High Interfacial Area Research Articles

Toward the Use of Composite Cathode with Significantly High Interfacial Area Density for Solid-State Li–S Batteries

Toward the Use of Composite Cathode with Significantly High Interfacial Area Density for Solid-State Li–S Batteries

Understanding the Wettability of C1N1 (Sub)Nanopores: Implications for Porous Carbonaceous Electrodes.

Understanding how water interacts with nanopores of carbonaceous electrodes is crucial for energy storage and conversion applications. A high surface area of carbonaceous materials does not necessarily need to translate to a high electrolyte-solid interface area. Herein, we study the interaction of water with nanoporous C1N1 materials to explain their very low specific capacitance in aqueous electrolytes despite their high surface area. Water was used to probe chemical environments, provided by pores of different sizes, in 1H MAS NMR experiments. We observe that regardless of their high hydrophilicity, only a negligible portion of water can enter the nanopores of C1N1, in contrast to a reference pure carbon material with a similar pore structure. The common paradigm that water easily enters hydrophilic pores does not apply to C1N1 nanopores below a few nanometers. Calorimetric and sorption experiments demonstrated strong water adsorption on the C1N1 surface, which restricts water mobility across the interface and impedes its penetration into the nanopores.

Titania stabilized Pickering emulsion for photocatalytic degradation of o-xylene

Efficient removal of insoluble volatile organic compounds (VOCs) from wastewater is a significant environmental challenge. In this work, we exploit the synergistic effect of photocatalysis and the high interfacial area of TiO2-stabilized Pickering emulsion to achieve efficient degradation of o-xylene, typically present in wastewater discharged from many industries. Interfacial photocatalysis is carried out by considering o-xylene in water Pickering emulsions stabilized by commercial titania nanoparticles in a multitube non-stirred reactor setup. Stable emulsions used for catalysis are formulated by optimizing o-xylene volume fraction, TiO2 concentration, pH, and homogenization conditions. The influence of photocatalyst loading, emulsion droplet size, and reaction conditions are systematically examined to determine their influence on the rate of photocatalytic degradation of o-xylene. Due to enhanced photocatalytic activity compared with conventional stirred batch photocatalysis, the TiO2-stabilized Pickering emulsion is found to increase the degradation rate and removal efficiency of o-xylene significantly. Furthermore, the Pickering emulsion stability during the photocatalytic process is studied, demonstrating the capacity of the emulsions to maintain stability and catalytic activity over a longer time period. The distinctive characteristics of Pickering emulsions – excellent storage stability and enhanced photocatalytic activity – make them a promising option for advanced wastewater treatment. The findings lead to the development of ecologically acceptable and sustainable VOC degrading strategies, which might be used in industrial and home wastewater treatment systems.

Elucidating flow-directed 98% CO2 absorption using millimeter-sized coiled flow inverters: Nanocellulose-aided sustainable scope

The Sustainable Development Goals (SDGs) adopted by the United Nations drive the global efforts to discover a sustainable carbon capture method for the reduction of anthropogenic CO2 emissions. Concentrated alkanolamine solutions are being used as CO2 capture mediums for batch processes amid several disadvantages, such as energy intensiveness and poor efficiency. In this work, millimeter-sized coiled flow inverters (CFI) have been explored as a point-source CO2 capture tool for highly efficient, continuous operations. Solvent and CO2 gas flow rates are found to dictate the slug flow regime and, more specfically, slug lengths. High interfacial area and residence time remain the driving factors for enhanced CO2 capture using CFI. About 98% CO2 absorption efficiency has been achieved for 3% aqueous diethanolamine solution in CFI . The efficacy of nanocellulose, a sustainable nanomaterial has been unearthed for CO2 capture at low flow rate.

Magnetic resonance velocimetry of thin falling films

Falling film microreactors are a type of liquid–gas contactor based on a gravity-driven film flow. These devices achieve high interfacial areas per unit volume compared to other contactors. Nevertheless, they are limited by the liquid-side mass transfer. To overcome this issue, the operating conditions must be chosen in a way to enhance gas absorption and ensure efficient transfer within the film. The present study looks into the use of magnetic resonance velocimetry to study the velocity field inside of falling films at the microscale. Two parameters were considered, the channel geometry, and the volumetric flow rate. The aim was not only to determine the conditions that optimize the interfacial area, but also to showcase the capabilities and advantages of magnetic resonance velocimetry for this type of flow configuration. In addition, a straightforward mathematical model, based on the Navier–Stokes equations, is used to predict the thickness of the film, since previous approaches, mainly those of Kapitza and Nusselt, are not valid for flows at the microscale, where surface tension phenomena predominate. It was shown that the round channel yields by far the highest surface-to-volume ratio, twice as high as for the rectangular channel for the same volumetric flow rate. In addition, film breakup was not observed in the round channel even for volumetric flow rates of down to 0.27mLmin−1.

BaTaO2N and quantum dots-based CuO nanocomposites for HER by solar electrochemical water splitting

Barium tantalum oxynitride (BaTaO2N) has been demonstrated to be an attractive catalyst for photo-electrochemical water splitting, especially oxygen evolution reactions. However, the hydrogen production rates and charge transfer resistances of BTN leave much to be desired from a practical standpoint. In fact, it has never been reported for photocathode applications. On the other hand, CuO has been reported for hydrogen evolution reactions. Given this, here nanocomposites of BaTaO2N and copper oxide quantum dots (CuO QDs), where the latter are digestively ripened, are reported for photoelectrochemical water splitting on a carbon paper substrate. To assess the role of ultra-small quantum dots, composites of commercially available CuO nanoparticles with BaTaO2N were also tested. BaTaO2N and CuO QD nanocomposites performed well and showed a high photocurrent density of 3.1 mA cm−2 at 0 V vs RHE. This was also accompanied by reduced charge transfer resistance (225.4 Ω) due to the high interfacial surface area provided by nanoscopic CuO on BaTaO2N.

High performance flow-focusing droplet microreactor. Extractive separation of rare earths as case of study

This work advances the knowledge of the design and manufacture of microdroplet reactors for reactive liquid–liquid systems assisted by advanced simulation techniques (CFD). The mathematical model is based on the integrated analysis of the fluid dynamics for multiphase systems, passive mixing of reactants inside and outside the microdroplet and interfacial reaction rate. To validate the results obtained with the predictive model a spiral microdevice with droplet generation using flow-focusing geometry has been designed and fabricated by additive manufacturing. First, the influence of fluid flowrate, hold-up and viscosity on the droplets frequency and size has been evaluated with the model and assessed experimentally. Next, the performance in the separation of a binary Dysprosium-Lanthanum system has been tested, working with a dispersed aqueous phase containing the rare earth elements (REEs) solution and a continuous organic phase constituted of a solution of the extractant Cyanex® 572 in Shellsol® D70. The extraction experiments have been conducted at residence times between 3 and 60 s to generate aqueous phase monodispersed droplets with high interfacial area that varies between 61.4 and 49.2 cm2·cm−3 depending on the operating conditions. At pH 1, 90 % of dysprosium has been extracted, and almost complete separation of both REEs has been achieved. Very good agreement between simulated and experimental results has been reached with an error lower than 12 %. Therefore, here we provide the tools to design and predict the microdroplet enhanced performance of extractive liquid–liquid microreactors.

Formation of small-granule starch oleogels based on capillary force: Impact of starch surface lipids on lubrication performance

Starch granule oleogels were prepared and their rheological properties were precisely tuned using the capillary bridging phenomenon. The addition of a small amount of water to an oily suspension of starch granules can lead to starch granule bridging and network formation, transitioning it from a fluid-like to a gel-like state. Small-granule starches with high specific surface area and interfacial area exhibited a greater number of liquid bridges and stronger starch granules interactions, making them more prone to forming structurally stable oleogel systems. By increasing the content of water and starch granule, the starch oleogels exhibited three distinct structural states: pendular state (water ≤ 3.28 %, starch ≤ 17.85 %), pendular bridging network (water: 4.92 %, starch: 24.59 %), and capillary aggregates (water ≥ 6.56 %, starch > 24.59 %). Furthermore, the influence of starch granule surface lipids on the lubrication performance of the oleogel system was investigated. Surface roughness increased after extraction of surface lipids, and the friction coefficient also showed a significant increase. Overall, capillary suspension system can potentially be used to design novel fat food products, and our findings have established the correlation between starch granule surface properties and sensory perception in food, providing valuable insights for adjusting the oral processing characteristics of food.

Vertically Aligned Nanocomposite Thin Films Incorporating 3D-Architectures for Micro-Battery Applications

Vertically aligned nanocomposite (VAN) thin films have shown strong potential in oxide nanoionics but are yet to be explored in detail in solid-state battery systems [1,2]. VANs, typically grown by pulsed laser deposition (PLD), are chessboard-like structures comprised of pillars of one phase embedded in a matrix the second phase. They form by solid-state thermodynamic self-assembly, allowing the spontaneous formation of interdigitated battery components in a single deposition without additional processing steps such as etching. Their 3D architectures are attractive because they may allow enhancements in capacity, current and power densities [3]. Furthermore, VAN films grow with a preferential orientation, allowing for selective growth of the optimum crystallographic orientation for high performance by altering the substrate phase and/or orientation. Also, owing to their large interfacial surface areas, VAN could serve as models to study interfaces and solid-electrolyte interphase formation during cycling due to their high interfacial surface areas.In this poster, first we present highly crystalline and epitaxial vertically aligned nanocomposite PLD films comprised of a LixLa0.32±0.05(Nb0.7±0.1Ti0.32±0.05)O3±δ-Ti0.8±0.1Nb0.17±0.03O2±δ-anatase (LL(Nb,Ti)O-(Ti,Nb)O2) electrolyte/anode system, the first anode VAN battery system reported (Figure 1) [4]. This system exhibits an order of magnitude increased Li+ ionic conductivity over that in bulk Li3xLa1/3-xNbO3 (LLNO) and is comparable with the best available Li3xLa2/3-xTiO3 (LLTO) pulsed laser deposition films. Then, we will highlight the considerations and challenges that VANs pose, and how to overcome them [5]. Finally, we will also present our recently submitted work on VAN based cathodes [6]. Our carefully selected materials combination exhibits remarkable high-rate performance, achieving discharge capacities > 70 mAh g-1 up to ~200 C with clear redox behavior of the cathode-of-choice. The enhanced electrochemical performance is enabled by the 3D VAN architecture. Interestingly, we elucidate the relationship between pillar morphology and electrochemical performance, namely there is an optimum size and orientation of cathodic nanopillars such that high discharge capacity under high-rate regimes is possible. These works open up the possibility of incorporating VAN films into an all solid-state battery, either as electrodes or electrolytes, by the pairing of suitable materials.

Probing of Near-Surface Cations during the Oxygen Evolution Reaction (OER) Using Operando XAS

Electrified solid-liquid interfaces are ubiquitous in technologies ranging from colloidal science to electrochemistry. Hence, an atomic-level characterization of the electrode-electrolyte interface is crucial for total control and optimization of the processes involved. While the electrode side of the interface has been quite extensively studied, the electrolyte side is comparatively poorly understood1. Specifically probing the near-surface electrolyte species during an electrochemical reaction is a major technical challenge in the field of catalysis and surface chemistry.We have developed an interface-sensitive X-ray absorption spectroscopy (XAS) approach which allows us to directly probe the near-surface cations and anions of the electrolyte under applied potentials. In this approach, we employ a mesoporous electrocatalyst film coated on a 𝑆𝑖𝑁𝑥 X-ray window. These mesoporous films exhibit an extremely high electrode-electrolyte interface area, enabling us to specifically probe the behaviour of interfacial ions via their K-edge spectra. Using this approach, we have recently investigated the interaction of Na+ cations with IrOx during the oxygen evolution reaction (OER), which is a bottleneck in major electrochemical processes like green hydrogen production and CO2 reduction. The cations and anions of the electrolyte reportedly influence the OER activity of electrodes during OER2,3. We used operando Na K-edge XAS to directly probe the concentration and coordination environment of the near-surface Na+ cations. Simultaneously, operando O K-edge XAS monitored the interfacial water structure and the evolution of catalyst’s surface structure. Contrary to expectations, we discovered that the positively charged Na+ ions are drawn to the IrOx surface by more positive potentials only at alkaline pH. This finding cannot be explained by any of the electrolyte theories4 put up thus far, emphasizing the necessity of a detailed investigation of interfacial electrolyte structures.

Including CFD rigorous models in the optimal design of carbon capture plants through trust-region methods

Efficient technology alternatives are required to fulfill the environmental goals of reducing CO2 emissions at short and medium term. In this context, carbon capture using hollow fiber membrane contactors is an interesting alternative due to its operational flexibility, modularity, and high interfacial area. To elucidate the true potential of this technology, cutting-edge modeling and optimization techniques must be applied to improve key process performance indicators. In the present study, we develop a CFD rigorous model for a MEA-based absorber using membrane contactors. This model is included as an external function in the formulation of an optimization problem through the trust-region filter method, to minimize the CO2 avoided cost of the capture plant. As results, we obtain an optimal design with a CO2 avoided cost of 54.16 $/t-CO2 and a specific energy demand of 3.52GJ/t–CO2.

Reducing moisture ingress in flexible sensors with laser patterned polyimide

Polymeric materials that can more effectively act as barriers to environmental factors such as moisture are of significant interest to the sensor fabrication industry. Moisture ingress may corrode metallic traces or cause the decohesion of bonded interfaces of flexible sensors. Often, imparting a higher degree of moisture resistance necessitates encapsulating the sensors or applying specialty coatings. In this study, a laser patterning process is used to modify standard polyimide coverfilms used in flexible sensor manufacturing. The study achieved patterned polyimide surfaces in the partial wetting Cassie-Baxter regime which displayed reduced moisture diffusivity compared to the original polyimide surface by an order of magnitude. These surfaces displayed periodic structures with deep channels, a high developed interfacial area ratio, and a low contact angle. A laser-patterned sensor that makes use of this coverfilm-enhancing technique is demonstrated. Avoiding the need to apply additional moisture resistant films and instead laser patterning existing coverfilms could provide significant benefits to the flexible sensor industry, simplifying the fabrication of more robust sensors that are less prone to environmental degradation.

Effect of carbonaceous reinforcements on mechanical properties of ZrB2-SiC composites via nanoindentation study

In the present work, silicon carbide (SiC) reinforced zirconium diboride (ZrB2) ceramic was studied. ZrB2 reinforced with 20 vol% SiC (ZS) and with additives multi-walled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), and CNT + GNP were consolidated via spark plasma sintering. ZS with carbon additives (CNT + GNP) composite (ZSCG) showed the highest densification (98.2 %) than that of ZS sample (91 %) via Archimedes' method. Crystallite size calculated via XRD showed a value of (56 ± 1) for ZS and the lowest crystallite size value (47 ± 1) for ZSCG, attributed to the pinning effect of carbonaceous reinforcements (CNT + GNP) at the grain boundaries, which restrict the grain growth in the composite. Nanohardness for the composite samples ranges from ~24 to 33 GPa. ZSCG composite showed the highest nanohardness of 33 GPa attributed to the bridging of long and flexible CNTs adjacent to GNPs to form 3-D hybrid structures restricting their agglomeration, which resulted in a high interfacial area between the matrix and the hybrid reinforcement leading to better load transfer. The theoretically calculated Young's modulus from various models (rule of mixture, Voigt Reuss, and Halpin Tsai (HT)) was compared with the experimental Young's modulus. The calculated Young's modulus value via the HT model (370–411 GPa) is in close agreement with the experimental values (364–401 GPa) owing to consideration of porosity and the interfacial debonding factor. Also, the lowest debonding factor was determined for the ZSCG composite (0.47) in comparison with the ZSC composite (0.86) suggesting increased bonding strength which results in the enhancement of mechanical properties. So, it was finally concluded that the finer crystallite size, improved hardness, less debonding factor, and better load transfer mechanism can make ZSCG composite a viable candidate for high-temperature applications.

Constructing Rich Interfacial Structure by Carbon Dots to Improve the Sodium Storage Capacity of Sb/C Composite

AbstractDesigning Sb/carbon composite is an effective strategy to enhance the cycle stability and rate capability of Sb anodes for sodium ion batteries. However, the introduction of carbon often leads to a loss in specific capacity and initial Coulombic efficiency (ICE). In this work, a new perspective is adopted by focusing on improving the “sloping capacity” contribution of carbon (C) in Sb/C composites, rather than solely increasing the platform capacity of Sb as traditionally done. Theoretical predictions indicate that constructing Sb/C composites with high Sb and carbon interfacial areas can provide more Na adsorption sites, thus enhancing the “sloping capacity” of amorphous carbon. Guided by DFT, a rational Sb/C/NSCDs‐2(N) is successfully developed by self‐embedding Sb nanodots into 2D‐amorphous carbon sheets doped with N/S. Sb/C/NSCDs‐2(N) exhibits abundant Sb/carbon interfacial areas and excellent nanoscale effects, demonstrating ideal electrochemical sodium storage performances. Impressively, the Sb/C/NSCDs‐2(N) provides a “sloping capacity” close to 160 mAh g−1. Significantly, owing to the fact that these interfaces and defects are not in direct contact with the electrolyte, the side reaction of electrolyte is effectively inhibited, leading to no decrease of ICE.

Euler-Lagrange Simulations of Microstructured Bubble Columns Using a Novel Cutting Model.

In the concept of a microstructured bubble column reactor, meshes coated with catalyst can cut the bubbles, which in turn results in high interfacial area and enhanced interface hydrodynamics. In previous work, we developed a closure model for the fate of bubbles interacting with a wire mesh based on the outcomes of energy balance analysis. In this paper, the model is validated using Euler-Lagrange simulations against two experimental cases of microstructured bubble columns. Before validation of the model, the definition of the deceleration thickness, as used in the calculation of the virtual mass term, is refined to introduce the effects of liquid viscosity and wire thickness. Proceeding with the validation, the inclusion of our cutting closure model results in an excellent match of the bubble size reduction by the wire mesh with the experimental data. Consequently, the simulations produce a more accurate prediction of the reactor performance for the gaseous reaction in view of the pH and gas holdup profiles. The effect of liquid viscosity on the bubble size reduction by the wire mesh is replicated accurately as well. Noticeably, the significance of bubble coalescence and breakup in bubble dynamics overperforms the role of bubble cutting at high superficial gas velocities; thus, further improvement is needed there. Finally, based on the validated cutting model, we share some perspectives on the design of wire meshes to increase the bubble interfacial area.

Membrane bubble aeration unit: Experimental study of the performance in lab scale and full-scale systems

The transfer of oxygen is limited at the gas/liquid interface by the low solubility of oxygen in water. Fine bubble diffusers have a standard oxygen transfer efficiency (SOTE) lower than 30% in a full-scale system. Porous membranes can be employed as diffusor to improve the efficiencies taking the advantage of the high exchange interfacial area and the low volume of equipment. The aim of this work is to study the feasibility of membrane systems for aeration in a full-scale system. Several membrane modules were prepared using hollow fibers hydrophobic membranes and compared with the traditional disk diffusor currently employed in wastewater treatment. The mass transfer coefficient (KLa) and SOTE were assessed by carrying out the aeration tests in both lab-scale and full-scale systems exploring different operating parameters such as system flow rate, the geometry of the module and the surface of the device. The advantage and disadvantages of employing membranes in the aeration process were highlighted. The membrane unit showed better overall mass transfer efficiency increasing from 28% at the lab-scale to 34% in the full-scale system. Unlike the conventional disk diffusers, it has been found that the membrane aerator can operate with significantly lower air flow rates, which leads to a doubling of the efficiency. Moreover, the membrane surface generating the bubbles can be easily increased while maintaining the same module footprint, which in turn allowing a further increase of efficiency from 9% to 24%. However, important phenomena of scaling were observed on the membrane surface.

A Model for the Fate of a Gas Bubble Interacting with a Wire Mesh.

In the concept of a microstructured bubble column reactor, microstructuring of the catalyst carrier is realized by introducing a static mesh of thin wires coated with catalyst inside the column. Meanwhile, the wires also serve the purpose of cutting the bubbles, which in turn results in high interfacial area and enhanced interface hydrodynamics. However, there are no models that can predict the fate of bubbles (cut/stuck) passing through these wires, thus making the reactor optimization difficult. In this work, based on several typical bubble-wire interacting configurations, we analyze the outcomes by applying the energy balance of the bubble focusing on buoyancy and surface tension. Two limiting cases of viscosity, corresponding to the ability of the bubble to reconfigure into the lowest energy state, are investigated. Upon analysis, it is observed that a narrow mesh spacing and a smaller bubble Eötvös number generally result in bubbles getting stuck underneath the wire. We have obtained the threshold grid spacing and the critical Eötvös number for bubble passage and bubble cutting, which are verified by the direct numerical simulation results of bubble passing through a single mesh opening. The derived energy balance is generalized to large meshes with multiple openings and different configurations. Finally, a closure model based on the outcomes of energy-balance analysis is proposed for Euler-Lagrange simulations of microstructured bubble columns.

Charge transfer and ZnO defect state mediated FRET dependent luminescence in nanocomposites based on PPy nanowires and ZnO microflowers

The role of Forster resonance energy transfer (FRET) and charge transfer on controlling the overall luminescence of the nanocomposites based on PPy and ZnO is discussed here. Polypyrrole-ZnO (PPy-ZnO) nanocomposites have been synthesised with the variation of ZnO content (10 wt %, 30 wt % and 50 wt %) in the nanocomposite through chemical oxidative polymerization method. Nanowires of PPy and PPy-ZnO nanocomposites are observed from SEM and TEM images. The diameters of nanowires in PPy-ZnO nanocomposites are found to vary with ZnO content. Ordering in the polymer chain with the incorporation of ZnO is observed from XRD spectra. Red shift of the absorption peak of PPy in PPy-ZnO nanocomposites gives the evidence of increase in order of the polymer chain which in turn increases the singlet exciton diffusion through the polymer chain. Two photophysical phenomena i.e. FRET and charge transfer have significant impact on controlling the overall luminescence of the composites depending upon the ZnO content in the composite. At lower amount of ZnO (10 wt %), FRET occurs predominantly from defect states of ZnO to PPy and overall enhancement of luminescence is noticed. But no significant enhanced luminescence is observed when higher amount of ZnO is added to the composite. This happens due to dominant charge transfer between PPy and ZnO since they have type II band alignment. When the amount of ZnO is high in the composite, the interfacial area between PPy and ZnO get increased. XPS spectra reveals that ratio of polaron to neutral nitrogen in PPy chain also increases in the composite with higher amount of ZnO which results in the modification of band structure of PPy. Thus high interfacial area between PPy and ZnO as well as modification of band structure in PPy increases the rate of charge transfer between PPy and ZnO. Therefore, inspite of possibility of FRET, charge transfer occurs more efficiently in the nanocomposite when the ZnO content is high in the composite. This ultimately prohibits the radiative recombination of singlet exciton inside the composite with higher amount of ZnO. Hence the Photoluminescence (PL) intensity quenches considerably. Thus optimizing the amount of ZnO in the composite, the photophysical phenomena as well as luminescence of the composite can be controlled for the potential application of different optoelectronic devices like solar cell.

Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium‐Ion Batteries

AbstractTunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high‐performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra‐thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol‐based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water‐binding capacity according to computational simulations. This strategy renders the electrolyte a room‐temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half‐cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.

Liquid–liquid two-phase flow in a wire-embedded concentric microchannel: Flow pattern and mass transfer performance

In this work, flow pattern and mass transfer of liquid–liquid two-phase flow in a wire-embedded concentric microchannel are studied using toluene–water system. Droplet flow, slug flow, oval flow and annular flow are observed in the wire-embedded concentric microchannel. The effects of embedded wires and physical properties on flow patterns are investigated. The embedded wire insert is conducive to the formation of annular flow. The flow pattern distribution regions are distinguished by the Caaq (capillary number)–Weorg (Weber number) flow pattern map. When Weorg＜0.001, slug flow is the main flow pattern, and when Weorg＞0.1, annular flow is the main flow pattern. Oval flow and droplet flow are between Weorg=0.001–0.1, and oval flow is transformed into droplet flow with the increase of Caaq. The effect of flow rate, phase ratio, initial acetic acid concentration, insert shape and flow patterns on mass transfers are studied. Mass transfer process is enhanced under annular flow conditions, the volumetric mass transfer coefficient is up to 0.36 s–1 because of the high interfacial area and interface renewal rate of annular flow.