Initial Stripping Research Articles

Influence of Chloride and Electrolyte Stability on Passivation Layer Evolution at the Negative Electrode of Mg Batteries Revealed by operando EQCM-D.

Rechargeable magnesium batteries are promising for future energy storage. However, among other challenges, their practical application is hindered by low coulombic efficiencies of magnesium plating and stripping. Fundamental processes such as the formation, structure, and stability of passivation layers and the influence of different electrolyte components on them are still not fully understood. In this work, we gain unique insights into the initial Mg plating and stripping cycles by comparing magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2)- and magnesium tetrakis(hexafluoroisopropyloxy)borate (Mg[B(hfip)4]2)-based electrolytes, each with and without MgCl2, on gold electrodes by highly sensitive operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) applying hydrodynamic spectroscopy. With the stable Mg[B(hfip)4]2-based electrolytes, highly efficient and interphase-free cycling is possible and passivation layers are attributed to electrolyte contaminants. These are forming and degrading during the so-called initial conditioning process. With the more reactive Mg(TFSI)2-based electrolyte, thick passivation layers with small pores are growing during cycling. We demonstrate that the addition of chloride lowers the amount of passivated Mg deposits in these electrolytes and accelerates the currentless dissolution of the passivation layer. This has a positive effect since we observe the most efficient cycling and uniform deposition when no interphase is present on the electrode.

Solvation Barrier Remodeling‐Dictated Fast‐Kinetics Top–Down Zn Stripping/Plating in Water‐Lean Organic Electrolytes

AbstractDifferent from “bottom–up” Zn plating/stripping, “top–down” Zn stripping/plating provides a new perspective to reinvent current aqueous Zn batteries (AZBs), yet related studies remain absent. Herein, a chelation‐induced solvation barrier remodeling strategy is initiated toward fast‐kinetics “top–down” Zn stripping/plating in original Zn2+‐free water‐lean organic electrolytes (WLOE) for durable Zn batteries. It is found that in WLOE, the initial Zn stripping kinetics of the Zn anode remarkably limits the “top–down” Zn stripping/plating. The intervention of multidentate chelant (2‐methoxyethylamine, MEA) in WLOE greatly lowers the solvation reorganization energy of in situ stripped Zn2+ from the Zn anode, enabling the fast‐kinetics “top–down” Zn stripping/plating. Spectral characterization and fitted overpotential‐reorganization energy correlation strongly confirm the underlying mechanism. As such, the Zn stripping/plating in the MEA‐mediated WLOE shows a 90‐fold‐enhanced current response, triple‐lowered overpotential, and 170‐fold‐prolonged cyclability (over 1700 h at 0.5 mA cm−2) of those in MEA‐free counterpart. The assembled Zn||LiFePO4 hybrid full cell in MEA‐regulated WLOE exhibits a distinct and high voltage plateau of 1.50 V and a low polarization voltage of 0.14 V, far surpassing those in conventional WLOE. This work opens a new avenue to break the kinetics bottleneck of Zn stripping/plating in WLOE for durable Zn batteries.

Revealing the plating/stripping processes on Zn anodes in Zn metal batteries via in situ AFM

Mechanistic insights into the interfacial evolution are essential for advancing rechargeable zinc metal batteries (RZMBs). Employing in situ atomic force microscopy (AFM), we observed the Zn plating and stripping processes on the Zn metal anode and investigated the effect of initial stripping over the interfacial evolution. During the initial stripping process, the interfacial evolution is uneven, and by-products form at the Zn anode, which contributes to the heterogeneous nucleation and quick dendrite growth during the subsequent plating, causing performance fading. In contrast, uniform Zn deposition and reversible dissolution can be achieved during the initial plating and following stripping processes. The Zn substrate remains flat without evident cracks or pits, which ensures the interfacial stability of the Zn metal anode during cycling. This work provides direct insights into the morphological evolution and interfacial mechanism of Zn metal anode, promoting the optimal design of advanced RZMBs.

Revealing the Structural Evolution of Electrode/Electrolyte Interphase Formation during Magnesium Plating and Stripping with operando EQCM-D.

Rechargeable magnesium batteries could provide future energy storage systems with high energy density. One remaining challenge is the development of electrolytes compatible with the negative Mg electrode, enabling uniform plating and stripping with high Coulombic efficiencies. Often improvements are hindered by a lack of fundamental understanding of processes occurring during cycling, as well as the existence and structure of a formed interphase layer at the electrode/electrolyte interface. Here, a magnesium model electrolyte based on magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2 ) and MgCl2 with a borohydride as additive, dissolved in dimethoxyethane (DME), was used to investigate the initial galvanostatic plating and stripping cycles operando using electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D). We show that side reactions lead to the formation of an interphase of irreversibly deposited Mg during the initial cycles. EQCM-D based hydrodynamic spectroscopy reveals the growth of a porous layer during Mg stripping. After the first cycles, the interphase layer is in a dynamic equilibrium between the formation of the layer and its dissolution, resulting in a stable thickness upon further cycling. This study provides operando information of the interphase formation, its changes during cycling and the dynamic behavior, helping to rationally develop future electrolytes and electrode/electrolyte interfaces and interphases.

Effect of Hydration Products on the Interfacial Bonding Properties between Asphalt Binder and Steel Slag Coarse Aggregate

Steel slag needs aging treatment before being used for the coarse aggregate of asphalt mixtures because it has volumetric instability due to the hydration of calcium oxide. This paper investigates the effect of hydration products on the bonding properties between asphalt binder and steel slag coarse aggregates subjected to natural aging treatment. A scanning electron microscope, a fluorescence microscope, and X-ray diffraction testing were used to study the surface morphology, microstructure, and mineral phase of the hydration product layer generated on the aggregate surface of steel slag. A modified water boiling test was conducted to evaluate the water stripping resistance of asphalt film with different boiling times. Pull-off testing on real steel slag aggregates was performed to investigate the effect of the hydration product layer and surface treatment on the bonding strength and interface failure mode. Test results indicated that the hydration products exhibited a loose and porous structure and formed an interlayer to prevent the asphalt film from directly adhering to the aggregate surface of steel slag. The hydration product layer could improve the initial stripping resistance but impair the long-term stripping resistance with increased boiling time. The interlayer of hydration products tended to be the weakest link between asphalt film and steel slag aggregate when subjected to pull-off strength damage. The bonding strength showed a negative linear relation with the stripping rate of asphalt film. After steel slag surface treatment with water-based capillary inorganic waterproofer, the pull-off failure of hydration product layer was avoided and thus improved the bonding strength between asphalt film and steel slag aggregate. The bonding strength and failure mode between asphalt-slag adhesion could be well examined by using pull-off tests. Better insights into asphalt–slag adhesion are useful to design durable asphalt mixtures containing steel slag aggregate.

Symmetric is nonidentical: Operation history matters for Zn metal anode

Zn metal electrode is the key to enabling the full vision of next-generation Zn-metal batteries (ZMBs). Thus far, the critical dendrite issue still restricts the Zn anode lifespan, which has even become the Achilles heel to the rejuvenation of ZMBs. This highlight previews the latest advance of Zn anode research, which suggests that Zn electrodes with initial stripping and plating can surprisingly lead to different morphology evolution routes. A proposed pre-deposition strategy is demonstrated to stabilize the Zn anode and homogenize further Zn plating/stripping.

Membrane assisted transport of thorium (IV) across bulk liquid membrane containing DEHPA as ion carrier: kinetic, mechanism and thermodynamic studies

Abstract Extraction and carrier mediated transport of thorium (IV) ions through bulk liquid membrane containing di-2-ethylhexyl phosphoric acid (DEHPA) in kerosene as metal ion carrier. The feed comprised of thorium (IV) ions solutions containing various concentrations of hydrochloric acid, while sulfuric acid solutions of different concentrations are used as a stripping agent. Various parameters about thorium (IV) ion extraction and transport were investigated: the feed solution acidity, initial metal ions aqueous solution concentration, carrier concentration and stripping agent concentration. More than 85% thorium (IV) is recovered in 960 min using 0.2 M DEHPA/kerosene as carrier and 1.5 M H2SO4 as stripping agent from the 0.0001 M HCl solution containing 50 mg L−1 thorium (IV) as feed. Assuming a consecutive, irreversible extraction and back-extraction (stripping) reactions a simple kinetic model was proposed for estimating the reaction rate constant or reaction rate coefficient under the investigated experimental conditions. The activation energy values of extraction and back-extraction reactions were calculated to be 29.94 kJ mol−1 and 20.55 kJ mol−1, respectively, which indicates that the extraction process was controlled by the mixed regime (both kinetic and diffusion), and the back-extraction process was mainly controlled by diffusion process.

Prediction of Zinc Extraction using Facilitated Emulsion Liquid Membrane Model

This study presents the modelling of zinc extraction facilitated by emulsion liquid membrane (ELM). The previously developed model was extended and modified in accordance with the present research objectives and scope. The modified model is based on the chemical interaction between the carrier molecules and zinc ions, as well as the mass transport mechanism. Furthermore, the model also accounts for the effect of Sauter mean diameter on the extraction efficiency. MATLAB was applied to simulate the ELM extraction of zinc based on the validated model. At the optimum conditions, MATLAB simulation produced a similar outcome to the one obtained experimentally. Using the validated model, several parametric studies were conducted, such as the treat ratio, initial zinc concentration, carrier concentration, and stripping agent concentration. The consistent results between the experimental and simulated data increased the reliability of the model as a viable prediction tool for zinc extraction using facilitated ELM.

Separation of Some Anionic Dyes Using Reverse Micelles of CTAB and SDS as Efficient Surfactants Adsorbents from Aqueous Medium

Extractive removal of anionic dyes, namely, Color Index (CI) Reactive Blue 222 and Reactive Yellow 145, using reverse micelles based on liquid-liquid extraction (LLE) was carried out from aqueous solutions using different anionic and cationic surfactants (e.g., sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB), resp.), which dissolved in ethyl acetate as solvent. The reverse micelle principal acts on the dye encapsulated in the solvent in an aqueous micropool. The experiments were carried out by mixing in a simple mixer a given amount of dyes and surfactants dissolved in a solvent in an aqueous process. Due to gravity, the dye is separated from water after the solvent phase is separated from the aqueous phase, including dye encapsulated in reverse micelles. Under various experimental conditions, extraction efficiency was studied, including solution pH, extraction time, initial dye concentration, extractant concentration, temperature, stripping agent, and solvent reusability. Dyes extracted were stripped quantitatively with NaOH solution. Recovery of the solvent and the reuse of dyes and surfactants after extraction of dye molecules from reverse micelles surfactant core considered are very important from an economic point of view. The optimized conditions were 7 ± 0.2 solution pH, 9 × 10−2 mol/L extractant concentration, 1M NaOH stripping agent concentration, 60 min extraction time, 6 × 10−5 mol/L dye concentration, and 1 : 1 aqueous to organic (A/O) ratio. 87–93% of dyes were extracted at experimental optimum conditions.

Asymmetric Impact of External Pressure on Li/Solid-Electrolyte Interfacial Stability

All solid-state batteries (SSB) have attracted a lot of attention as next-generation battery technology with exceptional potential to achieve high energy density, high safety and low cost. Despite development of a wide range of new solid electrolytes, poor interfacial stability within SSB is limiting its success as it leads to poor power density, low coulombic efficiency and short cycle life. Although there is adequate progress in Li/solid electrolyte interface, it still requires better understanding and improvements. The present work uses a Li/Li symmetric cell with a solid composite electrolyte (SCE) to showcase the non-trivial impact of pressure on the lithium stripping/plating at Li/solid electrolyte interface. Evolution of interphase between Li and solid electrolyte is influenced by applied pressure and whether lithium metal went through initial plating or stripping. SSB performance and stability exhibits a significant sensitivity to the applied uniaxial pressure. There is a non-monotonic correlation among the applied pressure, cell polarization, and coulombic efficiency. The performance enhancement reaches an optimum level after which there is a degradation of electrochemical performance with increased external pressure. The intermittent electrochemical characterization of the Li/SCE/Li cells during long-term cycling together with the postmortem analyses of the components are used to shed light on the impact of pressure on the interfacial stability of SSB.

Studying of the effect of many parameters on a bulk liquid membrane and its opposition in Cd(II) removal from wastewater

Because of their tendency to accumulate in the body and their highly toxic potential, heavy metal pollution is becoming one of the main problems globally. The presented study examined the likelihood of eliminating heavy metals by means of the Bulk Liquid Membrane (BLM) method, which is a tool of high importance in various applications of such type. BLM is a simple type of liquid membrane which is showing excellent membrane stability yet insignificant solute fluxes. Therefore, this study outlines the BLM’s membrane resistance in removing heavy metals and recovery from the waste-waters. The cadmium (Cd) ions are fully prepared from the acidic aqueous solutions in this study with the use of the BLM. With regard to stirred transfer cell type, an experimental research has examined the recovery and extraction of Cd ions from synthetic wastewater solution via carrier Tri-butyl-phosphate TBP [C12H27O4P] with the use of BLM as an approach of separation. The impact of some parameters such as feed and stripping stirring speed, carrier concentration, membrane stirring speed, initial feed concentration, temperature, feed, and stripping phase pH is assessed for Cd removal. At pH 4 for feed, pH 10 for strip, 10 %(v/v) carrier concentration, 2 ppm initial concentration, 150 rpm,(S:F) = (1:1) in toluene, and the room temperature the maximal efficiency of extraction and stripping of cadmium (II) metal ions was 82 % and 93 %.

Direct synthesis of a chelating carboxamide derivative and its application for thorium extraction from Abu Rusheid ore sample, South Eastern Desert, Egypt

ABSTRACT Direct synthesis of Pyridine-2,6-dicarboxylic a-+cid bis-(3-hydroxy phenyl)]amide, (Pydca), chelating ligand was applied for Th(IV) extraction from Abu Rusheid Ore Sample, South Eastern Desert, Egypt, between latitudes 24° 37ʹ 16ʹʹ N and longitudes 34° 46 ʹ 35 ʹʹ E and far from the Red Sea coast by about 42 km west, using poly phosphoric acid catalyst (PPA). The synthesis of new amide via direct condensation of organic acid and aromatic amine was performed in DMF at 100°C. The immediate condensation reaction led to construct the carboxamide derivative in one easy step dismantling the hard activation, halogenation, step resulting in a good yield production. This cross-coupling reaction appears simple, convenient and has a wide scope of activities. This protocol could be extended to industrial large-scale production processes. Experimental measurements have been optimised such as diluent type, pH, contact time, initial Th(IV) concentration, temperature, pydca conc., co-existing ions and stripping agents. It was found that a maximum value of Th(IV) retention (0.86 × 10−3 mol/L) is observed with 0.015 mol/L pydca/CCl4 chelating ligand at room temperature. From kinetic aspects, it was found that Th(IV) extraction follows the pseudo-first order kinetic model. The thermodynamic parameters, ΔS, ΔH and ΔG were also evaluated indicating an endothermic and spontaneous extraction process with increasing the randomness of the extraction system. Th(IV) can be completely back extracted from the loaded pydca chelating ligand using 0.5 M HNO3, 1 M H2SO4 and 1 M HCl. Finally, the optimised factors have been applied for Th(IV) recovery from Abu Rusheid Ore Sample, South Eastern Desert, Egypt, producing a thorium oxide concentrate with Th(IV) content of 81.43% with a purity of 92.67%.

(Electrodeposition Division Research Award) Electrodeposition of Semiconductor Films: Where Are We After Three Decades?

This perspective talk focuses on the history and status of electrodeposition for preparing thin films of inorganic and organic semiconductors, metal/semiconductor junctions, or even nanocomposite materials containing different phases. The use of light brings an added dimension and versatility to the preparative strategy. Variants on the basic cathodic or anodic deposition protocols will be elaborated as are approaches that rely on the initial deposition and stripping of a precursor layer. Another topic is operando compositional analysis of the depositing layers using a combination of electrochemical techniques with other complementary probes such as spectroelectrochemistry, electrochemical quart crystal microgravimetry (EQCM), and AC impedance spectroscopy. Finally, state-of-the art and future challenges will be discussed using examples drawn from the author’s and collaborators’ laboratories.

(Invited) Electrodeposition of Semiconductors: An Emerging and Hugely Popular Art

This perspective talk focuses on the history and status of electrodeposition for preparing thin films of inorganic semiconductors, metal/semiconductor junctions, or even nanocomposite materials containing different phases. The use of light brings an added dimension and versatility to the preparative strategy. Variants on the basic cathodic or anodic deposition protocols will be elaborated as are approaches that rely on the initial deposition and stripping of a precursor layer. Another topic is operando compositional analysis of the depositing layers using a combination of electrochemical techniques with other complementary probes such as electrochemical quartz crystal microgravimetry (EQCM) and AC impedance spectroscopy. Finally, state-of-the art and future challenges will be identified using examples drawn from the author’s and collaborators’ laboratories as well as other works.

Determination of the stripping process of asphalt mixtures and the effective mix design and SFE parameters on its different phases

Abstract In the present study, attempts were made to determine the process and different phases of stripping by conducting repeated load tests on 24 different asphalt mixtures and specify the effect of thermodynamic (free energy of adhesion, free energy of cohesion, and debonding energy) and mix design parameters (specific surface area of aggregates, asphalt film thickness, and permeability) on different phases of the process. The results revealed that the stripping process consisted of two separate phases with varying intensities and mechanisms. Free energy of cohesion and the debonding energy had the most significant effect on the rise and decline of loading cycles to the initial stripping point, respectively. In the phase after the initial stripping point where the system’s tendency to stripping grew even higher, the specific surface area of aggregates and the debonding energy had the greatest impact on the decrease and increase of the stripping rate respectively.

Effects of heavy, repeated bark stripping by Cervus nippon on survival of Abies veitchii in a subalpine coniferous forest in central Japan

The management of deer impacts on forested lands requires quantification of the negative factors (e.g., bark stripping) on tree survival in relation to other ecological variables (e.g., competition from neighboring trees). This study measured the effects of bark stripping by sika deer, Cervus nippon, and competition among trees on the survival of Abies veitchii in a subalpine coniferous forest in central Japan over 12 years. Most of the trees subjected to bark stripping by deer were small ( 65% of the stem circumference stripped) were severely affected. The effect on longevity for each tree after bark stripping was explained by maximum bark stripping intensity during the study period, rather than initial bark stripping intensity. When > 85% of the stem circumference had been stripped, survival rates decreased. Bark stripping influenced survival rates much more than competition from neighboring trees. Because bark stripping occurred repeatedly, frequent measurements are important to grasp the full effects caused by this action. Heavy bark stripping of a stem enhances tree mortality. Thus, management of bark stripping is an essential element of stand maintenance and species composition in subalpine coniferous forests in Japan.

In situ bismuth-modified gallium nitride electrode for sensitive determination of cadmium (II) with high repeatability

Bismuth-modified gallium nitride (Bi/GaN) electrode was fabricated using an in situ plating technique and simultaneously investigated for the detection of Cd2+ by square wave anodic stripping voltammetry (SWASV). Under the optimized conditions, the Bi/GaN electrode showed good linear amperometric responses for Cd2+ in the concentration range from 1 to 150μg/L. The sensitivity was 0.54418μALμg−1 (i.e., 59.8598AM−1) and the limit of detection (LOD) was 0.3μg/L (i.e., 2.72nM). Furthermore, the as-prepared Bi/GaN sensor has high repeatability, and retains 95% of its initial stripping peak current after 50cycles. More importantly, the applicability of the sensor in real samples such as tap water, milk, and fetal bovine serum was researched. The recovery ranges from 92.3 to 106.7%, indicating that the as-fabricated Bi/GaN sensor has potential to monitor Cd2+ in practical environments.

Reactive extraction of cobalt sulfate solution with D2EHPA/TBP extractants in the pilot plant Oldshue–Rushton column

In this study, a pilot plant Oldshue–Rushton extraction column has been proposed to extract and recover cobalt from sulfuric acid leach solution. The effect of D2EHPA and TBP concentration, initial aqueous pH and stripping solvent on the Co(II) extraction was investigated in the batch experiment. The results from batch experiments showed that the D2EHPA/TBP mixed extractant is a suitable choice for cobalt extraction from sulfate solution. In continuous experiments, the effects of variables such as rotor speed, dispersed and continuous phase velocities on holdup, mean drop sizes, extraction and stripping efficiencies were studied. Empirical correlations for prediction of the dispersed phase holdup and mean drop sizes in the literature were compared with the experimental results, and the modified correlations were proposed with reaction condition in the Oldshue–Rushton extraction column. The results of cobalt extraction with D2EHPA/TBP in the extraction column, showed the feasibility of the column for cobalt separation from sulfuric acid leach solution with extraction efficiency of 93% and stripping efficiency of 91.5% at high rotor speed (220rpm).

Valorization of ammonia concentrates from treated urban wastewater using liquid–liquid membrane contactors

The removal of ammonium from tertiary effluents by zeolites generates basic ammonia concentrates (up to 1–3 gNH3/L in 1–2g NaOH/L). This study evaluates the use of hollow fibre liquid–liquid membrane contactors (HFMCs) as a concentration and purification step for ammonia effluents to produce NH4NO3 and (NH4)2(HPO4) solutions for potential use as liquid fertilizers. The influence of various operational parameters (i.e., flow rate, initial ammonia concentration and stripping acid concentration) was investigated using a closed-loop setup. Due to the high basicity of the ammonia feed streams (pH>12), the mass transport process was primarily controlled by the free acid concentration in the stripping phase (e.g., HNO3 and H3PO4). A mass transport algorithm to predict the pH of the stripping stream was developed to describe the contactor performance, predict the requirements of the free acid concentration in the stripping phase and optimize the ammonia recovery. Therefore, the closed-loop configuration allowed for ammonia recovery ratios higher than 98% when the required free acid concentration of the stripping phase was maintained. The exhausted NH3/NaOH streams after NH3 removal can be re-used for regeneration of the ammonium-exhausted zeolite filters.

Application of pseudo-emulsion-based hollow fiber strip dispersion for the extraction of p-nitrophenol from aqueous solutions

ABSTRACTThe extraction of p-nitrophenol (PNP) from aqueous solutions through a pseudo-emulsion hollow fiber strip dispersion (PEHFSD) system was conducted in a microporous hydrophobic polypropylene hollow fiber membrane contactor. For the optimization of the process variables, face-centered central composite design (FCCD) has been used. It was observed that initial feed concentration, carrier composition and stripping phase concentration were the three FCCD factors, which influenced the nitrophenol extraction. Using the optimized process conditions for the separation of PNP, experiments were also performed for the separation of other nitrophenols through PEHFSD system. By the FCCD design and analysis, almost 99% extraction of all three nitrophenols was achieved at optimum conditions. A mass transfer model was also developed and aqueous and membrane resistances were evaluated as 196.46 s cm−1 and 50.14 s cm−1, respectively.