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Hot water treatment (HWT) is a versatile technique for synthesizing metal oxide nanostructures (MONSTRs) by immersing metal substrates in hot water, typically in glass beakers. The proximity of substrates to the heat source during HWT can influence the temperature of the substrate and subsequently impact MONSTR growth. In our study, zinc (Zn) substrates underwent HWT at the base of a glass beaker in contact with a hot plate and at four different vertical distances from the base. While the set temperature of deionized (DI) water was 75.0 °C, the substrate locations exhibited variations, notably with the base reaching 95.0 °C. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy showed stoichiometric and crystalline zinc oxide (ZnO) nanorods. ZnO rods on the base, exposed to higher temperatures, displayed greater growth in length and diameter, and higher crystallinity. Nanorods with increasing vertical distances from the base exhibited a logarithmic decrease in length despite identical temperatures, whereas their diameters remained constant. We attribute these findings to crucial HWT growth mechanisms like surface diffusion and "plugging", influenced by temperature and water flow within the beaker. Our results provide insights for optimizing synthesis parameters to effectively control MONSTR growth through HWT. [ABSTRACT FROM AUTHOR]

Although capacitive deionization (CDI) technology has been studied intensively for more than 20 years, its commercialization remains in the initial stage, which is partly caused by the insufficient knowledge exchange between academia and industry. This concept reviews multiple scaling‐up efforts in the CDI technology for treating real water streams, following a case‐by‐case fashion. While the cell architecture in pilot scales is limited to the membrane CDI, highlighting the necessary role of ion‐exchange components during scaling‐ups, different ways of electrode stacking, i. e. monopolar and bipolar, are available. The performance indicators of these CDI systems when treating real water streams are summarized to gain insights into industrial practices. Importantly, key discrepancies in cell components and performances between pilot‐scale and lab‐scale studies are emphasized. The main challenges in large‐scale CDI systems for industrial purposes are discussed, providing hints for a better integration of research and applications. [ABSTRACT FROM AUTHOR]

Silver (Ag) is deemed a promising anode material for capacitive deionization (CDI) due to its high theoretical capacity and efficient selectivity to Cl−. However, the strong volume change during the conversion reaction significantly undermines the cycling performance of the Ag electrode. Additionally, achieving well‐dispersed Ag in the active matrix is challenging, as Ag electrodes prepared by conventional thermal reduction tend to agglomerate. Herein, the organic linker confinement strategy is proposed, applying metal–organic framework (MOF) chemistry between Ag nodes and organic ligands to construct Ag‐based MOF. The uniform dispersion of Ag at the molecular level, confined in the organic matrix, efficiently enhances the utilization of active sites, and strengthens the interfacial stability of Ag. Consequently, the Ag‐MOF for the CDI anode exhibits an excellent Cl− removal capacity of 121.52 mg g−1 at 20 mA g−1 in 500 mg L−1 NaCl solution, and a high Ag utilization rate of 60.54%. After 100 cycles, a capacity retention of 96.93% is achieved. Furthermore, the Cl− capture mechanism of Ag‐MOF is elucidated through density functional theory (DFT) calculations, ex situ XRD, ex situ Raman and XPS. This ingenious electrode design can offer valuable insights for the development of high‐performance conversion electrodes for CDI applications. [ABSTRACT FROM AUTHOR]

Suffering from the susceptibility to decomposition, the potential electrochemical application of FeOCl has greatly been hindered. The rational design of the soft‐hard material interface can effectively address the challenge of stress concentration and thus decomposition that may occur in the electrodes during charging and discharging. Herein, interlayer structure manipulation of FeOCl/MXene using soft‐hard interface design method were conducted for electrochemical dechlorination. FeOCl was encapsulated in Ti3C2Tx MXene nanosheets by electrostatic self‐assembly layer by layer to form a soft‐hard mechanical hierarchical structure, in which Ti3C2Tx was used as flexible buffer layers to relieve the huge volume change of FeOCl during Cl− intercalation/deintercalation and constructed a conductive network for fast charge transfer. The CDI dechlorination system of FeOCl/Ti3C2Tx delivered outstanding Cl− adsorption capacity (158.47 ± 6.98 mg g−1), rate (6.07 ± 0.35 mg g−1 min−1), and stability (over 94.49 % in 30 cycles), and achieved considerable energy recovery (21.14 ± 0.25 %). The superior dechlorination performance was proved to originate from the Fe2+/Fe3+ topochemical transformation and the deformation constraint effect of Ti3C2Tx on FeOCl. Our interfacial design strategy enables a hard‐to‐soft integration capacity, which can serve as a universal technology for solving the traditional problem of electrode volume expansion. [ABSTRACT FROM AUTHOR]

The prevalence of polyfluoroalkyls and perfluoroalkyls (PFAS) represents a significant challenge, and various treatment techniques have been employed with considerable success to eliminate PFAS from water, with the ultimate goal of ensuring safe disposal of wastewater. This paper first describes the most promising electrochemical oxidation (EO) technology and then analyses its basic principles. In addition, this paper reviews and discusses the current state of research and development in the field of electrode materials and electrochemical reactors. Furthermore, the influence of electrode materials and electrolyte types on the deterioration process is also investigated. The importance of electrode materials in ethylene oxide has been widely recognised, and therefore, the focus of current research is mainly on the development of innovative electrode materials, the design of superior electrode structures, and the improvement of efficient electrode preparation methods. In order to improve the degradation efficiency of PFOS in electrochemical systems, it is essential to study the oxidation mechanism of PFOS in the presence of ethylene oxide. Furthermore, the factors influencing the efficacy of PFAS treatment, including current density, energy consumption, initial concentration, and other parameters, are clearly delineated. In conclusion, this study offers a comprehensive overview of the potential for integrating EO technology with other water treatment technologies. The continuous development of electrode materials and the integration of other water treatment processes present a promising future for the widespread application of ethylene oxide technology. [ABSTRACT FROM AUTHOR]

The increasing scarcity of fresh water due to rapid population growth and the establishment of new industries every single day has motivated researchers to use efficient technologies for the removal of dissolved salts from water. Various methods of salt removal and wastewater treatment have been established in last decades; however, membrane capacitive deionization has gained much attention due to its low energy consumption and low process costs in water treatment applications. The progress of membrane capacitive deionization for desalination and water treatments is systematically presented in this review. This review includes significant input on the membrane capacitive deionization progress, the current status of membrane capacitive deionization in the removal of salts and different pollutants, and a comparative discussion on various membranes and electrodes used in membrane capacitive deionization reported so far. It also highlights a summary and future scope in the area of membrane capacitive deionization. Based on the literature available and a review of the membrane capacitive deionization process, it could be a more effective and promising process for desalination and water purification. [ABSTRACT FROM AUTHOR]

The Electro-Fenton process is getting a rapid development recently as a novel advanced electro-oxidation technology for the removal of organic pollutants from water. In this work, a three-dimensional (3D) porous Fe 3 N/FeS composite electrode was created from a Fe 2 (SO 4) 3 -based composite ink by the direct-writing 3D printing technology combined with a high temperature heat treatment under ammonia atmosphere. Fe 3 N served as the conductive skeleton of the electrode, while FeS could provide Fe2+ to react with in-situ generated H 2 O 2 in the Electro-Fenton process to generate ·OH radicals. Thus, it could eliminate the need of external ferrous ion addition. The 3D porous Fe 3 N/FeS composite electrode had desired 3D interconnected macro-channels for efficient mass transport and rough rod surfaces to provide more active sites, which resulted in its superior degradation performance on organics than its traditional two-dimensional (2D) plate counterpart. A two-step H 2 O 2 production path was found on the 3D Fe 3 N/FeS composite electrode, which had been found to possess a faster reaction kinetics. It effectively degraded rhodamine B (RhB) within a wide pH range from ∼3 to ∼ 10, demonstrated stable performances in repeated uses, and had low iron ion leaching, all of which were beneficial for its potential applications. Furthermore, it also demonstrated effective degradation performances on antibiotics of amoxicillin (AMX) and tetracycline hydrochloride (TC-HCl) in both deionized (DI) water and tap water matrixes, indicating its potential to solve the emerging contaminant problem in real water treatment practices. [ABSTRACT FROM AUTHOR]

Concern for environmental protection has increased throughout the years from a global perspective. To date, the predominance of adsorption as treatment technique in environmental chemistry remains unchallenged. Moreover, the scientific attention for investigating nanobubbles due to their unique properties has turned the search for their application in environmental processes with special emphasis on water treatment. This study is aimed at investigating the effect of rotation on batch adsorption process using commercial activated carbon as adsorbent material, compared with the widely used method of agitation. As liquid medium, deionized water and deionized water enhanced with nanobubbles (of air) were used. The wastewater was simulated by dissolving a common dye as model pollutant, methylene blue, at concentration of 300 mg/L in the tested liquid. The results indicated that the utilization of nanobubbles resulted in an improvement on adsorption rate, compared to the corresponding values of deionized water solutions. These results may lead to promising applications in the future, since just 1 h of operation increases the water purification and thus provides a simply applied, cost-effective, and rapid alternative. [ABSTRACT FROM AUTHOR]

Capacitive deionization is an emerging water desalination technology for industrial applications. Recent advancements in electrode design and system development have led to the reporting of ultra-high salt adsorption performance, benefiting its potential application in agricultural water treatment at a potentially low cost. In this study, we provide a comprehensive summary of the porous electrode design strategy to achieve ultra-high ion adsorption performance, considering factors such as experimental parameters, chemically tuned material properties, redox chemistry and smart nanoarchitecture for future electrode design. Furthermore, we endeavor to establish a correlation between capacitive deionization (CDI) technology and its applicability in the agricultural sector, specifically concentrating on water treatment with an emphasis on undesirable ions associated with salinity, hardness, and heavy metals, to achieve harmless irrigation. Additionally, to ensure the efficient and cost-effective application of CDI systems in agriculture, a thorough overview of the literature on CDI cost analysis is presented. By addressing these aspects, we anticipate that ultra-high salt adsorption CDI systems hold great promise in future agricultural applications. [ABSTRACT FROM AUTHOR]

The desalination of seawater is one of the most established techniques in the world. In the middle of the 20th century using water evaporation systems, later with reverse osmosis membranes and nowadays the possibility of capacitive deionization membranes. Capacitive deionization is an emerging technology that makes it possible to obtain drinking water with an efficiency of 95%. This technology is in the development stage and consists of porous activated carbon electrodes, which have great potential for saving energy in the water desalination process, and which can be used for desalination process, using an innovative technology called capacitive deionization. A prototype has been designed and can operate with constant current charging and discharging. Adequate precision has been achieved, as can be seen in the results obtained. A philosophy of using free software with opensource code has been followed, such as: the Arduino and Processing Programming Editors; as well as the Arduino Nano Board, the analog-to-digital converter and the Adafruit digital-to-analog converter. Moreover, a low-cost system has been developed. A robust and versatile system has been designed for water treatment, and a flexible system has been obtained for the specifications established as it is shown in the results section. [ABSTRACT FROM AUTHOR]

In this study, the electrocoagulation (EC) treatment was used to minimize and separate pollutants from textile industrial wastewater (TIWW), including high color, chemical oxygen demand (COD), total organic carbon (TOC), and total dissolved solids (TDS). To enhance the EC treatment efficiency, a novel strategy has been followed in the study that involves thin‐film coating on 316 stainless steel (SS) electrodes with banana peel‐derived activated carbon (BPAC) by dip coating, spin coating, or spray coating. Among the different types of coating, thickness and contact angle measurements have elucidated that the spray coating of BPAC on SS electrode is the best tool with minimum thickness and contact angle. In this study, a bare SS electrode was used as the anode and a thin‐film spray‐coated BPAC on the SS electrode was used as the cathode. Moreover, optimization plays a key role in EC treatment process, where operating conditions such as a current density of 10 mA/cm2, contact time of 15 min, and a pH of 7 were fixed. As a result, the findings indicate comparatively high color removal of 98%, COD removal of 91%, TOC removal of 89.6%, and TDS removal of 68% are achieved with ease. Accordingly, in comparison with plain SS electrodes or dip‐ or spin‐coated BPAC on SS electrodes, spray‐coated BPAC on SS electrodes in EC treatment outperforms in removing high color, TOC, COD, and TDS. Overall, the study highlights the potential of EC treatment integrated with adsorption procedures for TIWW treatment. Particularly, the use of thin‐film spray‐coated BPAC on SS electrodes in the EC treatment process led to an effective and sustainable tool for treating and reuse of TIWW. It is due to its low operation and maintenance cost and studied in a short interval of time. Finally, the ultimate goal was firmly achieved in pilot‐scale studies by the safe discharge into the environment or reuse of treated textile wastewater. Thus, it is a promising alternative with an environmentally friendly footprint that could be easily implemented in any textile industry premises. Practitioner Points: Heavy metals, oils, facts, suspended solids, and other pollutants can be removed from industrial effluent by using electrocoagulation.The process is both cost‐effective and energy‐efficient, and it is easily integrated with other water treatment technologies.According to the findings of this study, minimum current density should be applied to BPAC–SS‐coated electrodes by DC power supplies to treat textile industry effluents at low operating costs.When compared with a plain SS electrode, the spray‐coated BPAC on SS electrode provides better performance in effluent treatment. [ABSTRACT FROM AUTHOR]

The effect of different water matrices on the photocatalytic degradation of dissolved pharmaceuticals was explored. The focus was on the degradation efficiencies in wastewater effluent from a bioreactor and water effluent from a central wastewater treatment plant and comparing the results with degradation in deionized H 2 O. The compounds tested included: oxytetracycline, marbofloxacin, ibuprofen, diclofenac, phenytoin, ciprofloxacin, sulfamethoxazole. For the experiments performed in this study, a compact packed-bed photocatalytic reactor was used in which the hybrid TiO 2 photocatalyst (sol-gel/P25) was deposited on ∼3 mm glass beads. As expected, the reactions proceed more slowly in wastewater than in deionized water, yet it is shown that removal of the compounds from the water is still possible even when other organic molecules are present. Total organic carbon measurements have shown that complete mineralization takes place albeit at slower rates than the initial degradation of parent compounds. The results show that an acidic pH can increase the reaction rates and the adsorption on the photocatalyst surface. Analyses of the degradation intermediates were performed using tandem liquid chromatography triple-quadrupole mass spectrometry system. Additionally, X-ray absorption spectroscopy was applied to get insight into the local structure of the photocatalyst before and after use. Understanding the effects that different wastewater compositions have on photocatalytic reactions will help to refine the potential applications of the technology. [ABSTRACT FROM AUTHOR]

The present study investigates the removal of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos herbicides from their 5 × 10–5 M aqueous solutions onto activated carbon cloth by adsorption and electrosorption. Analysis of these highly polar herbicides was achieved by UV–visible absorbance measurements, after derivatization with 9-fluorenylmethyloxycarbonyl chloride. The limit of quantification values of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were 1.06 × 10–6 mol L−1, 1.38 × 10–6 mol L−1, 1.32 × 10–6 mol L−1 and 1.08 × 10–6 mol L−1, respectively. Glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were removed from their aqueous solutions with higher efficiencies by means of electrosorption (78.2%, 94.9%, 82.3% and 97%, respectively) than of open-circuit adsorption (42.5%, 22%, 6.9% and 81.8%, respectively). Experimental kinetic data were fitted to pseudo-first order and pseudo-second order kinetic models. It was determined that pseudo-second order kinetic model represents experimental data better with satisfactory coefficient of determination, r2 (> 0.985) and normalized percent deviation, P (< 5.15) values. Adsorption isotherm data were treated according to Freundlich and Langmuir isotherm models. Based on the r2 (> 0.98) and P (< 5.9) values, it was found that experimental data well fitted to Freundlich isotherm model. Adsorption capacities of activated carbon cloth for glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos, expressed in terms of Freundlich constant, were calculated as 20.31, 118.73, 239.33 and 30.68 mmol g−1, respectively. The results show that the studied ACC can be used in home/business water treatment systems as an adsorbent due to its high adsorption capacity. [ABSTRACT FROM AUTHOR]

Titanium dioxide has attracted a great deal of attention in the field of environmental purification due to its photocatalytic activity under ultraviolet light. Photocatalytic efficiency and the energy required to initiate the process remain the drawbacks that hinder the widespread adoption of the process. Consistently with this, it is proposed here the polymerization of hexamethyldisiloxane fragments simultaneously to TiO2 sputtering for the production of thin films in low-pressure plasma. The effect of plasma excitation power on the molecular structure and chemical composition of the films was evaluated by infrared spectroscopy. Wettability and surface energy were assessed by a sessile drop technique, using deionized water and diiodomethane. The morphology and elemental composition of the films were determined using scanning electron microscopy and energy dispersive spectroscopy, respectively. The thickness and roughness of the resulting films were measured using profilometry. Organosilicon-to-silica films, with different properties, were deposited by combining both deposition processes. Titanium was detected from the structures fabricated by the hybrid method. It has been observed that the proportion of titanium and particles incorporated into silicon-based matrices depends on the plasma excitation power. In general, a decrease in film thickness with increasing power has been observed. The presence of Ti in the plasma atmosphere alters the plasma deposition mechanism, affecting film deposition rate, roughness, and wettability. An interpretation of the excitation power dependence on the plasma activation level and sputtering yield is proposed. The methodology developed here will encourage researchers to create TiO2 films on a range of substrates for their prospective use as sensor electrodes, water and air purification systems, and biocompatible materials. [ABSTRACT FROM AUTHOR]

Water pollution due to emerging organic pollutants, such as agrochemicals, has become a topic of growing interest worldwide. The increase of pollutants in aquatic systems stimulated the development of new strategies for water remediation. Plasma technology is an advanced oxidation process which has proved to be an efficient method for organic matter degradation. In this work, a novel design of a trielectrode plasma reactor based on a dielectric barrier discharge extended to a third electrode operated in ambient air is presented. The water to be treated flows through a gutter with low impedance and far from the electrodes connected to the voltage sources. The reactor operates in ambient air, and it does not rely on the use of expensive inert gases. The design of the reactor is easily scalable. The performance of the reactor, in terms of the removal efficiency and the energy yield, was tested in an aqueous solution of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), one of the most widely used around the world. The reactor presents a good efficiency in the removal of the herbicide 2,4-D and values of energy yield of about 240 mg/kW h. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the efficacy of activated carbon (AC) electrode embedded with naturally occurring metal oxides (MO) from rocks for antibacterial activities against both gram-negative (Escherichia coli) and gram-positive (Salmonella aureus) bacteria using capacitive deionization technique. The desalination and disinfection performance of the fabricated AC/MO electrode was evaluated through the batch mode experiments conducted at a potential difference of 1.2 V for 240 min (4 h). The results revealed that the AC/MO electrode achieved a complete removal efficiency of 100% for E. coli and 60% for S. aureus in the field water collected from Nduruma stream (natural water). The bacterial removal mechanism was attributed to the capacitive deionization (CDI) process and physical adsorption. The study highlights the potential of AC/MO electrode material as an effective antibacterial agent for the CDI process, which may have significant implications for the development of new technologies for water purification and disinfection. [ABSTRACT FROM AUTHOR]

This work presents an electrical double layer (EDL) model for capacitive deionization (CDI) by intercorrelating the salt adsorption, the electrode voltage, and the surface charge density. The counterion condensation is considered a crucial contribution to salt adsorption because of the high surface charge density in the charged micropores. The counterions condense when the surface charge density exceeds a critical value, which is predicted by the counterion condensation theory. The EDL model accurately correlates the NaCl salt adsorption and electrode voltage with various surface charge densities and well predicts the salt adsorption in a wide range of external salt concentrations. The EDL model reproduces the non‐monotonic relationship between the salt adsorption and the specific surface area observed in experiments and provides an explanation from the modeling perspective. Exhibiting superior accuracy and predictability for salt adsorption, the EDL model could serve as an enabling tool contributing to the development of CDI processes. [ABSTRACT FROM AUTHOR]

Interfacial solar evaporation technology is considered as one of the most promising green ways to solve the problems of freshwater scarcity and sewage treatment. Herein, we prepared a low-cost, easy-to-fabricate, and excellent performance polyaniline (PANI)-wood solar evaporator using a simple surface self-assembly technique. The evaporator achieves an evaporation rate of 1.66 kg m−2 h−1 under 1 sun and a photothermal conversion efficiency of 86.9%. In the process of seawater desalination, the purification rate of four ions in seawater reaches at least 99%. And water purified by evaporator meets the drinking water standard of the World Health Organization (WHO). In the experiment of evaporating organic dye aqueous solution, the light transmittance of the purified water is similar to that of deionized water. These performances are higher than those of most reported wood-based solar evaporators. Therefore, the efficient solar evaporation system has great potential in addressing desalination and water purification. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is an environmentally friendly desalination technique with low energy consumption. However, unmodified carbon electrode materials have poor sulfate selectivity and adsorption capacity. In this work, to improve sulfate selectivity, we prepared activated carbon materials loaded with different amino contents by grafting amino groups via acid treatment for different times. In the competitive ion adsorption experiments, the sulfate selectivity of AC was only 0.64 and the amino-modified AC increased by 1.98-2.52 times due to the formation of stronger hydrogen bonds between the amino group and sulfate. AC-NH2-4 had the best selectivity and the sulfate selective coefficient was 2.25. The desorption of sulfate was 92.46% within one hour. In addition, the surface of the amino-modified activated carbon showed significantly improved electrochemical properties and better capacitance. The specific capacitance of amino-modified AC in different electrolyte solutions was consistent with the competitive adsorption results. The specific capacitance of amino-modified AC in Na2SO4 electrolyte solution was the highest. The modified electrode material also had the advantages of a higher adsorption capacity and excellent regeneration performance after continuous electric adsorption–desorption cycles. Therefore, it may have development potential to selectively adsorb sulfate in practical applications. [ABSTRACT FROM AUTHOR]

Water resources are the basis for human survival and development. However, human beings face severe challenges of water pollution and freshwater shortage. With the critical advantages of low energy consumption, high efficiency, low cost, green and pollution-free, and renewable electrodes, capacitive deionization (CDI) has become an up-and-coming water treatment technology. After decades of development, the application of CDI has expanded from seawater desalination to many fields. However, the existing literature still needs a comprehensive overview of the multi-functional application of CDI technology in water treatment. Therefore, our work critically reviewed the latest research progress of CDI in water treatment to meet the technical requirements of various application fields. This paper first summarizes the various applications of CDI in water treatment, focusing on CDI's representative research results in heavy metal removal, organic contaminants removal, water softening, phosphate and nitrate removal, and water disinfection. In addition, we also discussed the latest research progress of energy recovery and energy consumption assessment for the CDI process. Finally, this paper discusses the challenges and future opportunities facing CDI technology. [ABSTRACT FROM AUTHOR]

Wastewater of industries, which is polluted with different dyes is becoming a severe issue, which should be tackled on priority bases such as to provide an eco-friendly environment. In addition to this, in search of an efficient green synthesized capacitive electrode material, we have synthesized cobalt oxide (Co 3 O 4) nano-materials by employing green chili and sunflower seeds extracts. The as synthesized samples are labeled as Co-P, Co-GC and Co-SF. The successful fabrication of these samples was tested by X-ray diffraction (XRD), scanning electron microscope (SEM), Xray photoelectron spectroscope (XPS). These tests have explored successful fabrication of Co 3 O 4 -based samples comprised on nanoparticles (NPs) in the range of 35–45 nm. Optical properties were studied by UV–vis spectroscope and Co-SF sample has exhibited lowest energy band gap i.e 2.41 eV. Photoluminescence (PL) analysis has explored that Co 3 O 4 NPs prepared by sunflower extracts have offered lowest recombination rate. Among of Co-P, Co-GC and Co-SF photocatalysts, Co-SF has shown excellent photodegradation activity, which is 90% against a water pollutant name as methylene blue (MB) under UV–Vis light. This sample also has shown a good catalytic stability i.e 80.7%. Moreover, for electrochemical performance analysis, cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopic (EIS) tests were also performed. Among of Co-P, Co-GC and Co-SF samples, Co-SF sample has offered 1080.32 F/g specific capacitance and 86.70% capacitance retention at higher scan rate i.e 10 A/g. Additionally, this optimized sample has also maintained 83.51% capacitance even after 5000 GCD cycles performed at 1 A/g, and good conductive nature. These extraordinary results have provided new platform for water purification and energy storage appliances. [ABSTRACT FROM AUTHOR]

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Copper ions (Cu2+) disposed to the environment at massive scale pose severe threat to human health and waste of resource. Electrochemical deionization (EDI) which captures ions by electrical field is a promising technique for water purification. However, the removal capacity and selectivity toward Cu2+ are unsatisfying, yet the recycling of the captured copper in EDI systems is yet to be explored. Herein, an efficient electrochemical copper pump (ECP) that can deliver Cu2+ from dilute brackish water into much more concentrated solutions is constructed using carbon nanosheets for the first time, which works based on reversible electrosorption and electrodeposition. The trade‐off between the removal capacity and reversibility is mediated by the operation voltage. The ECP exhibits a removal capacity of 702.5 mg g−1 toward Cu2+ and a high selectivity coefficient of 64 for Cu2+/Na+ in the presence of multiple cations; both are the highest reported to date. The energy consumption of 1.79 Wh g–1 is among the lowest for EDI of copper. More importantly, the Cu species captured can be released into a 20‐fold higher concentrated solution. Such a high performance is attributed to the optimal potential distribution between the two electrodes that allows reversible electrodeposition and efficient electrosorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • SO 4 2- is activated to persulfate and further generates sulfate radicals in situ. • Density functional theory and electrochemical analyses reveal interface oxidation processes. • Hybrid system achieves simultaneous removal of sulfamethazine and SO 4 2-. • MXene modified biochar electrode demonstrates excellent efficiency, stability and favorable cytocompatibility. • The multi-layered porous structure offers numerous activation sites. Electrochemical oxidation (EO) is a well-established method for pollutants removal. However, excessive addition of oxidant during EO may cause secondary pollution. Moreover, the unprocessed ions in the wastewater can cause further contamination. This research introduces a hybrid process that combines EO with capacitive deionization (CDI), in situ catalytically utilizing sulfate (SO 4 2-) and removing sulfamethazine (SMZ). This process realized by layered porous MXene-modified biochar electrodes (BCM) that demonstrate electrocatalytic and adsorption properties. The electrochemical oxidation system, constructed using BCM cathode and boron-doped diamond anode, harnesses in situ generation of oxidants from SO 4 2-, leading to the complete degradation of 30 mg/L sulfamethazine in 30 min through adsorbed radicals and metastable active species at the biphasic interface. Subsequently, the BCM-2 exhibits excellent CDI performance at 1.2 V, achieving a desalination capacity of 15.40–65.97 mg/g in 100–1000 mg/L Na 2 SO 4 solution. By combining EO with CDI, BCM simultaneously removes sulfamethazine and sulfate, resulting in a 60 % reduction in total organic carbon and a 14.4 % decrease in electrical conductivity after one process cycle. Moreover, BCM exhibits favorable cytocompatibility. [ABSTRACT FROM AUTHOR]

[Display omitted] • Discussed MXene-based capacitive deionization (CDI) electrode optimization. • Presented forefront applications of MXene-based CDI across multiple fields. • Envisaged challenges and future directions for MXene-based CDI. MXene, hailed for its hydrophilicity, conductivity, and modifiable interlayer spacing, emerges as a frontrunner in capacitive deionization (CDI) electrode materials. Yet, pristine MXene grapples with suboptimal ion removal and stability. This review delves into inventive strategies to fortify MXene-based CDI electrodes, spotlighting their avant-garde applications in combatting ion pollution, reclaiming resources, softening water, and thwarting bacteria. Future prospects for MXene in CDI are also deliberated, aimed at igniting inspiration in the CDI arena. Some strategies proposed herein can be applied to other electrode materials in the CDI domain, thus fostering advancement across the entire spectrum of CDI electrode materials. [ABSTRACT FROM AUTHOR]

Energy-efficient and low-cost desalination of water continues to be a problem that society is facing. With the advances in nanotechnology, a variety of nanopore membranes have emerged for desalination. In particular, YX 2 nanopores (Y W, Mo, etc. and X = S, Se, Te, etc.) have been considered as promising membranes for water purification. In this work, we used a combination of high-throughput molecular dynamics simulations and machine learning to reveal the nanopore mass transfer mechanism and rationally design the YX 2 nanopore. The pore size and the charge of the pore mouth were found to be the main factors affecting water permeation and salt rejection, as discovered through the machine learning study. The physical-chemical analysis provides us with a deep understanding of the charge-governed mechanism on the desalination performance of YX 2 nanopores. It revealed that YX 2 nanopores with a conical shape and minimized pore charges could be ideal candidates for excellent desalination performance. Based on this, we designed the YX 2 pore with a specific charge distribution, which could achieve high water permeation with high salt rejection. Therefore, the combination of machine learning and high-throughput computation methods could aid in designing materials with excellent performance for desalination. • A combination of high-throughput computational and machine learning is developed • YX 2 nanopores with a conical shape and minimized pore charges could be ideal candidates for excellent desalination performance. • The importantance of pore size and the charge of the pore mouth were explored on affecting water permeation and salt rejection [ABSTRACT FROM AUTHOR]

[Display omitted] • A NF/Mn 2 CoO 4 @MoO 2 electrode was prepared for Pb2+-targeted removal via CDI technology. • SCR of the electrode relies on preferential adsorption and sluggish desorption for Pb2+. • Synergistic effects of Mn 2 CoO 4 and MoO 2 are beneficial for Pb2+ capacitive removal. • Theoretical calculations confirm SCR is due to stronger bonding between Pb2+ and MoO 2. • Electrodepositing loaded MoO 2 onto NF/Mn 2 CoO 4 for 60 min achieved optimum capacitance. To achieve targeted removal of Pb2+ from industrial wastewater, a NF/Mn 2 CoO 4 @MoO 2 composite electrode, synthesised using the hydrothermal method combined with electrodeposition technology, was employed to construct an asymmetric capacitive deionization (CDI) system to selectively electro-adsorb and desorb Pb2+ ions. The electrode exhibited pseudocapacitive characteristics in solutions containing Pb2+, facilitating rapid and reversible redox reactions. The asymmetric CDI system, utilising graphite paper as the positive electrode and NF/Mn 2 CoO 4 @MoO 2 as the negative electrode, displayed exceptional adsorption performance at 1.4 V for 1 h, decreasing the Pb2+ concentration from 50 ppm to 4 ppb, achieving an adsorption capacity of 156.24 mg g−1, and displaying outstanding cyclic stability. Moreover, the electrode demonstrated preferential adsorption of Pb2+ in mixed solutions containing multiple heavy metal ions, with relative removal coefficients of 4.48 − 19.86 compared with other ions. Analysis of the adsorption mechanism indicated that during the adsorption process, Pb2+ was embedded between MoO 2 layers, disrupting the electron cloud symmetry and triggering an oxidation reaction. Octahedral MoO 2 then lost electrons and transformed into tetrahedral [MoO 4 ]2-, forming PbMoO 4 with embedded Pb2+ between the layers, and achieving effective removal of Pb2+ with high selectivity. Molecular dynamics simulations and density functional theory (DFT) calculations confirmed the high selectivity of the prepared electrode for Pb2+ ions based on stronger binding of Pb2+ to MoO 2 than other ions. The electrode has application potential for the capacitive removal of Pb2+ from industrial effluent through CDI technology. [ABSTRACT FROM AUTHOR]

The presence of microplastics (MPs) in water may affect the efficacy of the disinfection process and induce toxicity changes to MPs themselves during disinfection. Therefore, this study evaluated the two-way effects of polyethylene microplastic (MP) particles in water and wastewater during sodium hypochlorite (NaClO) disinfection. On the one hand, it has been confirmed that the presence of MPs reduced the disinfection efficiency of NaClO. The required CT (concentration of the disinfection × contact time) for a 2–4-log inactivation of Escherichia coli (E. coli) in different water samples was in the order of deionized water < turbid water (1 NTU) < water with MPs (1 mg/L) < turbid water (10 NTU). On the other hand, although exposure to MPs did induce significant changes in the activities of superoxide dismutase and glutathione, compared to pristine MPs, the MPs treated by NaClO at current conditions (0.3 and 3.0 mg/L for 30 min) did not show significant changes in their toxicity on zebrafish, at an MP exposure concentration of 1 mg/L. There was no significant difference in the survival rate and weight growth rate, neither as in the activities of the oxidative stress-related enzymes (superoxide dismutase, catalase, glutathione, glutathione peroxidase, and glutathione s-transferase) in both gut and muscle tissues of the zebrafish, between exposure to the pristine and NaClO-treated MPs. It is indicated that NaClO disinfection commonly applied for water and wastewater treatment would not pose a serious concern to effluent safety in the presence of mild levels of MPs. [Display omitted] • Microplastics in water reduced NaClO disinfection efficiency. • NaClO treatment of MPs did not induce changes in survival and weight growth rate. • MPs treated by NaClO did not alter the activity of oxidative stress-related enzymes. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is a potentially cost-effective method of desalinating brackish groundwaters though the technology has not yet been widely utilised for this particular application. Silicon (Si) is a common element in groundwaters which may cause problems due to its tendency to induce severe fouling of equipment used for water treatment. In this study we focus on the impacts of the presence of Si on the performance of CDI. A systematic evaluation procedure is proposed, which is used to distinguish the "dynamic" and residual Si scaling and the impacts of these types of fouling on desalination performance. Results show that Si has minimal influence on CDI performance within low concentration ranges (<0.5 mM). Sorption of deprotonated silicic acid species is largely avoided in CDI, which contributes to sustaining the removal of major ions and stable operation of the system. However, at high concentrations of Si (>2.0 mM), scaling was observed to form on the electrode surface, leading to noticeable deterioration in CDI electrode performance. The presence of ion exchange membrane in CDI (i.e. , membrane CDI or MCDI) can significantly alleviate Si scaling of the desalination system. Results of this study clearly demonstrate the scaling behavior of CDI and its derivatives when dealing with Si-laden water matrices, providing insights into the design and maintenance of CDI systems in practical applications. [Display omitted] • Impact of presence of Si on the performance of CDI and MCDI systems examined. • Si has minimal impact on CDI and MCDI performance at low concentrations (<0.5 mM). • Significant deterioration in CDI performance at Si concentrations >2 mM. • Presence of membranes in MCDI mitigates impact of Si, even at concentrations >2 mM. [ABSTRACT FROM AUTHOR]

Boron presents challenges in desalination owing to its small size and lack of charge. While various methods, such as reverse osmosis, capacitive deionization, and electrodeionization, have been utilized to control boron, they often suffer from high levels of energy consumption and complex processes requiring pH adjustment to generate the charged form of boron. Herein, we introduce a novel approach, i.e., redox-mediated electrodialysis (redox-ED) assisted by ion-exchange resins, aimed at energy-efficient boron control without requiring pH adjustment. Our system displays a remarkable boron removal efficiency of 99% with a low energy consumption of 0.009 kWh/g (0.09 kWh/m3). These results are likely due to the dissociation of water on the surface of the ion-exchange resins, which led to a local pH gradient and reduced systemic resistance through additional ion flux. Furthermore, via techno-economic analysis, the total cost of the redox-ED for boron removal revealed a 50% reduction with the scale-up strategy of electrode stacking, compared to those of traditional EDI systems. Overall, this study demonstrates the new potential of a sustainable boron removal technology without pH adjustment through the redox-ED system assisted by ion-exchange resins, providing an attractive option applicable to the boron removal industry. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical techniques for uranium extraction from water were reviewed. • The strengths, limitations, applicability of each method were evaluated. • The fouling of membranes and electrodes is a main challenge. • Environmental and economic considerations are discussed. Electrochemical removal of uranium from water is an emerging topic that addresses the treatment of drinking water, remediation of contaminated sites, and mining from seawater. Electrochemical strategies compare favorably to conventional processes, such as adsorption and coagulation/flocculation, with advantages in speed and efficiency, materials regeneration, uranium recovery, and recycling. This review assesses all published work on electrochemical techniques for uranium extraction from water, including capacitive deionization (electrosorption), electrodeposition, electrodialysis, and electrocoagulation. This work compares these approaches with conventional techniques and discusses their applicability in different use cases. Environmental and economic considerations are discussed, as well as the current outlook and opportunities for engagement in this emerging field. [ABSTRACT FROM AUTHOR]

• Nitrogen-doped porous carbon with controlled pore structure and wettability was synthesized. • The nitrogen-rich feature of carbon material enables both electrical conductivity and surface wettability. • SMS-AC realizes large adsorption capacity of 8.38 mg/g and high charge efficiency of 90.66 % Nitrogen-doped porous carbon with controlled pore structure and wettability was synthesized using spent mushroom substrate (SMS) via physical activation process. The nitrogen-rich feature of precursor enables the carbon material to possess both electrical conductivity and surface wettability, creating an effective conducting network in flow electrodes. These materials have been proven to be highly efficient for deionization due to their ability of maintaining surface wettability and electrical conductivity. Our results show that the SMS-1.5 sample has a high adsorption capacity of 8.38 mg/g, which is 1.8 times greater than the commercial YP-50. The corresponding charge efficiency was up to 90.66 % after being exposed to 1.6 g/L NaCl feed solution for 120 min in flow electrode capacitive deionization device. This study highlights the significance of the inherent nitrogen element in biomass for the synergistic promotion of electrical conductivity and surface wettability, providing a strategy for designing porous carbons with excellent desalination performance. [ABSTRACT FROM AUTHOR]

In this study, D-Xylose coated MNPs were synthesized and used as draw agent in forward osmosis (FO) process for water purification. Response surface methodology (RSM) was utilized for the design and optimization of synthesis parameters. In order to characterize the synthesized MNPs, FTIR, TEM, VSM, and UV characterization techniques were performed. The effect of independent parameters including D-Xylose mass, MNPs mass, and synthesis time on the osmotic pressure was investigated. Based on the optimization results, the osmotic pressure of a 2 wt./v% draw solution using 2.66 g D-Xylose, 0.13 g MNPs, and a 7.11 h synthesis time was 0.81 bar as the highest value. Using D-Xylose coated MNPs as draw agent and deionized water as the feed, the initial FO water flux was 2.98 LMH. Reusing the recovered MNP draw agent in two more consecutive tests resulted in the reduction of water flux to 2.68 and 2.30 LMH, respectively. Moreover, using 0.01 M NaCl solution as the feed, the initial water flux was reported as 1.3 LMH. To remove the draw agents from suspension, external magnetic field was applied to obtain a water turbidity of 0.08 NTU. [ABSTRACT FROM AUTHOR]

Rationale: The type and quantity of environmentally problematic disinfection byproducts (DBPs) produced during chlorination of water depend on the natural organic matter and organic contaminants that raw water contains, and on the operational conditions of the drinking water treatment process. There is a need for a fast and quantitative method that determines which DBPs are produced and monitors the chemical dynamics during a drinking water treatment. Methods: A small experimental chemical reactor (50 mL) was mounted directly onto the membrane inlet interface of a membrane inlet mass spectrometer (MIMS). In this setup, the membrane was the only separation between the reaction mixture in the chemical reactor and the open ion source of the mass spectrometer 2 cm away. Water samples to be chlorinated were placed in the reactor and the chlorination reaction was initiated by injection of hypochlorite. The formation of intermediates and products was monitored using either full‐scan mass spectra or selected ion monitoring of relevant ions. Results: An algorithm for analyte quantification was successfully developed for analysis of the complex mixtures of phenol (a model for waterborne organic compounds), chlorinated intermediates and trihalomethane products which simultaneously pass the membrane into the mass spectrometer. The algorithm is based upon the combined use of standard addition and an internal standard, and all analytes could be quantified at nanomolar concentrations corresponding to realistic water treatment conditions. Experiments carried out in the temperature range 15–60°C showed that the reaction dynamics change with operational parameters, for example in tap versus deionized water. Conclusions: We have successfully shown that an experimental laboratory reactor directly interfaced with a MIMS can be used for quantitative monitoring of the chemical dynamics during a water treatment. This technique could provide rapid assistance in the optimization of operating parameters for minimizing DBP production. [ABSTRACT FROM AUTHOR]

Faradic capacitive deionization (CDI) has emerged as an ideal candidate for developing effective water purification from low-concentration desalinated water. However, long-term desalination-stability CDI still faces the challenge in unstable electrode microstructure after hundreds of ion intercalations. Herein, ethylenediaminetetraacetic acid (EDTA)-modified Ti 3 C 2 T x (denoted as EDTA-Ti 3 C 2 T x) electrodes are proposed through intense chemical interactions without scarifying Ti 3 C 2 T x electronic conductivity, wherein the formed –COO-terminated bridge stabilizes Ti 3 C 2 T x interlayer spacing for strengthening long-term regeneration desalination. Simultaneously, abundant Na+ adsorption sites with highly hydrophilic surface in the binder-free high-conductivity EDTA-Ti 3 C 2 T x accelerated ion electro-sorption with efficient ion permeations. Importantly, in 500 mg L−1 NaCl solutions, EDTA-Ti 3 C 2 T x //activated carbon (AC) assembled CDI device delivered an extremely stable adsorption/desorption with salt adsorption-capacity (SAC) retention of 83 % after 500 cycles and a high desalination capacity of 51.0 mg g−1. In addition, the EDTA-Ti 3 C 2 T x presented without d -spacing changes after 100 cycle desalinations that was significantly different from structural collapse in Ti 3 C 2 T x. This study offers a new idea to overcome poor electrochemical desalination stability via organic molecules stabilized Ti 3 C 2 T x structure. [Display omitted] • The –COO-terminated bridge stabilizes Ti 3 C 2 T x interlayer spacing. • A high-conductivity binder-free EDTA-Ti 3 C 2 T x film electrode is proposed. • Abundant Na+ adsorption sites strengthen desalination capacity. • The EDTA-Ti 3 C 2 T x //AC CDI device exhibits an extremely stable SAC retention of 83 % after 500 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fundamental understanding of Prussian blue and its analogues for superior capacitive deionization is provided. • The advantages and challenges of Prussian blue and its analogues for capacitive deionization are explained. • The directions for future research and development are determined from a perspective of nanoarchitectonics. Capacitive deionization (CDI) offers an appealing electrochemical solution for water treatment, where electrode materials play a crucial role in ensuring the efficiency of CDI devices. The quest for novel electrode materials is driven by the need to enhance desalination capacity, cycling stability, ion selectivity, and energy efficiency, given that traditional carbon materials relying on electric double layer electrosorption principle often exhibit subpar desalination capabilities. Among the standout options, Prussian blue (Fe 4 [Fe(CN) 6 ] 3) and its analogs (PB/PBAs) have stood out in CDI systems due to their superior performance and durability as coordination polymers. Nevertheless, challenges persist in leveraging their full potential for CDI, stemming from issues like low desalination capacity, slow kinetics, poor conductivity, structural vulnerability, and limited electrochemical activity. Recent years have witnessed the emergence of innovative strategies aimed at addressing these obstacles, particularly through advancements in structural and compositional manipulation. This review seeks to consolidate the latest advancements in the nanoarchitectonics of PB/PBAs, exploring their classification, and synthesis methodologies, and delving into the fundamental principles governing their utility in CDI applications—anchored in considerations of thermodynamics, kinetics, and mechanisms. Notably, the review underscores the prevailing challenges faced by PB/PBAs in CDI deployment, prompting the discussion of proactive approaches to guide future material innovation and usage. By shedding light on the ongoing efforts to enhance PB/PBAs for CDI, this review anticipates that advancements in nanoarchitectonics will unlock fresh possibilities in the realm of high-performance CDI material design and implementation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Asymmetric membrane CDI (ACDI) is proposed for the removal of short-chain PFAS. • Deionization performance of ACDI for short-chain PFAS was better than MCDI. • Good deionization capacity (28.75 mg/g) & energy consumption (0.46 Wh/g) were achieved. • Even in the presence of competing ions, removal of short-chain PFAS was observed. Concerns have been raised over the persistence and potential health risks of perfluoroalkyl substances (PFAS). PFAS pose significant challenges in water treatment owing to their chemical stability and the difficulty of treating them with conventional purification methods. Although traditional water treatment methods for contaminant removal have been explored, their effectiveness against PFAS remains limited. This gap in knowledge highlights the need for innovative approaches. This study introduces asymmetric membrane capacitive deionization (ACDI) as a novel method for short-chain PFAS removal to address the shortcomings of existing techniques. ACDI refers to a configuration in which an anion exchange membrane is removed from a conventional membrane capacitive deionization with both a cation exchange membrane and an anion exchange membrane. Among the PFAS, perfluorobutanesulfonic acid (PFBS), which is known to be difficult to remove because of its short chain, has been the focus. The ACDI system demonstrated superior deionization capacity (28.75 mg/g) and energy efficiency (energy consumption of 0.46 Wh/g) compared to conventional CDI and membrane CDI systems. In addition, the effects of key operating parameters, such as voltage (0.5 ∼ 1.2 V), initial concentration (50 ∼ 500 mg/L), and flow rate (1 ∼ 5 mL/min), on the PFBS removal were systematically investigated and superior at 1.2 V, 500 mg/L, and 2 mL/min. This study suggests the need for further exploration of real-world applications considering the presence of competing ions in wastewater. This study provides valuable insights into advancing CDI technology for the sustainable treatment of industrial wastewater containing PFAS. [ABSTRACT FROM AUTHOR]

Water scarcity all over the world attracts alternative methods to purify saline water and supplement the available dwindling freshwater resources. Capacitive deionization (CDI) is hopeful to supply water to the population due to operation at low potential along with low energy expenditure when low salinity (5 mM NaCl) feed water solutions are desalinated. Electrode material is the main controlling factor in CDI system and a lot of efforts are devoted to develop excellent materials for better CDI performance. So far, carbon materials are widely used as the electrode for CDI, though limitations such as co-ion expulsion and faradaic reactions hinder their full utilization. Alternatively, battery materials are used since their performance is great due to mitigation of co-ions ejection as well as faradaic reactions. In 2019 our group reviewed factors affecting the performance of activated carbon electrode materials and revealed lack of selectivity, co-ion expulsion, low electrical conductivity and inappropriate pore size distribution to largely contribute to its low salt removal capacity [1]. Therefore, herein, we extend the discussion beyond AC to include other carbons such as aerogels, nanotubes, graphenes etc., and battery materials such as MXenes, sodium super ionic conductors, and BiOCl to mention the few. This article also discusses the extent CDI is applied in the laboratory scale as well as in the field for desalination of real water, wastewater remediation and removal of harmful contaminants to substantiate what it can offer beyond the laboratory experiments. The work is expected to save as a complete reference for the progress of CDI electrode materials and its applications in water purification. [Display omitted] • Capacitive deionization using carbon and battery materials is discussed. • Methods to enhance salt removal of electrode materials are uncovered. • Modification improves the performance of carbon and battery materials. • CDI is applied in desalination, wastewater remediation, and decontamination. [ABSTRACT FROM AUTHOR]

[Display omitted] • The applications of CDI from ion-selectivity to resource recovery. • Mechanisms for selective removal of Ca2+ and Mg2+ were defined and categorized. • Recent advances in electrode materials for Ca2+ and Mg2+ removal in CDI. • Clarified the impact of operating conditions and ionic properties on ion-selectivity. • Future perspectives and challenges for Ca2+ and Mg2+ selective removal were raised. Hardness problems caused by Ca2+ and Mg2+ significantly impact human production and life, greatly hindering the effective use of water resources. Meanwhile, the effective extraction of mineral resources such as calcium and magnesium from industrial waste brine has triggered widespread concern. Due to its sustainability, cost-effectiveness, and low energy consumption, CDI in water treatment applications began to be constantly expanded in recent years, and its research in Ca2+ and Mg2+ selective removal showed a trend of increasing year by year. However, no comprehensive review offers a thorough analysis of this topic. Therefore, our review critically assesses CDI research advances related to calcium and magnesium ion elimination. This article reviews and categorizes general aspects of CDI and selective calcium and magnesium removal mechanisms, summarizing relevant electrode materials and highlighting factors influencing process performance. Following this, this review summarizes the current scenarios for selective application and envisions potential future applications. Finally, the challenges and perspectives in implementing CDI for the selective removal of calcium and magnesium ions have been discussed. The insights from this review will promote the further development of CDI in the field of Ca2+ and Mg2+ selective removal, as well as advance the in-depth research of CDI in ion-selective removal. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is an electrochemical desalination technology that removes ions from brackish water through electrosorption within charged porous electrodes. Brackish waters contain ions that may form precipitates on the electrodes (e.g., Ca2+, Mg2+, CO 3 2−), especially in response to localized pH increases common at cathodes. Here we study the formation of calcium carbonate (CaCO 3(s)) on the cathode and its effect on Na+ removal using defined solution chemistries. We found that CaCO 3(s) formed during the charging phase at the cathode, but not the anode. Local precipitation was likely due to the in situ basic pH caused by the reduction of dissolved oxygen at the cathode. The deposition of solids reduced Na+ adsorption capacity by 67 % (0.94 ± 0.08 mg/g-C) compared to a control where no Ca2+ and HCO 3 − were present. We attributed this reduction primarily to the ∼30 % decrease in micropores available for electrosorption. These interior pores were blocked by non-porous CaCO 3 crystals. Cathodes with precipitation had reduced capacitance and increased resistance. The deposition of non-conductive crystals hindered the transfer of charge and restricted the movement of ions from the bulk solution toward the electrode surface and also through the pores' structure. Since precipitation was found to be detrimental to salt removal, future research is needed to reduce scaling and/or strategies to regenerate the electrosorption capacity of electrodes. For other applications, such as water softening, research to improve precipitation might be desired. [Display omitted] • Calcium carbonate precipitated on the cathode in flow-through capacitive deionization • Precipitation reduced sodium adsorption capacity by almost 70 % • Cathode micropore volume decreased by 30 % after precipitation • Precipitation was associated with an increase in resistance and decrease in capacitance [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is a novel and prospective technique mainly for desalination, featuring low-cost, easy maintenance, and environmental-friendly. As CDI develops by leaps and bounds, the electrode materials, the cell architectures, and the application fields have gained a lot of progress as reported. In order to optimize electrode materials, innovate cell architectures, broaden application fields, CDI adsorption mechanism exploration, as a necessary and important approach, have aroused enormous interest by researchers. This work provides a review of the strategies for investigating CDI adsorption mechanism form four aspects: experimental, mathematical model, computational chemistry, and machine learning, accompanied by discussing the prospects of these methods. Through a fine-grained summarization of the correlative reports from initial studies to the publications of late, it is expected that the meticulous statement of the characteristics, progress, and challenges of these exploration methods in this review can provide a fundamental support to facilitate prospective development of CDI. [Display omitted] • Techniques for mechanistic studies of CDI adsorption are reviewed. • Progress about four mechanism exploration strategies are discussed in-depth. • Challenges and perspectives for exploring CDI adsorption mechanism are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A review of electrochemical lithium extraction based on electrodialysis and capacitive deionization is provided. • The advantages and challenges of electrochemical lithium extraction technologies are explained. • The directions for future research and development are determined. Efficient lithium extraction and separation technologies are increasingly imperative owing to the rising demand for lithium in energy storage and electronics. However, the elevated energetic and monetary costs relative to conventional thermal and pressure separation methods, such as reverse osmosis and distillation, significantly diminish the attractiveness of this endeavor. Recently, electrochemical methods are extending into the Li+ separation and extraction technologies, including electrodialysis and capacitive deionization. This work systematically reviews recent advancements in these electrochemical extraction methods for lithium concentration. First, it systematically assesses the key evaluation parameters including extraction capacity, selectivity factor, and specific energy consumption. Moreover, advanced characterization methods crucial for comprehending the intricacies of these electrochemical technologies are outlined. Specifically, this study elucidates the extraction principles of these electrochemical methods, consolidates the current state of advancement in these extraction techniques, and juxtaposes the performance parameters of these methods. Finally, it anticipates current challenges and delineates future research directions for lithium extraction via electrodialysis and capacitive deionization techniques, thereby furnishing guidelines for lithium extraction endeavors. [ABSTRACT FROM AUTHOR]

• Novel E-CDI with catalytic electrodes was developed for phosphonate degradation. • C-MCE with outstanding ORR performance improved the self-generation of H 2 O 2. • A-MCE provided an ideal platform for the reaction between ·OH and phosphonate. • E-CDI exhibited higher degradation efficiency and lower cost than traditional AOPs. Phosphonate is becoming a global interest and concern owing to its environment risk and potential value. Degradation of phosphonate into phosphate followed by the recovery is regarded as a promising strategy to control phosphonate pollution, relieve phosphorus crisis, and promote phosphorus cycle. Given these objectives, an anion-membrane-coated-electrode (A-MCE) doped with Fe-Co based carbon catalyst and cation-membrane-coated-electrode (C-MCE) doped with carbon-based catalyst were prepared as catalytic electrodes, and a novel electrocatalytic capacitive deionization (E-CDI) was developed. During charging process, phosphonate was enriched around A-MCE surface based on electrostatic attraction, ligand exchange, and hydrogen bond. Meanwhile, Fe2+ and Co2+ were self-oxidized into Fe3+ and Co3+, forming a complex with enriched phosphonate and enabling an intramolecular electron transfer process for phosphonate degradation. Additionally, benefiting from the stable dissolved oxygen and high oxygen reduction reaction activity of C-MCE, hydrogen peroxide accumulated in E-CDI (158 μM) and thus hydroxyl radicals (·OH) were generated by activation. E-CDI provided an ideal platform for the effective reaction between ·OH and phosphonate, avoiding the loss of ·OH and triggering selective degradation of most phosphonate. After charging for 70 min, approximately 89.9% of phosphonate was degraded into phosphate, and phosphate was subsequently adsorbed by A-MCE. Results also showed that phosphonate degradation was highly dependent on solution pH and voltage, and was insignificantly affected by electrolyte concentration. Compared to traditional advanced oxidation processes, E-CDI exhibited a higher degradation efficiency, lower cost, and less sensitive to co-existed ions in treating simulated wastewaters. Self-enhanced and selective degradation of phosphonate, and in-situ phosphate adsorption were simultaneously achieved for the first time by a E-CDI system, showing high promise in treating organic-containing saline wastewaters. [Display omitted] [ABSTRACT FROM AUTHOR]

The facile synthesis approach for the adsorbent preparation and recyclability during decontamination of radioactive pollutants is a significant concern in water treatment. The objective of this study is to, synthesis via solid-state reaction of the nanostructured CaTiO 3 for the removal and recovery of strontium (Sr2+) from the various water sources. The influence of the adsorption-dependent parameters including, initial concentration, adsorbent dose, pH, contact time and co-existing ions interference were investigated. The prepared adsorbent was characterized by different analytical techniques like FT-IR, SEM with EDAX, TEM, TGA-DTG, Powder XRD and BET surface analysis. The kinetic models were also used, and according to the kinetic models, a pseudo-second-order kinetic model (R2 = 0.999) was better fitted to the adsorption of Sr2+ ions onto CaTiO 3 rather than pseudo-first-order kinetics, which could properly represent the observed adsorption of Sr2+. For the isotherm study, the results are best fitted to the Langmuir isotherm model (R2 = 0.98) with a maximum adsorption capacity of 102.04 mg/g. The common ions (Na+, Mg2+, Ca2+, and K+) and Sr2+ having a concentration of 1:2, 1:3, and 1:4, where 82.8, 79.5, and 68.2 % removal was achieved of Sr2+ in each respective matrix. In addition, the adsorption and corresponding recovery and removal for the different Sr2+spiked matrices in deionized water, tap water, well water, lake water, and seawater were investigated with 97, 65.6, 76.5, 73.9 and 17.8 % removal respectively. Also, the CaTiO 3 showed excellent recyclability with minimal loss even after 5 consecutive recyclability cycles and >90% removal of strontium achieved. Hence, prepared nanostructured CaTiO 3 could be considered a promising adsorbent for the removal and recovery of Sr2+ions from contaminated water bodies. [Display omitted] • CaTiO 3 nanostructured adsorbent was synthesized through single step synthesis. • Pseudo-second order kinetic model was best fitted to the adsorption of Sr2+. • Maximum adsorption capacity was found 102.04 mg/g. • Sr2+ spiked different water bodies were tested and found 76.5 to 17.8 % removal. • CaTiO 3 showed excellent five successive recyclability cycles. [ABSTRACT FROM AUTHOR]

Global water demand and environmental concerns related to climate change require industries to develop high-efficiency wastewater treatment methods to remove pollutants. Likewise, toxic pollutants present in wastewater negatively affect the environment and human health, requiring effective treatment. Although conventional treatment processes remove carbon and nutrients, they are insufficient to remove pharmaceuticals, pesticides, and plasticizers. Electrochemical processes effectively remove pollutants from wastewater through the mineralization of non-biodegradable pollutants with consequent conversion into biodegradable compounds. Its advantages include easy operation, versatility, and short reaction time. In this way, this review initially provides a global water scenario with a view to the future. It comprises global demand, treatment methods, and pollution of water resources, addressing various contaminants such as heavy metals, nutrients, organic compounds, and emerging contaminants. Subsequently, the fundamentals of electrochemical treatments are presented as well as electrochemical treatments, highlighting the latest studies involving electrocoagulation, electroflocculation, electroflotation, capacitive deionization and its derivatives, eletrodeionization, and electrochemical advanced oxidation process. Finally, the challenges and perspectives were discussed. In this context, electrochemical processes have proven promising and effective for the treatment of water and wastewater, allowing safe reuse practices and purification with high contaminant removal. [Display omitted] • The latest studies involving electrochemical treatments were discussed. • Inclusive explanations of electrochemical processes were highlighted. • Electrochemical treatments can produce chemicals and simultaneously degrade pollutants. • Electrocoagulation/flocculation removes efficiently macromolecular organic compounds. • Capacitive deionization and its derivatives have stood out in the removal of heavy metals. [ABSTRACT FROM AUTHOR]

Piezo-electricity, as a unique physical phenomenon, demonstrates high effectiveness in capturing the environmental mechanical energy into polarization charges, offering the possibility to activate the advanced oxidation processes via the electron pathway. However, information regarding the intensification of Fe(VI) through piezo-catalysis is limited. Therefore, our study is the first to apply Bi 2 WO 6 nanoplates for piezo-catalyzation of Fe(VI) to enhance bisphenol A (BPA) degradation. Compared to Fe(VI) alone, the Fe(VI)/piezo/Bi 2 WO 6 system exhibited excellent BPA removal ability, with the degradation rate increased by 32.6% at pH 9.0. Based on the experimental and theoretical results, Fe(VI), Fe(V), Fe(IV) and •OH were confirmed as reaction active species in the reaction, and the increased BPA removal mainly resulted from the enhanced formation of Fe(IV)/Fe(V) species. Additionally, effects of coexisting anions (e.g., Cl−, NO 3 −, SO 4 2− and HCO 3 −), humic acid and different water matrixes (e.g., deionized water, tap water and lake water) on BPA degradation were studied. Results showed the Fe(VI)/piezo/Bi 2 WO 6 system still maintained satisfactory BPA degradation efficiencies under these conditions, guaranteeing future practical applications in surface water treatment. Furthermore, the results of intermediates identification, ECOSAR calculation and cytotoxicity demonstrated that BPA degradation by Fe(VI)/piezo/Bi 2 WO 6 posed a diminishing ecological risk. Overall, these findings provide a novel mechanical energy-driven piezo-catalytic approach for Fe(VI) activation, enabling highly efficient pollutant removal under alkaline condition. [Display omitted] • Bi 2 WO 6 nanoplates was first used for piezo-catalyzation of Fe(VI). • The Fe(VI)/piezo/Bi 2 WO 6 system significantly enhanced the removal of BPA. • Piezo-activation enhanced the weak reactivity of Fe(VI) under alkaline conditions. • Bi 2 WO 6 mediated piezo-catalysis effectively fastened the formation of Fe(IV)/Fe(V). • Piezo-activation of Fe(VI) provides an energy-saving method for water remediation. [ABSTRACT FROM AUTHOR]

The efficiency of saturated Activated Carbon (AC) electrochemical regeneration was evaluated. Reactor configurations in cathodic/anodic process, applied current effect on the properties of AC and Methylene Blue MB-AC interactions and adsorption/desorption mechanisms were studied. The efficiency was measured by adsorption capacity adsorption/regeneration cycles and changes in the adsorbent characteristic were analyzed through FTIR, BET, Optical Microscopy (OM) and SEM before and after the regeneration. The energy consumption was analyzed to assess the economic feasibility. It was found that the electrochemical treatment was efficient in returning the AC adsorption capacity, maximum efficiencies of approximately 79% and 84% were reached when the Carbon Fiber Cloth-AC electrode was subjected to anodic and cathodic currents, respectively, at a current of 0.1 A. In addition, the material demonstrated good stability through adsorption-regeneration cycles by cathodic process, with the material's adsorption capacity being almost totally recovered for 8 consecutive cycles. The removal percentage around 80% was kept after the cycles, with optimal conditions when the electrode was subjected to cathodic currents, NaCI as electrolyte at a current of 0.1 A for 2 h. The characterization techniques provided results that allow to explain the higher and prolonged efficiency of the cathodic current. Furthermore, these reactor configurations achieved an electrical energy consumption of 2.3 and 2.1 kWh kg-1 of material for cathodic and anodic, respectively. These results indicate that the electrochemical is an economical and environmental suitable technique capable of restore carbon adsorbents to be reusable for several water treatment cycles. [ABSTRACT FROM AUTHOR]

The present research involves removing copper and nickel ions from synthesized wastewater by using a simple, cheap, cost-effective, and sustainable activated green waste tea residue (AGWTR) adsorption coupled with electrocoagulation (ADS/EC) process in the presence of iron electrodes. By considering previous studies, their adsorbents used for treating their wastewaters firstly activate them by applying either chemicals or activating agents. However, our adsorbent was prepared without applying neither chemicals nor any activating agents. The operating parameters such as pH, hydraulic retention time, adsorbent dose, initial concentration, current density, and operating cost for both metals were optimized. In ADS/EC, the removal efficiency was obtained as 100% for copper and 99.99% for nickel ions. After the ADS/EC process, Fourier transform infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) analysis were used to characterize the adsorbent green waste tea residue. The adsorption isotherm and kinetic model results showed that the Langmuir and the pseudo-second-order were well-fitted to the experimental adsorption data better than the Freundlich and pseudo-first-order models for both Cu2+ and Ni2+ with their maximum adsorption capacity of 15.6 and 15.9 mg g−1, respectively. The above results give an option to recycle the metal-based industrial effluents, tea industry-based wastes, enabling a waste-to-green technique for adsorbing and removing the heavy metals and other pollutants in water. [ABSTRACT FROM AUTHOR]

A photoelectrochemical (PEC) oxidation and flow-electrode capacitive deionization (FCDI) dual system was explored for the effective treatment of brackish water. Two anodic electrodes with electrochemically self-doped TiO2 arrays (blue-mesh/ blue-plate TiO2 nanotube arrays (BM-TNA & BP-TNA)) were fabricated by annealing at 600 °C, and applied for the treatment of a water system. Specifically, the BM-TNA confirmed lower electrical resistance and superior performance under multiple light source (UV-A, -B, and -C). Furthermore, the system generated powerful oxidizing reactive oxygen species (ROS), which were assessed via degradation of eight organic pollutants: bisphenol-A, 4-chlorophenol, cimetidine, sulfamethoxazole, benzoic acid, phenol, nitrobenzene, and acetaminophen. Decomposition efficiency was stable throughout a wide range of pH, and durability of the BM-TNA electrode was demonstrated through long-term operation. Concurrently, optimization of the FCDI process via key operational parameters (electrode mass loading, and applied voltage) achieved superior desalination performance, and specific energy consumption (SEC). In particular, increased mass loading enhanced charge transportation through the formation of stable charge-percolation pathways, leading to improved solution conductance. Finally, the feasibility of the dual system (PEC-FCDI) was verified through complete degradation of the organic substrates and successful desalination of the brackish water. [ABSTRACT FROM AUTHOR]

Environmental pollution requires advanced methods and materials to clean drinking water. In particular, 2D transition metal carbides, named MXenes, display unique properties such as specific surface area, surface functional groups, conductivity, and antibacterial effects. Here, we review the applications of MXenes for water purification, and the factors controlling the efficiency of MXenes. We present the history of MXenes and focus on applications for adsorption, capacitive deionization, membranes, and catalysis. [ABSTRACT FROM AUTHOR]