Cation Concentration Research Articles

Evaluation of land use and geological effect on groundwater characteristics in Bandung metropolitan using a hydrochemical and statistical approach

Abstract Groundwater is often used as clean water since it requires less water treatment. However, the quality will depend on the environmental conditions and human activities. Our research is conducted in Bandung Metropolitan, an urbanized area where groundwater is preferable, but the quality is becoming concerning. The objective of this study is to determine whether natural or human activities have a greater impact on groundwater quality. A total of 113 samples were collected from nine geological conditions spanning three primary land use types. The samples were analyzed for seven major ions (Na+, K+, Ca2+, Mg2+, HCO3 −, SO4 2 −, and Cl−), which occur naturally in natural water but may be elevated due to human activities. Based on the Piper diagram, fifty-three samples are categorized as Ca-HCO3, with the dominant cation being Ca2+ and the dominant anion being HCO3 −. Furthermore, the multivariate statistical analysis reveals that 74% of all ions are related to geological conditions and anthropogenic activities. In detail, high contents of Ca2+, as the dominant cation, are significantly correlated by all land uses and most geological formations. In addition, cation contents were significantly correlated with land uses, but the correlation varied for each type of geological formation. All land uses surely correlate with all major ions, but the geology depends on the type of formation.

Species–soil relationships across Amazonia: Niche specificity and consistency in understorey ferns

AbstractAimsKnowledge about species niches along environmental gradients is needed to understand community assembly and spatial variation in floristic composition and species richness. In Amazonian rainforests, such knowledge is largely lacking, although ferns have been used to infer overall floristic and edaphic patterns. Here we explore fern species distributions along an important edaphic gradient, how narrow their realised niches are and how sensitive inferences are to species commonness, data quality and the region being sampled.LocationAmazonia.MethodsWe used a large data set (1,215 transects across lowland Amazonia) to explore the realised niches of 54 species of two fern genera (Adiantum and Lindsaea) along a soil base cation concentration gradient. We used weighted averaging to estimate species optima and niche widths, and Huisman–Olff–Fresco modelling to assess species response shapes.ResultsOverall, species optima were rather evenly spread along the soil base cation concentration gradient, but Lindsaea optima were limited to the lower half of the gradient, whereas Adiantum optima were more often in the upper half. Most species had unimodal response curves. Mean niche width was ca. 25% of the observed gradient length for Adiantum and 17% for Lindsaea and was only weakly or not at all related to different aspects of species commonness. Species optima were robust to different modelling approaches and consistent across regional subsets. However, the central Amazonian data contained no transects with high soil base cation concentration, so species with high optima were either absent or obtained a lower optimum than in the NW and SW regions.ConclusionsOur results support niche‐related species sorting as an important process that defines species co‐occurrence, turnover and richness patterns within Amazonian rainforests. All Adiantum and Lindsaea species, including the most abundant ones, had narrow enough realised niches to be considered useful indicators of edaphic and floristic variation within the rainforest.

Theoretical and experimental investigation of the impact of oil functional groups on the performance of smart water in clay-rich sandstones

This research investigated the effect of ion concentration on the performance of low salinity water under different conditions. First, the effect of injection water composition on interparticle forces in quartz-kaolinite, kaolinite-kaolinite, and quartz-oil complexes was tested and modeled. The study used two oil samples, one with a high total acid number (TAN) and the other with a low TAN. The results illustrated that reducing the concentration of divalent ions to 10 mM resulted in the electric double layer (EDL) around the clay and quartz particles and the high TAN oil droplets, expanding and intensifying the repulsive forces. Next, the study investigated the effect of injection water composition and formation oil type on wettability and oil/water interfacial tension (IFT). The results were consistent with the modeling of interparticle forces. Reducing the divalent cation concentration to 10 mM led to IFT reduction and wettability alteration in high TAN oil, but low TAN oil reacted less to this change, with the contact angle and IFT remaining almost constant. Sandpack flooding experiments demonstrated that reducing the concentration of divalent cations incremented the recovery factor (RF) in the presence of high TAN oil. However, the RF increment was minimal for the low TAN oil sample. Finally, different low salinity water scenarios were injected into sandpacks containing migrating fines. By comparing the results of high TAN oil and low TAN oil samples, the study observed that fine migration was more effective than wettability alteration and IFT reduction mechanisms for increasing the RF of sandstone reservoirs.

Electrochemical migration and dendrite growth between two electrodes: Experiments and Brownian dynamics simulations

Electrochemical migration (ECM) is a common cause of failure in printed circuit boards (PCB) due to dendrite growth between exposed metallic conductors under moisture especially in the presence of flux residues. Understanding this phenomenon, therefore, is of interest from technological and economical points of view. Here, we report experimental results of water drop tests on surfaces contaminated by various amount of flux residues, which are supplemented with Brownian dynamics (BD) results to gain molecular insight into ECM and dendrite growth. BD is a particle simulation method where the ions are modeled explicitly. We show dendrite growth curves (the length of the longest dendrite as a function of time) obtained from visual examination with digital video microscope and from BD simulations. Results for the time to failure are also shown for various values of the electric field strength and cation (Sn2+) concentration (dilution of contamination). We report a mapping of experimental and simulation results that is necessary due to the large concentrations and electric field strengths used in the BD simulations.

PH Variation in the Acidic Electrochemical CO2 Reduction Process.

To address the carbonate problem in the alkaline electrochemical CO2 reduction reaction (CO2RR), more attention has been paid to the CO2RR conducted in acidic electrolytes. The pH stability of such an acidic electrolyte is vital to make sure that the conclusion made in the so-called acidic CO2RR is reliable. Herein, based on reported model electrocatalysts for acidic CO2RR, by monitoring the varying of pH and alkali cation (K+) concentration along with the CO2RR performance in initially acidic electrolyte solution (K2SO4 with pH = 3.5), we unveil their remarkable CO2RR performance along with the rapid pH increase up to 9.5 in the cathode chamber and decrease down to 2.4 in the anode chamber due to the diffusion of K+ along with protons through the proton exchange membrane from the anode to the cathode chamber. We further reveal the rapid collapse of their CO2RR performance in a constant acid solution. This means that some previously reported "remarkable acidic CO2RR performances" actually originate from the alkaline rather than acidic electrolyte, and the conclusions made in such work need to be reconsidered. We also summarize the actual relationship between the CO2RR performance and catholyte pH in widely used Bi- and Sn-based catalysts. This work provides deeper insights into the stability of acidity and the pH effect on electrocatalysts for the CO2RR.

A 44-year balanced fertilizer application affected rill erosion resistance by changing humus, aggregates, and polyvalent cation

Fertilizer application can affect the physicochemical properties of soil, such as the contents of large aggregates, humus, and exchangeable cations, thereby influencing soil erosion resistance. However, the rill erosion resistance and its key influencing factors of soil following long-term balanced fertilizer application remains unclear. This study aimed to analyze the change in rill erosion resistance following 44 years of balanced fertilizer application (No changes in the type of fertilizer) to non-calcareous soils and establish a Partial Least Squares Regression (PLSR) model of rill erodibility (kd) and soil critical shear stress (τc) to changes in the physical and chemical properties of the soil. Five treatments were designed: (1) CK (no fertilizer applied), (2) N (nitrogen), (3) NP (nitrogen plus phosphorus), (4) NK (nitrogen plus potassium), and (5) NPK (nitrogen, phosphorus, and potassium). Compared to CK, the N, NP, NK, and NPK application significantly increased τc by 49.6, 96.7, 73.6, and 36.2 %, respectively. Whereas, kd increased significantly only in the NPK treatment group. The optimal partial least squares regression model showed that mean weight diameter (MWD) had the greatest positive influence on soil critical shear stress, followed by fulvic acid (FA) content, whereas water-dissolved substances had a negative influence. Long-term balanced fertilizer application can increase MWD and τc by combining micro-aggregates and humus into large aggregates. Ca2+ content had the greatest positive effect on kd. Compared with that of CK, exchangeable Ca2+ content increased significantly with NP and NPK application (7.9 and 34.3 %, respectively). Ca2+ can increase kd by binding to the polar functional groups in FA to promote the shedding of hydration shells in large aggregates. Among all treatments, the NP treatment showed the best performance for reducing kd and increasing τc. This study could contribute to the understanding of the rill erosion process and modeling in non-calcareous soils and offer a reference for agricultural erosion control treatments.

Impact of Cation Concentration on Graphene Oxide Properties Fabricated from Disposed Batteries

Disposed batteries contain the hazardous sources that directly impact on the environment. Proper disposal of used batteries is a vital matter because of toxit component found in types of batteries. This study focuses on the reutilization of the disposed Zn-battery graphite to produce graphene oxide (GO) via electrochemical exfoliation. The influence of various electrolytes on the exfoliation process was investigated, and the optimal ID/IG values in Raman spectra were determined as 2.5% for KOH. Scanning electron microscopy (SEM) images confirmed the presence of multi-wall graphene oxide in the exfoliated samples. X-ray diffraction (XRD) spectra displayed a broadening of the peak at 2θ = 26.5°, further supporting the successful formation of graphene oxide. The exfoliated graphene oxide was found not to contain any toxic elements. This highlights the potential of using disposed batteries in producing low cost graphene oxide. The study contributes to environmental protection by repurposing graphite rods and reducing industrial waste.

Resources, energy consumption and economic analysis for flame synthesis of ternary cathode materials

Cathode materials account for around one third of the manufacturing cost of lithium-ion battery, which are the major factor preventing the wider applications of power battery packs. Flame synthesis (FS) is a new manufacturing technology of nanostructured materials with few equipment and high efficiency, which potentially can substantially bring down the manufacturing cost of cathode materials. The primary objective of the present study was to quantitatively evaluate the resources, energy consumption and economic feasibility of large-scale production of cathode materials though FS. In the analysis process, the mass flow of reactants and resultants as well as the minimum cathode material selling price (MCSP) of ternary cathode material LiNixCoyMn(1-x-y)O2 (x + y + z = 1) produced by FS were calculated, and compared with that of the conventional hydroxide co-precipitation method. Results show that the production of ternary cathode material through FS can reduce CO2 emissions by ∼60% and water consumption by ∼30%. MCSP of LiNi0.5Co0.2Mn0.3O2 (NCM523), LiNi0.6Co0.2Mn0.2O2 (NCM622), and LiNi0.8Co0.1Mn0.1O2 (NCM811) produced by FS are 224.8 k¥/t, 235.1 k¥/t, 240.0 k¥/t, which respectively are about 2%, 10% and 14% lower than the average selling prices in Chinese market, indicating that FS is economically feasible for producing ternary cathode materials. Particularly, for the production of high-nickel cathode materials, FS has notable potential in simplifying the production process and manufacturing costs. Sensitivity analysis of NCM811 produced by FS shows that when raw material price, fuel and power costs are reduced by 25%, MCSP can be as low as 186.4 k¥/t. When the metal cation concentration of the solution increases to 3.2 mol/L, it enables FS to meet the most rigorous energy consumption limitation standards in China. When the lithium excess is reduced from 10% to 5%, MCSP of NCM811 can be further reduced by 5.6 k¥/t, indicating that lithium loss due to high temperatures in FS is a moderate factor for reducing the manufacturing cost. Finally, this work presents a life cycle assessment (LCA) of NCM materials produced by FS in China. Comparison to the global warming potential (GWP) of the co-precipitation method in the literature indicated that GWP of FS is lower.

БИОХИМИЧЕСКАЯ ХАРАКТЕРИСТИКА ТЕХНИЧЕСКИХ ГИБРИДОВ ВИНОГРАДА СЕЛЕКЦИИ АЗОСВиВ

The aim of the study is to investigate new hybrid grape forms by their main biochemical parameters with the prospect of obtaining new high-tech varieties from them. The paper presents the results of scientific studies of biochemical parameters of new technical hybrid grape forms. These forms were obtained by breeders of the Anapa Zonal Experimental Station of Viticulture and Winemaking, a branch of Federal State Budget Scientific Institution North Caucasian FSC of Horticulture, Viticulture, Wine-making (AZOSViV, a branch of the North Caucasus FSC for Horticulture, Viticulture and Winemaking) and are characterized by late ripening, high productivity, winter hardiness and phylloxera tolerance. Biochemical analysis of the berry must of the studied hybrids was carried out at the institute. Sugars, titratable acids, ammonium compounds, cations and organic acids were studied. The technical grape variety of late ripe-ning Krasnostop Anapsky was used as a control for a comparative analysis of the main biochemical cha-racteristics. A pressing issue for breeders has always been the creation of new sustainable and high-tech grape varieties with their subsequent recommendation for implementation in the production process. The research results showed that the studied hybrids 59-39 and 62-23 annually have stable yields, high sugar accumulation compared to the control variety: 59-39 – 24.2 g / 100 cm3, 62-23 – 24.1, control – 24.0 g/100 cm3. The content of ammonium compounds in hybrid forms is small and comparable to the control. For example, in form 59-39, the content of ammonium compounds is 20 mg/dm3, which is at the level of the control variety. The concentration of metal cations in the juice of berries indicates a high content of these compounds in the soil. The content of potassium in the must is especially high. The studied hybrid forms of grapes have prospects for further study in order to obtain a new variety.

Ameliorative effect of poly-γ-glutamic acid biopreparation on coastal saline soil

To investigate the effect of poly-γ-glutamic acid (γ-PGA) biopreparation on ameliorating coastal saline soil, three treatments were established: soil salt washed treatment (CK), soil salt washed with added γ-PGA (PGA), soil salt washed with added γ-PGA biopreparation (PGAB). This study determined the effects of γ-PGA on coastal saline soil by analyzing soil aggregate, soil evaporation, soil vertical water and salt distribution, and soil cation content, soil pH, soil nutrient content and soil microorganism quantity. Results showed that γ-PGA had an ameliorative effect on saline soil, with the PGAB treatment exhibiting the most pronounced ameliorative effect compared to CK. Adding PGAB reduced soil evaporation by 30.45 %, soil salt content by 27.91 %, meanwhile increasing plant height by 33.86 %, plant fresh weight by 98.54 %, soil aggregate diameter by 6.68 times, soil water content by 26.47 % (P < 0.05). Additionally, soil total nitrogen was increased by 50.0 % in PGAB treatment, and available nitrogen and phosphorus contents were increased by 1.68 times and 85.83 % (P < 0.05), respectively. Populations of soil-culturable bacteria and fungi of PGAB treatment increased by 65.96 % and 1.23 times, respectively (P < 0.05). After salt-washing process, adding PGAB improved soil physicochemical properties, which altered the ecological environment of rhizosphere soil and promoted plant growth. The results can provide a practical approach for ameliorating coastal saline soils.

The role of chitosan grafted copolymer/zeolite Schiff base nanofiber in adsorption of copper and zinc cations from aqueous media

The objective of this research was to develop and assess chitosan-grafted copolymer/HZSM5 zeolite Schiff base nanofibers for Cu2+ and Zn2+ adsorption from aqueous media. Nanofibers were prepared via electrospinning and characterized using XRD, FTIR, 1H NMR, FESEM, TGA, BET, and XPS. The study evaluated the effect of unmodified HZSM5 and Schiff base functionalization on adsorption capacities. Incorporating 10.0 wt% zeolite Schiff base as the optimum content into the chitosan-grafted copolymer significantly enhanced adsorption, achieving increases of 98.2 % for Zn2+ and 42.2 % for Cu2+. Specifically, Zn2+ adsorption increased from 27.6 to 54.7 mg/g, and Cu2+ from 67.1 to 95.4 mg/g. Factors such as temperature, pH, adsorption time, and initial cation concentration were analyzed. Kinetic studies revealed a double-exponential model, and isotherm analysis indicated a good fit with the Redlich-Peterson model, showing maximum monolayer capacities of 310.1 mg/g for Cu2+ and 97.8 mg/g for Zn2+ (pH 6.0, 240 min, 45 °C). The adsorption thermodynamics indicated a spontaneous and endothermic adsorption. Reusability tests showed minimal capacity loss (4.91 % for Cu2+ and 5.59 % for Zn2+) after five cycles. The nanofiber displayed greater selectivity for Cu2+ over Zn2+ in multi-ion systems and real electroplating wastewater, highlighting its potential for targeted heavy metal removal.

Hydrochemical characterization and evaluation of irrigation water quality using indexing approaches, multivariate analysis, and GIS techniques in K'sob Valley, Algeria

Irrigation plays a vital role in addressing increasing need for food production and promoting economic advancement. To meet the demands for food supply and economic progress, it is essential to underscore the significance of assessing water quality in dry regions. The current study was carried out to evaluate and predict the suitability of water quality for agricultural use in the K'sob valley in the M'sila region (Northeast Algeria). A combination of irrigation water quality indices (IWQIs), Geographic Information System (GIS) analysis and multivariate statistical methods were used for this purpose. Several physicochemical parameters, such as temperature (T°), hydrogen ion concentration (pH), electrical conductivity (EC), total dissolved solids (TDS), turbidity (Turb), chemical oxygen demand (COD), Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, SO42−, NO3−, NO2−, NH4+, PO4− and SiO22+ were all measured from 40 samples collected at ten surface water locations during four seasons. The concentrations of the main cation and anion were shown as follows: Na+>Ca2+> K+ > Mg2+, and SO42− > HCO3− > Cl− > NO3− indicating mixed Na-Cl-K or Na-SO4 water facies. Significant seasonal variation for each parameter (T, pH, Turbidity, Salinity, COD, NH4+, Cl−, SO4−, and NO2−) was reported (p < 0.05). Additionally, a significant spatial variation (p < 0.05) was observed among different stations for the parameters: TDS, EC, Ca2+, Na+, HCO3−, SO4−, NO3−, and PO43− (p < 0.05). The irrigation water quality index (IWQI), sodium adsorption ratio (SAR), sodium percentage (Na%), Kelly index (KI), and permeability index (PI) had values varying between 28.1 and 56.8, 5.65 and 12.45, 75 and 87, 2.61 and 6.54 and 83, and 97, respectively, and a significant seasonal effect was recorded. According to the Wilcox diagram, 70% of samples were unsuitable for irrigation, while 30% of samples were questionable. The IWQI map revealed that 50% of the samples fell within the very poor category for irrigation, while 20% and 30% of the samples were inside the poor and unsuitable categories, respectively. The principal component analysis (PCA) and hierarchical cluster analysis (HCA) of K'SobValley water revealed three different categories of water based on elemental composition and seasonal variations. The results obtained in this study can be valuable for surface water management. Furthermore, the developed methodology can serve as a useful tool for identifying critical hydrogeochemical components in arid and semi-arid environments related to surface water.

The Effect of the Tetraalkylammonium Cation in the Electrochemical CO2 Reduction Reaction on Copper Electrode.

Aprotic organic solvents such as acetonitrile offer a potential solution to promote electrochemical CO2 reduction over the competing hydrogen evolution reaction. Tetraalkylammonium cations (TAA+) are widely used as supporting electrolytes in organic media due to their high solubility and conductivity. The alkyl chain length of TAA+ cations is known to influence electron transfer processes in electrochemical systems by the adsorption of TAA+, causing modifications of the double layer. In this work, we elucidate the influence of the cation chain length on the mechanism and selectivity of the CO2RR reaction under controlled dry and wet acetonitrile conditions on copper cathodes. We find that the hydrophobic hydration character of the cation, which can be tuned by the chain length, has an effect on product distribution, altering the reaction pathway. Under dry conditions, smaller cations (TEA+) preferentially promote oxalate production via dimerization of the CO2 ·- intermediate, whereas formate is favored in the presence of water via protonation reaction. Larger cations (TBA+ > TPA+ > TEA+) favor the generation of CO regardless of water content. In situ FTIR analysis showed that TBA+ cations are able to stabilize adsorbed CO more effectively than TEA+, explaining why larger cations generate a higher proportion of CO. Our findings also suggest that higher cation concentrations suppress hydrogen evolution, particularly with larger cations, highlighting the role of cation chain length size and hydrophobic hydration shell.

Synthesis of High-Purity Hydroxyapatite and Phosphoric Acid Derived from Moroccan Natural Phosphate Rocks by Minimizing Cation Content Using Dissolution-Precipitation Technique.

This study investigates, in the first part, the synthesis and purification of a poorly crystalline hydroxyapatite (HAp) using natural Moroccan phosphate (Boucraa region) as a raw material. Despite its successful preparation, the obtained HAp was contaminated by several metallic cations (mostly Cd, Pb, Sn, Ti, Mn, Mg, Fe, and Al) migrated from the natural rocks during the digestion process, inhibiting HAp application in several sectors. To minimize the existence of these elements, the dissolution-precipitation technique (DP) was investigated as a non-selective purification process. Following the initial DP cycle conducted on the precipitated HAp, the removal efficiency was approximately 60% for Al, Fe, Mg, Mn, and Ti and 90% for Cd and Pb. After three consecutive DP cycles, notable improvement in the removal efficiency was observed, reaching 66% for Fe, 69% for Mg, 73% for Mn, and 74% for Al, while Cd, Pb, and Ti were totally removed. In the second part of this study, the purified HAp was digested using sulfuric acid to produce high-quality phosphoric acid (PA) and gypsum (GP). The elemental analysis of the PA indicates a removal efficiency of approximately 89% for Fe and over 94% for all the examined cations. In addition, the generated GP was dominated by SO3 and CaO accompanied with minor impurities. Overall, this simple process proves to be practically useful, to reduce a broad spectrum of cationic impurities, and to be flexible to prepare valuable products such hydroxyapatite, phosphoric acid, and gypsum.

Analysis of the evolution and causes of groundwater chemistry after ecological water replenishment of the Jialu River, China

Ecological water replenishment is an important measure for conserving water sources and improving the water environment. To explore the evolution and causes of groundwater chemistry after ecological water replenishment in the Jialu River, this study utilized groundwater monitoring data from 2015 to 2019 following ecological water replenishment. Various methods, including Piper’s trilinear diagram, Gibbs diagram, principal component analysis, and ion ratio analysis, were employed for research purposes. The results indicate that (1) since the implementation of ecological water replenishment in the Jialu River, there has been a general downwards trend in total dissolved solids (TDS) in groundwater. The dominant cation in groundwater is Ca2+, whereas HCO3− is the dominant anion. The concentration of cations in groundwater has generally decreased, with noticeable reductions in SO42− and Cl− concentrations in the upper reaches of the recharge river contributing to improved groundwater quality. (2) A comparison with 2015 reveals a gradual transition at sampling points from chemical types such as HCO3-Ca·Mg and HCO3·Cl–Ca·Mg to an ecological water replenishment chemical type (HCO3-Ca).

Study on the role of microbial metabolites in in-situ noncontact bioleaching of ion-adsorption rare earth ore

Ion adsorption rare earth ore nearly satisfy global market demand for heavy rare earth elements (HREEs). Bio-leaching has important potential for the clean and efficient extraction of ion-adsorption rare earth ore. However, the complexities of in-situ mining restrict the use of contact/direct bio-leaching, and non-contact/indirect bio-leaching would be the best choice. This study explore the potential of fermentation broths prepared by Yarrowia lipolytica (ATCC 30162) for the bio-leaching of ion-adsorption rare earth ore, and three typical metabolites (potassium citrate (K3Cit), sodium citrate (Na3Cit) and ammonium citrate ((NH4)3Cit) of Yarrowia lipolytica were further evaluated in simulated bioleaching (non-contact bioleaching) of ion-adsorption rare earth ore, including leaching behavior, seepage rule and rare earth elements (REEs) morphological transformation. The column leaching experiments shown that direct leaching of REEs using fermentation broths results in incomplete leaching of REEs due to the influence of impurities. Using the purified and prepared metabolites as lixiviant, REEs can be effectively extracted (leaching efficiency >90%) at cation concentration was only 10 % of the commonly used ammonium sulfate concentration (45 mM). Cation type had less effect on leaching efficiency. During the ion-adsorption rare earth ore leaching process, rare earth ions form a variety of complex chelates with citrate, thus transferring rare earth elements from the mineral surface to the leachate. Experimental results showed that pH and concentration together determined the type and form of rare earth chelates, which in turn affect the leaching behavior of REEs and solution seepage rule. This study helps to provide a theoretical basis for the regulation and enhancement of ion-adsorption rare earth ore non-contact bioleaching process.

The Effect of Water Quality on PEM Electrolyzer Performance

There has been growing interest in the use of removable, clean, and sustainable energy sources as a solution to eliminate environmental problems caused by fossil fuels. In particular, the electrolysis of water to produce green hydrogen is one of the most promising technologies. Among various electrolysis techniques, proton exchange membrane water electrolyzer (PEMWE) stands out as the most promising for mobility and large-scale energy-storage applications (1). Hydrogen production by PEMWEs requires approximately 45 kg of high-quality water to produce 5 kg of hydrogen. It has been estimated that about 22% of the total cost of a state-of-the-art PEMWE system is for water deionization treatment (2). This water purity requirement is not only an economic barrier, but also a constraint for the use of this system in areas where high-quality water is not accessible or in areas where water for human consumption is a scarce resource. Therefore, studying the effect of water quality on PEMWE performance is an important first step in identifying key degradation mechanisms on the path to discovering new PEMWE architectures that are more tolerant of poor-quality feed waters.In this work, the effect of common impurities, such as Na+ and Mg2+, in feed water on the performance of common PEMWE architectures is studied. The main goals of the work are: 1) to understand the tolerance range for long term operation, 2) to identify major degradation mechanisms when the failure occurs. Experiments were carried out in an electrolyzer equipped with platinized Ti electrodes, IrO2 and Pt/C as anodic and cathodic catalysts, respectively, and a 115 Nafion® membrane. Durability studies of 100-hour duration and electrochemical characterization of the electrolyzer at different time intervals (polarization curves and impedance spectroscopy) were performed. The membrane/electrode assembly was probed by SEM /EDX before and after the experiments and cation concentrations in the water were monitored by ICP. An electrochemical model is proposed to explain the observed behavior of the electrolyzer with DI water and in the presence of impurities.The results show that the presence of cations affects the performance of the electrolyzer at different levels depending on the concentration of the cation and its valence (Mg2+ > Na+ >DI water). Mg+2 had the same effect as Na+ even at 5 times lower concentration. Cations have higher affinity than protons for sulfonic acid groups (-SO3 -), leading to a displacement of protons and a consequent reduction in the membrane proton conductivity. However. according to the polarization curves, there are effects beyond the ohmic potential due to the increase in membrane resistance. The major effect of cations is on the reaction kinetics, which is the primary reason for the observed increase in cell voltage. The presence of cations within the membrane blocks the transport of protons, which creates a lack of protons at the cathode, resulting in the kinetic change from proton reduction to reduction of water. Moreover, the EDX results showed that Na+ and Mg2+ ions transfer from anode to cathode and deposit on the membrane and catalyst layers, which may cover the active catalyst sites, block the proton transport inside the membrane and degrade the catalyst ionomer layers.References Sazali N. Emerging technologies by hydrogen: A review. International Journal of Hydrogen Energy. 2020 (45): 18753-18771Becker H, Murawski J, Shinde DV, Stephens IEL, Hinds G, Smith G. Impact of impurities on water electrolysis: A review. Sustainable Energy & Fuels. 2023;7(7):1565-603.

Durability and Performance of Poly(norbornene) Anion Exchange Membrane Alkaline Electrolyzer with High Ionic Strength Anolyte

Anion exchange polymer electrolytes enable low-temperature alkaline water electrolysis for reliable green hydrogen production. Anion exchange membrane water electrolysis (AEMWE) with alkaline electrolytes has several advantages over the proton exchange membrane water electrolysis using acid-based polymer electrolytes. The advantages include low-cost catalysts, all hydrocarbon non-fluorinated polymer membrane, and low-cost cell components. Long-term durability of AEMWEs in high pH operation has been challenging, although there have been significant performance improvements. AEMWE operated at low hydroxide anolyte provides improved chemical stability.In this study, an understanding of the high ionic-strength anolyte is provided along with demonstration of the AEMWE performance and durability. Anion exchange poly(norbornene) solid polymer electrolytes show high-performance, durable membrane electrode assemblies for alkaline electrolysis. Covalently bonded, self-adhesive solid polymer ionomers were used in electrodes for durable electrolysis. Hydration problem with the low pH alkaline anolyte in dry-cathode AEMWE is presented. The effect of anolyte concentration and mobile cations on the cathode electrolysis performance using a low hydroxide anolyte was investigated. High ionic strength anolyte was prepared by changing the mobile cation concentration while maintaining a constant anolyte pH. The mechanism of cathode hydration improvement through use of a high ionic strength anolyte is presented. Long-term durability with the optimal high ionic strength electrolyte is discussed.

Assessment of growth, and ion uptake of plant species, Conocarpus erectus and Dodonaea viscosa, on industrial solid waste

Present study assessed the growth of two plant species and ion uptake by them grown on different proportion of industrial solid waste and garden soil. The industrial waste having high concentration of chemicals were used with garden soil at different proportion i.e. 0% (T0), 5% (T1), 10% (T2), 15% (T3) and 20% (T4). Two species namely Conocarpus erectus (alien plant) and Dodonaea viscosa (indigenous) were used as test plants in pot study. Different parameters including growth, physiology, and anatomy of plants and concentration of cations (Na+, K+, Ca2+, and Mg2+) in the plant shoot and root were measured at different time duration (initial, 1st, 2nd, 3rd and 4th month). The key objective of the study was to use these plants to establish their plantations on the barren lands where industrial solid wastes were being disposed of. C. erectus showed better growth than D. viscosa, as well as more uptake of ions. A significant increase in plant growth was observed in fourth month in T1, where plant height reached 24.5% and 46% for C. erectus and D. viscosa, respectively. At harvest, in C. erectus, no significant difference in the fresh (65–78 g) and dry weight (24–30 g) of the shoot was observed across treatments compared to the control. In D. viscosa, at the time of harvest, the fresh and dry weights of the root and shoot showed a strong, significantly decreasing pattern across T1, T2, and T3, leading to the death of the plant at T3 and T4. Further, optimum ratio of waste soil to garden soil was found as 10:90 and 20:80 to establish the plantations of D. viscosa and C. erectus, respectively in areas where such solid waste from industries are disposed. Findings can be used for the restoration of such solid waste for the sustainable management of industrial areas and their associated ecosystems.

Preparation and performance of MOF-808 (Zr-MOF) for the efficient adsorption of phenoxyacetic acid pesticides

The organic herbicides of chlorophenoxyacetic acids, including 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA), have posed serious threats to aquatic ecosystems and human health due to extensive use, high solubility and degradation-resistant. In this study, the efficient adsorbent (MOF-808) was synthesized through solvothermal synthesis method and further evaluated for the adsorption performances of 2,4-D and MCPA. Results showed that MOF-808 exhibited the Type I nitrogen adsorption–desorption isotherm with a specific surface area of 2,155 m2·g−1, pore volume of 0.59 cm3·g−1 and pore size of 1.41 nm. It was suggested that the pseudo-second-order and Langmuir model were much better to illustrate the adsorption performances of MOF-808 for both 2,4-D and MCPA, and the maximum adsorption capacities of 793 and 775 mg·g−1 were achieved, respectively; besides, the adsorption processes were spontaneous and primarily driven by chemical adsorption with contributions from physical-chemical adsorption. Additionally, the adsorption capacities for 2,4-D and MCPA were decreased with the increasing of pH and cations concentrations; the optimal pH was 3.0 for 2,4-D and 4.0 for MCPA, and the effects of four cations on pesticides adsorption followed the order of Ca2+ > Mg2+ > Na+ > K+. Reuse experiments demonstrated that MOF-808 could retain a high removal rate of 95.9 % (2,4-D) and 95.8 % (MCPA) at the fifth cycle. The spectral analysis revealed that the adsorption mechanisms of 2,4-D and MCPA by MOF-808 involved electrostatic interactions, π-π interactions, hydrogen bonding, and complexation. In conclusion, the well-defined physicochemical properties and outstanding adsorption performance of the synthesized MOF-808 may provide a potential application for the removal of chlorophenoxyacetic acid herbicides from real wastewater.