation at birth. Statistical analyses were performed using receiver operating characteristic curve analyses, Welch 2 sample t tests, and multivariable logistic regressions (P<.05). There were 123 fetuses with isolated lung lesions identified. Eight (6.5%) had hydrops. The mean initial congenital pulmonary airway malformation volume ratio was 0.67±0.61 cm2 at 22.9±3.9 weeks' gestation. The mean maximum congenital pulmonary airway malformation volume ratio was 1.08 ± 0.94 cm2 at 27.0 ± 4.0 weeks' gestation. The mean final congenital pulmonary airway malformation volume ratio was 0.58±0.60 cm2 at 33.2±4.1 weeks' gestation. At a mean gestational age at delivery of 38.3±2.6 weeks, 15 (12.2%) underwent neonatal lung resection for symptomatic disease. In a multivariable regression, all 3 congenital pulmonary airway malformation volume ratio measurements showed a significant correlation with neonatal lung resection (P<.001). Optimal congenital pulmonary airway malformation volume ratio cutoffs were established based on an initial congenital pulmonary airway malformation volume ratio of ≥0.8 cm2, maximum congenital pulmonary airway malformation volume ratio of ≥1.5 cm2, and a final congenital pulmonary airway malformation volume ratio of ≥1.3 cm2 with associated areas under the curve of 0.89, 0.97, and 0.93, respectively. The final congenital pulmonary airway malformation volume ratio had the highest specificity for predicting surgical lung resection in the early postnatal period. Measuring congenital pulmonary airway malformation volume ratios throughout pregnancy in fetuses with pulmonary malformations has clinical value for prenatal counseling and planning care transition after delivery. Fetuses with a final congenital pulmonary airway malformation volume ratio of more than 1.3 cm2 are likely to require neonatal surgery and therefore should be delivered at tertiary care centers with a neonatal intensive care unit and pediatric surgical expertise.

Simultaneous Separation and Recovery of Phosphorus from Aqueous Solution by Bipolar Membrane Electrodialysis

Recycling phosphorus from phosphorus-containing wastes and byproducts is a promising secondary phosphorus resource. Steelmaking slag is generated in large quantities as a byproduct of the iron and steelmaking industry, and contains phosphorus that could be a possible secondary phosphorus resource. Phosphorus can be extracted from slag into aqueous solution; however, the phosphorus concentration is generally lower than other elements, causing a problem for phosphorus recovery. In this study, bipolar membrane electrodialysis was applied to separate and recover phosphorus from solution. The reaction and performance of phosphorus recovery were investigated. The effect of initial phosphorus concentration, volume ratio, and electric potential on recovery process was determined. Ion adsorption on an anion-exchange membrane during the initial stages and ion competition between H2PO4- and OH- in the later stages are the main factors affecting the extraction efficiency. In this study, the maximum concentration ratio achieved was 2.46, and the minimum phosphorus concentration in treated solution was 3.64 mg/L, which is under the Japanese effluent standard. In general, bipolar membrane electrodialysis has good potential for concentrating and recovering phosphorus from aqueous solution.

Determination of seven paraben preservatives in aquatic seasoning using solid-phase extraction coupled with high performance liquid chromatography

Seven parabens are widely used in soy sauce, vinegar, jam, oyster sauce, stuffing, and other foods. The long-term intake of large amounts of parabens and similar substances may be harmful to the human body. Therefore, the addition of paraben preservatives to food should be strictly controlled. The current detection method is applicable to single target compound and several food categories, and the experimental pretreatment method involves extraction with anhydrous ethyl ether, which is a toxic reagent. Moreover, interferences in the analysis of parabens via gas chromatography limit the versatility and accuracy of the detection method. Herein, a novel method based on solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC) was developed for the determination of seven paraben preservatives (methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, isopropyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate, and heptyl p-hydroxybenzoate) in oyster sauce, shrimp sauce, and fish sauce. Compared with the conventional method, the proposed work enables the determination of more compounds, thereby expanding its scope of application to different food types. This strategy also optimizes the pretreatment method and device parameters. The samples were extracted with methanol and 20% methanol aqueous solution by ultrasonication, respectively, and then centrifuged. The experimental pretreatment method was enriched, and sample clean-up was conducted using a MAX SPE column. The seven parabens were separated using a Chromcore 120 C18 column (150 mm×4.6 mm, 3.0 μm). Gradient elution was performed with acetonitrile-5 mmol/L ammonium acetate aqueous solution as the mobile phase (initial mobile phase volume ratio, 30∶70). The flow rate was 0.7 mL/min, and the column temperature was 35 ℃. A diode array detector with a detection wavelength of 254 nm was also used. The seven paraben preservatives showed good linearity in the range of 0.5-50.0 mg/L, with correlation coefficients greater than 0.9999. The limits of detection (LODs) and quantification (LOQs) for the seven paraben preservatives were 0.2-0.4 mg/kg and 0.5-1.3 mg/kg, respectively. A spiked recovery test was conducted using oyster sauce, shrimp sauce, and fish sauce at three spiked levels of 2, 40, and 200 mg/kg. Good recoveries for the seven paraben preservatives were obtained and the recoveries of the analytes in oyster sauce, shrimp sauce, and fish sauce were 91.0%-102%, 95.5%-106%, and 95.0%-105%, respectively, with relative standard deviations of ≤6.97%. Compared with the liquid-liquid extraction method, the proposed method demonstrated better purification effects. The recoveries of the seven paraben preservatives extracted using this method were also much higher than those obtained from liquid-liquid extraction. We determined the contents of these preservatives in 135 food products using the method established in this study and detected methyl p-hydroxybenzoate and ethyl p-hydroxybenzoate in soy sauce, vinegar, and pickles. Thus, the established method can be used for the effective determination of seven parabens in aquatic seasoning such as oyster sauce, shrimp sauce, and fish sauce.

Simultaneous carbon dioxide sequestration and nitrate removal by Chlorella vulgaris and Pseudomonas sp. consortium

Carbon dioxide and nitrogen oxides are the main components of fossil flue gas causing the most serious environmental problems. Developing a sustainable and green method to treat carbon dioxide and nitrogen oxides of flue gas is still challenging. Here, a co-cultured microalgae/bacteria system, Chlorella vulgaris and Pseudomonas sp., was developed for simultaneous sequestration of CO2 and removal of nitrogen oxides from flue gas, as well as producing valuable microalgae biomass. The co-cultured Chlorella vulgaris and Pseudomonas sp. showed the highest CO2 fixation and NO3−-N removal rate of 0.482 g L−1d−1 and 129.6 mg L−1d−1, the total chlorophyll accumulation rate of 65.6 mg L−1 at the initial volume ratio of Chlorella vulgaris and Pseudomonas sp. as 1:10. The NO3−-N removal rate can be increased to 183.5 mg L−1d−1 by continuous addition of 0.6 g L−1d−1 of glucose, which was 37% higher than that of co-culture system without the addition of glucose. Photosynthetic activity and carbonic anhydrase activity of Chlorella vulgaris were significantly increased when co-cultured with Pseudomonas sp. Excitation–emission matrix (EEM) fluorescence spectroscopy indicated that the humic acid-like substances released from Pseudomonas sp. could increase the growth of microalgae. This work provides an attractive way to simultaneously treatment of CO2 and NOX from flue gas to produce valuable microalgal biomass.

Separation of lithium chloride from ammonium chloride by an electrodialysis-based integrated process

Li+ and NH4+ have the same charge, valence, and similar ionic hydration radii. Hence, it is challenging to separate them through individual electrodialysis. Herein, an electrodialysis (ED)-based integrated process is proposed to separate Li+ from the mixed solution of LiCl and NH4Cl and simultaneously generate a concentrated LiOH solution. First, bipolar membrane electrodialysis (BMED) converts the mixed solution into the alkali solution of LiOH and NH3·H2O. The BMED performance was investigated by varying the operating parameters. The results show that the BMED membrane stack with the BP-A-C configuration performs better than the one with the BP-C configuration. A solution of 2.16 mmol/L LiOH and 0.05 mol/L NH3·H2O, selected as the initial alkali solution for the alkali tank, can reduce the energy consumption from 88.51 to 83.45 kW·h/kg, and improve the current efficiency from 53.45% to 56.69% slightly. Reducing the initial volume ratio of the alkali solution to the feed can concentrate the generated alkali solution and increase the LiOH conversion ratio simultaneously. Furthermore, reducing the initial feed concentration can efficiently improve the BMED performance. A maximum LiOH conversion ratio of 97.10% can be achieved in the BMED process. Second, ammonia removal with direct air stripping (AR-DAS) process is performed on the mixed alkali solution of LiOH and NH3·H2O to remove the ammonia and obtain the pure LiOH solution. The results show an ammonia removal ratio of more than 99%. Third, conventional electrodialysis (CED) concentrates the LiOH solution. Effects of the applied voltages and initial LiOH solution concentrations on the CED performance were investigated. The results show that a higher applied voltage increases energy consumption, while a higher initial LiOH solution concentration improves the LiOH concentration ratio. A maximum LiOH concentration ratio of 2.19 can be achieved in the CED process. Moreover, through analysis, the final solid products, generated by evaporation and crystallization, are LiOH·H2O crystals with the purity of 94.3 ± 3.56%. This work suggests that the ED-based integrated process is a highly effective approach to separating the mixed salt solutions of Li+ and NH4+.

Expanding the calibration range of compound-specific chlorine isotope analysis by the preparation of a 37 Cl-enriched tetrachloroethylene.

The recent development of reliable GC/qMS methods for δ37 Cl compound-specific stable isotope analysis (CSIA) paves the way for dual carbon-chlorine isotope analysis of chlorinated ethenes and thus allows deeper insights into underlying transformation processes/mechanisms. A two-point calibration is indispensable for the precise and correct conversion of raw data to the international δ37 ClSMOC scale. The currently available calibration standards for tetrachloroethylene (PCE) span only a very narrow range from -2.52‰ (EIL2) to +0.29‰ (EIL1), which is considerably smaller than observed δ37 Cl isotope enrichment in (bio-)transformation studies (up to 12‰). We describe the preparation and evaluation of a new 37 Cl-enriched PCE standard to avoid bias in δ37 Cl CSIA arising from extrapolation beyond the calibration range. The preparation comprised: (i) partial PCE reduction by zero-valent zinc in a system of PCE, ethanol (initial volume ratio 3/5) and trace amounts of water followed by (ii) liquid-liquid extraction and (iii) a subsequent fractional distillation to purify the 37 Cl-enriched PCE. The obtained PCE (PCEenriched ) showed a purity of 98.8% (mole fraction) and a δ37 ClSMOC value of +10.8±0.5‰. The evaluation of an experimental dataset with and without extrapolation showed no significant variation. The new PCE standard (PCEenriched ) expands the calibration range to 13.3‰ (previously 2.8‰) and thus prevents potential bias introduced by extrapolation beyond the calibration range.

Study on thrust performance of small water rocket launch

For water rocket test of low cost, quick assembly and simple, based on the single water rocket, using Bernoulli equation, the ideal gas adiabatic model and mass conservation theorem, this paper derived both the calculation method of thrust rocket the bottle under the different initial water volume ratio of water pressure, and the rule about how the water rocket thrust and pressure performance change. It is found that the pressure, the jet velocity of the water relative to the water rocket body and thrust of water rocket will decrease with the decrease of water amount under different initial charging pressure and different initial water amount. If the initial pressure is higher, the water rocket will gain more energy and launch faster; However, it doesn’t mean that the more initial water storage ratio is, the better. The maximum velocity obtained by water rocket under the same initial pressure increases first and then decreases with the initial water storage ratio and the optimal initial water storage ratio increases with the increase of initial pressure. According to data calculation, the numerical value increases with the increase of initial pressure. The optimal performance of water rocket can be obtained by taking the maximum pressure and the corresponding optimal initial injection water when the water rocket body is allowed.

Evaluation of bipolar membrane electrodialysis for desalination of simulated salicylic acid wastewater

Salicylic acid (SA) is an important chemical raw material, but its production process generates large amounts of phenol-containing hypersaline wastewater. Bipolar membrane electrodialysis (BMED) technology was proposed to remove Na2SO4 from this wastewater and generate NaOH and H2SO4. The influences of initial pH in feed solution, current density, flow velocity, initial Na2SO4 concentration and volume ratio on the BMED process were investigated. These findings revealed that pH had no significant effect on the desalination rate, but affected the migration of organics including phenol and SA. When the input current density was 40 mA/cm2, flow velocity was 4.0 cm/s and the volume ratio was 2:1, the concentrations of H2SO4 and NaOH could reach the maximum at 0.97 mol/L and 1.56 mol/L respectively, with initial Na2SO4 concentration of 80 g/L and corresponding to a desalination rate of 96.3%. The current efficiency of acid was 55.2% and that of base was 50.2%, and energy consumption was 2.89 kWh/kg H2SO4 and 3.98 kWh/kg NaOH. These results confirmed BMED technology could treat simulated SA wastewater effectively and produce H2SO4 and NaOH. It provides a theoretical basis and guidance for the practical treatment of this type of wastewater.

Efficient treatment of phenol wastewater by co-culture of Chlorella vulgaris and Candida tropicalis

The increased water contamination with phenolic compounds has emerged as an important environmental concern due to their considerable ecotoxicities and associated health issues. Here, a co-cultured microalgae/microorganism system, Chlorella vulgaris and Candida tropicalis, has been developed for efficient treatment of phenol and microalgal biomass accumulation. Our results show that the C. vulgaris and C. tropicalis co-culture system can achieve the highest phenol removal rate as 233.3 mg/L/d and the total chlorophyll accumulation as 23.0 mg/L with the initial volume ratio of C. vulgaris and C. tropicalis at 1:3, which are 5.2 and 7.2 times higher than that of C. vulgaris monoculture respectively. The maximum phenol removal ability of the constructed co-culture system was tested as 1500 mg/L within 6 days. Transcriptome analysis suggested that the co-cultured C. vulgaris/C. tropicalis can utilize phenol as carbon source for its growth and metabolism, and the removal mechanism of phenol was mainly due to the biodegradation process other than bio-absorption. Simulated wastewater experiment shows that the co-culture system can not only efficiently remove the phenol compounds, also can significantly decrease the ammonia nitrogen (NH3−N), total phosphorus (TP) and chemical oxygen demand (COD) of wastewater with removal efficiencies as high as 93%, 92%, 80% and 100%, respectively. Our work provided a promising way for the treatment of phenol compounds and then promoting the growth of C. vulgaris using phenol containing wastewater.

White carbon black wastewater treatment by electrodialysis: Salt separation, silicon sol transporting and wastewater recycling

White carbon black (WCB) as an important silica product has been widely used in many industrial processes. At present, precipitation method is commonly adopted for WCB production, in which a large amount of wastewater containing sodium sulfate and silica is produced. Therefore, it is important and urgent to develop an efficient, low-cost wastewater treatment process, which could extract sodium sulfate from wastewater as value-added byproducts and then recycle this wastewater back to WCB process. In this study, electrodialysis (ED) method, as a proven salt-separation technology, was used to treat WCB wastewater. The existence of silica in the wastewater brings more difficulties for its ED treatment. Firstly, to evaluate ED performance on treating WCB wastewater, the effects of applied voltage, flow rate and initial volume ratio on the overall current efficiency (η), recovery ratio (R), residual rate (γ) and concentration ratio (ω) were investigated. The results show that under the optimized conditions, the highest recovery ratio of Na2SO4 could reach 86.45%, the lowest overall residual rate of SiO2 could go down to 2.69%, and the dilute solution could achieve the reuse standard of waste water. Secondly, the influence of silica on ED performance was investigated. It is found that only about 5.91% of silica in wastewater was transporting from dilute solution to concentrated solution under the optimized conditions. The SEM images of ED membrane indicate that after ED experiments some SiO2 particles adhered to the surface of ion exchange membrane, which would not affect ED normal performance in a short term. These results illustrate that ED is an effective, low energy-cost and reliable process to treat WCB wastewater.

Amine-Based Deep Eutectic Solvents for Alizarin Extraction from Aqueous Media

Alizarin dye is toxic and has a negative influence on human life and the environment. Consequently, the scientific community faces a difficult issue in developing efficient approaches for removing alizarin from water streams. Six distinct deep eutectic solvents (DESs) containing different hydrogen bond acceptors (HBAs), namely trioctylphosphine, trioctylamine and trihexylamine, and two hydrogen bond donors (HBDs), namely salicylic acid and malonic acid, were used to rapidly remove alizarin from high concentration solutions up to 2000 mg/L at room temperature using the liquid–liquid micro-extraction method (LLE). DES-3 had the highest extraction efficiency for alizarin among the other synthesized DESs. The effect of process variables such pH, contact time, dye initial concentration, volume ratio, temperature and salt on alizarin extraction efficiency from water stream was explored, optimized and reported. Statistical analysis was conducted to ensure the accuracy of values for the optimized parameters. For a 1000 mg/L solution of alizarin with a DES/alizarin volume ratio of 1:10 at room temperature, the maximum elimination of 98.02 percent was achieved in 5 min. FTIR was used to analyze the structural properties of DES and the interaction between DES and alizarin. The thermal stability of DES-3 was determined using thermogravimetric analysis (TGA) and indicated that DES-3 has excellent thermal stability up to 320 °C. Human saline was used to test the toxicity of the synthesized DES in vitro. It was determined that synthesized DES is less harmful and more effective at removing alizarin.

The pore-scale mechanisms of surfactant-assisted spontaneous and forced imbibition in water-wet tight oil reservoirs

The imbibition of water with surfactants, including spontaneous imbibition and forced imbibition, is of great significance for enhanced oil recovery (EOR) in tight sandstone reservoirs. Up to now, the migration behaviors of the water and the oil in pores of different sizes, as well as the mechanisms of both spontaneous imbibition and forced imbibition with different surfactants, have not been comprehensively addressed yet. This work first measured the oil-water interfacial tensions (IFTs) and the contact angles in oil-water-rock system with two types of surfactants, namely medium-IFT (0.1–10 mN/m) and low-IFT (0.001–0.1 mN/m) surfactants, at different concentrations to comprehend the functionalities of surfactants on oil recovery. Secondly, the pore size distributions of tight sandstones were determined by the high-pressure mercury intrusion (HPMI) and the nuclear magnetic resonance (NMR) technology to characterized the pores into three types (micropores, mesopores, and macropores) according to the pore sizes. Eventually, this work presented the oil recovery results in these three types of pores for spontaneous and forced imbibition using the two types of surfactants in water-wet tight core samples. Both spontaneous and forced imbibition results showed that the oil recoveries with surfactants were higher than those with brine, which was primarily attributed to the increased oil in the mesopores and the macropores. However, the addition of low-IFT surfactants apparently reduced the oil recovery in micropores, hence resulted in a lower oil recovery in comparison with the medium-IFT surfactants. It was also found that the oil in micropores contributed more than 50% of the oil recovery in the imbibition, except for the imbibition with low IFT, due to the high initial oil volume ratios in micropores; there could be a moderate IFT value (e.g., 0.1–1 mN/m) with the use of surfactants to obtain the highest oil recovery. Moreover, in comparison with the spontaneous imbibition, the forced imbibition could enhance the imbibition of water into the micropores but prevent the oil from being extracted from the mesopores and the macropores, which consequently led to a higher contribution of the micropores on oil recovery than that of the larger pores, especially the mesopores.