Low-concentration Solutions Research Articles

Anchorable Polymers Enabling Ultra-Thin and Robust Hole-Transporting Layers for High-Efficiency Inverted Perovskite Solar Cells.

Currently, the development of polymeric hole-transporting materials (HTMs) lags behind that of small-molecule HTMs in inverted perovskite solar cells (PSCs). A critical challenge is that conventional polymeric HTMs are incapable of forming ultra-thin and conformal coatings like self-assembly monolayers (SAMs), especially for substrates with rough surface morphology. Herein, we address this challenge by designing anchorable polymeric HTMs (CP1 to CP5). Specifically, coordinative pyridyl groups are introduced as side-chains on poly-triarylamine (PTAA) backbone with varied contents by copolymerization method, resulting in chemical interactions between polymeric HTMs and substrates. The strong interaction allows them to be processed into ultra-thin, uniform, and robust hole-transporting layers through employing low-concentration solutions (0.1 mg mL-1, vs. 2.0-5.0 mg mL-1 for conventional PTAA), greatly decreasing charge transport losses. Moreover, upon systematically tuning the pyridyl substitution ratio, the energy levels, surface wetting, solution processability, and defect passivation capability of such anchorable HTMs are simultaneously optimized. Based on the optimal CP4, we achieved highly efficient inverted PSCs with power conversion efficiencies (PCEs) up to 26.21 %, which is on par with state-of-the-art SAM-based inverted PSCs. Furthermore, these devices exhibit enhanced stabilities under repeated current-voltage scans and reverse bias ageing compared with SAM-based devices.

"Stabilization" of Amorphous Ketoprofen in Thin Films.

It has been shown that depositing ketoprofen as thin films on glass substrates has a stabilizing effect on the amorphous state of ketoprofen. Polyethylene glycol (M = 6000 g/mol) was mixed with ketoprofen in a wide range of concentrations. Amorphous thin films were prepared by spin coating and subjected to storage conditions with different levels of relative humidity. The films were characterized by specular X-ray diffraction and atomic force microscopy to assess their stability in dry to wet atmospheres. In a dry atmosphere, the amorphous films remained stable for up to 4 months, although ketoprofen possesses a glass transition temperature of -6 °C. However, when subjected to a humid atmosphere (over 50% relative humidity), ketoprofen tends to crystallize in the amorphous films. At low solution concentrations (i.e., low film thickness and low ketoprofen loading) and high humidity, only nanometer-size crystals could be detected. Increasing the polymer mass ratio may favor or prevent crystallization of ketoprofen in the amorphous films depending on its own crystallization behavior in those films.

Hybrid Materials-Mg3Al-LDH/Ionic Liquids/Chitosan Used in the Recovery Process of Pd Ions from Aqueous Solutions.

The recovery of palladium from aqueous solutions is important due to its critical role in various industrial applications and the growing demand for sustainable resource management. This study investigates the potential of hybrid materials composed of Mg3Al layered double hydroxides (LDHs), chitosan, and ionic liquids (methyl trialchil ammonium chloride) for the efficient adsorption of palladium ions from low-concentration aqueous solutions. Comprehensive characterization techniques, including X-ray diffraction (RX), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TG), were employed to elucidate the structural and compositional properties of the hybrid materials. The results of the batch adsorption experiments demonstrate that each component contributes synergistically to the adsorption process, significantly enhancing the overall efficacy of palladium recovery. Furthermore, the method of preparing the adsorbent material was found to impact the effectiveness of palladium recovery. Among the materials tested, the chitosan/Mg3Al/IL hybrid exhibited the highest adsorption capacity (qmax = 98 mg/g), suggesting that the ionic liquid functionalization is most beneficial when applied during the hybrid material synthesis, rather than during the LDH synthesis process. This research underscores the viability of hybrid materials as a sustainable approach to palladium recovery, contributing to advancements in environmental remediation technologies.

Stream bryophytes promote “cryptic” productivity in highly oligotrophic headwaters

AbstractRecent observations document increased abundance of algae in the headwater streams of Hubbard Brook Experimental Forest (HBEF). It is possible that this “greening up” of HBEF streams may be due to climate change, with rising temperatures, altering terrestrial phenology, and shifting hydrologic regimes. Alternatively, stream “greening” could be from the slow recovery of stream chemistry after decades of acid rain, which has led to rising pH, declining concentrations of toxic Al3+, and low solute concentrations. Four years of weekly algal measurements on artificial moss and ceramic tiles, along with six nutrient enrichment experiments, revealed new insights about the interactions between these two autotrophs. We found that in protected weir ponds and in stream channels, algal biomass was higher on artificial moss substrates than on tiles—with this effect amplified in the stream channels. These results suggest that bryophytes can provide physical protection from flood scour or may trap nutrients to support algal growth. In stream channels, algal biomass was higher in well‐lit habitats and time periods indicating strong light limitation. We only measured nitrogen and phosphorus limitation of algal biomass in nutrient enrichment experiments conducted within weir ponds, with higher light availability and lower flow. By comparison, results from the remaining four instream experiments provided little evidence for nutrient limitation, with only one trial showing increased algal growth in response to nutrient addition. The most striking implication of our study is the role of bryophytes in providing refugia, and potentially nutrients, to algae in shaded and oligotrophic headwater streams.

Design a variety of cation exchange hydrogel resins using gamma irradiation to remove hard/scale metal cations from saline water under different circumstances

This study aims to develop a series of cation exchange hydrogel resins via gamma irradiation technique through copolymerizing styrene sodium sulfonate with three acrylamide derivatives (designated as poly(X-co-styrene sodium sulfonate), where X refers to acrylamide (PAASS), methacrylamide (PMASS), and isopropyl acrylamide (PIASS)). The prepared hydrogel resins were characterized and tested for the adsorption removal of hard/scale metal cations (e.g., Ca2+, Mg2+, Ba2+, and Sr2+) from saline water under varying conditions. Results demonstrated that PMASS and PIASS displayed closed porous networks with a significant pH-responsive swelling behavior, increasing from 1.41 to 5.62 g/g in acidic conditions and approximately 41.49 to 45.83 g/g under neutral conditions swelling ratios, while PAASS exhibited an open porous network structure with the stable swelling ratio of around 35 g/g within mild and neutral pH ranges. All hydrogel resins also showed rapid initial adsorption of Ca2+ > Mg2+ > Ba2+ > Sr2+, depending on ionic metal size, with adsorption equilibrium within 3–6 h. Maximum removal was achieved at neutral-basic pH when sulfonate groups were fully deprotonated with a total capacity of about ~ 147–175 mg/g overall mixed metal ions. When exposed to lower concentration solutions, about 87% of metal ions were effectively removed.

Regulation of the physicochemical properties of nutrient solution in hydroponic system based on the CatBoost model

Too high or low nutrient solution concentrations adversely affect hydroponic vegetables’ growth and yield performance. In addition, the temperature of the solution and the dissolved oxygen (DO) content of the water are critical factors. A real-time regulation model for nutrient solutions based on the CatBoost model was developed to address the issues of low automation and accuracy of nutrient solution configuration and management. The pH, electric conductivity (EC) and DO of the nutrient solution, and the corresponding water temperature of 96 groups of hydroponic lettuce nutrient solutions (KNO3, MgSO4, Ca(NO3)2, KH2PO4, NH4H2PO4, and microfertilizer) were measured using a gradient combination test designed according to the formula of hydroponic lettuce nutrient solution. A prediction model of the nutrient solution index was constructed using a gradient-enhanced decision tree algorithm and the accuracies of the random forest, XGBoost, and CatBoost algorithms were compared. The results show that the root mean square error (RMSE), mean absolute error (MAE) and coefficient of determination (R2) of the simulated and measured values of the EC prediction model established by the CatBoost model were 248.28 µS/cm, 203.19 µS/cm and 0.946, respectively. At the same time, it was found that the hydroponic variable fertilization control system, composed of four modules–data acquisition, data decision, field control, and manual control–could predict the EC and pH value changes of the nutrient solution and timely add compounds for control. The application of nutrients based on the developed system was good and the weight of the cream lettuce (Flandria RZ) grown using the system was more than 200 g, which meets the requirement for high-quality cream lettuce production. Therefore, the CatBoost model system can be used to improve the hydroponic production system of vegetables by managing nutrients effectively.

Kinetic and Isothermal Analysis of the Adsorptive Elimination of Direct Yellow 26 Dye Utilizing Activated Bioadsorbent From Textile Effluent.

Due to their widespread usage in recent years, synthetic dyes may be difficult to remove and pose a health concern. Bioadsorbents proved a low-cost and sustainable method for dye removal. In this study, straight yellow 26 is extracted from textile effluent using sugarcane bagasse. Sugarcane bagasse was treated with propionic acid to enhance the adsorption capability and 0.25 mm particle size was used for further studies which was confirmed by BET analysis. Standard solutions of direct yellow 26 dye were prepared from 10 to 100 ppm concentrations and absorbance was recorded with the help of a UV visible spectrophotometer. After optimizing different parameters (concentration of dye and bioadsorbent dose, pH, time, and particle size), the studies explored that the maximum dye removal percentage was 89% obtained at pH 3, contact time 120 min, particle size 0.25 mm, high adsorbent, and low concentration of dye solution. The kinetic studies were also employed to comprehend the adsorption isotherm and Freundlich isotherm that revealed the pseudo-first-order adsorption process.

Degradation of (1→3)(1→6)-α-D-dextran by ultrasound: Molecular weight, viscosity and kinetics

The (1→3)(1→6)-α-D-dextran (alternating dextran) produced by Leuconostoc citreum SK24.002 is a novel functional exopolysaccharide, and its low molecular weight derivatives have potential applications in the food, pharmaceutical, and chemical industries. In this work, we used sonication, a green polysaccharide disruption method, to study the degradation process of this dextran by changing the intensity and duration of the sonication treatment and the concentration of the dextran solution. The molecular weight and viscosity of the dextran products were measured with a high-performance size exclusion column chromatography–multi-angle laser light scattering–refractive index system and by rheometry, respectively. The degradation efficiency of dextran was directly affected by the duration and intensity of the ultrasonic treatment and the concentration of the dextran solution. The polydispersity index fluctuated as the duration of the sonication treatment increased. The combination of a high intensity (672 W/cm2) and long (120 min) sonication treatment and a low solution concentration (3 g dextran/100 mL) was most effective for reducing the apparent and complex viscosities of dextran. The storage modulus of dextran was always slightly larger than its loss modulus, indicating that it formed a gel-like structure. The second-order kinetic model (1/Mwt - 1/Mw0 = kt) was the best fit to explain the degradation dynamics of dextran by sonication at intensities of 168 W/cm2–834 W/cm2 and with dextran solution concentrations of 1 g/100 mL – 7 g/100 mL. Our findings show that sonication is an effective way to reduce the molecular weight of alternating dextran.

Adsorption of Heavy Metals from Low Concentration Solutions onto Dried Chlamydomonas reinhardtii

Adsorption of Heavy Metals from Low Concentration Solutions onto Dried Chlamydomonas reinhardtii

In Vitro and In Vivo Translational Insights into the Intraoperative Use of Antiseptics and Lavage Solutions Against Microorganisms Causing Orthopedic Infections.

The growing antibiotic resistance of microorganisms causing postoperative infections following orthopedic surgeries underscores the urgent need for localized antiseptic and lavage delivery systems to enhance infection control. This study evaluates the in vitro effectiveness of antiseptic and lavage solutions-including polyhexanide, povidone-iodine, low-concentrated hypochlorite, Ringer's solution, and saline-against Staphylococcus epidermidis, Staphylococcus aureus MRSA, Cutibacterium acnes, Corynebacterium amycolatum, Pseudomonas aeruginosa, and Candida albicans. Using microplate models (Minimum Inhibitory Concentration, Minimum Biofilm Eradication Concentration, and Biofilm-Oriented Antiseptic Test assays), flow-based models (Bioflux system), and surfaces relevant to orthopedic implants (e.g., stainless steel disks/screws, Co-Cr-Mo, Ti-Al-Nb orthopedic alloys, and ultra-high-molecular-weight polyethylene), as well as a bio-nano-cellulose scaffold representing tissue, we assessed the solutions' activity. The cytotoxicity of the solutions was evaluated using osteoblast and keratinocyte cell lines, with additional in vivo insights gained through the Galleria mellonella larval model. The results show that polyhexanide-based solutions outperformed povidone-iodine in biofilm eradication in most tests applied, particularly on complex surfaces, whereas iodine demonstrated higher cytotoxicity in applied in vitro and in vivo tests. Low-concentration hypochlorite solutions exhibited minimal antibiofilm activity but also showed no cytotoxicity in cell line and G. mellonella larval models. These findings highlight the importance of careful antiseptic selection and rinsing protocols to balance infection control efficacy with tissue compatibility in orthopedic applications.

Development of PEMFC Catalyst Layers with Low-Pt Loading Utilizing Stream-Jet Coating Technology

Global warming is one of the most serious problems we currently face. International efforts to reduce greenhouse gas emissions and achieve carbon neutrality are crucial for addressing this issue. As a result, the importance of hydrogen fuel cells, which are eco-friendly and capable of producing clean energy, is becoming more prominent. In particular, polymer electrolyte membrane fuel cells (PEMFC) are attracting attention as next-generation energy that can be applied to various industrial fields such as portable and transportation applications due to their efficient energy density and ability to operate at low temperatures. However, the high price of PEMFC membrane-electrode assembly (MEA) using Pt catalysts is a major issue that increases the cost of fuel cell systems and makes commercialization difficult. Therefore, reducing Pt usage, improving cell performance, and simplifying the MEA manufacturing process have become important research and development directions for PEMFC. As part of these efforts, various catalyst layer coating methods such as ultrasonic spraying, inkjet printing, and doctor blade are being studied. However, although ultrasonic spray coating has the advantage of a simple process, it has the problem of slow coating speed, making it difficult to manufacture large-area MEA [1]. On the other hand, doctor blade coating is suitable for mass production with high precision and fast coating speed, so it is mainly used in commercial MEAs. However, it is difficult to form thin film coatings due to the characteristic of using a highly concentrated solution [1, 2].In this study, a new coating technology using the stream-jet technique was introduced to reduce Pt usage and simultaneously fabricate large-area MEA. This technique is a method of coating by continuously spraying a solution through a micro nozzle using external pneumatic pressure. It has a fast coating speed with the micro nozzle moving at a speed of up to 1 m/s [3]. The stream-jet coating method with these characteristics is expected to be an advantageous coating technology for large-area PEMFC MEA manufacturing and future commercialization. Moreover, the micro nozzle moves in the X-axis direction, and the stage on which the sample is placed moves in the Y-axis direction to coat the electrode in the desired area. In this process, the amount of Pt used can be controlled by adjusting the printing interval and coating frequency of the stage moving in the Y-axis direction. Solutions of various concentration ranges can also be used to form a uniform thin film coating catalyst layer. Through this technology, we fabricated a MEA that effectively reduced Pt usage by coating a very thin catalyst layer of less than 5 um using a catalyst ink with a low concentration of less than 1 wt%. The Pt loading of the cathode was fixed at 0.11 ± 0.01 mgpt/cm2, and by using a low concentration solution, the anode Pt loading could be reduced to 0.025 ± 0.001 mgpt/cm2 without significant performance loss in the range of low current density. Additionally, it was confirmed that a catalyst layer with an area of 25 cm2 could be coated within a few seconds due to the fast coating speed. MEAs fabricated with stream-jet coating were compared for single-cell performance with commercial MEAs. As a result, it was confirmed that the performance of cells using stream-jet coating technology showed high mass activity performance compared to the Pt loading. This achievement is believed to be a technology that can secure the price competitiveness of fuel cells through stream-jet coating technology and contribute to the development of large-area MEA. Acknowledgements This work was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) and the Korea Evaluation Institute of Industrial Technology (KEIT). (Grant No.20019249) References B.H. Lim, E.H. Majlan, A. Tajuddin, T. Husaini, W. R. Wan Daud, N. A. Mohd Radzuan, and M.A. Haque, “Comparison of catalyst-coated membranes and catalyst-coated substrate for PEMFC membrane electrode assembly: A review.” Chinese J. Chem. Eng., 33, 1 (2021)I.S. Park, W. Li, A. Manthiram, “Fabrication of catalyst-coated membrane-electrode assemblies by doctor blade method and their performance in fuel cells.” J. power sources, 195, 7078 (2010)K.Y. Shin, M. Kang, M.K. Kim, K.S. Jung, C.S. Yoo, K.T. Kang, and S.H. Lee, “Large Area Organic Thin Film Coating Using a Micro Multi-nozzle Jet Head with Side Suction Channels.” Int. J. Precision Engineering and Manufacturing-Green Technology, 8, 829 (2021)

Coupling UiO-66 MOF with a Nanotubular Oxide Layer Grown on Ti-W Alloy Accelerates the Degradation of Hormones in Real Water Matrices.

To enable the photoelectrocatalytic treatment of large volumes of water containing low concentrations of pollutants, this study introduces a hybrid photocatalyst, composed of nanotubular oxides grown on TixW alloy (x = 0.5 and 5.0 wt %) modified with UiO-66 MOF, for degradation of estrone (E1) and 17α-ethinyl estradiol (EE2). The oxide layer (Nt/TixW) was prepared via anodization, while UiO-66 nanoparticles were synthesized by using a solvothermal process. Different techniques for modifying nanotubular oxides were evaluated to maximize the photocatalytic activity and the sorption process. In photo(electro)catalytic experiments using low concentrations of E1 and EE2 synthetic solutions and UV-vis radiation (100 W/cm2), all modified materials exhibited approximately 40% higher degradation compared to the unmodified photocatalyst, keeping the same sequential performance of the photocatalysts (Nt/TiO2 < Nt/Ti-0.5W < Nt/Ti-5.0W) independent of the treatment. This enhancement was attributed to the MOF's increased hormone sorption, with no synergistic interaction observed between the photocatalyst and the adsorbent. In real water supply matrices, the photoelectrocatalytic removal rate of E1 using Nt/Ti-5.0W modified UiO-66 under UV-vis radiation and 1.3 V was 0.168 s-1, while for EE2, it was 0.310 min-1, approximately 1.78 and 18.21 times faster than obtained with the unmodified photocatalyst. The slower degradation rate of EE2 compared to that of E1 is attributed to the formation of denser intermediates that compete with smaller organic molecules in the real matrix. The cooperative effect between NT/TixW and UiO-66 favored the confinement of pollutants and by-products within the UiO-66 cavity, minimizing the diffusion effects and promoting the degradation of these compounds by the OH· radical generated at the oxide/solution interface. Among the tested electrodes, NT/Ti5W modified with UiO-66 demonstrated the highest efficiency and stability during the recycle tests. This highlights its promise for applications in photocatalytic processes for treating water supplies with low pollutant concentrations.

(Invited) Zinc Oxide and Titanium Oxide Photocatalysts Fabricated By Electrochemical Methods and Boron Doped Diamond Electrochemistry

Photocatalytic Properties of Transparent ZnO Films Prepared by Anodization of Zinc PlateTransparent zinc oxide films were prepared by anodizing of zinc plate when the electrolyte was kept at low temperature（＜10℃）in low concentration of alkaline solution and under high bias voltage，Obtained transparent film was uniform，and it showed transparency even if it might be thick．Thus obtained transparent film is confirmed to be a pure zinc oxide，and its absorption edge is 380nm，which corresponds to the optical band gap energy of 3.2 eV，Moreover，it had high photocatalytic activity which was superior to the one prepared under no cooling. We have already reported that the photocatalytic properties were closely correlated with their orientation preference of（1010）. In this case，thus obtained transparent film also showed preferred orientation of the（1010），Effects of Electrolytic Condition to Photocatalytic Activity for Cathodically Deposited ZnO Films. Zinc oxide film was prepared easily by cathodic deposition from zinc nitrate aqueous solutions. Deposited film was evaluated as photocatalytic film under different deposition conditions. The Photocatalytic activity was evaluated by measuring acetaldehyde gas degradation. Film prepared in dilute solutions of Zn (NO3)2 showed superior photocatalysis activity. Film prepared under high current density showed superior photocatalysis. We monitored mass changes during cathodic deposition and confirmed that ZnO was completely deposited under the above conditions and that additional reactions took place under other preparation conditions. These additional reaction deactivated photocatalytic activity.Photocatalytic Properties of Titanium Oxide Film Prepared by Electrophoretic Sol－Gel Deposition Electrophoretic Sol-Gel Deposition was introduced to immobilize the TiO2 photocatalysis．Thus prepared coatings showed quite high－photocalytic activities without successive heat treatment．It is suggested that Non-heated coating showed high photocalytic activity because it responds effectively for light，which is attributed to the nano-structure of the deposited coating．Fabrication and Characterization of Diamond Quartz Crystal Microbalance Electrode Boron-doped diamond film on a quartz crystal electrode was prepared by a reflow technique. The mass sensitivity of this diamond-quartz crystal microbalance (QCM) sensor was determined by performing Fe electrodeposition. This novel electrochemical QCM sensor was quite stable under several electrochemical experimental conditions. Its wide potential window and significantly low background current are just the same as the performance of a diamond electrode. We also showed that the fabricated diamond-QCM electrode worked satisfactorily as a useful tool for electrochemical microgravimetry by examining hydrogen evolution, oxygen evolution, and oxidation of the diamond surface in acidic solutions. It was found that evolved H2 inserted into the bulk of as-grown diamond with a storage volume of 0.06 mol/dm3 in 0.5 mol/dm3 HCl solution, after sweeping the potential from 0 to -2.3 V at a scan rate of 10 mV/s, in contrast to O-terminated diamond-QCM, which inhibited hydrogen intercalation.Oxygen reduction on Au nanoparticle deposited boron-doped diamond films Nanoparticle Au was deposited on as grown boron-doped diamond (BDD). The coverage and the morphology of the deposited Au particles were investigated by means of the linear sweep voltammetry and scanning electron microscopy (SEM). From SEM, the gold electrodeposited randomly as small spherical particles with an average diameter of 60nm. The applications of the as grown BDD film deposited by Au for electrocatalytic reduction of the oxygen in acidic solution were investigated. The catalytic efficiency of the Au deposited as grown BDD with the coverage of 0.06 is near 20 times larger than that of polycrystalline gold. The mechanism of the highly electrocatalytic active was investigated by ac impedance and hydrodynamic voltammetric methods.Photoelectrodeposition of Copper on Boron-Doped Diamond Films: Application of Conductive Pattern Formation on Diamond. The Photographic Diamond Surface Phenomenon The photoelectrodeposition of copper on semiconducting B-doped diamond films was investigated. There were clear morphology differences between photoelectrodeposited and electrodeposited copper. Photoelectrodeposition proceeded by a uniform two-dimensional growth process, whereas electrodeposition involved isolated random deposition. By applying this effect we have succeeded in forming a conductive copper pattern on semiconducting B-doped diamond with the aid of a photo-mask. Interestingly, it was further found that changes occurring on the diamond surface during photoelectrochemical polarization in the absence of copper in solution facilitate subsequent copper electrodeposition in the dark, possibly due to the formation of subsurface hydrogen. We refer to this as the `photographic diamond surface phenomenon'.

Advanced Polybenzimidazole Derivatives in Ion-Solvating Membrane Water Electrolysis with Low KOH Concentration

The development of a polymer electrolyte with robust mechanical strength and exceptional electrochemical stability is crucial for alkaline water electrolysis while ensuring high hydroxide ion conductivity in low concentrations of KOH solution. The Ion-solvating Membrane Water Electrolysis (ISMWE) is gaining interest due to its adaptability to lower KOH solution concentrations, utilizing a polymer-based separator doped with KOH, resulting in a unified system consisting of polymer, water, and KOH, facilitating the use of non-platinum metal catalysts. Herin, we have employed the in-situ directing casting method to fabricate poly(2,5-benzimidazole) (ABPBI). The repeating benzimidazole units comprising the ABPBI membrane can retain significant amounts of KOH, leading to a dramatic increase in ion conductivity during electrolysis. The membrane was subjected to electrochemical evaluation through various conditions using an alkaline water electrolysis cell station, involving two different temperatures for cell operation, 60 ℃ and 70 ℃, and four different concentrations of KOH: 0.5M, 1M, 2M and 3M, utilizing both PGM catalysts and non-PGM catalysts. Additionally, we have fabricated ABPBI derivatives that exceed the mechanical and electrochemical performance of the pristine membrane. The physical characteristics of membranes are evaluated using techniques such as UTM, TGA, SEM, XRD, and XPS. From our results, the use of ABPBI polymer as Ion-solvating membrane, which allows for the utilization of high-efficiency and durable alkaline electrolysis. This study highlights the potential of ABPBI structures as the backbone and anion exchange sites for ISMWE operating with low KOH concentration solution. Figure 1

Monitoring ammonia and water transport through anion exchange membranes in direct ammonia fuel cells

Anion exchange membrane direct ammonia fuel cells (AEM-DAFCs) can generate clean electricity with zero carbon emissions. However, their performance are hindered by severe ammonia crossover, which causes a mixed potential at the cathode, thereby reducing the cell voltage. Meanwhile, the produced intermediates, such as Nads species, adsorb onto catalyst, causing poisoning and thus impeding the oxygen reduction reaction (ORR). Another key issue for AEM-DAFCs is to maintain an appropriate water content at the cathode, which is crucial for promoting ORR and avoiding water flooding. In this work, an in-situ observation method is developed to quantitatively characterize the rates of ammonia and water crossover. Besides, a half-cell configuration is designed and developed to evaluate the cathode potential drop caused by ammonia crossover. The effects of operating conditions (such as ammonia concentration and cell temperature) and membrane electrode assembly (MEA) design parameters (such as membrane thickness and cathode wettability) on behaviors of ammonia and water crossover are thoroughly examined. The findings show that ammonia crossover can be substantially reduced by using a low-concentration ammonia solution or a thicker membrane. Moreover, this study offers guidance on developing fuel and water management strategies to enhance the performance of AEM-DAFCs.

Polyoxometalate oxate solution: An electrolyte additive to sustainably improve the anodes electrode of aqueous Zn ion batteries

Aqueous zinc-ion batteries (AZIBs) are favored by researchers because of their high safety performance and abundant zinc resources. In this work, low-cost was selected as the electrolyte additive to continuously improve the problems faced by the anode. Molybdenum-based solution can be reduced on the surface of zinc anode to form a uniform protective layer, and polyoxometalate can disperse metal elements more evenly, so that Zn2+ deposition is more uniform and AZIBs has more stable cycling performance. The symmetric battery assembled after adding Polyoxometalate oxate solution can maintain a stable potential of more than 1900 h at 5mA cm−2 and 1mAh cm−2, which is three times the cycle time of the battery assembled with ZnSO4 as the electrolyte (600 h). In addition, Mo has a certain anti-corrosion effect, which can prevent the corrosion reaction on the surface of zinc anode. The Tafel diagram shows that the corrosion current decreased from 1.995 mA cm−2 to 1.584 mA cm−2 after the addition of polyoxometalate oxate solution. The contrast effect is more obvious in SEM images. Different from the traditional zinc anode surface optimization, the addition of polyoxometalate oxate solution can continuously form auxiliary nucleation sites on the negative electrode surface to make Zn2+ deposition more uniform. When Na doped vanadium dioxide was used as the cathode to form full battery, the specific capacity could still reach 143.73mAh g−1 after 1000 cycles at the current density of 2 A/g. In this study, adding low concentration of polyoxometalate oxate solution to the electrolyte can continuously generate a stable protective layer during the battery operation, providing a feasible scheme for continuous improvement of AZIBs zinc anode.

Identifying solute loss from karst conduit to fissures under concentrated recharge conditions

The aquifer within karst areas exhibits significant heterogeneity, accompanied by intricate runoff processes and swift hydrological responses. The solute transport process within karst conduits is influenced by various factors, including karst development characteristics and variations in hydrodynamic conditions, thereby displaying a high level of complexity. This complexity plays a crucial role in governing the safe utilization of karst water resources and the prevention of groundwater pollution. In this paper, a typical karst conduit system in southern China is chosen to investigate the influence mechanism of hydrodynamic conditions on the solute transport process within the karst conduit. This investigation is conducted through multiple sets of field artificial tracer tests. An intriguing phenomenon was observed: When the mean flow velocity of the conduit flow is either low (<200 m/h) or high (>1000 m/h), the solute concentrations and recovery rates are low. Conversely, the solute concentration and recovery rate are highest at a medium flow velocity (560 m/h), with the recovery rates ranging from 0.13 % to 92.44 %. A theoretical formula has been derived to estimate the solute loss from conduit flow to fissure flow. When the conduit is filled with water, an increase in the mean flow velocity leads to an augmentation in the amount of water recharged from the conduit into the fissures, as well as an increase in the stored solute mass, which results in a decrease in the solute recovery rate. The condition that poses the highest risk of groundwater pollution occurs at a medium flow velocity, where the solute concentration and recovery rate are all at their maximum levels. When the recharge rate at the sinkhole is very small, both the cross-sectional area and the mean flow velocity of the karst conduit are reduced. The rough bottom of the karst conduit leads to an increase in dispersivity, resulting in low solute concentration and recovery rate. The results elucidate the reasons behind the significant variations in solute recovery rates under different hydrodynamic conditions. They provide novel evidence for comprehending the water and solute exchange processes between conduits and fissures under concentrated recharge conditions. Furthermore, these findings offer a valuable reference for assessing the risk of groundwater pollution in karst areas.

Germination and Seedling Performance of Watermelon as Affected by Chemo-priming

Seed priming is a very important operation for healthy germination and seedling growth. Though a growing body of literature, the report on seed priming on watermelon is hardly available. Thus an experiment was conducted to study the germination and seedling performance of three watermelon cultivars viz. Asian 2, Pakorea F1 and Black Red with six seed priming treatments such as hydropriming with distilled water, halopriming with 1.5N NaCl and 3% KNO3, osmopriming with 3% PEG (Polyethylene Glycol), oxidative priming with 0.1N HCl solution and control i.e. no priming. The seeds were primed overnight with the aforesaid liquids and were allowed to grow both in petridishes in dark condition within laboratory and in pot soil under natural condition in an open grill house. All three watermelon cultivars showed significant difference due to seed priming with aforesaid primers. Germination Index (GI) was found higher in Asian 2 and Black Red cultivars due to HCl priming and in Pakorea F1 due to NaCl priming, while priming with PEG and KNO3 inhibited the GI of respective cultivars. Seedling Vigor Index (SVI) was found higher in Pakorea F1 with HCl priming whereas lower in Asian 2 and Black Red cultivars with PEG priming. Both in dark (Lab) and light (open field) conditions, total seedling dry matter was found higher in Asian 2 and Black Red cultivars due to HCl priming and lower in Pakorea F1 due to PEG priming. Results showed that low concentrated (0.1N) HCl solution can be used as priming medium to enhance germination and seedling growth of watermelon seeds.

Theoretical analysis and application of immobilized methanotrophs as typical adsorbent materials for adsorption/degradation of trichloroethylene

ABSTRACT Trichloroethylene (TCE) contamination presents a significant environmental challenge, necessitating efficient treatment solutions. This study aimed to develop an optimized immobilized bioreactor using methanotrophs for TCE degradation. Activated carbon fibres were identified as the optimal immobilization material, with an adsorption rate of 6–23 h – significantly faster than over 50 h for other materials – and the highest methane oxidation capacity of 0.970 mL·g−1·h−1. Adsorption kinetics indicated that activated carbon fibres followed a second-order kinetic model with a constant of 0.598 g·mg−1·h−1, suitable for low-concentration bacterial solutions. Thermodynamic analysis confirmed an exothermic process, favouring lower temperatures (288.15 K). The negative interaction energies, as per DLVO theory, suggested electrostatic attraction as a key mechanism. The bioreactor achieved 99% TCE removal within 1 h at an initial concentration of 10 mg·L−1, with visible microbial immobilization within 5 days. This research provides a novel and effective approach for using immobilized methane-oxidizing bacteria in TCE treatment, offering both theoretical and practical advancements for chlorinated hydrocarbon wastewater management.

Effect of synthesis temperature on the properties and photocatalytic performance of peroxo-titanate nanotubes prepared by bottom-up synthesis method

The alkaline treatment synthesis of titania/titanate nanotubes (TNTs) requires highly concentrated alkaline solutions (≥ 10 mol/L), which pose environmental and productivity limitations. In contrast, a bottom-up synthesis method for peroxo-titanate nanotubes (PTNTs) has been developed. This method offers two advantages: it can synthesize materials using low-concentration alkaline solutions (1.5 mol/L) and produce photocatalytic materials that are responsive to visible light. In general, the higher the crystallinity of a catalyst, the better its properties. However, PTNTs synthesized at temperatures close to their boiling point (around 100 °C) exhibit low crystallinity. This study hypothesizes a hydrothermal synthesis method at higher temperatures will enhance the crystallinity and photocatalytic performance of PTNTs, synthesizing them at temperatures ranging from 120 to 200 °C using a method capable of exceeding the boiling point. Higher synthesis temperatures resulted in improved morphological and crystallographic properties of the PTNTs. However, the formation of peroxo-bonding, crucial for visible light responsiveness, decreased. Nevertheless, peroxo-bonding formation was still achievable at the highest temperature of 200 °C, and the sample exhibited the best Rhodamine B (Rh B) photodegradation performance under visible light due to its enhanced specific surface area and crystallinity. This study highlights the novelty and environmental significance of hydrothermally synthesized PTNTs as superior photocatalysts by optimizing the synthesis temperature while using lower concentration alkaline solutions.