Chemical Dissolution Research Articles

Anodic Synthesis of Highly Ordered TiO2 Nanotube Arrays: Role of Electrolyte Composition on the Structural, Morphological, Optical, and Photo-electrochemical Properties

The fluoride species present in two different anodizing electrolytes were used to produce TiO2 nanotube arrays (TiO2 NTAs) by simultaneous anodic reaction and chemical dissolution. In this investigation, two different electrolytes were used for the preparation; [Eth-TiO2 NAs: 95 ml ethylene glycol+0.5% NH4F+5 ml DI water] and [Gly-TiO2 NAs: 75 ml glycerine+0.5% NH4F+25 ml DI water]. The effects of the prepared electrolytes used in the synthesis of TiO2 nanotube arrays on structural element composition, morphology, and optical properties are the focus of this study and are characterized by X-ray diffraction (XRD), scanning electron microscopy field emission (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and UV-vis diffusion reflection spectroscopy (DRS), respectively. The photoelectrochemical properties of TiO2 NTAs prepared in different electrolytes were investigated. The photoelectrochemical performance of TiO2 NTAs in Na2SO3 (0.1 M) and Na2S (0.1) was examined under the light of 100 mW/cm2 from a xenon lamp. Comparing the photoelectrochemical (PEC) results of both electrolytes, we find that Eth-TiO2 NTAs contribute a wide surface area resulting in an enhanced PEC response. TiO2 NTs, which were prepared with Eth-TiO2 NTAs, exhibited the highest photocurrent density, 0.326 mA cm–2, and photoconversion efficiency (0.22%).

Aging damage characteristics of acid‐etched sandstone samples

AbstractTo investigate the erosive damage effect of the acidic solution on sandstone, experiments were conducted to examine the macro‐ and micro‐characteristics of sandstone samples under different acid etching times. Microscopic morphology changes, pore structure characteristics, mineral composition changes, and mechanical response characteristics were obtained before and after acid etching. Finally, a comprehensive evaluation index for acid etching damage was proposed. The results show that: (1) Acidic solution will erode the sandstone skeleton and cause the sandstone to collapse. The etched surface appears “flocculent” and yellow sediment is produced. (2) The pores in sandstone samples are mainly micro‐ and mesopores, and the total porosity increases exponentially with the duration of acid etching. The volume fraction of micropores can reach up to 81.5%. (3) The acid etching process of sandstone samples includes physical diffusion and chemical dissolution, which can be divided into four stages and three regions from the outside to the inside. After acid etching, the uniaxial compression failure mode of the sample changes from shear to mixed shear‐tensile failure. (4) The comprehensive evaluation index based on three failure modes generated during the loading process shows good consistency with the overall changes of characteristics parameters such as elastic modulus, peak stress, and peak strain. The research findings of this paper can provide theoretical support for the assessment of rock mass stability and disaster prevention in acidic environments.

Seasonal Changes in the Oxidative Potential of Urban Air Pollutants: The Influence of Emission Sources and Proton- and Ligand-Mediated Dissolution of Transition Metals.

The inhalation of fine particulate matter (PM2.5) is a major contributor to adverse health effects from air pollution worldwide. An important toxicity pathway is thought to follow oxidative stress from the formation of exogenous reactive oxygen species (ROS) in the body, a proxy of which is oxidative potential (OP). As redox-active transition metals and organic species are important drivers of OP in urban environments, we investigate how seasonal changes in emission sources, aerosol chemical composition, acidity, and metal dissolution influence OP dynamics. Using a kinetic model of the lung redox chemistry, we predicted ROS (O2 •-, H2O2, •OH) formation with input parameters comprising the ambient concentrations of PM2.5, water-soluble Fe and Cu, secondary organic matter, nitrogen dioxide, and ozone across two years and two urban sites in Canada. Particulate species were the largest contributors to ROS production. Soluble Fe and Cu had their highest and lowest values in summer and winter, and changes in Fe solubility were closely linked to seasonal variations in chemical aging, the acidity of aerosol, and organic ligand levels. The results indicate three conditions that influence OP across various seasons: (a) low aerosol pH and high organic ligand levels leading to the highest OP in summer, (b) opposite trends leading to the lowest OP in winter, and (c) intermediate conditions corresponding to moderate OP in spring and fall. This study highlights how atmospheric chemical aging modifies the oxidative burden of urban air pollutants, resulting in a seasonal cycle with a potential effect on population health.

An experimental study on wire arc additive manufacturing (WAAM) of 308L stainless steel and its chemical dissolution

Wire arc additive manufacturing (WAAM) is a potential method of producing complicated metal parts directly from computer-aided design (CAD) models. In this experiment, stainless steel 308 L alloy was deposited with a GMAW-interfaced three-axis special purpose Cartesian robot. The major goal was to understand the behaviour of deposited material and, later, its dissolution in specific concentrations of chemical combinations. The deposited samples were investigated for better understanding of the impact of welding current on bead properties, surface roughness, and microstructure. Furthermore, the dissolving behaviour of deposited samples was investigated in various acidic bath mixes to better understand the rate of dissolution. The results reveal that WAAM parameters, particularly current, have a considerable impact on bead properties, roughness, and microstructure. On the other hand, dissolution experiments demonstrated that the faster breakdown of WAAM deposited stainless steel occurs when a 1:1 ratio mixture of acids is used.

Correlation between Electrolyte Concentration and Lithium Morphology during Lithium Bis(fluorosulfonyl)amide–Tetraglyme Electrolyte Deposition–Dissolution Reactions

Electrodeposition and chemical dissolution reactions of Li are strongly affected by the electrolyte concentration at the electrode surface. In this study, we investigated the processes involved in the formation of Li deposits at various electrolyte concentrations and different numbers of deposition–dissolution cycles. Growth of the deposits during the cycles was assessed using a digital microscope. The thickness of the fibrous layer was strongly dependent on the electrolyte solute–solvent molar ratio. The thickness of the fibrous layer increased as the number of cycles increased when the electrolyte solute–solvent molar ratio was low but decreased when the molar ratio was high. Temporal changes in the electrolyte concentration and in the diffusion layers near the electrode were identified using a laser interference microscope. The results led us to conclude that there are three fibrous Li deposit growth models that occur at different solvent–solute molar ratios.

Effect of nitrogen on the microstructure and strengthening mechanism of high performance tinplate

In order to meet the high strength and high formability requirements of the tinplate market, the nitrogen strengthening method was used for the chemical composition of the tinplate, and the action mechanism of nitrogen on the full-process tinplate substrate was explored. The present study designed tinplate with different nitrogen contents (named as 20N steel and 150N steel), and conducted phase transformation research and recrystallization temperature tests. SEM, XRD, EBSD, TEM, chemical dissolution analysis and tensile tests were carried out, and the influence of annealing process on the microstructure, mechanical properties and precipitation of annealed sheet was also explained. With the increase of nitrogen content, the phase transformation temperature decreases, the hardness increases and the recrystallization temperature increases. The microstructures of 20N steel and 150N steel annealed at different annealing temperatures are composed of ferrite and cementite distributed in chains. At the same annealing temperature, the recrystallization degree of 20N steel is higher, the {111} texture accounts for a larger proportion, and the grain size is larger. With the increase of annealing temperature, the yield strength and tensile strength show a downward trend, while the elongation shows an upward trend. Compared with 20N steel, the yield strength and tensile strength of the 150N annealed sheet are significantly improved, and the elongation is slightly reduced. The calculation results show that the mechanism of nitrogen improving the strength of tinplate is mainly solid solution strengthening, and the improvement effect of fine grain strengthening and precipitation strengthening is weak.

Permeability evolution of sandstone caprock transverse fractures during intermittent CO2 injection in coal-bearing strata

The caprock of coal-bearing strata plays a critical role in CO2 geological storage, with the presence of fractures posing a heightened risk of CO2 leakage. The cyclic effects of CO2 injection and in situ stress influence the permeability of caprock fractures. However, the combined impact of CO2 and in situ stress on fracture permeability remains uncertain. This study conducted cyclic seepage experiments under varying amplitude stresses on fractured sandstone samples soaked in ScCO2 for different times (0, 15, 30, and 60 days). The microstructural characteristics of the fractured sandstone surfaces were analyzed using scanning electron microscopy and x-ray diffraction. The experimental results indicated that soaking in ScCO2 reduces sandstone fracture permeability, but the extent of this reduction is nonlinearly related to the soaking time. During the stress cycling process, due to the effect of plastic deformation, the permeability of sandstone fractures decreases with increasing cyclic amplitude and remains relatively constant with decreasing cyclic amplitude. At the same cyclic amplitude, the permeability of sandstone fractures initially increases and then decreases with prolonged soaking time. The impact of ScCO2 and stress cycling on the permeability of sandstone fractures is the result of a series of combined chemical–mechanical effects. The combined effects of chemical dissolution and mechanical degradation significantly influence the permeability of sandstone fractures, and this impact is notably time-dependent. During short-term soaking, geochemically induced changes in the surface structure of fractures cause fluctuations in permeability, while in long-term soaking, the combined chemical–mechanical effects promote a reduction in fracture permeability.

Gold and Gold Alloys Electropolishing in Choline Chloride-Glycerol Deep Eutectic Solvents

Electropolishing (EP) is a finishing technique used to reduce the roughness of metallic surfaces while enhancing their brightness. This process enables the treatment of complex shaped parts and reduces processing time compared to conventional mechanical polishing methods. Electropolishing of precious metals typically requires the use of electrolytes containing cyanides and other toxic compounds, which reduces its attractiveness from an industrial perspective. Deep Eutectic Solvents (DES) are emerging as a good alternative for the chemical and electrochemical dissolution of valuable metals, like gold, silver and copper. However, their use in the specific context of electrochemical polishing of precious alloys has not been considered so far. This work aims to evaluate the effectiveness of choline chloride-based DES in electropolishing 18K gold alloys. Their performance will be assessed in terms of roughness reduction, brightness enhancement and color preservation, all characteristics associated with the presence of a uniform dissolution.

Impact of Hot-Melt Extrusion on Glibenclamide's Physical and Chemical States and Dissolution Behavior: Case Studies with Three Polymer Blend Matrices.

This research work dives into the complexity of hot-melt extrusion (HME) and its influence on drug stability, focusing on solid dispersions containing 30% of glibenclamide and three 50:50 polymer blends. The polymers used in the study are Ethocel Standard 10 Premium, Kollidon SR and Affinisol HPMC HME 4M. Glibenclamide solid dispersions are characterized using thermal analyses (thermogravimetric analysis (TGA) and differential scanning calorimetry), X-ray diffraction and scanning electron microscopy. This study reveals the transformation of glibenclamide into impurity A during the HME process using mass spectrometry and TGA. Thus, it enables the quantification of the extent of degradation. Furthermore, this work shows how polymer-polymer blend matrices exert an impact on process parameters, the active pharmaceutical ingredient's physical state, and drug release behavior. In vitro dissolution studies show that the polymeric matrices investigated provide extended drug release (over 24 h), mainly dictated by the polymer's chemical nature. This paper highlights how glibenclamide is degraded during HME and how polymer selection crucially affects the sustained release dynamics.

Totally Tubular TiO2 Nanotubes as Semiconducting Material for Dye-Sensitized Photoelectrodes

The use of chemical bonds to store solar energy is a promising approach to address the intermittency of the sun by harnessing sunlight to drive chemical transformations. One strategy to drive these processes is to use a bespoke semiconductor surface implemented in a photoelectrode to absorb light and generate charge carriers that can drive redox reactions such as the direct oxidation of adsorbed species on the photoanode. To minimize recombination of photogenerated electron-hole pairs, molecular donor-chromophore-acceptor (D-C-A) systems can be used to sensitize wide bandgap semiconductors for visible light absorption and to generate (high energy) long-living charge separated states. Such assemblies represent a photoelectrode for dye-sensitized photoelectrochemical cells (DS-PECs). Presented here are recent findings using molecularly sensitized TiO2 nanotubes as a nanohybrid architecture for DS-PECs. The highly ordered and oriented 1D-nanostructures are purpose-grown using a self-organizing electrochemical anodization approach. The nanotube mouth is functionalized with a Cu(I)-based donor-chromophore-acceptor system by direct assembly at the surface. The resulting photoanodes are investigated against different water oxidation catalysts (e.g., [Cp*Ir(pyalk)OH], pyalk = 2-(pyridine-2-yl)propan-2-ol; CoOx) for their ability to generate oxidizing equivalents that can subsequently drive follow-on oxidation reactions. A more common TiO2 nanostructure morphology (e.g., nanospheres) and simpler Cu(I)-based chromophores are also examined for comparative purposes to highlight the advantages of the proposed assembly.It is well understood that the role of the semiconductor is to connect the molecular components and transfer/store charge carriers from the excited dye to drive redox processes. The TiO2 nanotubes used here are synthesized by self-organized electrochemical anodization (SOA); a process Involving an anode/cathode arrangement where Ti is used as the anode. This process is a balance between the electrochemical formation of TiO2 and simultaneous chemical dissolution in fluoride-containing electrolytes. The resulting semiconducting film is found to be a vertically oriented, size-controlled, and back-contacted nanostructured array of TiO2 on a foil of titanium. In addition to this composition inheriting high chemical stability, the morphology can grant added benefits such as two-dimensional confinement, directional charge transport and orthogonal charge separation.[1]A crucial limiting factor for the performance of this system is the recombination of the electron-hole pairs. By using a transition metal complex or chromophore (C) that is covalently linked with electron donating (D) and electron accepting (A) moieties, the energy levels can be aligned for charge-transfer processes between the electroactive groups for directional electron transport and formation of a charge-separated state.[2] Copper(I) D-C-A assemblies are also of interest when taking into consideration the low-cost and photophysical properties when compared to typical ruthenium(II) polypyridine chromophores used in these types of cells. Transient photocurrent measurements of the photoelectrode suggest that the TiO2 nanotubes’ mouths generate a base photocurrent, which could be associated with graphitic-like carbon impurities extending light absorption for photoactivity. Furthermore, once the surface is decorated with the copper(I) D-C-A assembly, the photocurrent is significantly increased, enabling light-driven oxidation of CoOx photoelectrochemically deposited on the surface of the photoelectrode.REFERENCES[1] Nguyen, N. T.; Altomare, M.; Yoo, J. E.; Taccardi, N.; Schmuki, P. Noble Metals on Anodic TiO2 Nanotube Mouths: Thermal Dewetting of Minimal Pt Co-Catalyst Loading Leads to Significantly Enhanced Photocatalytic H2 Generation. Adv. Energy Mater. 2016, 6, 1501926. DOI: 10.1002/aenm.201501926[2] Singh, Z.; Kamal, S.; Majewski, M. B. Copper(I) Donor−Chromophore−Acceptor Assembly for Light-Driven Oxidation on a Zinc Oxide Nanowire Electrode. J. Phys. Chem. C. 2022, 126, 39, 16732-16743. DOI: 10.1021/acs.jpcc.2c04652 Figure 1

Investigating Cobalt Degradation in Acidic Environments for Oxygen and Hydrogen Electrocatalysis with Time-Resolved Mass Spectrometry Techniques

Cobalt is an important additive within commercially available energy devices including hydrogen fuel cell vehicles, lithium-ion batteries for electric vehicles and portable devices, and electrolyzers for water splitting. Regarding devices that include a proton exchange membrane (PEM), such as proton exchange membrane fuel cells (PEMFCs) and proton exchange membrane water electrolyzers (PEMWEs), cobalt-based materials are commonly used to perform the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), respectively. However, given the acidic environment induced by the PEM (pH = 1), cobalt is thermodynamically unstable at ORR and HER relevant potentials, which results in cobalt dissolution and consequently decreases in device performance and lifetime. Minimizing electrode degradation of cobalt-based materials in acidic environments therefore requires a holistic understanding of cobalt’s degradation mechanisms, as it would be necessary to simultaneously monitor electrochemical output (current/voltage), cobalt dissolution, and product formation, which is not possible with one technique alone. To gain such an understanding, in this presentation I will discuss our work on developing comparable time-resolved techniques such as on-line inductively coupled plasma mass spectrometry (ICP-MS) and electrochemical mass spectrometry (EC-MS) to investigate the relationship between applied potential, time, cobalt dissolution, and product formation.With usage of EC-MS, it was observed that cobalt is active for HER in 0.1 M HClO4. and undergoes little to no cobalt dissolution (< 1 ng s-1) at potentials where cobalt is evolving H2 per ICP-MS measurements. This suggests that cobalt stability in acid strongly coincides with hydrogen evolution. In addition, when comparing cobalt’s material stability from the on-line ICP-MS experiments with its thermodynamic stability from its Pourbaix diagram, there is little to no cobalt dissolution at potentials outside its thermodynamic stability window. This is unexpected, as cobalt is projected to be thermodynamically stable only at potentials less than -0.277 VRHE (Co2+/Co = -0.277 VRHE for a dissolved total metal ion concentration of 1 M at pH = 1), whereas our data shows that cobalt dissolution is suppressed until -0.05 VRHE. Through combining findings from both EC-MS and ICP-MS, we have postulated a stability mechanism related to surface hydrogen coverage on cobalt that can be used to explain why cobalt is stable during HER and at potentials it is thermodynamically expected to be unstable.In addition to cobalt being HER active, we also uncovered its activity for ORR in O2 saturated 0.1 M HClO4. Cobalt dissolution under O2 versus N2 saturated 0.1 M HClO4 was then compared, and it was observed that in the presence of O2, cobalt dissolution occurs faster (~3x more dissolution), likely due to O2 induced chemical dissolution. However, after 3 cycles, the observed cobalt dissolution rates under both gas types are equivalent (~225 ng s-1), indicating an important relationship between time, potential, and electrochemical environment. Altogether, this work showcases how time-resolved techniques such as ICP-MS and EC-MS can be connected to unravel stability mechanisms of materials and motivative future studies to apply a holistic approach when evaluating material stability.

Microhardness and energy dispersive X-ray evaluation of dentinal walls following chemical and electrochemical dissolution of fractured nickel-titanium file: An in vitro study

PurposeChemical dissolution of nickel-titanium (NiTi) files involves the application of a fluoride solution in direct contact with a damaged instrument, whereas electrochemical dissolution involves the application of an electrical current to the electrolyte, which accelerates fragment dissolution. This study aimed to determine the hardness and concentration of calcium and phosphorus (Ca and P) ions in dentinal walls following chemical and electrochemical dissolution of fractured ProTaper F2 files with a novel chemical solution.Materials & Methods: Thirty human maxillary first molar palatal roots with fractured ProTaper F2 files in the middle third (length, 2.5 mm were divided into three groups according to the treatment techniques used with a novel solution (NaF 12 g/L + NaCl2 60 g/L + MgCl2 60 g/L + CaCl2 60 g/L) at pH 5: Group 1: distilled water (control group), Group 2: electrochemical dissolution, and Group 3: chemical dissolution using the novel solution. The novel solution was placed for 10 min using an electrochemical technique, and for 30 min in contact with the separated instrument in the chemical group. The Vickers microhardness test was performed in three areas: at 3, 6, and 9 mm from the apex, and an energy-dispersive X-ray test for both Ca and P ions was performed. The analysis of variance (ANOVA) and Tukey's tests were used for statistical analysis. ResultsAccording to the one-way ANOVA analysis, no difference was observed between the tested approaches (P > 0.05) in the three areas evaluated (3, 6, and 9 mm), with no difference in the Ca/P ratio between the tested groups. ConclusionCompared to the control group, the use of chemical and electrochemical dissolution methods with the novel solution did not affect dentin hardness or dentinal structure in terms of the Ca/P ratio, thereby indicating promising results while saving time.

Microwave-assisted hydrothermal synthesis of carbonated apatite with calcium and phosphate resources derived from green mussel shell and bovine bone wastes

Resources recovery of calcium and phosphates from respective green mussel shells and bovine bones by calcination and chemically extracting are viable precursors for carbonate-rich apatite biomedical material applications. Because of their high osteoconductivity, carbonate-rich apatite bioceramics are being studied intensively for synthetic bone transplants. In the study, powder processing routes of calcination and following chemical dissolution in MgCl2 and H2SO4 were each for recovering calcium of mussel shells and phosphate of bovine bones yielding a crystal-forming solution feedstock for use in microwave-irradiated synthesis. FTIR spectra and XRD patterns validated the crystallinity and phase identification for as-synthesized powders. As a result, the presence of CO3, PO43-, and OH- bands in carbonate-calcium phosphate complexes were present in FTIR spectra. According to the XRD Rietveld method, the as-synthesized powder product contained brushite, carbonated hydroxyapatite (CHA), calcite, and gypsum. The recoverable CHA crystallites' size was 40 nm. This present study demonstrated that microwave irradiation synthesis of CHA powder with calcium and phosphates derived from mussel shells and bovine bones is the potential to yield a large amount of CHA for bioceramics and would aid in the design of a powder processing step for preparing the CHA powder precursor in biomedical applications.

Optimization of electrolytic plasma polishing process and surface performance analysis for 6061 aluminum alloy

Electrolytic Plasma Polishing (EPP), an innovative technology for polishing, has been utilized to improve the surface performance of 6061 aluminum alloys. An orthogonal experimental approach was carried out to investigate the multiple factors influencing the surface quality of aluminum alloys during the polishing process. The results indicated that peaks and scratches on the surface were successfully removed after polishing, with the average roughness reduced to 0.138 μm, approximately 1/8 of the original roughness. Additionally, the EPP process enhanced the substrate's corrosion resistance and hydrophobicity. Finally, it is proposed that the mechanism of surface smoothing effect of EPP is attributed to the combined action of plasma chemical dissolution and cavitation forces peeling. This research indicates EPP as a promising finishing technique with considerable potential for enhancing the surface performance of aluminum alloys in electronic component applications.

Microwave-Assisted Pyrolysis of Carbon Fiber-Reinforced Polymers and Optimization Using the Box-Behnken Response Surface Methodology Tool.

This article introduces an eco-friendly method for the reclamation of carbon fiber-reinforced polymers (CFRP). The research project involved numerous experiments using microwave-assisted pyrolysis (MAP) to explore a range of factors, such as the inert gas flow, the power level, the On/Off frequency of rotation, and the reaction duration. To design the experiments, the three-level Box-Behnken optimization tool was employed. To determine the individual and combined effects of the input parameters on the thermal decomposition of the resin, the data were analyzed using least-squares variance adjustment. The results demonstrate that the models developed in this study were successful in predicting the direct parameters of influence in the microwave-assisted decomposition of CFRPs. An optimal set of operating conditions was found to be the maximum nitrogen flow (2.9 L/min) and the maximum operating experimental power (914 W). In addition, it was observed that the reactor vessel's On/Off rotation frequency and that increasing the reaction time beyond 6 min had no significant influence on the resin elimination percentage when compared to the two other parameters, i.e., power and carrier gas flow rate. Consequently, the above-mentioned conditions resulted in a maximum resin elimination percentage of 79.6%. Following successful MAP, various post-pyrolysis treatments were employed. These included mechanical abrasion using quartz sand, chemical dissolution, thermal oxidative treatment using a microwave (MW) applicator and thermal oxidative treatment in a conventional furnace. Among these post-treatment techniques, thermal oxidation and chemical dissolution were found to be the most efficient methods, eliminating 100% of the carbon black content on the surface of the recovered carbon fibers. Finally, SEM evaluations and XPS analysis were conducted to compare the surface morphology and elementary constitution of the recovered carbon fibers with virgin carbon fibers.

Compaction Creep and Evolution of Transport Properties of Carbonate Fault Gouges During the Percolation of CO2‐Rich Fluids

AbstractTo investigate the impact of CO2‐rich fluids on compaction behaviors and transport properties in carbonate fault zones, we conducted compaction‐coupled fluid flow experiments with CO2‐rich fluids percolating precompacted calcite aggregates. Our findings reveal distinct responses among samples subjected to different fluid conditions. Specifically, samples exposed to dry conditions exhibited negligible compaction strain, while those under wet‐closed conditions displayed relatively minor strain. In contrast, samples subjected to flow‐through conditions demonstrated significant compaction strain, with strain rates higher by 2–3 orders of magnitude than closed conditions due to enhanced pressure solution, subcritical cracking, and chemical dissolution. Strain rate, permeability, and grain size distribution exhibited spontaneous variations in response to fluid flow and compaction. Microstructures and mechanical and transport data suggest that deformation during the initial infiltration of CO2‐rich fluids was dominated by subcritical cracking, followed by pressure solution as grain size evolved, which resulted in compaction and reduced permeability. The persistent infiltration of CO2‐rich fluids further enhanced inhomogeneous dissolution‐precipitation with preferred dissolution channels serving as fluid pathways. The re‐precipitations may cement fault rocks and form low permeability seals, resulting in anisotropic fluid flow and localized fluid pressure in fault zones. As applied to nature, our results provide experimental evidence for the evolution of internal structures and transport behaviors, shedding important light on the mechanisms and sealing potential of carbonate faults in response to the infiltration of CO2‐rich fluids during the post‐seismic and inter‐seismic processes.

From insoluble to processable: Aminic solvent dissolution of donor–acceptor conjugated network polymers for fabrication of photocatalytic thin film

Conjugated network polymers (CNPs) have gained considerable attention as heterogeneous photocatalysts, however, their limited solubility in solvents poses a significant challenge in employing CNPs for photoreactors. Herein, we report the chemical dissolution of CNPs in aminic solvents to enhance solution processability. The CNPs, synthesized via the Knoevenagel polycondensation, were dissolved into corresponding polymer inks, forming thin films on various substrates through mild heating. Residual functional groups on the CNP surface provided latent reactive sites for liquid amines, facilitating structural disentanglement and dissolution without hindering the π-conjugation. The resulting polymer films on FTO electrodes exhibited broader light absorbance and > 2-fold enhanced photoresponse compared to CNP powder films. Photocatalytic production of H2O2 using the large-area polymer film (254.4 cm2) demonstrated sustained activity with a production rate of 0.21 mM H2O2 h−1 over 14 h without sacrificial agents. These findings lay the groundwork for applying CNP photocatalysts in chemical, optical, and electronic applications.

Effect of dissolved oxygen on corrosion behavior and mechanism of X70 pipeline steel in simulated low temperature bentonite-containing alkaline chloride environment

Effect of dissolved oxygen (DO) on the corrosion behavior of X70 pipeline steel in low temperature bentonite-containing alkaline chloride environments was comprehensively investigated. The cathodic reduction reaction is inhibited and corrosion current density gradually descent as the DO decreases, resulting in a significant improvement in the corrosion resistance of X70 pipeline steel. The content of Fe3O4 and α-FeOOH in the corrosion products film increases, refinement of rust grains and crack decreases effectively suppressing the penetration of corrosive substances. Pitting initiates within ferrite grains and at phase interface, while reducing the DO can restrain the chemical dissolution of MnS to retard the pit initiation.

Effect of mineral dissolution on fault slip behavior during geological carbon storage

Geological carbon dioxide storage is one of the most effective technologies to reduce greenhouse gas emissions to the atmosphere. The mineral dissolution is inevitable during the long-term storage process, while the chemical effect on fault slip behavior remains poorly understood. In this paper, we present a hydro-chemical–mechanical coupled fault reactivation study using the unified pipe-interface element method (UP-IEM). The impact of chemical dissolution on stress redistribution is considered. The accuracy of the numerical method to simulate reactive solute transport and fault frictional slip are confirmed by analytical solution and numerical verification. Two different fault tectonic scenarios, of which fault locating in the caprock and fault crosscutting the reservoir and caprock, are designed to investigate the fault slip behavior induced by mineral dissolution. The effect of dissolved CO2 solute concentration, fault aperture, reservoir permeability and chemical reaction rate are discussed. Results show that fault locating in the caprock is easier to be activated. The chemical reaction has a more significant effect on fault slip behavior than fluid pressure during the long-term low-velocity CO2 leakage. The increase of CO2 solute concentration and reservoir reaction rate cause an obvious growth on fault slip displacement. The decrease of fault initial aperture results in the fault slip velocity slower and the slipping area smaller. The high-permeability reservoir keeps the fault more stable than low-permeability reservoir under the influence of mineral dissolution.

Digging into boring bryozoans: new characters and new species of Immergentiidae

Immergentia is an endolithic genus of ctenostome bryozoans and the sole member of the Immergentiidae. Etchings of their typical spindled-shaped and sometimes enantiomorphic borehole aperture in calcium carbonate substrates are accomplished by chemical dissolution. The tentacle crown of the bryozoan is essentially the only body part that extends beyond the shell surface when protruded. Previously, species were mainly described using external colony and zooidal characteristics or whole mounts, with partial histological sections conducted on a single species in 1947. Modern approaches, however, are hitherto missing. We examined the soft body morphology of Immergentia from different locations with confocal laser scanning microscopy and the production of 3D reconstructions. In addition, zooidal characteristics such as tentacle number, size, tubulets, and interzooidal distances were used to distinguish and describe species. The combination of conventional and modern methods revealed the presence of a cardiac constrictor and intercalary kenozooids that can interpose between the cystid appendages, something not previously reported in immergentiids, thus necessitating an amendment of the family diagnosis. The polypide typically has eight to ten tentacles, and the anus is positioned in the low or mid-lophophoral area. In addition, sequence data, including the mitogenome and the nuclear ribosomal genes (18S and 28S) of four species from five locations, are presented for the first time. Based on molecular and morphological data, a novel intertidal immergentiid from France, Immergentia stephanieae sp. nov., and a subtidal species from New Zealand, I. pohowskii sp. nov., are described. This work supplements the rather sparse existing knowledge on Immergentiidae and proposes additional characteristics to complement existing descriptions in order to enhance future species identification.