Alkaline Environment Research Articles

Effects of Restoration Strategies on Soil Health after Lycium chinense Removal in the Qaidam Basin

Ecological restoration of arid land plays a pivotal role in maintaining ecological sustainability and enhancing the resilience of local communities. As an ecologically significant arid land, the Qinghai Qaidam Basin has been severely impacted by human activities such as the widespread planting of Lycium chinense, leading to considerable degradation of vegetation and soil carbon and nutrients. Currently, this vital area is undergoing extensive ecological restoration through the employment of a variety of strategies, but the impact remains inadequately understood. This study seeks to compare the effects of different restoration strategies in the Qinghai Qaidam Basin, focusing on soil properties across five scenarios: a controlled desert area, natural restoration after the removal of L. chinense, continued planting of L. chinense, restoration through the planting of Haloxylon ammodendron, and mixed reseeding after four years of restoration. Our findings indicate that mixed reseeding significantly improved soil water storage to 4.26%, especially in the deep soil layer. The planting of H. ammodendron strategy efficiently reduced soil pH in such an alkaline environment. Soil nutrients, including total nitrogen (TN), total phosphorus (TP), and total potassium (TK), were predominantly concentrated in the top soil layer, with reduced concentrations observed in the medium and deep soil layers. Although soil organic matter remained relatively stable across all restoration strategies, its content was notably lower in the deeper layers. Overall, mixed reseeding proved to be the most efficient strategy for enhancing soil water retention and nutrient levels. In contrast, despite achieving high vegetative coverage to 62.6%, planting of L. chinense was less ecologically beneficial due to its extensive irrigation requirements and adverse effects on soil structure. These findings suggest that restoring degraded areas to an ideal ecological state cannot be achieved within a few years, underscoring the importance of sustained restoration efforts. This study offers valuable insights and practical guidance for the ecological restoration of arid lands, contributing to the development of sustainable land management practices in similar regions.

NiIr nanowireassembles as an efficient electrocatalyst towards oxygen evolution reaction in both acid and alkaline media.

Oxygen evolution reaction (OER) is the rate-limiting step in water electrolysis due to its sluggish kinetic, and it is challenging to develop an OER catalyst that could work efficiently in both acid and alkaline environment. Herein, NiIr nanowire assembles (NAs) with unique nanoflower morphology were prepared by a facile hydrothermal method. As a result, the NiIr NAs exhibited superior OER activity in both acid and alkaline media. Specifically, in 0.1 M HClO4, NiIr NAs presented a superior electrocatalytic performance with a low overpotential of merely 242 mV at 10 mA cm-2 and a Tafel slope of only 58.1 mV dec-1, surpassing that of commercial IrO2 and pure Ir NAs. And it achieved a significantly higher mass activity of 148.40 A/g at -1.5 V versus RHE. In 1.0 M KOH, NiIr NAs has an overpotential of 291 mV at 10 mA cm-2 and a Tafel slope of 42.1 mV dec-1. Such remarkable activity makes the NiIr NAs among the best of recently reported representative Ir-based OER electrocatalysts. Density functional theory (DFT) calculations confirmed alloying effect promotes surface bonding of NiIr with oxygen-containing reactants, resulting in excellent catalytic properties.

Intimate microbe-water-mineral interactions mediate alkalization in the pyroxene-rich iron ore mines in Panxi area, Southwest China

In contrast to acid mine drainage, the microbial assembly and (bio)geochemical processes in alkaline mine conditions remain under-investigated. Here, microbe-water-mineral interactions were systematically investigated in two representative iron mines with alkaline conditions in the Panxi mining area, Southwest China. Compared to reference riverine samples less interfered by mining activities, the iron ore samples, composed of vanadium-titanium magnetite and pyroxene-rich bedrocks, exhibited elevated levels of Fe, HCl-extractable Fe(II), total sulfur, nitrate and sulfate, but lower total carbon (TC). Meanwhile, the mine drainage showed significantly higher sulfate, but lower TC concentrations than the riverine samples. Intriguingly, the Serpentinimonas spp., typically reported in serpentinites, prevailed in the microbial communities from the mine samples exhibiting higher pH. This suggests that the alkaline environments in Panxi mines result from serpentinization-like reactions. Enrichment of Thiobacillus spp. was observed in the mine-dwelling microbial communities, positively correlated with total sulfur, sulfate, nitrate, and Fe(II). Genome-resolved metagenomics suggested a chemoautotrophic lifestyle for the Thiobacillus species (e.g., carbon fixation, sulfur oxidation, and oxygen respiration), which may generate H+ and mitigate alkalization. This study provides valuable insights into progressive development of alkaline mine ecosystems and offers guidance for developing appropriate engineering strategies to restore the abandoned alkaline mines.

UV-modified biochar-Bacillus subtilis composite: An effective method for enhancing Cd(II) adsorption from water

The adsorption of Cd(Ⅱ) in sewage by single-modified biochar systems have limitations, whereas composite modification can enhance the efficiency. In this study, reed straw biochar and Bacillus subtilis were used as raw materials. UV radiation was employed to modify the biochar, and subsequently, Bacillus subtilis was loaded onto the biochar by adsorption, creating modified biochar composites. The Cd(II) adsorption performance and removal efficiency of these composites were then investigated. It was characterized by BET, SEM-EDS, FT-IR, XRD and ZETA potential analysis. Adsorption experiments were conducted under varying conditions (initial Cd(Ⅱ) concentration, UV radiation time, initial pH, etc.), with adsorption isotherms and kinetic models used. Results indicated that 24 hours UV radiation significantly enhanced adsorption performance, increasing the biochar’s surface area by 40 % and pore volume by 20 %, and introducing numerous pores and oxygen-containing functional groups to the biochar's surface. Significantly enhancing the saturation adsorption capacity for Cd(II) from 23.98 mg/g to 49.93 mg/g after UV- Modified biochar was loaded with Bacillus. Modified biochar composites performed better compared to single-modified biochar across different initial Cd(Ⅱ) concentrations, particularly in slightly alkaline environments. The primary adsorption mechanisms were chemical adsorption, such as ion exchange and surface precipitation. The synergistic effect of UV radiation and microbial loading significantly enhanced Cd(Ⅱ) adsorption efficiency. This study demonstrates that composite modification is a more efficient method, aiding in the removal of heavy metal ion Cd(Ⅱ) from water.

Licea nemotatarica sp. nov.—a corticolous myxomycete from northern nemoral border of Eastern European boreal ecotone

A morphologically atypical corticuloid representative of Licea was discovered at the northern border of the distribution of broadleaved forests in Eastern Europe. The species, named L. nemotatarica, contains several morphological and ecological features that strongly distinguish it from similar species such as L. nigromarginata, L. tuberculata, L. mariae and L. castanea. These include the peculiar light silvery or golden-green colouring of the smooth spores, their relatively small size, the wavy fusion of the peridium plate, the concentration of granular material on the surface in the form of a relief pattern, and the fact that it lives in the slightly alkaline and neutral environment of the bark of deciduous trees. The species also does not spread outside the forest protection zone established by Emperor Peter the Great in the 18th century. Based on the calculation of spore productivity, we assume that the species inhabits primarily the bark of Quercus robur and Tilia cordata, and secondarily Acer platanoides and Populus tremula, where it becomes active only after reaching a certain alkalinity in the cultures during decomposition.

The Effects of Ester and Ether Polycarboxylate Superplasticizers on the Fluidity and Setting Behavior of Alkali-Activated Slag Paste.

This study aims to investigate the comparative performance of ester- and ether-based polycarboxylate superplasticizers in maintaining the fluidity and controlling the setting time of alkali-activated slag (AAS) paste. The experiments employed rheological tests, mini-slump tests, ultrasonic pulse velocity (UPV) measurements, and gel permeation chromatography (GPC) analysis. The results indicate that ether-based superplasticizers maintain fluidity approximately 25% longer than their ester-based counterparts and extend the setting time by about 30%. The enhanced performance of ether-based superplasticizers is attributed to their superior molecular stability in highly alkaline environments, which mitigates early polymer degradation. Additionally, the Na2O/SiO2 ratio was maintained at 1:1 throughout the experiments to ensure consistency in the activation process. The relationship between fluidity loss and the onset of setting occurs more rapidly in AAS paste than in conventional cement-based systems. These findings provide valuable insights for the development of environmentally friendly construction materials by optimizing the use of superplasticizers in alkali-activated systems.

Optical investigation of degradation of graphene oxide in alkaline environment: Evidence of two distinct photon-emitting phases in visible region.

In this work we show a procedure of treating of the graphene oxide in alkaline environment as a function of the treatment time in order to obtain novel structures with strong luminescence properties, water-stable, useful as potential replacement for critical raw materials employed as example in optical and optoelectronic devices or for diagnostic and therapeutic technology. These structures have distinct blue and green-luminescence properties which derived most likely from different structural conformations, one associable with that of carbon quantum dots (or as an alternative to that of the Oxidative Debris), the other, lighter and more similar to organic compounds, reported in literature as fulvic-like molecules, but whose nature has to be further investigated. We show that the lighter fraction has a dual mechanism of photoemission: the excitation-independent PL for excitation wavelength within 350 nm and the excitation-dependent component for excitation wavelength ranging in the visible spectrum. The PL dual behaviour could depend on fluorescent nanoclusters composed by specific organic fluorophores with a carbonaceous core. FTIR analysis shows reasonably the same functional groups unless of some difference discussed in the text, meanwhile UV–Vis and PL analysis clearly highlight two distinct emissions (450 nm and 530 nm) in the visible region of the electromagnetic spectrum. Excitation-dependent photoluminescence, water stability and organic fluorescent nanostructures are issues particularly required for application in the biological field but also in materials science.

High Efficiency Alkaline Iodine Batteries with Multi‐Electron Transfer Enabled by Bi/Bi2O3 Redox Mediator

The multi‐electron transfer I‐/IO3‐ redox couple is attractive for high energy aqueous batteries. Shifting from an acidic to an alkaline electrolyte significantly enhances the IO3‐ formation kinetics due to the spontaneous disproportionation reaction, while the alkaline environment also offers more favorable Zn anode compatibility. However, sluggish kinetics during the reduction of IO3‐ persists in both acidic and alkaline electrolytes, compromising the energy efficiency of this glorious redox couple. Here, we establish the fundamental redox mechanism of the I‐/IO3‐ couple in alkaline electrolytes for the first time and propose that Bi/Bi2O3 acts as a redox mediator (RM) to “catalyze” the reduction of IO3‐. This mediation significantly reduces the voltage gap between charge/discharge from 1.6 V to 1 V with improved conversion efficiency and rate capability. By pairing the Zn anode and the Bi/Bi2O3 RM cathode, the full battery with I‐/IO3‐ redox mechanism achieves high areal capacity of 12 mAh cm‐2 and stable operation at 5 mAh cm‐2 for over 400 cycles.

Facile preparation of photothermal and superhydrophobic melamine sponge for oil/water separation and anti-icing

The preparation of superhydrophobic sponges with excellent physiochemical performance, affordability, and versatility is still a big challenge. Herein, a photothermal and superhydrophobic melamine sponge has been successfully achieved by decorating lignin particles (LPs)@MXene composite onto the skeletons of melamine sponge (MS) via the self-polymerization of dopamine. The obtained superhydrophobic MS (labeled as MS@PDA/LPs@MXene) shows a water contact angle of 153.7°, and maintains surface superhydrophobicity under harsh conditions (i.e., acidic, alkaline environments, high temperatures, frictional damage, and icing/de-icing cycles). Notably, the MS@PDA/LPs@MXene exhibits an exceptional oil adsorption capacity of carbon tetrachloride up to 143.6 times of its own weight, a high separation efficiency of 99.3 %, and a retained separation efficiency of 98.9 % after 15 cyclic adsorption processes, respectively. Owing to a synergistic photothermal effect of PDA and LPs@MXene, the MS@PDA/LPs@MXene possesses a maximum surface temperature of 62.8 °C under solar irradiation (1.0 kW/m2, 1 sun), and realizes the ice-free property at a low temperature of −17.9 °C (relative humidity, 90 %) on a continuous cooling stage under solar irradiation (0.5 sun). Furthermore, the LPs@MXene composite coating can be applied on various substrates (i.e., Al sheet, Cu sheet, filter paper, carbon cloth, steel mesh and NdFeB magnet) to obtain surface superhydrophobicity, showing excellent anti-corrosion property for the permanent NdFeB magnet. Thus, this paper proposes a facile and cost-effective strategy to prepare superhydrophobic melamine sponge with multifunctional properties, and provides new insights into the rational design of high-performance superhydrophobic sponges for their applications in oil/water separation and anti-icing.

High Efficiency Alkaline Iodine Batteries with Multi-Electron Transfer Enabled by Bi/Bi2O3 Redox Mediator.

The multi-electron transfer I-/IO3- redox couple is attractive for high energy aqueous batteries. Shifting from an acidic to an alkaline electrolyte significantly enhances the IO3- formation kinetics due to the spontaneous disproportionation reaction, while the alkaline environment also offers more favorable Zn anode compatibility. However, sluggish kinetics during the reduction of IO3- persists in both acidic and alkaline electrolytes, compromising the energy efficiency of this glorious redox couple. Here, we establish the fundamental redox mechanism of the I-/IO3- couple in alkaline electrolytes for the first time and propose that Bi/Bi2O3 acts as a redox mediator (RM) to "catalyze" the reduction of IO3-. This mediation significantly reduces the voltage gap between charge/discharge from 1.6 V to 1 V with improved conversion efficiency and rate capability. By pairing the Zn anode and the Bi/Bi2O3 RM cathode, the full battery with I-/IO3- redox mechanism achieves high areal capacity of 12 mAh cm-2 and stable operation at 5 mAh cm-2 for over 400 cycles.

Alkali Activation of Metakaolin and Wollastonite: Reducing Sodium Hydroxide Use and Enhancing Gel Formation through Carbonation

Alkali activated materials (AAMs) offer significant advantages over traditional materials like Portland cement, but require the use of strong alkaline solutions, which can have negative environmental impacts. This study investigates the synthesis of AAMs using metakaolin and wollastonite, aiming to reduce environmental impact by eliminating sodium silicate and using only sodium hydroxide as an activator. The hypothesis is that wollastonite can provide the necessary silicon for the reaction, with calcium from wollastonite potentially balancing the negative charges usually countered by sodium in the alkaline solution. This study compares raw and carbonated wollastonite (AAM-W and AAM-CW) systems, with raw materials carefully characterized and binding networks analyzed using TGA, FT-IR, and XRD. The results show that while wollastonite can reduce the amount of sodium hydroxide needed, this reduction cannot exceed 50%, as higher substitution levels lead to an insufficiently alkaline environment for the reactions. The carbonation of wollastonite enhances the availability of silicon and calcium, promoting the formation of both N-A-S-H and C-A-S-H gels.

Photoelectrochemical Ethylene Glycol Oxidization Coupled with Hydrogen Generation Using Metal Oxide Photoelectrodes.

Photoelectrochemical (PEC) water splitting represents a promising approach for harnessing solar energy and transforming it into storable hydrogen. However, the complicated 4-electron transfer process of water oxidation reaction imposes kinetic limitations on the overall efficiency. Herein, we proposed a strategy by substituting water oxidation with the oxidation of ethylene glycol (EG), which is a hydrolysis byproduct of polyethylene terephthalate (PET) plastic waste. To achieve this, we developed and synthesized BiVO4/NiCo-LDH photoanodes capable of achieving a high Faradaic efficiency (FE) exceeding 85% for the oxidation of EG to formate in a strongly alkaline environment. The reaction mechanism was further elucidated using in-situ FTIR spectroscopy. Additionally, we successfully constructed an unassisted PEC device for EG oxidation and hydrogen generation by pairing the translucent Mo:BiVO4/NiCo-LDH photoanode with a state-of-the-art Cu2O photocathode, resulting in an approximate photocurrent density of 2.3 mA/cm2. Our research not only offers a PEC pathway for converting PET plastics into valuable chemicals but also enables simultaneous hydrogen production.

Photoelectrochemical Ethylene Glycol Oxidization Coupled with Hydrogen Generation Using Metal Oxide Photoelectrodes

Photoelectrochemical (PEC) water splitting represents a promising approach for harnessing solar energy and transforming it into storable hydrogen. However, the complicated 4‐electron transfer process of water oxidation reaction imposes kinetic limitations on the overall efficiency. Herein, we proposed a strategy by substituting water oxidation with the oxidation of ethylene glycol (EG), which is a hydrolysis byproduct of polyethylene terephthalate (PET) plastic waste. To achieve this, we developed and synthesized BiVO4/NiCo‐LDH photoanodes capable of achieving a high Faradaic efficiency (FE) exceeding 85% for the oxidation of EG to formate in a strongly alkaline environment. The reaction mechanism was further elucidated using in‐situ FTIR spectroscopy. Additionally, we successfully constructed an unassisted PEC device for EG oxidation and hydrogen generation by pairing the translucent Mo:BiVO4/NiCo‐LDH photoanode with a state‐of‐the‐art Cu2O photocathode, resulting in an approximate photocurrent density of 2.3 mA/cm2. Our research not only offers a PEC pathway for converting PET plastics into valuable chemicals but also enables simultaneous hydrogen production.

Self-Standing Mo/MoO2 Porous Flake Arrays for Efficient Hydrogen Evolution Reaction in High-pH Media.

The alkaline hydrogen evolution reaction (HER) is limited by scarce proton availability, resulting in slower reaction kinetics compared to those under acidic conditions. Enhancing the local chemical environment of protons on the catalyst surface can improve the intrinsic reaction kinetics. Here, we design a Mo/MoO2 metallic heterojunction that creates an acidic-like environment with a proton-rich surface, significantly enhancing HER performance in alkaline electrolytes, as confirmed by in situ spectroscopy and electrochemical analysis. A self-standing Mo/MoO2 catalytic electrode is fabricated via a controlled pyrolysis-reduction strategy. This electrode exhibits exceptional HER activity, with low overpotentials of 65 mV at 10 mA cm-2 and 315 mV at 500 mA cm-2, a Tafel slope of 38.2 mV dec-1, and stability exceeding 60 h at -300 mA cm-2 in alkaline solution. The porous flake array structure of the Mo/MoO2 heterojunctions enhances the adjacent hydronium (H3O+) concentration, resulting in a ΔGH* value of 0.15 eV and a water dissociation energy barrier of 0.37 eV in an alkaline medium. The successful preparation of a large-area electrode (2 cm × 2 cm) demonstrates the scalability of this approach for fabricating molybdenum-based catalytic electrodes with enhanced HER activity in alkaline environments.

Integrating Pt single atoms and Mo into PtNi/C through Mo doping-displacement synchronisation strategy for enhanced HER at all pH values

This paper proposes a Mo doping-displacement synchronization strategy to integrate Pt SAs and Mo atoms into PtNi/C, synthesizing Pt SAs/Mo-doped PtNi octahedra/carbon support catalyst (Pt SAs/Mo-PtNi/C). In this approach, Mo atoms are doped into PtNi alloy octahedra and displace some Pt atoms, forming Mo-PtNi octahedra. Importantly, the substituted Pt atoms can adhere to carbon substrate, creating Pt SAs. Pt SAs/Mo-PtNi/C exhibits lower overpotentials (38, 59, and 110 mV at 10 mA cm−2) and smaller Tafel slopes (44, 51, and 139 mV dec-1) in acidic, alkaline, and neutral environments. Additionally, the electron pathway of Mo-PtNi → Pt SAs/C has been confirmed, and Pt SAs/Mo-PtNi/C exhibits an optimized hydrogen adsorption energy (ΔGH*=-0.29 eV). Furthermore, catalyzed by Pt SAs/Mo-PtNi/C, the H-O bond length of H2O extends to 1.11 Å and the bond angle reduces to 102.741°, directly confirming that the Pt SAs and doped Mo could facilitate H-O bond breaking. The proposed Mo doping-displacement synchronization strategy not only simplifies the fabrication process of Pt SAs catalyst, but also improves its durability and activity across a wide pH range, thereby potentially advancing hydrogen production technologies.

Nitrite manipulation in water by structure change of plasma electrolysis reactor

In this study, experimental reactors for cathodic nitrogen plasma electrolysis were designed by the composition of galvanic (voltaic) and electrolytic cells with wide and narrow connectors filled with tap water and agar solutions. The designed reactor can be used to simultaneously perform and manage nitrification in acidic and alkaline environments. According to the reactor’s performance, it can be installed on the irrigation system and used depending on the soil pH of the fields for delivering water and nitrogen species that are effective in growth. The nitrification process was investigated by choosing the optimal reactor with a wide connector based on different changes in oxidation-reduction potential and pH on the anode and cathode sides. The nitrite concentration changed directly with ammonium and nitrate concentrations on the cathode side. It changed inversely and directly with ammonium and nitrate concentrations on the anode side respectively. Nitrite concentration decreased from 5.387 ppm with water connector, to 0.326 ppm with 20% agar solution, and 0.314 ppm with 30% agar solution connectors on the anode side. It increased from 0 ppm to 0.191 ppm with a water connector, 0.405 ppm with 20% agar solution, and 7.454 ppm with 30% agar solution connectors on the cathode side.

Physiological and molecular responses of juvenile silver crucian carp (Carassius gibelio) to long-term high alkaline stress: Growth performance, histopathology, and transcriptomic analysis

Salty-alkaline waters are widely distributed globally, and how to effectively develop saline-alkaline water to improve the utilization rate of water resources has become a global challenge. This study examined the survival performance of juvenile silver crucian carp (Carassius gibelio) under alkaline gradient acclimation conditions and explored the regulatory mechanisms for their adaptation to high alkalinity. Compared to directly immersing in high concentrations, alkaline gradient acclimation significantly improved the survival rate of juvenile silver crucian carp. Long-term high alkaline stress caused significant reduction in the growth performance of juvenile silver crucian carp. After alkaline stress, the enzyme activities of Na+-K+-ATP (NKA) and Ca2+-Mg2+-ATP (CMA) in the gills were significantly decreased. Meanwhile, histopathology of the gills showed structural changes, indicating that the physiological functions of juvenile silver crucian carp were impaired under alkaline conditions. Transcriptomic analysis found that the expression of genes related to metabolism and immune response pathways in the gill and kidney underwent significant changes. Genes related to carbohydrate metabolism were upregulated while those related to protein metabolism were downregulated, indicating that alkaline stress caused the organism to utilize carbohydrates rather than proteins as much as possible to meet enhanced metabolism. The HIF pathway that maintains the body's survival was significantly up-regulated, at the expense of high energy consumption. Dysregulation of genes related to the formation of neutrophil extracellular traps (NETosis) pathway indicated that the immune function of the fish was suppressed. Overall, this study revealed the physiological and molecular responses of juvenile silver crucian carp to alkaline stress, deepening our understanding of their adaptation strategies and the potential impact of alkaline environments on aquatic life.

Coaxial Electrospun wound dressing integrated with Ag-doped hydroxyapatite for wound healing: Tetracycline delivery

The human body's natural defense against inflammation in wounds can sometimes be insufficient. Introducing a wound dressing with this capability could significantly enhance the healing process. This study aimed to create a PVP/PVA-based coaxial electrospun wound dressing integrated with tetracycline-loaded Ag-doped hydroxyapatite (Ag@iHA) in three concentrations [G1, G2, and G3]) with a focus on drug release and antibacterial activity. Nanoparticles were analyzed using DLS, Zeta potential, SEM, EDX, XRD, and FTIR. The final wound dressing was studied from the viewpoint of physicochemical properties biologically, and finally, it was assessed under an in vivo study (9 Wistar rats, six days). Drug release was measured at three pH (5.4, 7, and 9). The results showed a remarkable success in the integration of silver ion in the hydroxyapatite structure, with a 90–600 nm size. Increasing the content of hydroxyapatite improved the quality of nanofibers that were produced. The nanofibers had high hydrophilicity (<5˚) and swelling rates (70–118 %), which were wholly degraded after 14 days. The amount of the released drug was completely different at each pH and was higher in an alkaline environment, as seen in wounds. The survival percentage (>90 %) of L929 cells showed the biocompatibility of nanofibers. In the animal study, all groups reduced the growth of microorganisms, but the most efficacy belonged to the G3 group. In conclusion, this novel wound dressing has the potential to significantly accelerate the body's natural healing process by controlling the growth of microorganisms.

Flow-electrode capacitive separation of organic acid products and recovery of alkali cations after acidic CO2 electrolysis

Acidic CO2 electrolysis, enhanced by the introduction of alkali cations, presents a strategic approach for improving carbon efficiency compared to processes conducted in neutral and alkaline environments. However, a significant challenge arises from the dissolution of both organic acids and alkali cations in a strongly acidic feed stream, resulting in a considerable energy penalty for downstream separation. In this study, we investigate the feasibility of using flow-electrode capacitive deionization (FCDI) technology to separate organic acids and recover alkali cations from a strongly acidic feed stream (pH ~ 1). We show that organic acids, such as formic acid and acetic acid, are retained in molecular form in the separation chamber, achieving a rejection rate of over 90% under all conditions. Alkali cations, such as K+ and Cs+, migrate to the cathode chamber in ionic form, with their removal and recovery significantly influenced by their concentration and the pH of the feed stream, but responding differently to the types and concentrations of organic acids. The energy consumption for the removal and recovery of K+ is 4 to 8 times higher than for Cs+, and the charge efficiency is significantly influenced by the types of organic acid products and alkali cations. We conduct a series of electrochemical measurements and analyze the impedance spectroscopy, identifying that hindered mass transfer governed the electrode process. Our findings underscore the potential of FCDI as an advanced downstream separation technology for acidic electrocatalysis processes.

Enhancing the performance of recyclable polyurea through coordination of rigid chain segments and graphene platelets

In response to the global focus on environmental preservation and sustainable practices, developing nanocomposites featuring recyclable and healing properties is indispensable for high-performance and long-life structures. This study presents a facile approach to develop a recyclable and thermally-induced healing polyurea (PU)/graphene platelet (GNP) nanocomposites with high mechanical properties. A straightforward synthesis method was employed using isophorone diamine (IPDA) as chain extender with rigid cyclic structure. GNPs were modified with IPDA before adding into PU, showing remarkable enhancements in mechanical performance. At 0.10 wt.% GNPs, PU nanocomposites exhibited the maximum mechanical properties, with modified GNPs (M-GNPs) significantly outperforming pristine GNPs. Specifically, the tensile strength of PU increased by 41.3 % with M-GNPs, compared to only 12 % with pristine GNPs, underscoring the critical role of modifying the reinforcing phase. Furthermore, the nanocomposites demonstrated outstanding healing capabilities, achieving 89 % healing efficiency after 24 h at 120 °C. In addition, PU/M-GNP nanocomposites showed exceptional resistance to acidic and alkaline environments in comparison to neat PU. The study not only exemplifies developing high-strength and environmentally friendly materials but also holds promise for diverse applications, including aerospace, vibration damping, and protective coatings.