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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]

Super activated carbon is a promising electrode material for capacitive deionization (CDI), an emerging sustainable desalination technology. Increasing its CDI performance requires improving hydrophilicity while maintaining high specific surface area. Traditionally this is challenging, but modifying super activated carbon with earth-abundant metal ions at room temperature can achieve both aims through a low-energy process aligned with sustainability. The modified super activated carbon showed higher specific surface area, improved hydrophilicity, and enhanced desalination performance. Particularly, the salt adsorption capacity of Cu2+- modified super activated carbon in 500 mg/L NaCl solution at 1.2 V increased from 35.4 mg/g to 49.3 mg/g, among the highest for sustainable carbon materials. The capacity increase was enabled by simultaneously increasing specific surface area and hydrophilicity through themetal modification process. Along with high charge efficiency (93.4%), fast adsorption rate, and good cycling stability (80% capacity retention over 50 cycles), the modified super activated carbon displayed superior overall desalination performance. This study exemplifies how sustainable design principles can be applied to synthesize high-performance CDI electrode materials, through green chemistry and engineering for optimized efficiency. [ABSTRACT FROM AUTHOR]

As a universal demand due to global water scarcity, capacitive deionization (CDI) has emerged as an energy-effective, eco-friendly desalination technology for removing dissolved salts from brackish water by forming electric double-layers through adsorption onto electrode surfaces, and there is a potential direction to be used for desalination of drinking water. It is still necessary to enhance desalination performance to desalinate raw salty water. In this work, commercial activated carbon electrodes were prepared for investigation in a CDI cell for water desalination with a minimum required construction at two different masses, and the investigated cells were subjected to 25 cycles of adsorption and desorption (each cycle 800 s) in a direction to investigate the deep cycles of stability and refreshment methods. The CDI cell with low-mass electrodes shows a higher electrosorption capacity of 33.77 mg/g using NaCl solution with an initial concentration of 870 ppm at the applied voltage of 2 V. An interesting refreshment behavior was observed and investigated for the high-mass cell electrodes after stability measurement for 25 cycles using different strategies. This refreshment behavior will open the route for more understanding of the ion's kinetics by adsorption and desorption on the electrode surfaces and the changes in the electrode structures. This paper presented a relatively simple and easily scalable treatment for recovering the stability of the capacitive deionization cells and demonstrated the great potential of its use in water desalination applications. [ABSTRACT FROM AUTHOR]

Sulfate is a typical characteristic pollutant in mine water. Because of its high concentration and large discharge of mine water, it has become a difficult problem in mineral exploitation. Capacitive deionization (CDI) is an innovative and economical removal technology. There are few reports on the use of CDI to remove SO42− from mine water. In this study, a CeO2 activated carbon electrode with good wettability, excellent electrochemical performance, and suitable pore structure was prepared by the sol-gel method. The application of the CeO2 activated carbon electrode to the capacitive method for treating high SO42− mine water was investigated using simulated wastewater and actual mine water. The study structure shows that CeO2:activated carbon (AC) has the best wettability, the highest specific capacitance, and the lowest electrical conductivity when the mass ratio of CeO2 is 5%. At 100 mg/L, the electrode has the maximum SO42− ion specific adsorption capacity (SAC). At 1 V and 20 mL/min, this value is measured. The electrode has a SAC value of 9.36 mg/g, far higher than the AC electrode's 4.1 mg/g. The effect of CDI process factors such the voltage, flow rate, and initial concentration was studied to find the best treatment method. SAC retention is 91% after 10 adsorption–desorption cycles, demonstrating outstanding electrode performance. Under the best CDI process (1.4 volts, 30 mL/min), mine water was treated. After 20 cycles of treatment, the concentration of SO42− in mine water decreased from 1170 mg/L to 276.46 mg/L, and the removal rate was 76.37%. This study proved that the CeO2 modified activated carbon electrode capacitance method can effectively remove sulfate ions and other ions from mine water. [ABSTRACT FROM AUTHOR]

In this work, a new voltammetric procedure for acyclovir (ACY) trace-level determination has been described. For this purpose, an electrochemically activated screen-printed carbon electrode (aSPCE) coupled with well-conductive electrolyte (CH3COONH4, CH3COOH and NH4Cl) was used for the first time. A commercially available SPCE sensor was electrochemically activated by conducting cyclic voltammetry (CV) scans in 0.1 mol L−1 NaOH solution and rinsed with deionized water before a series of measurements were taken. This treatment reduced the charge transfer resistance, increased the electrode active surface area and improved the kinetics of the electron transfer. The activation step and high conductivity of supporting electrolyte significantly improved the sensitivity of the procedure. The newly developed differential-pulse adsorptive stripping voltammetry (DPAdSV) procedure is characterized by having the lowest limit of detection among all voltammetric procedures currently described in the literature (0.12 nmol L−1), a wide linear range of the calibration curve (0.5–50.0 and 50.0–1000.0 nmol L−1) as well as extremely high sensitivity (90.24 nA nmol L−1) and was successfully applied in the determination of acyclovir in commercially available pharmaceuticals. [ABSTRACT FROM AUTHOR]

The development of efficient energy storage systems is critical in the transition towards sustainable energy solutions. In this context, the present work investigates the viability of using orange juice, as a promising and sustainable precursor, for the synthesis of activated carbon electrodes for supercapacitor technologies. Through the carbonization-activation process and controlling the preparation parameters (KOH ratio and activation time), we have tailored the specific surface area (SSA) and pore size distribution (PSD) of the resulting carbon materials—crucial parameters that support supercapacitive performance. Several spectroscopic, morphological, and electrochemical techniques are used to characterize the obtained carbon materials. In particular, our optimization efforts revealed that a 5:1 KOH ratio with an activation time up to 120 min produced the highest SSA of about 2203 m2/g. Employing these optimal conditions, we fabricated symmetric coin cell supercapacitors using Na2SO4 as the electrolyte, which exhibited interesting specific capacitance (~56 F/g). Durability testing over 5000 cycles sustained the durability of the as-made activated carbon electrodes, suggesting an excellent retention of specific capacitance. This study not only advances the field of energy storage by introducing a renewable material for electrode fabrication but also contributes to the broader goal of waste reduction through the repurposing of food byproducts. [ABSTRACT FROM AUTHOR]

Agricultural residues are the most available biomass resources in the world and can be exploited to produce various activated carbons at low cost. The textural properties of activated carbon, including surface area, pore size, pore size distribution, and certain surface functionalities are the main factors in the application of bio‐based electrode materials for energy storage devices and electrochemical catalyst for CO2 reduction reactions, gas adsorption and separation, in water and wastewater treatment. This paper reviews the physical characteristics of activated carbons produced from various biomass resources using different methods. The effects of different activation methods, sources of biomass, and other parameters on the surface properties such as specific surface area and pore volume of activated carbon are discussed. The differences in the characteristics of activated carbon made from different agricultural biomass resources under the same parameters are evaluated. Eventually, the application of abundant agricultural residues for fabricating supercapacitors' electrode materials is also discussed. [ABSTRACT FROM AUTHOR]

Strategically upcycling industrial wastes such as petroleum coke and dye wastewater into value-added materials through scalable and economic processes is an effective way to simultaneously tackle energy and environmental issues. Doping carbon electrodes with heteroatoms proves effective in significantly enhancing electrochemical performance through alterations in electrode wettability and electrical conductivity. This work reports the use of dye wastewater as the sole dopant source to synthesize N and S co-doped petroleum coke-based activated carbon (NS-AC) by the one-step pyrolysis method. More importantly, our wastewater and petroleum coke-derived activated carbon produced on a large scale (20 kg/batch) shows a specific surface area of 2582 m2 g−1 and an energy density of about 95 Wh kg−1 in a soft-packaged full cell with 1 M TEATFB/PC as the electrolyte. The scalable production method, together with the green and sustainable process, can be easily adopted and scaled by industry without the need for complex processes and/or units, which offers a convenient and green route to produce functionalized carbons from wastes at a low cost. [ABSTRACT FROM AUTHOR]

[Display omitted] Porous carbon materials have been regarded as a promising alternative to activated carbon for desalination via capacitive deionization (CDI) due to refined architectures and functionalities. However, it is still challenging to obtain a controlled hierarchical pore structure and considerable nitrogen-doped content by convenient method. Herein, nitrogen-doped hierarchical porous carbon foams (NHCFs) with different microstructural features, nitrogen contents and nitrogen species were successfully fabricated via a stepwise pyrolysis carbonization strategy using easily available melamine foam. Due to the synergistic effect of hierarchical porous structure and doped nitrogen, the optimized NHCF sample carbonized at 800℃ (NHCF-800) exhibited a maximum desalination capacity of 30.1 mg g−1 at the optimal operating parameters (500 mg/L NaCl solution, 1.2 V) and an excellent regeneration performance after 50 continuous adsorption–desorption cycles. Furthermore, density functional theory (DFT) was also conducted to elaborate the disparity of sodium adsorption energy among the nitrogen species for in-depth understanding, and it mainly benefits from the ascendency of the pyrrolic-N and pyridinic-N over the graphitic-N dopant. This work paves the way of rational regulation of nitrogen-doped process and hierarchical porous structure carbon as CDI electrode materials for desalination. [ABSTRACT FROM AUTHOR]

The rapid rise of the world population increases the annual amount of waste textile products. Textile products create a significant amount of CO2, water, and chemical footprints during production. Therefore, the reusability of textile products has an important environmental and economic impact. Waste denim was used in this study to produce activated carbon (AC) samples as the alternative substance for supercapacitor electrodes. Characterisation studies showed that AC samples contain nitrogen originating from the elastane in the denim structure. Electrochemical characterisation tests proved the pseudocapacitive behaviour of the denim-derived AC due to the nitrogen content. Specific capacitance values observed for the three-electrode and two-electrode cell configurations were 95.93 F/g and 54.64 F/g at 1 A/g, respectively. Good capacitive retention (83.01%) of the cell after 3000 galvanostatic charge-discharge cycles at 1 A/g shows that waste denim can be considered as raw material for energy storage systems. [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]

The primary goal of the current study is to improve the specific capacitance of electric double-layer (EDLC) device using biomass (Tribulus Terrestris) derived activated carbon electrodes synthesized by chemical activation method. Furthermore, high surface area carbon electrodes are characterized using X-ray diffraction (XRD), RAMAN spectroscopy, and scanning electron microscopy (SEM) to confirm the morphological structure. Finally, the electrochemical performance of fabricated EDLC proves a good agreement data using Cyclic Voltammetry (CV), Low Impedance Spectroscopy (LIS), and Galvanostatic Charge–Discharge (GCD) analysis showing the high specific capacitance of 115 Fg−1 for the optimized 1:2 activated carbon material. [ABSTRACT FROM AUTHOR]

Capacitive Deionization (CDI) is a low energy, environmentally friendly desalination technology. In this study, PTFE activated carbon electrodes were prepared based on emulsion spraying technology and applied to CDI. In this article, resistivity, contact angle, specific surface area was tested. Combined with scanning electron microscope(SEM) and cyclic voltammetry(CV), the influence of KH550 dosages (2 g, 4 g, 6 g, 8 g) and layers of spraying (1–6 layers) on electrode performance was investigated. Coupling reagent KH550 played a role to enhance the adhesion of PTFE, and bridge activated carbon to form path for electron together with PTFE. When 4 g KH550 is added, a continuous conductive path was achieved, so the electrode exhibit good conductivity, with a resistivity of 7.65 Ω/cm. As layer increasing, more active carbon, the adsorbent, were joined together by binder, PTFE and KH550. Therefore, the specific surface area and capacitance increased. When 4 layers were sprayed, the electrode obtained a better specific capacitance, 0.564 F/cm2, but the mass transfer resistance became higher. Electrode, prepared by 4 g KH550 and 3 layers, was used for desalination. For low-concentration brine, salt removal rate and charge efficiency were 8.849 mg/g and 46.75%, respectively. This research provides a simple route for the preparation of activated carbon electrodes for the preparation of CDI, which was easy to expand production. The prepared electrode has great application potential in brackish water desalination. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is a promising and cost-effective technology that is currently being widely explored for removing dissolved ions from saline water. This research developed materials based on activated carbon (AC) materials modified with zinc oxide (ZnO) nanorods and used them as high-performance CDI electrodes for water desalination. The as-prepared electrodes were characterized by cyclic voltammetry, and their physical properties were studied through SEM and XRD. ZnO-coated AC electrodes revealed a better specific absorption capacity (SAC) and an average salt adsorption rate (ASAR) compared to pristine AC, specifically with values of 123.66 mg/g and 5.06 mg/g/min, respectively. The desalination process was conducted using a 0.4 M sodium chloride (NaCl) solution with flow rates from 45 mL/min to 105 mL/min under an applied potential of 1.2 V. Furthermore, the energy efficiency of the desalination process, the specific energy consumption (SEC), and the maximum and minimum of the effluent solution concentration were quantified using thermodynamic energy efficiency (TEE). Finally, this work suggested that AC/ZnO material has the potential to be utilized as a CDI electrode for the desalination of saline water. [ABSTRACT FROM AUTHOR]

Adsorption cooling and desalination (ACD) system presents a solution for water, energy, and environmental dilemma. This study expresses an enhancement of adsorption system performance in terms of cooling and desalination effects by improving an activated carbon Maxsorb III (Max) as an adsorbent. Max has been initially treated with HCl. Then, it has been activated by impregnating it in salt hydrates ((NH4)2CO3). Characterization methods, including XRD, N2 and water adsorption isotherm, and water adsorption kinetics have been conducted for raw Max, treated Max, and activated Max with (NH4)2CO3. The experimental values have been fitted with the Dubinin & Astakhov equilibrium model for isotherm and the model of linear driving force for kinetics. These fitted parameters have been utilized in a previously validated model to estimate adsorption cooling-desalination system performance with and without heat recovery. Max/(NH4)2CO3 achieves a water uptake of 0.53 kgH2O.kg-1. Max/(NH4)2CO3 produces 13.2 m3.ton-1 of freshwater per day with a specific cooling power of 373 W.kg-1 and 0.63 COP. Also, the freshwater reaches 22.5 m3.ton-1 of Max/(NH4)2CO3 per day with condenser-evaporator heat recovery. These results indicate the potential of utilizing the Max material in dual cooling and desalination applications to achieve double what silica gel can offer. [ABSTRACT FROM AUTHOR]

Magnetic activated carbon particles (Fe3O4/active carbon composites) as auxiliary electrodes (AEs) were fixed on the surface of Ti/Sb-SnO2 foil by a NdFeB magnet to form a new magnetically assembled electrode (MAE). Characterizations including cyclic voltammetry, Tafel analysis, and electrochemical impedance spectroscopy were carried out. The electrochemical oxidation performances of the new MAE towards different simulated wastewaters (azo dye acid red G, phenol, and lignosulfonate) were also studied. Series of the electrochemical properties of MAE were found to be varied with the loading amounts of AEs. The electrochemical area as well as the number of active sites increased significantly with the AEs loading, and the charge transfer was also facilitated by these AEs. Target pollutants' removal of all simulated wastewaters were found to be enhanced when loading appropriate amounts of AEs. The accumulation of intermediate products was also determined by the AEs loading amount. This new MAE may provide a landscape of a more cost-effective and flexible electrochemical oxidation wastewater treatment (EOWT). [ABSTRACT FROM AUTHOR]

In this study, carbon aerogels (CAs) were synthesized by the sol-gel method, using environmentally friendly glucose as a precursor, and then they were further activated with potassium hydroxide (KOH) to obtain activated carbon aerogels (ACAs). After the activation, the electrochemical performance of the ACAs was significantly improved, and the specific capacitance increased from 19.70 F·g−1 to 111.89 F·g−1. Moreover, the ACAs showed a stronger hydrophilicity with the contact angle of 118.54° compared with CAs (69.31°). When used as an electrode for capacitive deionization (CDI), the ACAs had not only a better diffuse electric double layer behavior, but also a lower charge transfer resistance and intrinsic resistance. Thus, the ACA electrode had a faster CDI desalination rate and a higher desalination capacity. The unit adsorption capacity is three times larger than that of the CA electrode. In the desalination experiment of 100 mg·L−1 sodium chloride (NaCl) solution using a CDI device based on the ACA electrode, the optimal electrode spacing was 2 mm, the voltage was 1.4 V, and the flow rate was 30 mL·min−1. When the NaCl concentration was 500 mg·L−1, the unit adsorption capacity of the ACA electrode reached 26.12 mg·g−1, much higher than that which has been reported in many literatures. The desalination process followed the Langmuir model, and the electro-sorption of the NaCl was a single layer adsorption process. In addition, the ACA electrode exhibited a good regeneration performance and cycle stability. [ABSTRACT FROM AUTHOR]

One of the global problems is environmental pollution by different biowaste. To solve the problem, biowaste must be recycled. Waste-free technology is also a way of saving exhaustible raw materials. Research on electrochemical energy sources is currently the most dynamically developing area of off-grid energy. Electrochemical capacitors can operate for a long time without changing performance, they have smaller dimensions, high mechanical strength, and a wide operating temperature range. These properties are effective energy-saving devices. Therefore, supercapacitors are widely used in various industries. This review discussed the methods of obtaining and the characteristics of biowaste-derived activated carbon and carbon–manganese oxide (AC-MnO2)-based supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

A kenaf-derived activated carbon (KAC) for a high-power density supercapacitor was developed in this study through phosphoric acid activation. The N2/77K isothermal adsorption–desorption curve was used to estimate the textural properties of KAC based on BET and BJH and the pore size distribution based on NLDFT. The electrochemical properties of KAC were analyzed by using the coin-type cell applying 1 M SPBBF4/PC electrolyte, and the specific surface area and total pore volume were 1490–1942 m2/g and 1.18–3.18 cm3/g, respectively. The pore characteristics of KAC varied according to the activation temperature, and most KAC showed a mesoporous structure. As the activation temperature increased, the mesopore volume increased up to 700 °C, then decreased. The mesoporous structure of KAC resulted in a substantial decrease in the Warburg impedance as the ion diffusion resistance decreased. Hence, the specific capacitance of KAC decreased from 82.9 F/g to 59.48 F/g as the charge–discharge rate increased from 1 mA/g to 10 mA/g, with the rate of reduction at approximately 30%. The rate of reduction of KAC's specific capacitance was 50% lower compared with commercial activated carbon; hence, KAC is a more suitable electrode-active material for high power density supercapacitors. [ABSTRACT FROM AUTHOR]

Electrochemical storage of neutralised protons in porous carbon materials such as activated carbons and multi-layer graphene is becoming possible using novel technologies such as the proton battery and proton flow reactor. This set-up is a promising option for electrical energy storage at various scales, and possibly for exporting a zero-emission hydrogen-based fuel. This paper focusses on understanding and identifying the contributions to hydrogen storage in activated carbon from phenolic resin (aC PR) from processes such as electric double layer capacitance, electrosorption, cationic concentration by intercalation in ultramicropores, and reversible faradaic (redox) reactions between hydronium, and negatively-charged carbon surfaces inside pores with and without intermediary oxygen groups. A combination of XPS, Raman, and infrared spectroscopy is employed to identify the forms of C ⋯ H reactions involved, together with temperature programmed desorption, cyclic voltammetry and galvanostatic charging and discharging. Experimental evidence for the formation of C⋯H bonding in aC PR is presented, which promises to be sufficient for use of this and similar carbon materials as a solid-state hydrogen storage material with competitive energy density. [Display omitted] • Principal mechanisms for electrochemical hydrogen storage in carbon-based materials are discussed. • C...H bonding is characterised through XPS, Raman, and infrared techniques. • Hydrogen stored in an activated carbon is retained and recovered after drying the powder. [ABSTRACT FROM AUTHOR]

Freshwater reserves are being polluted every day due to the industrial revolution. Man-made activities have adverse effects upon the ecosystem. It is thus the hour of need to explore newer technologies to save and purify water for the growing human population. Capacitive deionization (CDI) is being considered as an emerging technique for removal of excess ions to produce potable water including desalination. Herein, cost-effective activated carbon incorporated with carbon nanotubes (CNT) was used as a freestanding electrode. Further, the desalination efficiency of the designed electrodes was tuned by varying binder concentration, i.e., polyvinylidene difluoride (PVDF) in the activated carbon powder and CNT mixture. PVDF concentration of 5, 7.5, 10, and 12.5 wt% was selected to optimize the freestanding electrode formation and further applied for desalination of water. PVDF content affected the surface morphology, specific surface area, and functional groups of the freestanding electrodes. Moreover, the electrical conductivity and specific surface area changed with PVDF concentration, which ultimately affected the desalination capacity using the freestanding electrodes. This study paves the way to produce cost effective carbon-based freestanding electrodes for capacitive deionization and other applications including battery electrodes. [ABSTRACT FROM AUTHOR]

Electric double-layer capacitors (EDLCs) are an excellent electrochemical energy storage system (ESS) because of their superior power density, faster charge–discharge ability, and longer cycle life compared to those of other EES systems. Activated carbons (ACs) have been mainly used as the electrode materials for EDLCs because of their high specific surface area, superior chemical stability, and low cost. Petroleum pitch (PP) is a graphitizable carbon that is a promising precursor for ACs because of its high carbon content, which is obtained as an abundant by-product during the distillation of petroleum. However, the processibility of PP is poor because of its stable structure. In this study, pre-oxidized PP-derived AC (OPP-AC) was prepared to investigate the effects of pre-oxidation on the electrochemical behaviors of PP. The specific surface area and pore size distribution of OPP-AC were lower and narrower, respectively, compared to the textural properties of untreated PP-derived AC (PP-AC). On the other hand, the specific capacitance of OPP-AC was 25% higher than that of PP-AC. These results revealed that pre-oxidation of PP induces a highly developed micropore structure of ACs, resulting in improved electrochemical performance. [ABSTRACT FROM AUTHOR]

The carbonization of 2-methylimidazole zinc salt (ZIF-8) in a nitrogen atmosphere to obtain ZIF-8-derived porous carbon (ZDPC) was explored. ZDPC and activated carbon (AC) were applied to prepare composite electrodes, which were used in capacitive deionization (CDI) for the treatment of vanadium-containing solutions. After carbonization at 950 °C, ZDPC has a high specific surface of 1043.12 m2 g−1, an average pore diameter of 1.73 nm, and a high specific electrochemical capacitance of 156.89 F g−1. It was found that the electrosorption capacity of the ZDPC/AC composite electrode for V(V) was 77.27 mg g−1. The adsorption of V(V) onto ZDPC/AC composite electrodes conforms to the Langmuir isotherm adsorption model, indicating that V(V) is adsorbed as a monolayer on the electrodes. The pseudo-first-order kinetic model fits better toward the adsorption processes of V(V), which shows that the adsorption process is dominated by physical adsorption. The high capacitive adsorption performance of the ZDPC/AC composite electrode proves the huge potential application of ZDPC in the field of capacitive adsorption for metals. [ABSTRACT FROM AUTHOR]

• The continuous adsorptive removal of phenol using low-cost activated carbon was studied. • Effects of electromagnetic field (EMF), and electric potential (EP) in the phenol removal were studied. • EMF enhanced the removal performance of activated carbon electrodes on the aluminum substrate. In this study, we introduce an electrode configuration setup to study the effect of an electromagnetic field (EMF) and electric potential (EP) on phenol removal in a continuous adsorption process. Feed water contaminated with dissolved phenol was exposed to EMF and passed through charged activated carbon electrodes prepared from Phoenix dactylifera (palm tree) biowaste. This study investigated the effects of magnetic field exposure, electric potential, feed salinity, and electrode substrate type. The results revealed that the highest adsorption uptake capacity of 47.2 mg/g was achieved using an aluminum substrate (AS) with EMF at zero salinity. The phenol adsorption kinetics followed a pseudo-second-order adsorption rate and diffusion model, indicating that intraparticle diffusion was the primary rate-limiting mechanism. The increased phenol adsorption uptake capacity brought on by the EMF may result from the improved mass transfer and mobility of the adsorbate and, consequently, the increased effectiveness of the internal diffusion of the pollutants. Finally, a regeneration efficiency of 99 % was achieved using NaOH at a salinity of 5,000 ppm. [ABSTRACT FROM AUTHOR]

The heavy metals pollutants resulting from industrial wastewater are a major environmental problem due to their toxicity and non-biodegradability. Their removal became a trending environmental subject. The preparation of low-cost and eco-friendly adsorbents for industrial wastewater treatment has been widely investigated. Furthermore, the use of polymeric material for this purpose is highly increasing. In this study, banana stem agro-waste was valorized by preparing and characterizing its derived activated carbon used as a filler to improve the adsorption performance of polyurethane foams. The loaded polyurethane was synthesized in the shape of pellets, characterized by SEM, and tested in removing Pb2+ and Cu2+ from aqueous solutions. The effects of AC filler concentration, number of filtering passes, and pH were examined. The loaded polyurethane demonstrated a good adsorption capacity that was enormously improved compared to the unloaded polymer. 77 % Pb2+ and 40 % Cu2+ removal were reached after one filtering pass only. The optimum pH was determined to be 4. After the 10th pass, and at any pH, almost 100% of the studied metals were eliminated. Rapid and straightforward selectivity and seawater deionization tests were carried out and confirmed the capacity performance of the prepared pellets in removing different aqueous ions. [ABSTRACT FROM AUTHOR]

Lithium-ion capacitors are considered highly promising as a hybrid-type energy storage system and are suitable for large-scale energy storage applications because of their superior power and energy density as well as prolonged cycle life. In this study, we developed an activated carbon (AC)-based electrode with excellent capacitive performance using salacca peel, a native Indonesian fruit, as the carbon precursor. The AC was synthesized via hydrothermal treatment of salacca peel with cerium (III) chloride (CeCl3) as the catalyst, followed by microwave-assisted chemical activation; the obtained sample was denoted as AC–S–CE. The addition of CeCl3 during the hydrothermal carbonization facilitated the formation of micropores in the AC; this resulted in a considerably greater surface area (1264.4 m2 g–1) and a more defective graphitic structure than that of AC synthesized in the absence of CeCl3 (AC–S, 988.9 m2 g–1) and of commercially available AC (742.8 m2 g–1). In terms of being an LIC cathode, all the ACs exhibited a non-faradaic charge–discharge mechanism. AC–S–CE exhibited a higher capacitance of 90.6 F g–1 at 0.05 A g–1 and improved cycling performance compared with those of AC–S and commercially available AC. [ABSTRACT FROM AUTHOR]

A combination of biomass-derived activated carbon and nano-carbonaceous materials has been considered as a sustainable approach to developing the highly electro-adsorptive electrode for desalination by capacitive deionization (CDI) technology. These composites can propose many enormous advantages such as non-toxicity, eco-friendly, high conductivity, and scalability. This work aimed to fabricate the composite coconut-shell-derived activated carbon/carbon nanotubes electrode with low CNTs content (1 wt%) for desalination. The nitrogen adsorption/desorption demonstrates the decrease of surface area of AC/CNTs-1% composite as compared to AC-pristine due to the blocking of micropores of AC. The SEM images evidenced good connection between CNTs and AC particles, where the fibrils of CNTs were featured as the electrical bridges to improve the electron transfer between the AC particles in the electrode structure. Comparison of the CDI performance of AC/CNTs-1% composite electrode in two regimes (batch mode and single-pass mode) in Ragone plot showed that the single-pass mode provided the essential factors of salt absorption capacity and average salt adsorption rate which shifted toward much upper and right regions, indicating the superior desalination performance. At the operation of 1.2 V, the batch mode and single-pass mode can deliver the salt absorption capacity of 10.93 mg g−1 and 11.97 mg g−1, respectively. The durability test of our CDI system in single-pass mode showed a stable performance on 100 cycles with the energy consumption of 0.284 kWh m−3 which is suitable for large-scale CDI applications using the renewable energy sources. [ABSTRACT FROM AUTHOR]

This study used heat-activated carbon (350 °C in the air) for the adsorption and removal of furfural from wastewater. The characteristics of air oxidation activated carbon (ACAOx) were tested. The results indicated that oxygen-containing functional groups were generated, with 1306 m2/g BET surface area of ACAOx. Salt concentration, temperature, and initial pH slightly affected the adsorption of furfural. Furfural removal efficiency was dependent on the dosage of ACAOx. The intra-particle and boundary-layer diffusions were likely contributed to the rate-limiting mechanisms of furfural adsorption. The activated carbon via air oxidation emerged as an acceptable and cost-effective adsorbent for furfural from wastewater. [ABSTRACT FROM AUTHOR]

• An efficient method is presented for the recovery of In3+ from acidic solution. • The activated carbon electrode shows good capability for electrosorption of In3+. • The recovery of In3+ is mainly based on electrical double-layer charging. • In3+ ions are preferentially electrosorbed in a competitive environment. High-efficiency recycling technology for endangered elements effectively mitigates the risk of resource shortages and promises the sustainability of supply chains, which is significant to the industry. In this study, an activated carbon (AC)-based capacitive deionization (CDI) for the selective electrosorption and recovery of indium ions (In3+) from acidic aqueous solution is proposed. The effects of applied voltage, pH, and initial concentration of indium were investigated to optimize the operation parameters for In3+ electrosorption. The results of cyclic voltammetry and the galvanostatic charge/discharge measurements indicate that the AC electrode shows good capability for the electrosorption of In3+ based on electrical double-layer capacitance. As demonstrated, In3+ can be successfully removed by CDI without deposition when the pH < 4, as confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The deionization capacity of In3+ is 7.95 mg/g with an energy consumption of 0.84 kWh/mol in single-pass mode CDI with an initial concentration of 50 mg/L (pH = 3) at 1.2 V. However, the removal of In3+ is affected by the solution pH since hydrogen ions (H+) compete for electrosorption. Note that In3+ ions with high valence are preferentially electrosorbed on the electrode surface over H+ ions, exhibiting a selectivity coefficient of 2.12. Herein, in the charging step, a large number of H+ ions in solution are rapidly electrosorbed onto the electrode, while these H+ ions are gradually replaced by a small number of In3+ ions in solution. Therefore, this electrosorption process shows great potential for effectively recovering indium ions from acidic aqueous solutions. [ABSTRACT FROM AUTHOR]

In this paper, the effect of hydrogen ions on the adsorption onto granular activated carbon (GAC) with the inorganic contaminant phosphate, which exists as a form of four species depending on the solution pH, is investigated. Various batch isotherm and kinetic experiments were conducted in an initial pH 4 as an acid, a pH 7 as neutral, and a pH 9 solution as a base for the GAC conditioned with deionized water and hydrochloric acid, referred to as GAC and GACA, respectively. The physical properties, such as the total surface area, pore volume, pore size distribution, and weight of the element, obtained from Brunauer–Emmett–Teller (BET) and scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM–EDX) represent no significant differences. However, the hydrochloric acid (HCl) condition results in an alteration of the pH of the point of zero charge from 4.5 to 6.0. The optimized initial pH was determined as being acid for the GAC and as being neutral for the GACA. According to the Langmuir isotherm, the relatively high Qm was obtained as being acid for the GAC and clearly distinguishes the pH effect as being the base for the GACA. An attempt was made to assess the adsorption mechanism using the pseudo-first-order (PFO), the pseudo-second-order (PSO), and the intraparticle diffusion models. The higher R2 for the PSO in the entire pH range indicated that chemisorption was predominant for phosphate adsorption, and the pH did not change the adsorption mechanism. A prolonged Bed Volume (BV) for the GACA demonstrated that the hydrogen ions on the surface of the GAC enhanced phosphate adsorption. [ABSTRACT FROM AUTHOR]

This work reports the development of multifunctional or polymorphous surfaces using zinc oxide (ZnO) nanorods, silica (SiO 2), and fluoropolymer functionalization in a sequential process. Firstly, zinc oxide nanorods were grown on activated carbon cloth (ACC) using a simple low-temperature synthesis process. ZnO nanorods-coated ACC substrate was applied to investigate the antimicrobial properties, and the results showed inhibition of 50% for Escherichia coli (E.coli) and 55% for Bacillus subtilis (B.subtilis) over 48 h of incubation time. Subsequent in-situ modification of silica nanoparticles like layer on ZnO nanorods-coated ACC surface was developed and used as an electrode for brackish water desalination in a capacitive deionization system. ZnO–SiO 2 modified ACC surface enhanced the desalination efficiency by 1.6 times, the salt removal rate (SRR) by threefold, and the durability (fouling prevention) for long-term usage compared to pristine ACC. Further modification of the ZnO–SiO 2 -ACC surface using fluoropolymer rendered the surface superhydrophobic and oleophilic. Vegetable (1.4 g/g) and crude oil (1.6 g/g) adsorption capacities were achieved for modified surface which was 70% enhancement compared with pristine ACC. The dynamic oil spill adsorption test exhibited the complete removal of oil spills on water surfaces within a few seconds, suggesting a potential application in oil spill cleaning. [Display omitted] • ZnO nanorods coated activated carbon cloth (ACC-ZnO) showed antibacterial properties. • In-situ deposition of SiO2 layer on ACC-ZnO was made and used as CDI electrode. • ACC-ZnO-SiO2 electrodes exhibited higher salt removal efficiency and rate. • Fluoropolymer functionalized ACC-ZnO-SiO2 surface improved oil adsorption capacity. • Multifunctional surface can be utilized as simple and cost-effective wastewater treatment. [ABSTRACT FROM AUTHOR]

Achieving a net-zero target via a circular economy approach necessitates maximizing the recycling of waste into higher-value materials. In the present study, spent coffee grounds (SCG) from industrial food processing biomass waste are converted into a high-performance anode material used in lithium-ion batteries via one-step carbonization of ZnCl 2 at 550 °C. The hybrid composites (HCs) are collected after the process contained C- and Zn-based mixed oxides, such as zinc silicate (Zn 2 SiO 4) and zinc ferrate (ZnFe 2 O 4). The content of Zn-based mixed oxides in HCs increases with the initial ZnCl 2 :SCG mass ratio and reaches its maximum at a ratio of 2:1 wt/wt (HCs_2). The electrochemical performance of the HC-based anodes is proportional to the loaded Zn content when the ZnCl 2 :SCG mass ratio increases from 0 to 2. The optimized anode (HCs_2) exhibits a charge capacity of 692 mAh g−1 and capacity retention of 86 % at the 100th cycle, whereas the corresponding values for HCs_0 anode (without ZnCl 2 treatment) are 311 mAh g−1 and 73.3 %. The superior electrochemical performance of the optimized anode is attributed to the nanosized Zn 2 SiO 4 and ZnFe 2 O 4 , stabilization effect of activated carbon matrices, and a strategy that increases the proportions of high-capacity components. [Display omitted] • ZnCl 2 activation converts spent coffee grounds to valuable hybrid composites (HCs). • The HCs consisting of C-based and Zn-based oxides is prepared via a simple pyrolysis. • Carbon matrices and nanosized Zn-based oxides support to improve electrochemical performance. • HCs_2 electrode exhibits stable cyclability, delivers a capacity of 692 mAh g−1 after 100 cycles. • The HCs are suggested as a low-cost and green anode for advanced lithium-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • A parametric investigation of the electrochemical desalination cell was carried out. • The longer residence time of the flow electrode and the feed water augmented the desalination. • Surface area of carbon and redox couple play a crucial role in desalination. • A reduction of 235 mg/L of total dissolved solids in tap water was observed. Flow Electrode Capacitive Deionization (FCDI) is a promising technology that uses carbon materials as flow electrodes in aqueous conditions to enable continuous desalination. In this work, the parametric investigation of the FCDI cell was carried out for low and high surface area activated carbon. When 1 mM/1 mM ferri-/ferrocyanide redox couple in the 1 M NaCl supporting electrolyte containing the 5 wt% high surface area activated carbon and 0.5 wt% MWCNT is circulated as flow electrode at the flow rate of 8 mL/min in the electrode chamber and 0.1 mM NaCl feed water is circulated in single-pass mode at 8 mL/min, the FCDI system achieved a significant improvement in desalination performance up to 76.38 % of SRE, with a high average salt removal rate of 43.925 µg/cm2s @ 2 V, charge efficiency of 20.11 % and average energy consumption of 0.27 kWh/mol, through a thorough parametric investigation. When the FCDI cell was tested with tap water, the average salt removal rate, average energy consumption, and salt removal efficiency were calculated at 6.11 μg/cm2s, 2.46 kWh/mol, and 46.61 % respectively, resulting in the reduction of total dissolved solids of 600 mg/L at the inlet to 365 mg/L at the outlet. The combination of microporous high surface area carbon and ferro-ferri redox couple propelled the desalination performance in comparison with the macroporous low surface area carbon, maximizing the ion removal rate, which further reduced the energy consumption and operating voltage for the process. [ABSTRACT FROM AUTHOR]

Edible white-rot fungi are commonly cultivated on wood-based substrates and selectively degrade lignin to a larger extent during their growth. Spent mushroom substrate (SMS) is produced in huge amounts by the mushroom industry and today there is a lack of proven methods to valorize this kind of biomass waste, which in most cases is landfilled or used as fuel. This study demonstrates that birch wood-based SMS from the cultivation of oyster mushrooms can be converted into high-quality activated carbon (AC) with an extremely high surface area of about 3000 m2/g. These activated carbons showed good performance when used in electrodes for supercapacitors, with energy storage parameters nearly identical to AC produced from high-quality virgin birch wood. Moreover, AC produced from SMS showed high potential as an adsorbent for cleaning reactive orange-16 azo dye from aqueous solutions as well as contaminants from synthetic effluents and from real sewage water. The kinetics of adsorption were well represented by the Avrami fractional order model and isotherms of adsorption by the Liu model. The theoretical maximum reactive orange-16 adsorption capacities were approximately 519 mg/g (SMS-based carbon) and 553 mg/g (virgin birch-based carbon). The removal of contaminants from synthetic effluents made of different dyes and inorganic compounds was around 95% and 83% depending on the effluent composition. The removal of contaminants from raw sewage water was around 84%, and from treated sewage water was around 68%. Overall, the results showed that activated carbon prepared from waste generated during cultivation of white-rot fungi is as good as activated carbon prepared from high-quality virgin wood. [Display omitted] • Spent mushroom substrate (SMS) was used as precursor for production of activated carbon (AC). • Chemical activation with KOH at 850 °C led to specific surface area of around 3000 m2/g. • SMS-based AC showed excellent properties for supercapacitors and water treatment. • SMS-based supercapacitors retain 91% of their capacitance after 10,000 cycles. • Maximum reactive orange-16 adsorption capacity according to the Liu model was 519 mg/g. [ABSTRACT FROM AUTHOR]

The CoNi-based hydroxide nanosheets (CoNiNSs) are promising active materials for supercapacitors. At the same time, the fabrication of freestanding electrodes is essential to achieve high electrochemical performance without introducing inactive components. To further improve the utilization of electrochemically CoNiNSs, in this study, a nickel-based foam/tube current collector (NF@NT) is rationally fabricated to support CoNiNSs (NF@NT/CoNiNSs). As expected, the freestanding NF@NT/CoNiNSs-2 electrode with optimum CoNiNSs content exhibits favorable electrochemical performance: (i) in the three-electrode system, the specific capacitance is 4.2 F cm−2 at 10 mA cm−2 and 2.38 F cm−2 at 50 mA cm−2, as well as capacitance retention of 97.1 % after 20,000 cycles at 20 mV s−1; (ii) matched with activated carbon (AC), the capacitance of corresponding NF@NT/CoNiNSs-2//AC device maintains 90.74 % after 27,500 cycles at 50 mA cm−2, which also delivers an energy density of 80.8 Wh kg−1 at a comparable power density of 5997.52 W kg−1. • The freestanding NF@NT/CoNiNSs electrode for supercapacitors is fabricated via direct growth of CoNiNSs on NF@NT. • The NF@NT/CoNiNSs electrode endows large contact area with electrolyte, short ion diffusion transport, and fast electron pathway. • The NF@NT/CoNiNSs//AC maintains 90.74 % capacitance after 27,500 cycles at 50 mA cm−2. • The NF@NT/CoNiNSs//AC delivers an energy density of 80.8 Wh kg−1 at a comparable power density of 5997.52 W kg−1. [ABSTRACT FROM AUTHOR]

A novel approach was employed to fabricate a biofilm-derived activated carbon (BioAc) electrode on a carbon cloth (Cc) substrate for electrochemical nitrite sensing in water samples. The biofilm/Cc electrode was developed using a bioelectrochemical reactor, featuring a three-electrode system with nutrient media and microbial sources. The resultant biofilm electrode was activated at 450 °C for 2 h to eliminate impurities and enhance porosity. Morphological analysis of the BioAc/Cc electrode revealed a surface characterized by a compact film composed of numerous carbon nanoparticles. X-ray diffraction (XRD) analysis exhibited broad, highly crystalline peaks, enhancing both the electrode surface area and conductivity. Amperometry tests on the modified BioAc/Cc electrodes demonstrated a detection limit of 0.015 μM, a sensitivity of 1946.54 μA mM−1 cm−2, and a linear range spanning 0.35–478.21 μM at neutral pH conditions. Moreover, the electrodes demonstrated good stability with a RSD of 2.25% after 60 days and high reproducibility with an RSD of 1.64%. Real-time results showed 99.2 and 100.1% recovery for tap water and drinking water, respectively, highlighting the potential for commercialization in the future. These findings suggest that the BioAc/Cc electrode holds substantial potential for precise nitrite detection in environmental and wastewater applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanoporous carbon materials are well recognized as the main components of electrodes in capacitive deionization. Herein, the activated carbons were produced based on rice husk which is an abundant waste material in southern regions of Kazakhstan. The resulting carbons were characterized electrochemically by comparing their performance with well-known brands of commercial porous carbons (i.e. Norit DLC Super 30, Kuraray YP 50F). The features of carbon/carbon electrochemical cells were analyzed using the means of galvanostatic cycling with potential limitation and cyclic voltammetry. Whilst the surface morphology and elemental composition of carbons were observed using scanning electron microscopy combined with energy dispersive X-ray spectroscopy. Using the method of low-temperature nitrogen adsorption it has been established that the specific surface of home-made carbon produced based on rice husk is equal to 2290 m²g-1. The salt adsorption analysis has been performed using different concentrations of inlet solutions of sodium chloride. Our study has shown that the manufacturing and application of activated carbons based on rice husk can be highly efficient because the resulting electrode materials exhibit a high electrosorption capacity of 20.02 mg g-1, which exceeds similar values obtained in the case of application of commercial porous carbons. [ABSTRACT FROM AUTHOR]

Membrane capacitive deionization (MCDI) is a modification of capacitive deionization (CDI) using ion-exchange membranes (IEM) in front of the electrodes. Electrode properties, especially the specific surface area, are known to be strongly related with desalination performance in CDI, but the effects of other properties in MCDI are not fully understood. The objective of this study was to investigate the effect of hydrophilicity in activated carbon electrodes on desalination performance in MCDI. Two types of activated carbon (P60 and YS-2) whose specific surface areas were similar were used as electrode materials, but they had different hydrophilicity (i.e., P60 was originally hydrophobic and YS-2 was relatively hydrophilic due to its nitrogen-containing surface chemistry). These hydrophilic electrodes (either the electrode itself or modified with polydopamine (PDA)) led to an increase in the salt adsorption capacity (SAC) in MCDI because they facilitated the access of both ions and water molecules into the electrode pores. In particular, the SAC of the P60 electrode displayed a large increase to almost reach that of the YS-2 electrode due to the improved hydrophilicity with PDA modification and the insignificant effects of PDA modification on an already hydrophilic YS-2 electrode. Additionally, PDA-modified IEM in MCDI reduced the SAC as a result of the additional insulating PDA layer with little changes in hydrophilicity. [ABSTRACT FROM AUTHOR]

This study presents the development of green and sustainable supercapacitor electrodes using activated carbons derived from industrial waste from red pepper (RPW) via conventional chemical activation using ZnCl 2 at various carbonization/activation temperatures. The activated carbon samples were subjected to various analytical techniques, including elemental analysis, N 2 adsorption-desorption, Raman, FT-IR, and SEM-EDS. The resulting carbon samples were then used to prepare standard coin-sized supercapacitor cells, which were tested using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques with a 6 M KOH electrolyte. The BET surface area and surface functionality of the samples decreased as the temperature increased. The material produced at the highest temperature (AC800) exhibited the lowest gravimetric capacitance value (131 F/g). However, it demonstrated perfectly reversible electrochemical behavior with the highest capacitance retention of 50 % (between 0.5 A/g and 10 A/g) and cyclic stability (>96 %) over 10,000 cycles among all the other materials. Conversely, the electrode material produced at the lowest temperature (AC600) had the highest gravimetric capacitance value of 175 F/g but the lowest electrochemical stability due to the contribution of pseudo faradaic processes in the storage mechanism. [Display omitted] • Activated carbons (ACs) were derived from RPW with ZnCl 2 at various temperatures. • ACs were examined as supercapacitor electrodes materials. • The temperature had significant impact on the textural properties and capacitive behavior of ACs. • AC600 had the highest gravimetric capacitance thanks to the contribution of pseudo capacitance. • AC800 showed best reversibility, cyclic stability, and capacitance retention as the electrode material. [ABSTRACT FROM AUTHOR]

Global demand for lithium (Li) resources has dramatically increased due to the demand for clean energy, especially the large-scale usage of lithium-ion batteries in electric vehicles. Membrane capacitive deionization (MCDI) is an energy and cost-efficient electrochemical technology at the forefront of Li extraction from natural resources such as brine and seawater. In this study, we designed high-performance MCDI electrodes by compositing Li+ intercalation redox-active Prussian blue (PB) nanoparticles with highly conductive porous activated carbon (AC) matrix for the selective extraction of Li+. Herein, we prepared a series of PB-anchored AC composites (AC/PB) containing different percentages (20%, 40%, 60%, and 80%) of PB by weight (AC/PB-20%, AC/PB-40%, AC/PB-60%, and AC/PB-80%, respectively). The AC/PB-20% electrode with uniformly anchored PB nanoparticles over AC matrix enhanced the number of active sites for electrochemical reaction, promoted electron/ion transport paths, and facilitated abundant channels for the reversible insertion/de-insertion of Li+ by PB, which resulted in stronger current response, higher specific capacitance (159 F g−1), and reduced interfacial resistance for the transport of Li+ and electrons. An asymmetric MCDI cell assembled with AC/PB-20% as cathode and AC as anode (AC//AC-PB20%) displayed outstanding Li+ electrosorption capacity of 24.42 mg g−1 and a mean salt removal rate of 2.71 mg g min−1 in 5 mM LiCl aqueous solution at 1.4 V with high cyclic stability. After 50 electrosorption-desorption cycles, 95.11% of the initial electrosorption capacity was retained, reflecting its good electrochemical stability. The described strategy demonstrates the potential benefits of compositing intercalation pseudo capacitive redox material with Faradaic materials for the design of advanced MCDI electrodes for real-life Li+ extraction applications. [Display omitted] • Redox-active PB intercalation material with AC for efficient Li+ extraction. • AC facilitate electron and Li + transport to redox-active sites of PB. • AC/PB exhibit high specific capacitance (159 F g−1) and rapid Li+ diffusion. • Excellent Li + extraction of 24.42 mg g−1 in Asymmetric AC//AC/PB-20 MCDI cell. • Excellent cyclic stability and Li + retention of 95.11% even after 50 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • State of the art in electrosorption of organic compounds (EOC) critically reviewed. • EOC shows promise against poorly adsorbable, highly polar, and ionized pollutants. • Enhanced adsorption and active control of ad-/desorption by electric potential. • Insightful performance parameters proposed to unify rapidly growing EOC research. • EOC application for on-site regenerable adsorbers and in treatment trains discussed. The widespread contamination of water resources with emerging organic contaminants necessitates the development of sustainable and cost-effective water treatment technologies. Adsorption, as a widely used water remediation process, is hampered by severe performance limitations against ionic and hydrophilic organic contaminants. In addition, no facile on-site regeneration techniques are available. Electrosorption of organic compounds (EOC) is a promising alternative to not only improve adsorption performance, but also to facilitate adsorbent regeneration by green electricity. The number of studies on EOC has grown exponentially over the past decades. There are numerous examples showing that applied electric potentials can significantly enhance the adsorption affinity, capacity, and kinetics of conductive carbon adsorbents. However, whether these effects are specific to certain compound classes or more generally applicable remains unclear as well as the optimal criteria for designing EOC processes. Therefore, we critically evaluated the current state of the art of EOC in terms of active control of adsorption and desorption processes and the achievable effects for ionic and neutral organic compounds. Through a detailed consideration of compound speciation and surface chemistry of electrode materials, we derive mechanistic insights into the EOC process and discuss differences between electrosorption of inorganic and organic compounds. We provide definitions and propose insightful performance parameters to unify the rapidly growing EOC research. Potential application scenarios and future research directions are discussed. Overall, EOC is less likely to be a one-fits-all solution for removing contaminants, but adds a valuable tool especially for the hydrophilic and ionic organic contaminants that challenge conventional adsorption processes. [ABSTRACT FROM AUTHOR]

In this study, adsorption kinetics of phenanthrene (PNT) and trichloroethylene (TCE) by a graphene nanosheet (GNS), a graphene oxide nanosheet (GO), a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube (MWCNT), and two coal based activated carbons (ACs) (F400 and HD3000) were examined in distilled and deionized water (DDW) and under natural organic matter (NOM) preloading conditions. The results showed the times needed for the adsorption of PNT and TCE to reach apparent equilibrium (i.e., ≤3% change per day) followed the order of GO ≥ MWCNT > GNS > SWCNT ∼ HD3000∼F400 and SWCNT > GNS ∼ HD3000 > F400 ∼ MWCNT > GO, respectively. The pseudo second order model successfully represented kinetics data for three classes of carbonaceous adsorbents. The Weber-Morris intraparticle diffusion model indicated three steps adsorption process for PNT and two step adsorption for TCE. In addition, the times needed to reach apparent equilibrium for the adsorption of PNT and TCE in the presence of hydrophobic (HPO) and hydrophilic (HPI) NOM solutions increased for all adsorbents (except for GO). In general, both NOM showed similar impacts on the adsorption rates of PNT and TCE. Aggregation of both GNS and CNTs rapidly occurred during initial couple hours of contact time during preloading, and spiking both PNT and TCE further increased their aggregation. Image 1 • Graphenes and CNTs showed faster sorption kinetics for PNT and TCE as compared to ACs. • The adsorption kinetics rate of TCE on graphenes, CNTs and ACs were faster than PNT. • The Pseudo-Second-Order Kinetic Model successfully described the kinetic data. • The presence of NOM reduced the PNT and TCE uptakes of all adsorbents. [ABSTRACT FROM AUTHOR]

Membrane capacitive deionization (MCDI) as a promising approach was developed to simultaneously conduct water desalination and metal recovery by using activated carbon fiber (ACF) as electrodes. The removal performance of two metal ions (Cu2+, Zn2+) was firstly investigated at different voltages. Experiments showed that the adsorption amount of Cu2+ was higher than that of Zn2+ under the voltage of 0.4–0.6 V. However, inverse result was obtained at the voltage of 0.8–1.2 V that the adsorption amount of Cu2+ was lower than that of Zn2+. The analysis of scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) showed that Cu2+ removal involved the adsorption and electrodeposition, and the reduction potential of Cu2+ was found to be 0.6 V. At a higher voltage, Cu2+ was reduced and the reduction product consisting of Cu/Cu 2 O would decrease the effective surface area and cause serious degradation of electrode properties, which inhibited Cu2+ adsorption. Comparatively, Zn2+ reduction was only observed at the voltage of 1.2 V. FTIR showed that the difference of the reduction potential was partly attributed to the type of functional groups of ACF and its affinity towards ions. Considering the gap of the reduction potential, the feasibility of selective reduction and recovery of Cu(0) from CuCl 2 /ZnCl 2 mixed solution was studied by controlling the applied voltage and the optimal voltage was determined to be 0.8 V. The recovery efficiency of Cu(0) in the competitive environment could reach to 42.8% at the voltage of 0.8 V. Moreover, the electrode regeneration was investigated and it was found that the performance of fouled electrode could be effectively recovered for further reuse via cleaning methods. [ABSTRACT FROM AUTHOR]

Abstract The authors tailored coconut-based activated carbons with a quaternary ammonium epoxide (QAE) surfactant that greatly increased the carbon's capacity for sorbing nitrate from water. This QAE-tailored carbon processed deionized water spiked with 50 mg/L NO 3 − through rapid small scale column tests; and achieved half-breakthrough at 477 bed volumes. This favorably compared to 52 bed volumes for the pristine coconut activated carbon. The QAE employed herein was QUAB 360. Most favorable pretreatment of the carbon was achieved via NaOH immersion, which created extensive phenolic functionality on the carbon's graphene edges, and raised the carbon's slurry pH to 9.3–9.6. These phenolics served as the anchor for the QUAB's epoxide reactions. This pretreatment offered the highest QUAB loading onto the carbon, which in turn netted the most nitrate removal. Per X-ray photoelectron spectroscopy, favorable QUAB360 preloading incurred a 1.62% increase in the quaternary N content of these activated carbons. The phenolic functionality that followed pretreatment was discerned by Boehm titrations; and these mathematically matched with Gaussian-based models that were fitted to incremental titration data. The most favorable QUAB-loaded variants were the ones whose pretreated precursors had exhibited the highest peak of functionality in the 9.3–10.4 pH range—corresponding to the pK a of phenolics. If the precursor pH was below the 9.3–9.6 range—as induced by acids or H 2 O 2 , then the QUAB's epoxide intermediate apparently over-reacted with the hydroxylated functionality of other QUAB molecules, rather than with phenolic functionality of the carbon's graphene edge sites. Graphical abstract Image 1 Highlights • QAE preloading onto GAC can be able to remove the low concentrations of contaminants as well as the higher one. • mechanismThe carbon slurry pH influenced the pathway of the QAE epoxide-forming reactions and the anchoring mechanism. • pK distribution with Gaussian-based models for characterizing the surface acidity of pretreated activated carbon variants. • The proportion of functional groups calculated by pK distribution are close to the ones obtained by the Boehm titration. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract In this study, nitrite desorption from activated carbon fiber (ACF) in capacitive deionization (CDI) and membrane capacitive deionization (MCDI) was examined and the effects of the operation parameters (pH, voltage, temperature and flow rate) and co-existing matters were deeply investigated. Desorption mechanisms were analyzed via Brunauer–Emmett–Teller (BET) and Fourier transform infrared spectroscopy (FTIR). Results showed that the final desorption ratio increased from 0 to 100% in MCDI and the enhancement was also observed in CDI that the ratio increased from 18.7 to 83.5% when solution pH increased from 2 to 10. Increasing the voltage and solution temperature also contributed to the ion desorption both in CDI and MCDI, while the effect of flow rate was negligible. Generally, MCDI showed greater desorption performance than CDI due to the elimination of co-ions effect. However, it was interesting to find that when the voltage was in the range of 0.4-0.6 V, the desorption ratio increased from 38.4% to 50.8% in MCDI which was lower than that in CDI (45.4% to 55.8%). One possible explanation was that the presence of membranes would inevitably introduce additional resistance into the system and decrease effective voltage especially at lower voltage. Compared to the desorption performance in MCDI when the solution pH was 2, the greater desorption performance was observed in CDI which was mainly attributed to the site competition. As for the influence of coexisting matters, the presence of bovine serum albumin (BSA) posed an adverse effect for the ion desorption both in CDI and MCDI. The inhibition effect was more serious in CDI, and pore blockage caused by BSA attachment onto ACF was the main mechanism. Therefore, this study would provide some referential advice for the investigation of ion desorption in CDI and MCDI. [ABSTRACT FROM AUTHOR]

Abstract Three kinds of anion exchange resins (AERs) (D201, D301, D314) and one kind of cation exchange resin (D860) were used with activated carbon (AC) to fabricated the ion exchange resin-AC (IER/AC) composite electrodes in capacitive deionization (CDI) for selective adsorption of V(V). The characteristics of four kinds of composite electrodes, such as wettability, pore distribution and electrochemical properties, indicates IER/AC composite has great potential as electrode materials for the electro-adsorption in CDI. The pH of solution has apparent influence on the adsorption capacity of the composite electrodes for V(V) because of the various V(V) species in the solution with different pH. The reduction rate of V(V) on IER/AC electrodes mainly relates to the amount of V O 2 + in solution. The adsorption capacity of AER/AC electrodes for V(V) is slightly affected by the applied voltage may be due to that the adsorption of V(V) is mainly dependent on ion exchange with AERs and only a minority of V(V) is adsorbed by electrostatic adsorption. The adsorbed V(V) on D860/AC electrode decreases with the rising applied voltage because the pH increases with the increase of voltage. The separation of V(V) from V(V), Al and P indicates that the selective adsorption capability of IER/AC composite electrode is related to the migration rate of V(V), Al, P at different voltages and the selectivity of resins. This study may provide reference for recovering and separating metal ions from aqueous solution with CDI. Highlights • Resin-carbon electrodes were fabricated to explore the effect of resins on the electrodes. • Resin-carbon electrode had great potential application in capacitive deionization. • The ionic species of vanadium in solution affect its adsorption and reduction. • The applied voltage has apparent influence on the selectivity of electrodes. [ABSTRACT FROM AUTHOR]

A high quality of activated-carbon electrode materials is of great importance for improving the electrochemical performance of desalination in membrane capacitive deionization. In this study, porous activated carbon was prepared by pyrolytic carbonization and chemical activation of lignocellulosic loofa sponge ( Luffa cylindrica , LS) to act as a carbonaceous electrode. After activation, a hierarchically porous structure formed, characterized by the generation of micro-/mesopores on the channel walls. The total specific surface area and pore volume of the activated carbon material rose as the alkali/char ratio increased. The LS-based carbon electrode LSCK14, referring to the activation product produced with a KOH/char ratio of 4, displayed excellent electrochemical behavior, characterized by a remarkable specific capacitance of 93.0 F g −1 at 5 mV s −1 in 1 M NaCl solution, as well as extraordinary reversibility for capacitive charge storage. Moreover, the electrosorption capacity was investigated in batch-mode membrane capacitive deionization at 1.0 V while treating a 10 mM NaCl electrolyte. As demonstrated, the LSCK14 activated carbon electrode presented a superior electrosorption capacity of 22.5 mg g −1 . The improved capacitor characteristics and high electrosorptive performance of this material can be attributed to its unique porous characteristics (high surface area, micrometer-scale channels and both meso- and micropores). Consequently, activated carbons derived from resource-recovered LS, which combine a multi-channeled structure, mesopores and micropores, were demonstrated to be a promising electrode material for electrochemical water desalination. [ABSTRACT FROM AUTHOR]

Asymmetrical capacitive deionization (A-CDI) is expected to be a promising desalination technique with high salt removal capacity. In this work, the novel A-CDI are proposed where the negative and positive electrode are Na 4 Ti 9 O 20 (NTO) and activated carbon (AC), respectively. Basically, the NTO nanotubes with the specific surface area of 142.43 m 2 /g have been prepared by hydrothermal reaction. The electrochemical test shows that the specific capacitance of optimum NTO electrode can reach 120.45 F/g in 1 M Na 2 SO 4 solution with the scan rate of 1 mV/s by employing three-electrodes method. Moreover, the electrosorption capacity of AC/NTO asymmetrical electrodes is approach to 23.35 mg/g in NaCl solution with an initial concentration of 250 ppm. To improve the conductivity of NTO, reduced graphene oxide (rGO) is proposed to couple with NTO, named as rGO@NTO, to constitute the AC/rGO@NTO A-CDI. As a result, the AC/rGO@NTO A-CDI exhibited an ultrahigh desalination capacity of 41.8 mg/g in NaCl solution with an initial concentration of 250 ppm under 1.4 V, which is almost twice higher than that of AC/NTO electrodes and the highest value among all reported data anywhere. Besides, the charge efficiency of AC/rGO@NTO approaches to 1, implying the co-ions impaction has been successfully restricted. [ABSTRACT FROM AUTHOR]

A feasibility study for water recycling and reuse of a reverse osmosis (RO) brackish wastewater by capacitive deionization (CDI) was carried out in the present work. Palm-shell wastes enriched in carbon was recycled to yield valuable activated carbon (AC) that has advantages of high surface area, high specific capacitance, and low electrical resistance as the CDI electrodes. The GAC prepared by dispersion of AC in the graphene (rGO) layers has a high surface area and electrical conductivity for CDI. The GAC electrodes have increasing electrosorption efficiencies from 1.6 to 3.0% during the repeated electrosorption-regeneration cycles under +1.2 → 0 → +1.2 V while the efficiencies the AC electrodes decrease from 2.7 to 1.6%. It is clear that the GAC-based electrodes have a better electrosorption efficiency and stability in, for example, the three repeated electrosoption-regeneration cycles for CDI of the wastewater. This work also exemplifies that the AC recycled from biomass such as palm-shell wastes can be used in CDI electrodes for recycling and reuse of wastewater. [ABSTRACT FROM AUTHOR]

A single-pass-mode capacitive deionization (CDI) reactor was used to remove arsenic from groundwater in the presence of multiple ions. The CDI reactor involved an applied voltage of 1.2 V and six cell pairs of activated carbon electrodes, each of which was 20 × 30 cm 2 . The results indicate that this method achieved an effluent arsenic concentration of 0.03 mg L −1 , which is lower than the arsenic concentration standard for drinking water and irrigation sources in Taiwan, during the charging stage. Additionally, the ability of the CDI to remove other coexisting ions was studied. The presence of other ions has a significant influence on the removal of arsenic from groundwater. From the analysis of the electrosorption selectivity, the preference for anion removal could be ordered as follows: NO 3 − > SO 4 2− > F − > Cl − >As. The electrosorption selectivity for cations could be ordered as follows: Ca 2+ > Mg 2+ > Na + ∼ K + . Moreover, monovalent cations can be replaced by divalent cations at the electrode surface in the later period of the electrosorption stage. Consequently, activated carbon-based capacitive deionization is demonstrated to be a high-potential technology for remediation of arsenic-contaminated groundwater. [ABSTRACT FROM AUTHOR]