Industrial Water Research Articles

Spatial and temporal variability of meteorological droughts including atmospheric circulation in Central Europe

Drought is one of the natural phenomena influencing many aspects of human activities like water scarcity, food production, agriculture, industry and ecological conditions of the environment. For decades, drought has caused huge financial losses in Europe and around the world. In the area of the Polish Carpathians, there are periods with a deficit of rainwater and increasing frequency of dry months especially in the cold half-year. However, only a limited number of studies exist about the spatial and temporal variability of meteorological drought and the main mechanisms determining its performance in Central Europe. The aim of this work is to perform the spatial and temporal analysis of drought, expressed as SPI, in a heterogenous area of the Polish Carpathian and the highland region in the East-Central part of Europe based on long-term precipitation data. Moreover, for the first time in this work drought characteristics assessed by means of the SPI were discussed considering the atmospheric circulation calendar. In this work monthly precipitation from 55 rainfall stations were analysed from 1961 to 2022. The 3-, 6-, 9-, and 12-month Standardized Precipitation Index (SPI) was used as indicators of meteorological drought. For the 3-month SPI, the main climatic mechanisms determining extreme droughts were defined based on the calendar of synoptic circulations. The Mann-Kendall test was used to detect the trend of extreme droughts. Statistically significant trends of SPI were observed on 52.7% of all analyzed stations and, in most cases, a positive trend was observed, indicating an increase in water resources in the Upper Vistula Basin. Statistically significant trends were more frequently observed in stations located in the western part of the analyzed region. Long-term droughts, represented by the 12-month SPI, occurred in all stations but not in all years. Short-term droughts (3-month SPI) were most frequent in the winter season, 6- and 9-month SPI in winter and spring, and 12-month SPI in winter and autumn. The spatial distribution of droughts was highly diverse. The most intensive drought occurred in 1984, with the 6-month SPI covering 98% of the analyzed region, and the 9- and 12-month SPI covering 90% of the entire region. Droughts exhibit a seasonal pattern, with a dominant 10-year periodicity for all analyzed variants of SPI. Additionally, Fourier analysis revealed a 2-year periodicity for the 3-, 6-, and 9-month SPI and a 31-year periodicity for the 12-month SPI. The results provide insights into the typical climatic conditions in Poland, with strong seasonality in precipitation. The study highlighted that short-term extreme droughts, represented by the 3-month SPI, are often caused by anticyclonic situations with high-pressure wedges Ka and Wa, as observed in 52.3% of cases. These findings are crucial for understanding the spatial and temporal variability of short and long-term extreme droughts in Central Europe, particularly for the agriculture sector which is dominant in the northern part of the analyzed region, where drought frequency is highest.

The spatial distribution of surface and groundwater abstractions in Slovakia in the period 2013–2022 vs 2022

Abstract. In recent years, the impacts of climate change have become increasingly apparent; Slovakia has witnessed a rise in extreme weather conditions caused by climate change. To address these challenges, we analyze and prepare documents focused on monitoring and issuing drought warnings. These documents, including Slovakia's water resource balance, serve as fundamental materials for water management planning. The water resource balance assesses the relationship between water demands and available resources in the past year, identifying areas and times where water demands exceed supply. Additionally, our analysis provides a detailed map of surface and groundwater abstractions across Slovakia, categorizing total and individual abstractions by sector (e.g., public water supply systems, agriculture, and industry). We present surface and groundwater abstraction averages for the period of the last decade 2013–2022, along with its spatial distribution in Slovak districts. This comprehensive approach enables us to better understand and manage our water resources effectively.

Evaluation of return cooling water reuse in the wet cooled power plant to minimise the impact of water intake and drainage

The treatment and reuse of industrial water is a matter of great interest, given the severe shortage of water resources. It is widely acknowledged that power plants, particularly wet-cooled power plants, consume a significant amount of water. Therefore, research on the circulating cooling system (CCS) and the treatment of the return cooling water is of utmost importance. This study examined data on CCS inlet (water body), make up, and cooling water parameters, calculated a water balance, and predicted the hydrochemical quality of cooling tower blowdown water (CTBD). The study was conducted for an operating power plant to propose an effective treatment scheme for the return of CTBD to the process cycle. Additionally, it evaluated the possibility of recycling CTBD in the clarifier through laboratory modeling. Therefore, based on the results of this study, an effective treatment scheme is proposed to return CTBD to the technological cycle to ensure environmental sustainability. Recycled water was used as the water supply for the cooling tower, and a lime softening treatment was applied to clean the CTBD. According to the results, it is possible to recover quality indicators from a portion of the return cooling water after lime softening treatment. The novelty of this study lies in the successful demonstration of a lime softening regime that enables the blending of up to 25 % CTBD with make up water, without necessitating an increased CaO dose. This regime maintains TH levels at 2.2 mg-eq/dm³ and ensures that the discharge velocity of 0.7 m/s remains within regulatory standards. Additionally, it maintains standard concentrations of chloride (Cl⁻) and sulfate (SO₄²⁻) in CTBD at 200 mg/dm³ and 250 mg/dm³, respectively.

Current Challenges in Monitoring Low Contaminant Levels of Per- and Polyfluoroalkyl Substances in Water Matrices in the Field.

The Environmental Protection Agency (EPA) of the United States recently released the first-ever federal regulation on per- and polyfluoroalkyl substances (PFASs) for drinking water. While this represents an important landmark, it also brings about compliance challenges to the stakeholders in the drinking water industry as well as concerns to the general public. In this work, we address some of the most important challenges associated with measuring low concentrations of PFASs in drinking water in the field in real drinking water matrices. First, we review the "continuous monitoring for compliance" process laid out by the EPA and some of the associated hurdles. The process requires measuring, with some frequency, low concentrations (e.g., below 2 ppt or 2 ng/L) of targeted PFASs, in the presence of many other co-contaminants and in various conditions. Currently, this task can only (and it is expected to) be accomplished using specific protocols that rely on expensive, specialized, and laboratory-scale instrumentation, which adds time and increases cost. To potentially reduce the burden, portable, high-fidelity, low-cost, real-time PFAS sensors are desirable; however, the path to commercialization of some of the most promising technologies is confronted with many challenges, as well, and they are still at infant stages. Here, we provide insights related to those challenges based on results from ab initio and machine learning studies. These challenges are mainly due to the large amount and diversity of PFAS molecules and their multifunctional behaviors that depend strongly on the conditions of the media. The impetus of this work is to present relevant and timely insights to researchers and developers to accelerate the development of suitable PFAS monitoring systems. In addition, this work attempts to provide water system stakeholders, technicians, and even regulators guidelines to improve their strategies, which could ultimately translate in better services to the public.

Efficient density functional theory directed identification of siderophores with increased selectivity towards indium and germanium

Siderophores are promising ligands for application in novel recycling and bioremediation technologies, as they can selectively complex a variety of metals. However, with over 250 known siderophores, the selection of suiting complexants in the wet lab is impractical. Thus, this study established a density functional theory (DFT) based approach to efficiently identify siderophores with increased selectivity towards target metals on the example of germanium and indium. Considering 239 structures, chemically similar siderophores were clustered, and their complexation reactions modeled utilizing DFT. The calculations revealed siderophores with, compared to the reference siderophore desferrioxamine B (DFOB), up to 128 % or 48 % higher selectivity for indium or germanium, respectively. Experimental validation of the method was conducted with fimsbactin A and agrobactin, demonstrating up to 40 % more selective indium binding and at least sevenfold better germanium binding than DFOB, respectively. The results generated in this study open the door for the utilization of siderophores in eco-friendly technologies for the recovery of many different critical metals from various industry waters and leachates or bioremediation approaches. This endeavor is greatly facilitated by applying the herein-created database of geometry-optimized siderophore structures as de novo modeling of the molecules can be omitted.

Effective Removal of Cu(II) Ions from Aqueous Solution by Cross-Linked Chitosan-Based Hydrogels

The elimination of metal ions from industrial waste water is one of the most significant environmental needs. For the first time, two chitosan hydrogels that we had previously synthesized, cross-linked with varying concentrations of trimellitic anhydride isothiocyanate (represented by H1 and H2), were utilized in this investigation to adsorb Cu(II) ions. We found that pH 6, 25 °C, 200 mg L−1 of Cu(II) ions concentration, and 15 mg of hydrogel dosage were the ideal parameters for Cu(II) ion elimination. The kinetics of their adsorption fitted to the pseudo-second-order model with the highest correlation coefficient (R2) values equal to 0.999 and 1.00 for H1 and H2, respectively. The experimental qe values were found when H1 was equal to 97.59 mg g−1 (theoretical value is equal to 98.04 mg g−1) and H2 was equal to 96.20 mg g−1 (theoretical value is equal 99.01 mg g−1). The hydrogels achieved a removal effectiveness of 97.59% and their adsorption isotherms matched the Freundlich model, indicating the multi-layered and homogeneous adsorption nature. The removal of copper ions is significantly driven by the physisorption phenomenon. The hydrogels have a great possibility to be utilized as promising, efficacious, reusable adsorbents for industrial wastewater remediation. Thus, incorporation of a cross-linker, containing binding centers for Cu(II) ions, between chitosan chains is a good way to obtain suitable efficient adsorbents which are good choices for application in the field of metal elimination.

Vapor Pressure and Evaporation Studies of Saline Solutions on Natural and Synthetic Fabrics for Industrial Water Treatment.

In the present paper, we have conducted a comprehensive analysis of vapor pressures of both saturated and unsaturated solutions, alongside a study of evaporation using synthetic and natural fabrics for industrial applications in brackish water treatment under zero liquid discharge (ZLD) philosophy. By determining the vapor pressures of saturated solutions, we obtained results consistent with those of other researchers, extending the range of tested temperatures from 1 to 50 °C and successfully fitting the parameters of an Antoine-type equation. Similarly, positive results were achieved for unsaturated solutions, where various parameters of different equations accounting for the salt concentration were estimated, simplifying the fitting procedure. Natural evaporation tests from water surfaces using saturated solutions revealed that salts with higher associated vapor pressures exhibit higher evaporation rates. On the other hand, hydrated salts retain water in their structure and are significantly affected by ambient humidity. Evaporation studies on natural and synthetic fabrics with saturated NaCl and CuSO4·5H2O solutions showed distinct behaviors. NaCl increased both the evaporation rate and salt deposition with each cycle. In contrast, CuSO4·5H2O reduced the absorption capacity by blocking the fabric's structure, decreasing the evaporation efficiency over successive cycles.

Rapid detection of fertilizer information based on Raman spectroscopy and machine learning

The rapid detection of fertilizer nutrient information is a crucial element in enabling intelligent and precise variable fertilizer application. However, traditional detection methods possess limitations, such as the difficulty in quantifying multiple components and cross-contamination. In this study, a rapid detection method was proposed, leveraging Raman spectroscopy combined with machine learning, to identify five types of fertilizers: K2SO4, (CO(NH2)2, KH2PO4, KNO3, and N:P:K (15-15-15), along with their concentrations. Qualitative and quantitative models of fertilizers were constructed using three machine learning algorithms combined with five spectral preprocessing methods. Two variable selection methods were used to optimize the quantitative model. The results showed that the classification accuracy of the five fertilizer solutions obtained by random forest (RF) was 100 %. Moreover, in terms of regression, partial least squares regression (PLSR) outperformed extreme learning machine (ELM) and least squares support vector machine (LSSVM), yielding prediction Rp2 within the range of 0.9843–0.9990 and a root mean square error in the range of 0.0486–0.1691. In addition, this study evaluated the impact of different water types (deionized water, well water, and industrial transition water) on the detection of fertilizer information via Raman spectroscopy. The results showed that while different water types did not notably affect the identification of fertilizer nutrients, they did exert a pronounced effect on the quantification of concentrations. This study highlights the efficacy of combining Raman spectroscopy with machine learning in detecting fertilizer nutrients and their concentration information effectively.

REUSE OF TREATED WATER FROM BOJONGSOANG DOMESTIC WASTEWATER TREATMENT INSTALLATION AS WATER FOR INDUSTRIAL PURPOSES

Subdistrict Bojongsoang and its surroundings are based on the 2016-2036 Bandung Regency Spatial Planning, the designated area where the industry is. Currently, there are 125 existing industries operating. The area is also included in groundwater withdrawal through well artesian on a massive scale, including into the national protected area (CAT: Groundwater Basin) Bandung - Soreang Area. Excessive groundwater extraction poses challenges coupled with significant water demand from society and industry. This will result in deteriorated groundwater conditions that require prompt restoration, having already suffered damage. On the other hand, there is Bojongsoang WWTP, which can treat wastewater at 2800 l/s; meanwhile, at the moment, this capacity processing is utilized about 37-40% or about 100m3/day. This research uses a descriptive method. The research results prove that reusing water from Bojongsoang WWTP could produce raw water for the necessity industry of 300 l/s.

The Priority of Water Consumption in the Spanish Tourism Industry: A Dilemma for Residents and Researchers

Spain is one of the most water-stressed countries in the world. Regional governments face the challenge of ensuring long-term water security for residents and tourists. In 2024, Catalonia declared a state of emergency to tackle the problem of a lack of water. Catalonia and Andalusia regions imposed water restrictions, prohibiting residents from washing the exterior of their houses and cars or filling their swimming pools to guarantee tourism activities in hotels and other tourism companies. The research objective of the present study is to tackle the priority of water consumption in the Spanish tourism industry so that the availability of water is guaranteed for residents, without constraints on the supply. This research uses qualitative and quantitative methods to obtain a comprehensive view of the water consumption in Spain’s territory and the main zones of water scarcity that are affecting residents and the tourism industry. In addition, this study uses the Web of Science (WoS) database to analyse the bibliometrics on the topic of water consumption in the tourism industry from 2000 to 2023, as well as quantify the number of articles published by researchers. Findings reveal that although the tourism industry is the economic engine of Spain, water consumption by tourists is above the level of consumption of residents, and this asymmetrical situation should be reversed in favour of the welfare of Spanish citizens. It is noteworthy that the water scarcity in Spain and its continuing restrictions in the Andalusian and Catalonian regions have caused huge problems with drinking water supply in the last few years. Indeed, local and regional Spanish governments cannot demand that a resident consume 133 L per day, while a tourist is allowed to consume between 400 and 1000 L per day. For this reason, water availability must be a priority for residents and, especially, for the tourism industry. Economic interests cannot override citizens’ needs and well-being. This research has helped us better understand the complex relationships between the use of water in the tourism industry and by residents in the context of climate change.

Simple generic self-assembly fabrication of transition metal borates on polyaminophenylboric acid modified foam nickel for highly-efficient overall water splitting

Water electrocatalysis for hydrogen production as a prospect strategy to store renewable energy and reduce carbon emissions has attracted great attention, and exploring water electrolysis catalysts has become a research hotspot for widespread industrial water electrolysis application. Very recently, transition metal borates have been demonstrated great potential for electrocatalytic hydrogen or oxygen evolution in alkaline media. However, a generic method for fabricating transition metal borates as bifunctional oxygen catalysts are still challenging. Herein, through a two-step process including poly-aminophenylboronic acid electrodeposition and subsequent electrostatic self-assembly of transitional metal ions, for the first time, to our best knowledge, a simple and generic approach to fabricate polyaminophenylborate transition metal salt modified nickel foam electrodes (PAB-M/NF, M represents transition metal element) was developed for highly efficient water splitting. As a proof of concept, the obtained PAB-Ru/NF exhibited remarkable bifunctional HER and OER catalytic activities and stability in alkaline medium. To drive the HER and OER with a current density of 10 mA cm−2 in 1 M KOH electrolyte, PAB-Ru/NF only required an overpotential of 14 mV and 301 mV, respectively. Moreover, even at a great current density of 250 mA cm−2, PAB-Ru/NF can exhibit very favorable long-term stability for over 35 h. When assembled into an electrolyzer with PAB-Ru/NF as both the anode and cathode, a current density of 10 mA cm−2 can be achieved at a very low cell voltage of 1.50 V. In addition, the other PAB-M/NF catalysts (M including but not limited to Fe, Co and Ni) prepared by the same way also show excellent bifunctional HER and OER catalytic activities and durability. This study provides a prospective and economically feasible generic approach for developing practical bifunctional catalysts for industrial water electrolysis.

Health risk assessment of heavy metals and physicochemical parameters in natural mineral bottled drinking water using ICP-MS in South Africa

The contamination of natural mineral bottled drinking water with trace, heavy metals and rare-earth elements is a growing concern globally, especially in regions with limited access to safe drinking water sources. In South Africa, the safety of bottled water remains a critical issue due to potential health risks associated with heavy metal exposure. This study aimed to evaluate physicochemical parameters alongside to assess the health risks due to heavy metals in natural mineral bottled drinking water available in South Africa, using inductively coupled plasma mass spectrometry analysis. A total of 21 bottled water samples from different brands were collected and analysed for heavy metal concentrations including Pb, Cd, As, Cr, Ni, Ba and Hg, as well as physicochemical parameters such as pH, conductivity, dissolved oxygen and total dissolved solids among others. The results revealed physicochemical parameters were within acceptable ranges, indicating overall water quality. Varying levels of heavy metals across different brands observed with concentrations of Al, Fe, Mg, Ca, K and Mn in some samples exceeding permissible limits set by WHO and SAWQG for drinking water quality. The mean concentration of the heavy metals is in the decreasing toxicity order of Sr > Al > Ba > Mn > Cu > Cr > Zn > Fe > As > Co > U > Ni > Cs > Pb > Cd > Hg. The mean values of the chronic daily intake (CDI) for the concentration of heavy metals for adults are in the order of Cr > Fe > Sr > Ba > Mn > Cu > Zn > Li > V > As > Ni > Be > Pb > Hg > Cd and were below acceptable limits. The estimated values of both HQ and HI (with mean of 2.07E−03 and range of 0.00 to 1.76E−02) for the heavy metals are all found to be less than 1. The total mean value of ILCR is 4.67E−06, and range of 0.00 to 2.76E−05, which is insignificant and within the permissible level of the cancer risk guidance limit of 1.00E−06 to 1.00E−04. The results show that consumption of natural mineral bottled drinking water of South Africa is safe and may not cause any significant health risk to the populace. However, the long-time potential effects due to the few exceeded metals levels needed to be considered. Our findings contribute to the ongoing discourse on water quality assurance, offering insights into the overall integrity of the natural mineral bottled water supply chain in South Africa. This research not only serves as a foundation for regulatory measures but also underscores the significance of maintaining high-quality standards in the bottled water industry for public health and environmental sustainability.

Photocatalytic nanohybrid UV-light-driven PVDF/GO-NiFe@SiO2 membrane coupled with bentonite adsorption and ozonation process for a sustainable textile wastewater treatment

The textile industries face significant environmental challenges due to the presence of complex pollutant dyes in its wastewater, making it one of the world's major sources of industrial water pollution. Numerous studies have been employed to overcome this problem, including physical, chemical, and biological treatments. However, most of those methods still suffered to achieve higher dye removal performance. This study provides new insight regarding textile wastewater treatment containing indigo red as the main colorant by carrying out a hybrid process combining bentonite adsorption, ozonation, and photocatalytic membrane filtration. For the membrane, we propose a modified polyvinylidene fluoride (PVDF) membrane incorporated with graphene oxide (GO) and nickel-iron doped silica (NiFe@SiO2) photocatalyst, which is named PVDF/GO-NiFe@SiO2 membrane. The membrane was employed under different sets of filtrations (dark and under ultraviolet irradiation) to treat natural dye wastewater from textile industry effluent. Further improvement was achieved when UV light irradiation was subjected to the process. This sequential adsorption-ozonation-membrane process under UV exposure exhibited improved dye removal from 55.11 % to 97.22 %. The results show that the proposed hybrid process successfully improved the membranes' antifouling behavior, thus boosting the membranes' performance and durability. From a broader perspective, our work promotes new insights for the integration of other physical, chemical, and biological treatment methods to improve the performance and durability of membrane-based processes, particularly for dye wastewater treatment.

A High-Entropy Oxyhydroxide with a Graded Metal Network Structure for Efficient and Robust Alkaline Overall Water Splitting.

Designing high-entropy oxyhydroxides (HEOs) electrocatalysts with controlled nanostructures is vital for efficient and stable water-splitting electrocatalysts. Herein, a novel HEOs material (FeCoNiWCuOOH@Cu) containing five non-noble metal elements derived by electrodeposition on a 3D double-continuous porous Cu support is created. This support, prepared via the liquid metal dealloying method, offers a high specific surface area and rapid mass/charge transfer channels. The resulting high-entropy FeCoNiWCuOOH nanosheets provide a dense distribution of active sites. The heterostructure between Cu skeletons and FeCoNiWCuOOH nanosheets enhances mass transfer, electronic structure coupling, and overall structural stability, leading to excellent activities in the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and water splitting reaction. At 10mAcm-2, the overpotentials for OER, HER, and water splitting in 1.0m KOH solution are 200, 18, and 1.40V, respectively, outperforming most current electrocatalysts. The catalytic performance remains stable even after operating at 300mAcm-2 for 100, 100, and over 1000h, correspondingly. This material has potential applications in integrated hydrogen energy systems. More importantly, density functional theory (DFT) calculations demonstrate the synergy of the five elements in enhancing water-splitting activity. This work offers valuable insights for designing industrial water electrolysis systems.

Pywr-DRB: An open-source Python model for water availability and drought risk assessment in the Delaware River Basin

The Delaware River Basin (DRB) in the Mid-Atlantic region of the United States is an institutionally complex water resources system that provides drinking water for 13.5 million people, plus water for energy, industry, recreation, and ecosystems. This paper introduces Pywr-DRB, an open-source Python model exploring the impacts of reservoir operations, transbasin diversions, and minimum flow targets on water availability and drought risk in the DRB. Pywr-DRB draws on streamflow estimates from emerging data resources, bridging advances in large-scale hydrologic modeling with an improved representation of the basin's evolving water infrastructure and management institutions. Our detailed model diagnostic assessment demonstrates that Pywr-DRB provides substantial improvements over sole use of hydrologic models in capturing the DRB's dynamics. We also explore how water management alters model-derived risk estimates for low flows and water demand shortfalls. Our approach to diagnostic benchmarking and water systems modeling is broadly applicable to other major basins.

Understanding Mass Transport at High Current Densities in an Industrial Scale PEM Electrolysis Test Cell - a Segmented Along-the-Channel Approach

Industrial PEM water electrolysis stack designs can suffer from an unevenly distributed water amount over the cell area. This can lead to performance differences and thermal hot spots due to the lack of reactant supply and poor thermal management. Undersupplied spots could also degrade more quickly [1,2]. Especially in the water flow direction, gradients are expected due to the water consumption and gas evolution and accumulation along the supply channels.To face these issues, we built up a segmented along the channel (AtC) PEM electrolysis test cell in industrial scale for locally-resolved investigations. The cell has a length of 30 cm at 2 cm cell width with a straight parallel flow field. To minimize transverse currents the cell is divided into 10 equal segments along the channels. The main focus of our investigation is locally-resolved electrochemical impedance spectroscopy (EIS). With a shunt resistor approach, it is feasible to measure the impedance of each segment and the mean cell in parallel. Additionally, it is possible to measure the current density and temperature distribution of the anodic bipolar plate highly resolved using 120 sensors over the cell length.With this test cell we want to understand mass transport processes along the channel in industrial scale. Diffusion and mass transport overpotentials are usually dominant at high current densities. To be able to face extreme conditions and investigate possible future operation points the cell was designed up to 10 A∙cm-2 (600 A absolute) and successfully tested. Furthermore, an operation of 10 bar differential and equal pressure is possible.Figure 1 shows the cell design (a), the mean cell polarization curve of the AtC cell (60 cm²) in comparison with measurements of the same setup in our 4 cm² test cell (b) and locally-resolved high frequency resistance (HFR) free EIS at 7 A∙cm-2 (c). It is noticeable, that the here used commercially available materials do not show high mass transport limitations, neither in the 4 cm² ISE-reference cell nor in the 60 cm² AtC cell. An increase of the slope of the polarization curve towards higher current densities remains out, see Figure 1 (b). Instead of this the slope of the polarization curve is constantly decreasing. This can not only be explained by the temperature increase of the catalyst-coated membrane (CCM) due to higher heat dissipation. Using EIS, we here can detect an additional electrochemical process at low frequencies of inductive type which is increasing with increasing current density. In the locally-resolved EIS in Figure 1 (c) the inductive process (positive imaginary values) is detectable as the so called “inductive loop”. This phenomenon has a negative resistance magnitude and therefore a beneficial impact on the cell performance. Inductive Loops are discussed in several electrochemical applications, like batteries and fuel cells [3,4]. Despite this, in PEM electrolysis this process has not been discussed yet. We could show that this phenomenon is reproducible and has an important impact on the cell performance and impedance-based performance analyses when operating at current densities > 1 A∙cm-2 [5].For diffusion analyses, the inductive loop is essential to be considered since both processes happen at similar frequencies. In Figure 1 (c) an increasing of the number of time constants at frequencies < 100 Hz is detectable towards the cell outlet (e.g. segment 9 and 10). These slow processes are most likely diffusion related.Our upcoming investigations will face locally-resolved measurements with varying structural parameters of porous transport layers (PTL) and CCMs with different anodic catalyst loadings to gain a better understanding of mass transport processes for future PEM electrolysis cells along the channel.Reference List:[1] IMMERZ, C., et al. Experimental characterization of inhomogeneity in current density and temperature distribution along a single-channel PEM water electrolysis cell. Electrochimica acta, 2018, 260. Jg., S. 582-588.[2] VERDIN, B., et al. Operando current mapping on PEM water electrolysis cells. Influence of mechanical stress. International Journal of Hydrogen Energy, 2017, 42. Jg., Nr. 41, S. 25848-25859.[3] KLOTZ, Dino. Negative capacitance or inductive loop?–A general assessment of a common low frequency impedance feature. Electrochemistry Communications, 2019, 98. Jg., S. 58-62.[4] GERLING, Christophe, et al. Experimental and Numerical Investigation of the Low-Frequency Inductive Features in Differential PEMFCs: Ionomer Humidification and Platinum Oxide Effects. Journal of The Electrochemical Society, 2023, 170. Jg., Nr. 1, S. 014504.[5] HENSLE, Niklas, et al. On the role of inductive loops at low frequencies in PEM electrolysis. Electrochemistry Communications, 2023, 155. Jg., S. 107585. Figure 1

Efficient Taste Analysis via Single-Channel Hybrid Electronic Tongue

The prospective applications of electronic tongues (e-tongues) in the food, water, beverage, and pharmaceutical industries have long been hampered by the inconvenient nature of series measurements using expensive and specialised sensor arrays. A cost-efficeint and easier solution to this problem arises in the shape of a single-channel hybrid e-tongue, presenting a novel approach to overcoming restrictions. This progress uses data fusion from potentiometry and impedimetry to combine these measures into a single channel made up of unfunctionalized metal electrodes supported by a pH electrode.The hybrid e-tongue combines potentiometric response, which includes pH and open circuit potential, with impedimetric response, which takes into account comparable electric circuit parameters such as charge transfer resistance and double-layer capacitance. The taste discriminability of this low-cost single-channel hybrid e-tongue is validated using two metal electrodes, Pt and Ni, and two separate sample preparations of basic taste analytes, each at concentrations around the human tongue threshold.Principal component analysis (PCA) plots are used to test qualitative discrimination by reducing dimensionality and clustering analytes. Silhouette coefficients (SC) and hierarchical cluster analysis are used to assess clustering quality. Even without particular sample preparation, the Pt and Ni electrodes exhibit substantial clustering with SC values of 0.83 and 0.74, respectively. This significant outcome highlights the efficacy of the hybrid e-tongue in improving taste discriminability.Comparisons with potentiometric and impedimetric measurements performed independently show that the hybrid e-tongue, assisted by data fusion at a single channel, improves accuracy and clustering significantly. This finding not only speeds up the analysis process, but it also improves the overall effectiveness of taste discrimination.Correlations between taste analytes and physicochemical factors are formed using heatmap plots and PCA loading plots to provide a fuller knowledge of the hybrid e-tongue's mechanics. These visualisations provide vital insights into the complex interplay of several physicochemical processes, offering insight into the mechanism underlying the hybrid e-tongue's excellent performance.discrimination.Despite its remarkable capabilities, the study acknowledges that taste discriminability diminishes due to the buffer activity of the standard reference solution used for sample preparation. This recognition prompts further exploration and optimization of the solution to ensure the broad applicability of the hybrid e-tongue across various scenarios.In conclusion, the reported single-channel hybrid e-tongue represents a significant advancement in taste analysis technology. By addressing the challenges associated with series measurements on complex sensor arrays, this innovation opens new avenues for commercial e-tongues in diverse industries. The amalgamation of potentiometry and impedimetry in a single channel not only enhances accuracy and clustering but also provides valuable mechanistic insights. As the research community continues to refine and optimize this technology, the future holds great promise for the widespread adoption of single-channel hybrid e-tongues in analytical applications, advancing how we perceive and understand taste.

Electrooxidation of Poly(methyl-methacrylate) and Poly(ethylene glycol): Hydrogen Production from Plastic Wastes Electrolysis

Introduction. Green H2 production by water electrolysis at low temperature has some bottlenecks mostly dealing with the anodic reaction, the oxygen evolution reaction (OER), given its thermodynamic and kinetic limitations [1]. One strategy to reduce the energy requirements for this H2 production route is the replacement of the conventional OER (with a thermodynamic potential of 1.23 V vs. Reversible Hydrogen Electrode (RHE)) by a less-energy intensive reaction like the electrooxidation of organic molecules (in some cases presenting a thermodynamic potential as low as c.a. 0 V vs RHE). This approach also addresses the possibility of converting organic wastes into value-added chemicals avoiding the CO2 emissions derived from conventional treatments (e.g., incineration) [2, 3]. Our research group is focused on the electrochemical valorization of several organic wastes like polyethylene glycol (PEG) or poly(methyl-methacrylate) (PMMA). Both are commonly found in urban and industrial water effluents and concern has been raised about the true fate of these polymers in the environment. Herein, the possibility of generating H2 and value-added organic molecules from these plastic wastes has been explored. Experimental. A binary solvent strategy was followed to dissolve the PMMA polymer, by using 1 M H2SO4 in 80% v/v 2-propanol/water electrolyte. Then the electrooxidation of PMMA was studied in a 2-electrode batch cell at 70ºC with different PMMA concentrations (0.1-2 wt.%). On the other hand, the electrooxidation of ethylene glycol (EG) and PEG with various molecular weights (from 200 to 4000 g mol-1), which are soluble in water, was carried out in aqueous solutions (PEG concentrations from 1 to 20 g/L) between 30 and 80 °C by using a Polymer Electrolyte Membrane (PEM) reactor. Pt/C electrodes were used in all cases. A commercial Pt cathode was employed and the anode material was prepared by the spray-deposition of a Pt(20 wt.%)/C catalyst powder onto a carbon paper gas-diffusion layer. The liquid products at the anodic compartment were analysed by size-exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy while the production of hydrogen in the cathodic compartment was online monitored with a mass spectroscopy. Results and discussion. In the case of PMMA electrooxidation, despite the dissolution challenge, polymer macromolecules showed to partially block the accessibility of the Pt active sites on the electrode and strongly degraded its electrochemical performance [4]. In the case of PEG, it was much more easily electrooxidised, at low cell voltages, from around 0.4 V at 80°C (Figure 1a), near to values recorded with EG, suggesting a first step linked with the electrooxidation of the terminal groups of the macromolecules chain. Current densities larger than 100 mA.cm-2 at 0.8 V and 80°C were achieved for low molecular mass molecules (200 and 400 g/mol). A decrease of the PEG molecular weight in the anodic solution was demonstrated by SEC, confirming that the electro-oxidation process likely follows two main mechanisms, involving the consumption of terminal –OH or intermediate -C-O-C- bonds cleavage (Figure 1b), depending on the polymer molecular weight. This study demonstrates the proof-of-concept of the low-temperature electro-oxidation of polymers containing C-O bonds in their main chain. Conclusions. With a further macroporous electrode enegineering and catalyst development, the electrolysis of plastic wastes stands as a promising technology not only for the production of hydrogen from macromolecules by electrochemical means, but also as a potential pathway to depolymarize plastic wastes, thus increasing their degradability. References. [1]. Y. Cheng, S.P. Jiang, Advances in electrocatalysts for oxygen evolution reaction of water electrolysis-from metal oxides to carbon nanotubes, Prog. Nat. Sci.: Mater. 25 (2015) 545-553.[2]. M. Simões, S. Baranton, C. Coutanceau, Electrochemical valorisation of glycerol, ChemSusChem. 5 (2012) 2106–2124[3]. Y.X. Chen, A. Lavacchi, H.A. Miller, M. Bevilacqua, J. Filippi, M. Innocenti, et al. Nanotechnology makes biomass electrolysis more energy efficient than water electrolysis. Nat. Commun. 5 (2014) 1-6.[4]. N. Grimaldos-Osorio, F. Sordello, M. Passananti, J. González-Cobos, A. Bonhommé, P. Vernoux, A. Caravaca. From plastic-waste to H2: A first approach to the electrochemical reforming of dissolved Poly(methyl methacrylate) particles. Int. J. Hydrogen Energy. 48 (2023) 11899-11913. Acknowledgments The authors gratefully acknowledge the French institution “Ecole Urbaine de Lyon” (EUL - Institut de Convergences) for funding a PhD grant of Dr. N. Grimaldos-Osorio. Figure 1

Flux synthesis of two-dimensional covalent organic frameworks.

Covalent organic frameworks (COFs) are crystalline porous polymers constructed from organic building blocks into ordered two- or three-dimensional networks through dynamic covalent bonds. Attributed to their high porosity, well-defined structure, tailored functionality and excellent chemical stability, COFs have been considered ideal sorbents for various separation applications. The synthesis of COFs mainly employs the solvothermal method, which usually requires organic solvents in sealed Pyrex tubes, resulting in unscalable powdery products and environmental pollution that seriously limits their practical applications. Herein, our protocol focuses on an emerging synthesis method for COFs based on organic flux synthesis without adding solvents. The generality of this synthesis protocol has been applied in preparing various types of COFs, including olefin-linked, imide-linked, Schiff-based COFs on both gram and kilogram scales. Furthermore, organic flux synthesis avoids the disadvantages of solvothermal synthesis and enhances the crystallization and porosity of COFs. Typically, COF synthesis takes 3-5 d to complete, and subsequent washing procedures leading to pure COFs need 1 d. The procedure for kilogram-scale production of COFs with commercially available monomers is also provided. The resulting COFs are suitable for separation applications, particularly as adsorbent materials for industrial gas separation and water treatment applications. The protocol is suited for users with prior expertise in the synthesis of inorganic materials and porous organic materials.

A comprehensive study of laser irradiated hydrothermally synthesized 2D layered heterostructure V2O5(1−x)MoS2(x) (X = 1–5%) nanocomposites for photocatalytic application

Abstract It has been studied that both two-dimensional (2D) MoS2 and V2O5, which are classified as transition metal dichalcogenides and transition metal oxides, are good photocatalyst materials. For this purpose, the hydrothermal method was practiced to synthesize V2O5(1−x)MoS2(x) (X = 1–5% w/w) nanocomposites with different 1–5% w/w weight percent of MoS2 as a prominent photocatalyst under laser irradiation for 2, 4, 6, 8, and 10 min to tune photocatalytic degradation of industrial wastage water. The surface of the 2D molybdenum nanolayered matrix was efficaciously decorated with V2O5 nanoparticles. The crystal phase and layered structures of the V2O5(1−x)MoS2(x) (X = 1–5% w/w) nanocomposites samples were verified by X-ray diffraction and scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy respectively. In the range of the UV visible spectrum, the increment in light absorption from 3.6 to 14.5 Ω−1 cm−1 with an increase of active surface from 108 to 169 μ m 2 {{\rm{\mu }}{\rm{m}}}^{2} with increased MoS2 doping percentage. Furthermore, dielectric findings like the complex dielectric function, tangent loss, electrical conductivity, quality factors, and impedance of V2O5(1−x)MoS2(x) (X = 1–5% w/w) nanocomposites are studied. According to photoluminescence studies, the intensity of peaks decreases when laser irradiation time and doping percentages of MoS2 are increased. As a result, a small peak indicates a decrement rate of electron–hole pair recombination, which increases the capacity for separation. Thermo-gravimetric analysis and differential thermal analysis results revealed that weight loss decreased from 0.69 to 0.35 mg and thermal stability increased with increased doping concentrations. Methylene blue was degraded in 150 min, proving that the prepared MoS2-doped V2O5 material was a stable and economically low-cost nanocomposite for photocatalytic activity.