Strong Acid Research Articles

Strong Acid‐free Homogeneous Catalytic Systems for the Ester Products Synthesis by Alkenes Alkoxycarbonylation: Recent Advances

Alkoxycarbonylation represents a method for the ester products synthesis from available reagents – unsaturated compounds, alcohols, and CO. The beginning of research on this reaction was laid in W. Reppe’ works in 1953. In early works, halides and carbonyls of Co, Ni, Rh, and Ir were used as catalysts, and alkoxycarbonylation was often complicated by the unsaturated compounds hydroformylation or alcohol carbonylation. In recent decades, in the presence of the most active and selective Pd‐phosphine systems with strong protonic acids, the products are typically only isomeric esters, which corresponds to the creating waste‐free production principles. At present, a large‐capacity synthesis process for methyl methacrylate, dubbed Alpha, is in operation, with the initial stage being ethylene methoxycarbonylation. In light of these developments, there is a growing interest among chemists and technologists in alkenes alkoxycarbonylation. The use of strong protonic acids as co‐catalysts is essential for the formation of active catalytic complexes. However, these acids are highly corrosive and can cause the alkenes isomerisation. This review is devoted to the analysis of acid‐free homogeneous Pd‐, Ru‐, Co‐, and Ni‐catalysts employed in alkenes alkoxycarbonylation over the past 15 years. As a result, polymers, monomers and other valuable linear and branched esters were obtained.

Synthesis of n-Butene via Dimethyl Ether-to-Olefin Reaction over P-Loaded Ferrierite Zeolites

In the dimethyl ether (DME)-to-olefin (DTO) reaction over 20 types of P-loaded ferrierite zeolites with different P loading amounts, the synthesis of n-butenes such as 1-butene, trans-2-butene, and cis-2-butene was investigated to maximize the n-butene yield by optimizing the P loading amount. The zeolites were characterized using X-ray diffractometry (XRD), N2 adsorption-desorption isotherms, and NH3 temperature-programmed desorption (NH3-TPD). Micropore and external surface areas, total pore and micropore volumes, and weak and strong acids affected the DTO reaction’s characteristics. The P-loaded ferrierite zeolite with a P loading of 0.3 wt.% calcined at 500 °C exhibited an n-butene yield of 35.7 C-mol%, which exceeds the highest yield reported to date (31.2 C-mol%). Multiple regression analysis using the obtained data showed that the strong acid/weak acid ratio and total pore volume had a high correlation with the n-butene yield, with a contribution rate of 64.3%. Based on the multiple regression analysis results, the DTO reaction mechanism was discussed based on the proposed reaction model involving the dual-cycle mechanism.

Ultra-Antifouling Liquid-Like Surfaces for Sustainable Viscous Water-in-Oil Emulsions Separation and Oil Recovery.

The demand for efficient separation techniques in industries dealing with high viscosity emulsions has surged due to their widespread applications in various scenarios, including emulsion-based drug delivery systems, the removal of emulsified impurities in formulations and oil spill remediation. However, membrane fouling is a major challenge for conventional separation methods, leading to decreased efficiency and increased maintenance costs. Herein, a novel approach is reported by constructing liquid-like surfaces with double anti-fouling structure, incorporating soft nanomicelles within a rigid, chemically cross-linked network for both anti-membrane-fouling and effective viscous water-in-oil emulsion separation. The coating significantly outperforms perfluorinated and commercial polytetrafluoroethylene (PVDF) membranes, effectively preventing the adhesion of viscous oils like crude oil and pump oil, and alleviating severe membrane fouling. For high-viscosity emulsions (97.3 cP and 52.8 cP), it maintains over 99% separation efficiency after 3h continuous use. Even after 15h immersion in strong acids, alkalis, salts, or organic solvents, its separation efficiency remains above 95%. In addition, thanks to the anti-membrane-fouling ability, this work achieved 6h continuous emulsion separation performance for the first time, demonstrating unparalleled long-term stability. Overall, this study offers valuable insights into the development of innovative coatings for efficient and eco-friendly separation of high-viscosity emulsions.

The Impact of Acid Strength and Mineral Composition on Spontaneous Imbibition with Reactive Fluids

Capillary rise experiments are conducted in a set of calcareous and siliceous rocks with varying mineralogy and petrophysical properties to understand the coupled impact of reactivity and spontaneous imbibition. A capillary rise experiment is performed in each sample: first with deionized water, then with a dilute acidic solution, and finally again with deionized water, and the capillary rise profile for each is recorded. Pre- and post-acid petrophysical properties such as porosity, permeability, pore size distribution, and contact angle are measured for each sample. The mineral makeup of the rocks significantly influences how the acidic fluids penetrate the samples. The primary reactions are the dissolution of Ca- and Mg-rich minerals which alter the pore network. The higher acid strength results in higher capillary rise in calcareous rocks and results in an increase in the average pore size. The same pH acid results in lower capillary rise in the siliceous rocks, and a general decrease in the average pore size is observed. Changes in contact angle indicate increased water affinity in carbonate and reduced affinity in sandstone. The link between capillary interactions and fluid reactivity is often overlooked in fluid flow studies, and this research sheds light on the importance of reactivity during spontaneous imbibition, offering insights into dissolution and precipitation processes during capillary flow.

Direct Solvent‐Free Amide Bond Formation Catalyzed by Anatase‐TiO2 Surface: Insight from Modeling

Amide bond formation processes are of paramount relevance for a broad spectrum of applications. Conventional amidation protocols typically rely on drastic reaction conditions and the use/disposal of large amounts of chemicals. These limitations may be bypassed by heterogeneously catalyzed amidation at dry conditions. However, progress is hindered because the mechanisms of these processes are largely unexplored. By using ab initio metadynamics, a concerted one‐step mechanism is proposed for the solvent‐free condensation of methylamine and formic acid on TiO2(101)‐anatase, leading to methylformamide with concomitant release of molecular water. The activation barrier—14.3 kcal mol−1—is in line with the mild conditions experimentally adopted in amide bond syntheses on TiO2 nanoparticles. The mechanism disclosed herein reveals the key role of Ti4+ sites located on stoichiometric (101) anatase surfaces in promoting amide‐bond formation at the TiO2/vapor interface. The acid strength of the adsorbed HCOOH molecules may be tuned by the HCOOH surface coverage, thus influencing the outcome of the amidation reaction. These molecular‐level insights may foster further endeavors to improve/upscale TiO2‐catalyzed amide syntheses at dry conditions, while raising the interest toward amidation processes at the surface/vapor interface promoted by economically and environmentally sustainable metal oxide nanomaterials.

Limonene oxide isomerization: a broad study of acid catalyst effects

AbstractIn this work, a broad screening of possible catalysts for limonene oxide isomerization was performed. The catalysts included both Brønsted and Lewis acids as homogeneous or heterogeneous catalysts. The aim was to show the efficiency of different catalysts in the studied reaction and use one homogeneous (methanesulfonic acid) and two heterogeneous (zeolite beta-25, montmorillonite K10) catalysts to evaluate the influence of the acid site type on the selectivity. When the selected catalysts were used, almost total conversion up to 1 h was observed (2?50% of the catalyst was based on type, 80 °C, and 16.6 V% of the solution was limonene oxide in toluene). The strength of the acid/acid catalyst influenced the composition of the products. When a strong acid (methanesulfonic acid) was used, the products formed by dehydration (p-cymene) and isomerization of the double bond (carvenone) were detected in large amounts. Using the majority of catalysts, the main products were cis- and trans-dihydrocarvone, and the minor products were carveols and carvone. The water content of the acid catalyst strongly affected the selectivity. Limonene diol was formed as a hydration product, which decreased the selectivity for the desired products. We have described a wide spectrum of possible catalysts for limonene isomerization. Moreover, our study enables the simple choice of catalyst on the basis of the desired composition of the products.

Organoleptic and Physicochemical Profile Comparison of Cow Milk Yogurt and 'Eggurt' Made from Different Egg Whites

Yogurt is a widely consumed fermented dairy product known for its distinctive flavor, nutritional value, and health benefits. To expand its nutritional profile and enhance textural qualities, this study explores the use of egg whites as an alternative ingredient in yogurt production. The research compares the sensory and physicochemical properties of traditional milk yogurt with "eggurt" a yogurt variant made using different egg white sources: free-range chicken, caged chicken, and duck eggs. Four samples were prepared, including one control (milk yogurt) and three “eggurt” variants. Sensory quality was evaluated through organoleptic testing using a structured Likert scale to assess attributes such as color, surface gloss, aroma, mouthfeel, and flavor. Physicochemical analysis included moisture content, total dissolved solids, viscosity, ash content, and acidity measurements. Results showed that free-range “eggurt” was most like milk yogurt in terms of texture and flavor, displaying balanced viscosity and minimal surface liquid separation. In contrast, caged “eggurt” exhibited increased surface liquid, higher ash content, and stronger acidity, while duck eggurt was noted for its excessive thickness, very high viscosity, and pronounced acidity. These textural and compositional differences, despite the higher production costs, suggest that free-range “eggurt” is the most promising alternative, offering a comparable sensory experience to traditional yogurt while enhancing texture and overall quality.

Advancing a Comprehensive Model for Carbon Steel Corrosion in Weak Acids: Validation Using Valeric and Acetic Acids

Acidic corrosion in industrial environments represents a serious threat that requires an active prevention and management strategy. In this context, weak acids can create a severe corrosion environment for metallic surfaces, sometimes exceeding the severity observed in strongly acidic solutions under similar conditions. While most of the research efforts of the last decades in the field of the predictive modeling of acidic corrosion have been focused on the specific case of sweet corrosion caused by carbonic acid, the goal of this work is to describe and validate a predictive model to be used as a more transversal tool for acidic corrosion. The model, called the Tafel–Piontelli model, leverages Tafel law to mechanistically describe the electrochemical behavior of carbon steel in acidic aqueous environments. Two different acids, acetic and valeric, were used to experimentally evaluate the performance of the model in weakly acidic solutions, varying the pH and the temperature conditions. Potentiodynamic polarization tests and mass loss tests were performed, allowing us to assess the kinetic parameters (the Tafel slope and the exchange current density of the cathodic and anodic reactions) and corrosion rates of the corrosion process. The promising results suggest that the Tafel–Piontelli model is able to adapt to different scenarios and its intrinsically theoretical nature allows us to extend its predictions outside the range of experimental conditions used to validate it.

Synergizing Plasmonic Local Heating and 3D Nanostructures to Boost the Solar-to-Vapor Efficiency Beyond 100.

Solving the global challenge of freshwater scarcity is of great significance for over one billion people in the world. Solar water evaporation based on plasmonic nanostructures is one of the most promising technologies due to its high efficiency. However, the efficiency of this plasmonic nanostructure-based technology can hardly achieve 100%. Therefore, it is highly desired to develop new solar converters utilizing plasmonic local heating and reasonable structure design to break the limit of solar-to-vapor efficiency for freshwater production. Here, a plasmonic sponge is developed as a solar evaporation converter with excellent full-solar-spectrum absorption, good heat localization performance, and fast evaporation kinetics through 3D nanostructures, achieving a 131% solar-to-vapor efficiency. Distinct from the traditional 2D localized heating-based evaporation and nonmetallic 3D water evaporation, the 3D plasmonic sponge can simultaneously achieve highly efficient local heating and super large water-air interfaces for boosting solar-to-vapor efficiency. The 3D plasmonic sponge can be also used as a universal converter for purifying seawater, metal ion solutions, organic pollutant solutions, and strong acid and strong alkaline solutions. The full-solar-spectrum absorption, high efficiency, and universality in water purification suggest that the novel 3D plasmonic solar converter can bring a significant way to alleviate the crisis of freshwater resources.

Low-Temperature Borylation of C(sp3)-O Bonds of Alkyl Ethers by Gold-Metal Oxide Cooperative Catalysis.

Since ether moieties are often found not only in petrochemical products but also in natural organic molecules, the development of methods for manipulating C-O bonds of ethers is important for expanding the range of compound libraries synthesized from biomass resources, which should contribute to the goal of carbon neutrality. We report herein that gold nanoparticles supported on Lewis acidic metal oxides, namely α-Fe2O3, showed excellent catalytic activity for the reaction of dialkyl ethers and diborons, which enables the conversion of unactivated C(sp3)-O bonds to C(sp3)-B bonds at around room temperature. Various acyclic and cyclic ethers as well as a series of diborons participated in the heterogeneous gold-catalyzed borylation of unactivated C(sp3)-O bonds, to give a series of alkylboronates in high yields. Mechanistic studies corroborated that the present borylation of C(sp3)-O bonds of dialkyl ethers proceeded at the interface between gold nanoparticles and Lewis acidic metal oxides. Furthermore, adsorption IR measurements supported the notion that strong Lewis acid sites were generated at the boron atom of diborons adsorbed at the interface between Lewis acidic metal oxides and gold nanoparticles, which enabled us to ensure that the cooperation of gold nanoparticles and Lewis acidic metal oxides was responsible for the efficient transformation of unactivated C(sp3)-O bonds in ethers under mild conditions. This novel reaction technology which is specific to heterogeneous catalysts enables the activation of stable C(sp3)-O bonds of oxygenated chemical feedstock, which is beneficial for the sustainable synthesis of value-added organoboron compounds.

Enhanced sludge solid-liquid separation based on Fe2+/periodate conditioning coupled with polyoxometalates: Cell destruction and protein adsorption

Dewatering of waste activated sludge is a necessary step for achieving subsequent reduction, stabilization, and resource utilization. In this study, Fe2+/periodate (PI) coupled with polyoxometalates (POMs) conditioning was tested for realizing sludge deep dewatering. After the addition of POMs (0.20 mmol g−1 VSS), Fe2+/PI/POMs conditioning enhanced the efficiency of sludge dewatering by 42.93% compared to Fe2+/PI conditioning. It was found that the electrostatic repulsion posed a significant influence on the interaction between POMs and proteins. The reduction of electrostatic repulsion facilitated the proximity of POMs to the sludge flocs and promoted its reaction. The strong acidity and interaction with cells of POMs could induce the damage or apoptosis in sludge cells, resulting in the release of intracellular substances. The active radicals generated by Fe2+/PI process attacked TB-EPS, causing the dissolution of EPS and the decomposition of hydrophilic substances. With the assistance of Fe2+/PI process, POMs exhibited an enhanced cell-disruptive effect, thereby inducing the liberation of a greater quantity of intracellular substances. Moreover, Fe2+/PI/POMs conditioning effectively lowered the zeta potential of sludge system, facilitating the interaction between negatively charged POMs anions and the positively charged regions of proteins. This interaction tended to favor adsorption and precipitation rather than destruction. The adsorption and sedimentation of proteins by POMs further reduced the hydrophilicity of sludge system, thereby enhancing sludge dewaterability. Furthermore, POMs could enhance the electron transfer capacity of sludge system, which was beneficial for subsequent filtrate denitrification treatment.

Revealing the Overlooked Catalytic Ability of γ-Al2O3: Efficient Activation of Peroxymonosulfate for Enhanced Water Treatment.

Activated alumina (γ-Al2O3) is one of the few nanomaterials manufactured at a ton-scale and successfully implemented in large-scale water treatment. Yet its role in advanced oxidation processes (AOPs) has primarily been limited to functioning as an inert carrier due to its inherently nonredox nature. This study, for the first time, presents the highly efficient capability of γ-Al2O3 to activate peroxymonosulfate (PMS) for selectively eliminating electron-rich organic pollutants in the presence of Cl-. Through experimental and theoretical analysis, we revealed that γ-Al2O3, characterized by uniquely strong Lewis acid sites, enabled robust inner-sphere complexation between PMS and Al(III) sites, triggering the oxidation of Cl- to free chlorine through a distinctive, low-energy-barrier Eley-Rideal pathway. Such a unique pathway resulted in a 42.7-fold increase in free chlorine generation, culminating in a remarkable 145.9-fold enhancement in the degradation of carbamazepine (CBZ) compared with the case without γ-Al2O3. Furthermore, this catalyst exhibited high oxidant utilization efficiency, stable performance in real-world environmental matrices, and sustained long-term activation for over 1206 bed volumes (BV) with a CBZ removal rate exceeding 90% in fixed-bed experiments. These favorable features render γ-Al2O3 an extremely promising nanomaterial for sustainable water treatment initiatives.

Dual Role of Aerosols on Reactive Bromine Recycling in Extrapolar Marine and Continental Regions

AbstractReactive bromine species play important roles in atmospheric chemistry and influence the abundance of climate‐ and air quality‐relevant trace gases. While extensive studies have focused on bromine chemistry in polar regions, the bromine species in extrapolar regions, particularly regarding pollution‐related bromine recycling, have received less attention. In this study, we examine the factors influencing the bromine recycling at a clean marine site of the North Atlantic (Cape Verde, CVAO), a semipolluted coastal site of the South China Sea (Hok Tsui, HT), and a polluted continental site of North China (Wangdu, WD), using an observation‐based model combined with updated halogen chemistry. Our results indicate that aerosol‐related multiphase processes significantly affect bromine recycling in these extrapolar sites. Nitrate photodissociation efficiently recycled bromide into the gas phase in regions characterized by strong aerosol acidity (HT) or high aerosol concentrations (WD). Concurrently, bromine species are lost from the gas phase toward aerosol surfaces, with this process being more effective at higher liquid water content (WD > HT > CVAO). In semipolluted and polluted sites, the aerosol‐related processes resulted in elevated bromine levels in the daytime compared to nighttime, leading to larger effects of bromine species on ozone than previously thought. Our study suggests the need for a better understanding of the complex effects of aerosols on reactive halogen chemistry.

Innovative surface engineering of sustainable polymers: Toward green and high-performance materials

The development of sustainable polymers is critical to the progression of greener manufacturing processes, especially for the additive manufacturing technologies of fused deposition modeling (FDM). The study aims to explore potential application surface engineering techniques that enhance the performance of these sustainable polymers within the context of FDM. Various surface modification methods, such as plasma treatment, chemical etching, and UV irradiation, were utilized on biodegradable and recycled polymers, with the treatment process conducted under controlled conditions. Mechanical testing was done using a Tinius Olsen universal testing machine, with surface morphology analyzed through scanning electron microscopy. The outcome indicated that the tensile strength of polylactic acid improved by 15% with plasma treatment, while the thermal stability of recycled polyethylene terephthalate improved by 12% with chemical etching. Surface engineering developments on various techniques will be reviewed, particularly in optimizing them within FDM processes for different types of polymers. Different surface modifications will be compared here, analyzing aspects such as adhesion, endurance, and more overall performance. This comparison provides a fundamental outlook into the relationship between surface treatment and polymer performance, paving the way for optimization of FDM processes in sustaining material applications. These findings serve as further guidance toward making additive manufacturing much more sustainable and efficient through advanced surface engineering. The numerical improvement of material properties observed in the study will aid in further endeavors towards achieving sustainability and efficiency in additive manufacturing.

Effects of Different Weak Small Organic Acids on Clofazimine Solubility in Aqueous Media

Background/Objectives: Clofazimine (CFZ) is a Biopharmaceutics Classification System (BCS) II drug introduced in the US market in 1986 for the treatment of leprosy. However, CFZ was later withdrawn from the market due to its extremely low aqueous solubility and low absorption. In the literature, the intrinsic solubility of CFZ has been estimated to be <0.01 μg/mL, and solubilities of its different salt forms in simulated gastric and intestinal fluids are <10 µg/mL. These are extremely low solubilities for the dissolution of a drug administered orally at 100–200 mg doses. Methods: In the present investigation, seven weak organic acids (adipic, citric, glutaric, maleic, malic, succinic, and tartaric) were tested by determining the aqueous solubility of CFZ as the function of acid concentration to investigate whether any of the acids would lead to the supersolubilization of CFZ. Results: There were only minimal increases in solubilities when concentrations of acids in water were increased up to 2.4 M. The solubilities, however, increased to 0.32, 1.23, and 10.68 mg/mL, respectively, in 5 M solutions of tartaric, malic, and glutaric acids after equilibration for 24 h at 25 °C. Crystalline solids were formed after the equilibration of CFZ with all acids. Apparently, salts or cocrystals were formed with all acids, except for glutaric acid, as their melting endotherms in DSC scans were in the range of 207.6 to 248.5 °C, which were close to that of CFZ itself (224.8 °C). In contrast, the adduct formed with glutaric acid melted at the low temperature of 77 °C, and no other peak was observed at a higher temperature, indicating that the material converted to an amorphous state. Conclusions: The increase in CFZ solubility to >10 mg/mL in the presence of 5 M glutaric acid could be called supersolubilization when compared to the intrinsic solubility of the basic drug. Such an increase in CFZ solubility and the conversion of the glutarate adduct to an amorphous state are being exploited to develop rapidly dissolving dosage forms.

Propylene oligomerization over SiO2-overcoated oxides

Catalytic oligomerization of light olefins is an important CC coupling strategy that can be used to produce high-value transportation fuels and chemicals from shale gas and biomass feedstocks. In this work, vapor-phase propylene oligomerization was studied over a series of overcoated SiO2-MOx materials, whose acid site densities and strengths are tunable by the amount of SiO2 deposition and the nature of the core oxide. These materials contain acid sites only on particle external surfaces, limiting pore diffusion artifacts. SiO2-MOx materials were prepared by depositing stoichiometric amounts of tetraethyl orthosilicate (TEOS) onto Al2O3, anatase TiO2, Nb2O5, and ZrO2. Compared to the unmodified oxides, which are poor propylene oligomerization catalysts, the SiO2-MOx materials exhibit moderate activity with Al2O3, TiO2, and Nb2O5 core materials performing better than commercial amorphous silica alumina (ASA) on a surface area basis. The activity of the materials appears to be primarily driven by their Brønsted acid strength as measured by 31P TMPO MAS NMR with the rates ranked in order SiO2/Al2O3 > SiO2/TiO2 ≈ SiO2/Nb2O5 > SiO2/ZrO2. This study shows that SiO2-overcoated materials are a tunable class of materials that are active for vapor-phase propylene oligomerization.

Preparation, characterization, and ex vivo evaluation of isoxanthohumol nanosuspension

This study assessed the equilibrium solubility, oil–water distribution coefficient, and dissociation constant of Isoxanthohumol (IXN), and formulated IXN nanoparticles (IXN-Nps) using a micro media grinding method. The research characterized the particle size, polydispersity index, zeta potential, morphology, and structure of the nanoparticles, and evaluated the optimal cryoprotectant. Additionally, the study examined the toxicity and in vitro and in vivo release of IXN on HT-29 cells. IXN is classified as a Biopharmaceutical Classification System (BCS) II class drug with weak acidity. The average particle size of IXN-Nps is 249.500 nm, with a polydispersity index (PDI) of 0.149 and a zeta potential of −25.210 mV. The research identified 5 % mannitol as the optimal cryoprotectant. Compared to IXN, the half-maximal inhibitory concentration of IXN-Nps decreased to one-third, demonstrating a significant inhibitory effect on HT-29 colon cancer cells. The in vitro cumulative release rate of IXN-Nps within 24 h was 3.5 times higher than that of the IXN solution. In vivo pharmacokinetic results revealed that the oral bioavailability of IXN-Nps increased significantly by 2.8 times compared to the IXN solution. The correlation coefficient (r = 0.9227) exceeded the critical value for significance at the 0.01 (r = 0.834) level, indicating a strong correlation between in vivo and in vitro results. Consequently, the nanosuspension overcame the low solubility limitation of IXN and proved to be an effective method for enhancing the oral bioavailability of IXN

Enhanced butanol production through intracellular NADH regeneration in CdSe-C. Acetobutylicumg semi-photosynthetic biohybrid system

Current environmental challenges and energy crises highlight the urgent need for a transition in energy mix. In this study, an innovative semi-photosynthetic biohybrid system that combined light-activated cadmium selenide quantum dots (CdSe QDs) with engineered Gram-positive anaerobic bacteria, Clostridium acetobutylicumg (C. acetobutylicumg), was developed to enhance renewable butanol production. The results demonstrated that CdSe QDs could be biosynthesized intracellularly within C. acetobutylicumg through the introduction of glutathione pathway, without causing significant damage to bacteria. Furthermore, this system showed remarkable tolerance to butanol and weak acids. Under illumination, the biological synthesized CdSe QDs enabled C. acetobutylicumg to achieve a 45.5 % increase in NADH/NAD+ ratio compared to C. acetobutylicumg without CdSe QDs. When utilizing undetoxified rice straw hydrolysate in photo-fermentation, this system achieved a butanol titer of 14.82 g/L and a yield of 0.29 g/g. Overall, this work aims to effectively harness solar energy and biomass resources for sustainable clean biofuel production.

Enhanced chemical stability and H+/V4+ selectivity of microporous sulfonated polyimide via a triptycene-based crosslinker

Long durability of sulfonated polyimide in vanadium redox flow battery (VRFB) is urgently required to be solved. Herein, we synthesize a triptycene-based crosslinker and use it as chemical crosslinking point to modify a linear sulfonated polyimide for promoting its antioxidative stability. The novel triptycene-based cross-linked sulfonated polyimide (TCSPI-X) membranes featuring covalently crosslinked network display lower water uptake and swelling ratio than the commercial perfluorinated ionomer membrane (Nafion 117) membrane. More importantly, unnoticeable proton conductivity loss is appeared. We speculate this is because of the covalently crosslinking structure provides stable proton transportation channels, and the formation of micropores induced by rigid triptycene unit decrease proton migration resistance. In which, the TCSPI-5 (with 5 % molar triptycene unit) exhibit higher voltage efficiency as compared with the pristine membrane TCSPI-0. Combined with the excellent vanadium ions resistance, the TCSPI-5 reaches energy efficiency of 78 % at the current density of 140 mA cm−2. In addition, TCSPI-5 also shows high oxidation resistance even under strong acid and pentavalent vanadium ions (V5+) conditions. The above results suggest the potential of TCSPI-X membranes in VRFB application.

Fluorine-free, superhydrophobic self-healing and UV-blocking cotton fabric for oil/water separation.

The discharge of oily wastewater not only pollutes waters but also deteriorates our living environment. Superhydrophobic cotton fabric is considered as an important remedy material for oily wastewater cleanup due to outstanding advantages including low cost, high porosity and switchable wettability. However, the existing superhydrophobic fabrics cannot exhibit durable superhydrophobicity during real-life applications due to poor interaction between the coatings and fabric substrates. To address this issue, one-step strategy is proposed to fabricate superhydrophobic cotton fabric by immersion in a octa-[2-(carboxyl methyl thio) ethyl]-polyhedral oligomeric silsesquioxane/cerium dioxide/polydimethylsiloxane (POSS/CeO2/PDMS) coating. As expected, the finished cotton fabric exhibits robust superhydrophobic resistance to mechanical abrasion and chemical corrosions. Notably, the finished cotton fabric shows thermal self-healing superhydrophobicity even if undergone repetitive abrasion cycles and air plasma etching. It is proposed that the rising temperature accelerates the rotations of PDMS chains and the migrations of MAPOSS and CeO2, contributing superhydrophobic self-healing of the damaged cotton fabric. Meanwhile, the superhydrophobic fabric displays high oil/water separation efficiency even in strong acid and alkali environments. Additionally, the POSS/CeO2/PDMS coating improves mechanical, thermal and UV-blocking properties of the finished cotton fabric. This work will pave a way to exploitation and applications of novel multifunctional textiles.