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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]

In recent scenarios, plenty of research has been conducted on porous activated carbon derived from biowaste precursors. The well‐developed surface area and porous nature of biowaste‐derived activated carbon material make them good candidates for electrochemical devices to use as electrode material. In the present work, we have used waste peanut shells (W.P.) as a precursor material to derive large surface area activated carbon. Chemical activation is used to activate the activated carbon, for which ZnCl2 is used as an activating agent. The waste peanut shell‐derived activated carbon (WPAC) is studied via XRD, FESEM, and BET. Prepared carbon shows a large BET surface area of 1366 m2 g−1 and a well‐developed pore structure; the presence of pores is also confirmed by FESEM images. A solid‐state supercapacitor is also fabricated using waste peanut shell‐based activated carbon and ionic liquid‐based polymer electrolyte. The EDLC is further studied using electrochemical characterizations such as CV, EIS, and GCD. The EIS study found that the WPAC‐based EDLC cell shows a specific capacitance of 25 F/g at 10 mHz. A DSSC is also fabricated using the WPAC on the counter electrode, and it shows an efficiency of 0.96% with a fill factor of 27.79. [ABSTRACT FROM AUTHOR]

As the cardinal part of capacitive deionization apparatus, the performance of electrode directly determines the capacitive deionization's adsorption rate, adsorption capacity and selectivity. However, the adsorptivity and reusability of electrode material for special adsorbate need to be developed urgently for the application of capacitive deionization in wastewater purification. In this research, we successfully enhanced the Cu(II) adsorptivity of activated carbon fiber felt (ACFF) to 23 mg/g (4.47 times of ACFF0) by the sonication‐assisted chemical reactivation process with the solution of 20 wt % NaOH used as activator (ACFF‐N20). As ACFF‐N20 used as cathode, the Cu(II) electro‐adsorptivity of ACFF‐N20 under a current of 0.15 A is 84 mg/g for 130 mg/L Cu(II) standard working fluid. For the Cu(II) wastewater with a concentration of 50 mg/L, it can be purified to 0.14 mg/L by one step of capacitive deionization, which below the drinking standard of World Health Organization. By the technology of low‐temperature pickling regeneration, the regeneration rates of ACFF‐N20 are 102 %–106 % for five recycling times of Cu(II) electrosorption process. Based on fitting analysis of adsorption processes using different kinetic models, it was found that Langmuir model is more convergent than Freundlich model to the adsorption isotherms. Additionally, Bangham adsorption kinetic model and pseudo‐first order adsorption kinetic model have the best fitting correlation for the Cu(II) static adsorption and electrosorption of ACFFs. [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]

This study investigates the influence of oxygen functional groups in biomass-based activated carbon (AC) as an efficient, high-performance supercapacitor electrode. To create activated carbons with variable oxygen concentration, the surface of produced AC was altered using oxygen as an oxidizing agent at various temperatures. Nitrogen adsorption–desorption isotherms, scanning electron microscopy (SEM), energy dispersive X-ray analyzer (EDX) analysis, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) spectroscopy, Boehm titration and X-ray Photoelectron Spectrometer (XPS), are used to characterize the physico-chemical characteristics of the obtained carbons. Afterward, cyclic voltammetry, constant current charge–discharge and electrochemical impedance spectroscopy (EIS) were used to evaluate the electrochemical properties and behavior of ACs based electrodes. Indeed, the oxidative treatment increases the oxygen functional content while reducing the specific surface area. According to the results of the characterization, the electrode test reveals that the modified materials improve the electrochemical properties and enhance the material's double-layer capacitance. The AC treated with oxygen at 623 K displayed outstanding capacitance of 550 F g−1 at specific current of 0.1 A g−1 in NaOH (2 M) electrolyte and exhibits an excellent stability after 1000 cycles with a capacitance retention of 85.5%. In addition to being inexpensive, the prepared materials have excellent electrochemical performance and good stability, which make them appropriate for supercapacitor applications. [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]

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]

[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]

Activated carbon is the most commonly used electrode material in electrochemical double-layer capacitors. The rational utilization of biomass (waste) to prepare porous activated carbon as efficient electrode material for supercapacitor application is observed. Herein, we have prepared activated carbon from Canna indica as a tolerable and earth-bountiful carbon source via the facile physicochemical method. The microwave method has provided the highest order of activated carbon with an irregular partial lamellar structure morphology compared to the traditional activation method. Microwave-assisted acid-treated activated carbon (R3 sample) exhibited superior electrochemical properties compared with other samples (as-prepared biochar (R1 sample) and chemically activated (R2 sample)). Hence, R3 coated conductive electrode offered a high Cs of 112.9. F/g at 4 A/g in 1 M Na2SO4 with the cyclability of 76.8% after 3000 cycles at 20 A/g. A fabricated symmetric R3//R3 device showed the Cs of 54.3 F/g at 1 A/g with the energy/power density of 14.8 Wh/kg and 666.5 W/kg. The symmetric device offered a high cyclability of 86% after 3000 cycles at 20 A/g. This work delivers an effective tactic and cost-effective approach for synthesizing of activated carbon as a value-added product from biowaste for energy storage applications. [ABSTRACT FROM AUTHOR]

The waste-to-wealth practice has evolved into the circular economy concept, in which every by-product is converted into a usable product, enabling the concept of zero-waste. As a result, research on converting wastes, particularly bio and agricultural wastes, into usable products is prioritized. Activated carbons are one of these products, which are derived through a variety of physical and chemical processes from agricultural and biowaste. These activated carbons have applications in various fields, including energy storage, catalysis, and water purification. However, the quality of this activated carbon is dependent on the bioresource's structure and chemical composition. As a result, many sources to produce activated carbon, including stems, wood, leaves, root, bark, fiber, flower, and seeds, have been identified and are being explored for their potential use as an electrode material for supercapacitors. Out of these sources, fiber from different bioresources shows improved performance as supercapacitor electrodes due to their higher cellulose and lignin contents. In this study, we systematically review various sources of activated carbon and their performance as supercapacitor electrodes. The electrochemical characterization methodologies used to characterize this fiber-based activated carbon are examined critically, and factors influencing its improved/poor performance are collated. Additionally, the most performing fiber-based sources of activated carbon for supercapacitor electrodes are identified, along with a future perspective. [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]

Activated carbon derived from biomass waste and their application as supercapacitor electrodes have aroused a considerable research interest in recent years. In this work, we demonstrate the use of Coffea canephora leaf (CCL) waste for the preparation of activated carbon as supercapacitor electrodes via chemical activation with straightforward pyrolysis at high temperatures for the first time. Potassium hydroxide with three different concentrations, i.e. 0.1 M, 0.3 M, and 0.5 M, was used as activating agent. The as-prepared activated carbon using 0.3 M KOH (CCL-0.3) displayed good physicochemical properties and exhibited superior electrochemical performance than the other two samples (0.1 and 0.5 M). CCL-0.3 achieved the specific capacitances of 297 F g−1 and 220 F g−1 at 1 A g−1 in 1 M H2SO4 and 1 M Na2SO4 electrolytes, respectively. Moreover, CCL-0.3 in 1 M H2SO4 exhibits the equivalent series resistance (Rs) and the charge transfer resistance (Rct) value of CCL-0.3 in 1 M H2SO4 of 0.73 Ω and 4.9 Ω, respectively. Additionally, this study provides strategies for preparing activated carbon as supercapacitor electrode materials with superior performance via chemical activation with straightforward pyrolysis for the renewable energy storage devices. [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]

Activated carbons are one of the most important classes of high‐surface‐area porous materials. Owing to their unique structure, low price, and large‐scale production technology, these porous carbons have been traditionally used as sorbents for eliminating contamination. In the past decade, many innovations have been seen in the synthesis, structure, applications, and theoretical and experimental methods. Herein, a comprehensive review of the up‐to‐date progress of activated carbons is presented from the viewpoint of synthetic chemistry and materials science. First, the critical textural properties are discussed, with special emphasis on the porous texture, heteroatom doping, surface functional groups, and partial graphitization. Next, the advanced synthetic strategies of activated carbons are summarized. Special attention is given to the reaction mechanism between activating agents and carbon sources, as well as the design of controlled forms and morphology. Then, their applicability in various emerging fields is covered, including supercapacitors, capacitive deionization, batteries, electrocatalysis, and carbon capture. In particular, this review highlights the potential synthesis–structure–property correlations of these porous materials. Finally, we present the future challenges and outlook for their success in energy and environmental science. [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]

We propose an aqueous copper battery via Cu2+/Cu+ and Cu3+/Cu2+ redox conversion chemistry on an activated carbon (AC) electrode enabled by a 30 m ChCl + 1 m CuCl2 electrolyte, where Cu3+/Cu2+ redox promotes the discharge capacity by ∼50 mA h g−1 at ∼1.0 V vs. Ag/AgCl with stable cycling. [ABSTRACT FROM AUTHOR]

The growing demand for rare earth elements (REEs) necessitates cheap and environmentally friendly technologies for REEs recovery. Herein, we fabricated a pyrrolic-N doped activated carbon electrode (PPyN-AC) via two facile steps of in-situ polymerization of pyrrole monomers and further carbonization. Capacitive deionization (CDI) using PPyN-AC as electrodes is the first time applied for REEs capture from aqueous solution. PPyN-AC possesses a high N doping rate (9.55 at.%) and excellent capacitance (128.98 F/g). The CDI flow-by tests shows that the electrosorption capacity of La(III) by PPyN-AC electrode was 23.66 mg/g within 25 min at optimal conditions. The rapid and efficient La(III) electrosorption performance is attributed to the pyrrole-N configuration in the carbon matrix. Beyond that, the PPyN-AC electrode could selectively capture La(III) from a quaternary-component system of La(III), Fe(III), Ca(II) and Na(I) in aqueous solution. The REE selectivity mechanism, which involves the ionic charge, hydrated radii of metal ions, and hard-soft Lewis acid-base principle, was proposed. Overall, this work demonstrates a new efficient approach for the selective recovery of REEs from aqueous solution with minimal land and energy demands. The study reported a straight route to prepare pyrrolic-N doped AC serving as capacitive deionization electrode for the recovery of REEs from wastewater. The proposed PPyN-AC electrode exhibits excellent selectivity toward La(III) in the presence of competitive ions. [Display omitted] • Capacitive deionization (CDI) system for REEs recovery is first proposed. • CDI realized 23.66 mg/g La(III) uptake within 25 min by PPyN-AC electrode. • PPyN-AC selectively electrosorbed La(III) from a mixture of La–Fe–Ca–Na. • The pyrrole-N configuration contributes in the selective capture of REEs. [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]

• Activated carbon derived from agriculture by-products obtain high surface area, high porosity, and low density. • Deionization efficiency of CDI, MCDI, and FCDI reached 80–90 % and water recovery rate 90 %. • The roller, spray coating, and mill ball grinding are useful to fabricate electrodes for industry applications. • The adsorption capacities of AC and AC-modified electrodes were 25–40 mg/g. • Life span and deionization efficiency of the flow electrode are higher than electrode plate. Capacitive deionization (CDI), membrane capacitive deionization (MCDI), and flow capacitive deionization (FCDI) are emerging technologies applied to remove ions from brackish water or saline wastewater based on electrode double layer (EDL) mechanisms. The electrode itself can be seen as the most important factor that determines the deionization efficiency of the CDI system. Electrode fabrication using activated carbon derived from agriculture byproducts is a useful solution to decrease cost, restrict environmental pollution, and enable agriculture waste recovery. In this review, the primary parameter's impact on activated carbon (AC) and the electrode fabrication process from the agriculture byproducts is detailed in a discussion to find the most optimal conditions. With excellent characteristics for the activated carbon such as a surface area of up to 2500 m2/g, it can be used to fabricate electrodes that have a high adsorption capacity of approximately 25 mg/g, able to be advanced to 40 mg/g with a modified AC. It can achieve a cycle performance of 95–97 %. The deionization efficiency of the CDI, MCDI, and FCDI systems can be up to 90 % with an input salt concentration from 2000 to 3000 mg/L where the water recovery ratio achieved is 50–90 %, alongside a salt rejection rate of about 7–75 %. AC can be modified to increase its special properties such as surface area, conductivity, and ion selectivity using different methods. The drawbacks and challenges of the CDI technology are also mentioned along with useful solutions such as electrode coating techniques using an anilox roller and a spray, for use in industry applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Scheme 1. Schematic illustration of the procedures for activation of WP. • Activating WP with K 2 C 2 O 4 , H 3 PO 4 or ZnCl 2 forms products of distinct nature. • H 3 PO 4 /ZnCl 2 catalyzes formed more bio-oil but less gas, and K 2 C 2 O 4 is opposite. • K 2 C 2 O 4 and ZnCl 2 are more effective than H 3 PO 4 for creating pores from WP. • ZnCl 2 creates abundant macropores via converting fibers in WP to graphitic crystals. • K 2 C 2 O 4 shows lower environmental impact than ZnCl 2 in activating WP. Waste paper (WP) is rich in cellulose, which can be activated to produce porous carbon, bio-oil, and combustible gases. During chemical activation of WP, the use of varied chemical agents not only generates activated carbon of distinct pore structure but also bio-oil/gases of different property. In this study, the activation of WP with varied chemical agents was conducted. The distinct characteristics of activated carbon and also bio-oil/gases were correlated with the different nature of the used chemical agents. The results indicated that H 3 PO 4 and ZnCl 2 catalyzed polymerization reactions for producing more bio-oil while less gases owing to their Brønsted and Lewis acidic sites. K 2 C 2 O 4 showed high activity for cracking/gasification reactions, forming bio-oil with higher abundance of organics with smaller π-conjugated structures. In addition, ZnCl 2 could create a very coarse porous structure with abundant macropores via destroying fiber structure in WP and promoting the growth of graphitic crystals. In comparison, K 2 C 2 O 4 hindered the aromatization and facilitated the formation of amorphous activated carbon. K 2 C 2 O 4 and ZnCl 2 were much more effective than H 3 PO 4 for creating micropores and mesopores from WP, the derived activated carbon showed superior performances as the electrode of supercapacitor and adsorbent for adsorption of oxytetracycline from aqueous solution. In addition, K 2 C 2 O 4 as activating agent showed lower environmental impact than ZnCl 2 in terms of energy consumption, environmental pollution and the greenhouse effect. [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 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]

[Display omitted] 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, NaCl 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 possibility of hydrogen electrosorption in microporous activated carbons for acidic and alkaline electrolytes is shown. The electrochemical behavior of activated carbon fiber CH-900-20 has been investigated to find out the main factors, which influence the charging processes of microporous electrodes. The following methods were used: cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry, and chronopotentiometry. A comparative analysis of the influence of the electrolyte type and electrode structure on the capacitance performances of carbon has been carried out. It is assumed that there is a potential barrier at the interface between micropores and macropores. The features of the process of hydrogen electrosorption in carbon micropores have been analyzed in detail. A possible mechanism of electrosorption in micropores that decreases the capacitance of the electric double layer with a corresponding drop of the electronic conductance of activated carbons in acidic electrolytes has been suggested. The influence of temperature on the kinetics of hydrogen electrosorption has been shown and the activation energy of this process has been estimated. An assumption has been made about the influence of the semiconductor conductivity of activated carbons on the capacitive and resistive characteristics of the electrodes. [Display omitted] • The capacitance characteristics of microporous carbon fiber in alkaline and acidic electrolytes are compared. • The possibility of hydrogen electrosorption in micropores of activated carbons for acidic media is shown. • The characteristics of the electrodes made of pre-dispersed powder and the initial activated carbon fiber are compared. [ABSTRACT FROM AUTHOR]

Flow electrodes, which are integral to flow-electrode capacitive mixing (F-CapMix), primarily consist of activated carbon (AC), conductive additive and an aqueous electrolyte with a salt. For the better performance of F-CapMix, the AC must have a high surface area and excellent electrical conductivity to facilitate efficient charge percolation and electron transport between the AC particles within the flow electrode. In this study, nitrogen-doped activated carbon (N-doped AC) was synthesized through a straightforward process involving the heating of a mixture of raw AC and melamine in a covered container. The resulting N-doped AC powder exhibited an average of 20 % higher electrical conductivity than raw AC powder without sacrificing the surface area (AC: 2284.7 m2/g vs N-doped AC: 2125.6 m2/g) owing to the incorporation of graphitic nitrogen and oxidized nitrogen into the raw AC surface. The surface characteristics of N-doped AC were found to be similar to those of raw AC. Electrochemical impedance spectroscopy analysis of F-CapMix utilizing N-doped AC in the flow electrode revealed reduced resistance and increased capacitance, leading to an enhancement in power density from 0.706 to 0.828 W/m2. Consequently, integrating N-doped AC into the flow electrode can contribute to the improved performance of F-CapMix. [Display omitted] • N-doped AC exhibited an average of 20 % higher electrical conductivity than raw AC. • Surface area, and pore size and volume of N-doped AC were similar to those of raw AC. • Integrating N-doped AC into flow electrode improves the performance of F-CapMix. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activated carbon prepared from Cassia fistula biomass for supercapacitor application. • The activated carbon electrode achieved a specific capacitance of 136.5 Fg−1 at 0.5 Ag−1. • The symmetric supercapacitor achieved a specific energy density of 7.2 WhKg−1. • The aqueous symmetric supercapacitor shows a capacitive retention of 96.4 % with remarkable durability. Activated carbon derived from biomass sources has been renowned as one of the key materials and economical precursors for numerous energy conversion and storage applications. Herein, we utilized a less explored Cassia fistula (Pulp and seed) biomass as the carbon source for supercapacitor application. Further, a less toxic and low activation method has been implemented to activate the biomass-derived carbon. The highly dense seed resulted in better porous compared to the pulp source. The electrochemical performances of the bio-carbon electrodes have been examined by CV, GCD, and EIS studies. The activated carbon derived from the Cassia fistula seed (CFSA) electrode achieved a specific capacitance value of 136.5 Fg−1 at 0.5 Ag−1 in 3 M KOH. Moreover, the electrode demonstrates an extremely long stability by sustaining 98 % of initial capacitance after 10,000 cycles, which signifies the robust electrochemical stability behavior of the obtained electrode. Further, the aqueous symmetric supercapacitor achieved a maximum energy and power density of 7.2 WhKg−1 and 3488.1 WKg−1, respectively. Likewise, after 10,000 stability cycles, the cell retains 96.4 % capacitance at 5 Ag−1 which denotes the noteworthy capacitive behaviour of the CFSA electrode. Thus, the present work suggests an eco-friendly resource for developing an effectual carbon electrode for energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The roles of specific N-containing groups on HCHO removal were comprehensively studied. • The ACN-600 exhibited the superior HCHO adsorption capacity (16.37 mg/g). • DFT calculation results indicated that pyrrolic-N exhibited the highest HCHO adsorption energy (−32.83 kJ/mol). • Pyridinic-N could trigger the Cannizzaro-type disproportionation reaction. Inserting nitrogen (N) heteroatoms into the carbonaceous adsorbents has been confirmed to be one of efficient strategies for enhancing HCHO removal. However, the essential promotion mechanisms of specific N-containing groups (such as pyridinic-N, pyrrolic-N, and quaternary-N) remain blurred. Herein, a series of N-doped activated carbons were prepared by annealing the melamine impregnated activated carbons at 600–900 °C and used for HCHO elimination. It manifested that the HCHO elimination performance of samples was remarkably improved after N-doping and their HCHO adsorption capacities were in the order of ACN-600 (16.37 mg/g) > ACN-750 (9.87 mg/g) > ACN-900 (7.28 mg/g) > AC (5.09 mg/g). DFT calculation results revealed that there existed stronger attractive noncovalent interactions between pyrrolic-N doped carbon and HCHO due to the formation of stronger H-bonds. Therefore, the HCHO physisorption energy on pyrrolic-N doped carbon was the highest (−32.83 kJ/mol). Compared with the single physisorption mechanism of previous studies, the in-situ DRIFTS results manifested that the pyridinic-N atom (as a typical strong Lewis base) could trigger the Cannizzaro-type disproportionation reaction, which would transform toxic HCHO into relatively less toxic methanol and formic acid. Benefiting from the dual enhanced mechanisms of attractive noncovalent interactions and Cannizzaro-type disproportionation reaction, the ACN-600 manifested excellent HCHO removal performance. This study not only intrinsically discloses the promotion mechanism of specific N-containing groups on HCHO removal at molecular level but also provides guidelines for rational design and development of carbonaceous materials for effective HCHO elimination. [ABSTRACT FROM AUTHOR]

• A concentrated real pharmaceutical wastewater was treated successfully with TOC removal at 87 %. • The system requires no chemical inputs other than catalytic amount of iron. • The system remained stable through 10 treatment cycles. • The regeneration of activated carbon was confirmed using various characterization methods. This study proposes a sustainable approach for hard-to-treat wastewater using sintered activated carbon (SAC) both as an adsorption filter and as an electrode, allowing its simultaneous electrochemical regeneration. SAC improves the activated carbon (AC) particle contact and thus the conductivity, while maintaining optimal liquid flow. The process removed 87 % of total organic carbon (TOC) from real high-load (initial TOC of 1625 mg/L) pharmaceutical wastewater (PWW), generated during the manufacturing of azithromycin, in 5 h, without external input of chemicals other than catalytic amounts of Fe(II). Kinetic modelling indicated that adsorption was the dominant process, while concomitant electrochemical degradation of complex organics first converted them to short-chain acids, followed by their full mineralization. In-situ electrochemical regeneration of SAC, taking place at the same time as the treatment, is a key feature of our process, enhancing its performance and ensuring its stable operation over time, while eliminating cleaning downtimes altogether. The energy consumption of this innovative process was remarkably low at 8.0×10−3 kWh g TOC −1. This study highlights the potential of SAC for treating hard-to-treat effluents by concurrent adsorption and mineralization of organics. [Display omitted] [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]

Composite electrode materials for removing paraquat from contaminated water were synthesized by loading aluminium oxide (Al 2 O 3) onto activated carbon (AC) via co-precipitation method. The composite properties were investigated by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. Capacitive deionization batch experiments compared the electrosorption of paraquat herbicide by the composite electrode and the pristine activated carbon. The performance of the composite electrodes showed that the removal efficiency and adsorption capacity depend on the aluminium oxide loading, applied potential, flow rate, and charging time. At 1.2 V, a flow rate of 15 mL/min, a charging time of 3 h and 20 mg/L PQ initial concentration, the composite electrode (AC/Al 2 O 3 -1:1) demonstrated a removal efficiency, electrosorption capacity, and energy consumption of 95.5 %, 1.27 mg/g, and 0.055 kWh/m3, respectively, compared to 62 %, 0.83 mg/g, and 0.11 kWh/m3 for the unmodified AC. The presences of other ions/pollutants were found to have negligible interference on PQ pesticide removal as the removal efficiency and electrosorption capacity of the AC/Al 2 O 3 -1:1 composite in both artificial (95.5 %, 1.27 mg/g) and natural water (87.5 % 1.17 mg/g). The study confirmed that composite electrode can reused several times, as there was no significant decrease in its regeneration efficiency even after multiple cycles. • Drinking water with pesticides can result in severe health problems. • Capacitive deionization (CDI) is a promising method for pesticide removal. • Presence of different ions and other contaminants does not affect the removal of PQ • Aluminium oxide-modified carbon composite is a promising CDI electrode material for paraquat removal. • Surface modification of activated carbon with aluninium oxide minimizes energy consumption. [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]

Capacitive deionization (CDI) holds great promise for phosphorus adsorption and recovery from wastewater, while current electrodes exhibit poor salt adsorption capacity (SAC) and selectivity due to co-ion effect and interference of co-existed ions with high concentration. Herein, to overcome these issues, a facile route was proposed to prepare a covalent organic framework-membrane coating electrode (COF-MCE) by depositing polyvinyl alcohol/polyethyleneimine membrane onto activated carbon fiber (ACF) followed by the in-situ growth of COF-LZU1. Compared to ACF and MCE, COF-MCE, with abundant functional groups and specific sites, facilitated electrical double layer (EDL)-based adsorption and induced hydrogen-bond interaction with phosphorus, contributing to a higher SAC of phosphorus (10.5 mg/g) in treating 1 mM NaH 2 PO 4. When treating different mixtures of NaH 2 PO 4 /NaCl, NaH 2 PO 4 /NaNO 3 , and NaH 2 PO 4 /Na 2 SO 4 with molar ratio of 1:5, COF-MCE exhibited the high phosphorus selectivity of 3.62, 5.98 and 7.01, respectively, which was attributed to the synergistic effects of EDL-based adsorption, hydrogen-bond and pseudocapacitance. Desorption experiments revealed that high reversal voltage and alkaline condition can weaken the hydrogen-bond interaction and strengthen the electrostatic repulsion between COF-MCE and phosphorus, thus improving the desorption and recovery of phosphorus. These findings confirmed the high potential of COF-MCE in the effective electrosorption and recovery of phosphorus from wastewater. • COF-MCE was prepared by casting followed by in-situ growth of COF powders. • Inhibited co-ion effect and enhanced EDL formation led to superb P adsorption. • Hydrogen-bond and redox-reaction interaction contributed to high selectivity for P. • A reversal voltage and high pH weakened the interaction and favored P recovery. [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]

Lacquer wood (LW) goes through one-step and two-step H 3 PO 4 activation process to prepare activated carbons (ACs) at different temperature, and its performance was evaluated by testing CV, EIS, GCD and cycling respect to an electrode material in supercapacitors. The performance of lacquer wood activated carbon prepared by different activation methods and temperature (300, 400, 500, 600, 700, and 800 °C) was studied, and the influence on its electrochemical properties provides valuable guidance for the high-efficient energy utilization of lacquer wood. The results showed that the AC generated via one-step activation process at 400 °C demonstrate excellent specific surface area (S BET 1609.09 m2/g) than those from two-step activation method. Besides, the biomass-derived ACs presented overall better electrochemistry characteristic than those from charcoal-derived ACs. The largest specific capacitance (354 F/g) was obtained in the ACs-based electrodes which was generated from one-step activation process (activated at 600 °C). After 10000 cycles, its capacity retention reached 95.3%, which provides a meaningful guidance into the application of energy storage supercapacitors. This study proves that the LW derived ACs are promising electrodes of the high-performance supercapacitors, which is beneficial for value-added and industrial supercapacitors application of lacquer wood ACs. [Display omitted] [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]

Capacitive deionization (CDI) is an efficient new technology that can be used to remove charged pollutants. However, differences in the electrode selectivity for different ions limit its further application. Therefore, the electrosorption behavior and selectivity of four anions in a CDI system with activated carbon electrodes were investigated using mixed solutions. The results showed that the adsorption capacities and selectivities of the anions varied due to differences in their hydration energy and valence. The preferential electrosorption order was as follows: NO3− > Cl− > SO24− > phosphate (P). In addition, the competitive mechanism between different anions and P was studied. P competed with SO24− the most for electrosorption sites due to their spatial similarity. However, because the NO3− adsorption capacity was the highest, P had the lowest electrosorption selection coefficient when it coexisted with NO. Finally, the mechanism of the electrosorption selectivity was verified. The results indicated that the electrosorption selectivity of P was improved by decreasing the voltage to weaken the competition between P and other anions for sites and by adjusting the pH to optimize the hydration energy and electronegativity of P. This research may provide readers with a deeper understanding of electrosorption selectivity. [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]

Researchers are trying to tackle water scarcity in numerous ways. One of those ways is the use of nanotechnology in water processing and purification. The current work involves the fabrication and optimization of activated carbon and graphene‐based hybrid water purification system. Five different concentrations of methylene blue and deionized water (DI) dye solutions were used, and they were filtered in three different cycles. For the potential usage on the consumer side, a small‐scale, low‐cost water filter is developed using activated carbon, commercial filter paper, and graphene nanoplatelets. The filter paper is used to hold mixtures of the activated carbon and graphene nanoplatelets within the water filter. The conductivity, TDS, and pH are measured for the feed water and the processed water using an Oakton EcoTestr and Apera Instruments PH60 Premium Pocket pH meter, respectively. A UV‐Vis spectrometer is used to measure the absorption of solutions. The distribution and adsorption of the dye particles were observed by scanning electron microscopy. Practitioner points: These results show the effectiveness of the system in the removal of dye particles above a given particle size.The concentration of the dye solution decreased after every cycle.The GnPs filtration system more effectively dye particles as compared to the filtration system containing only Activated carbon.UV‐Vis spectroscopy results showed that the methylene blue dye particles decreased after every cycle.This research can open a broad area of projects toward waste/wastewater practice for particles above a certain particle size. [ABSTRACT FROM AUTHOR]

Activated carbon (AC), which has attracted considerable attention as an electrode material, holds much promise for electroanalysis. The unique physical and chemical properties of AC, such as the high surface area, good thermal and electrical conductivity, good anti‐causticity, high stability, and low cost make it an electrode material which can generate large profits from a commercialization perspective. Number of biomass‐derived ACs (BACs) with a variety of pore sizes, porosity, morphology, and crystallinity have been prepared from a range of sources of biomass, including agro‐wastes on a large scale. BACs exhibit unique and tunable electrochemical properties depending on their physicochemical properties and thus, have found number of applications in industries, pharmaceutical industry, and water treatment plants. From an electrochemical perspective, researchers have demonstrated the impact of BAC as an electrode material for detecting electroactive drugs, environmental pollutants, and developing electrochemical biosensors. Hence, this paper thoroughly reviews and summarizes the literature published within the last ten years, focusing specifically on the types of analytes detected and electrochemical techniques employed and evaluating their performance (in terms of sensitivity, selectivity, and dynamic ranges) and feasibility for electroanalysis. In addition, the review outlines some constructive advice and scope for further research. [ABSTRACT FROM AUTHOR]

With the attention to the world ecology and economy, people are observing the abundant, low-cost, and clean renewable energy from sun and wind. However, most of the renewable energy sources are intermittent and cannot meet the needs for applications, except for converting to electricity. In order to satisfy the demand of people for new energy storage equipment, supercapacitors using biomass-based carbon materials as electrode materials have attracted much attention, because the multi-level structure of the natural biomass material is conducive to ion transmission. The fine structure of natural biomass cannot be synthesized artificially. The preservation of natural multi-scale structure can provide better electrochemical performance of the biomass-based carbon material. The biomass waste of sword beans shell with the characteristics of fast growth, a large amount of sword bean shells can be continuously produced as raw materials every year, but are often discarded or burned, which contributes to the environmental pollution. It is a promising precursor for obtaining hierarchically porous carbon-based material used as active component of high-storage capacity supercapacitors. The activated carbon with high surface area derived from sword shell by using KOH activation method and used as supercapacitor electrode materials. Taking the specific capacitance value of electrode material as the response value, the activation temperature and the activation ratio as the experimental factors, the Central Composite Design (CCD) method was employed to carry out the response surface optimization study, and the electrochemical performance of the activated carbon prepared under the optimal process conditions was explored. The research results show that the activation temperature and activation ratio have significant effects on the specific capacitance of activate carbon material. The coefficient R2 of the model is 97.54%, and the correction coefficient Adj R2 is 95.78%, indicating that the model can better predict the specific capacitance value of sword shell-based activated carbon with high reliability. The specific capacitance can reach a peak value under the condition of activation temperature 700 ℃ and the activation ratio 4∶1. The optimized process parameters determined by center composite design approach were the activation temperature of 694 ℃ and the activation ratio of 4.17∶1. The verification experiment shows that the average specific capacitance of the sword shell activated carbon material is 254 F/g, which is basically consistent with the predicted value. Furthermore, the Cyclic Voltammetry (CV) curves and Galvanostatic Charge-discharge (GCD) curves of different carbon materials were compared. A quasi-rectangular shape with wide hump peaks can be observed in CV curves, which can be attributed to the synergy between the Electric Double-layer Capacitance (EDLC) and the pseudocapacitance. The nitrogen fixation of legumes can provide carbon materials with nitrogen to produce redox reactions and provide pseudocapacitance. The GCD curves show nearly triangular shapes with a small deviation from linearity, which indicated excellent capacitive behavior of the electrode materials. The Nyquist plots from the Electrochemical Impedance Spectroscopy (EIS) analysis reveal that sword shell-based activated carbon has good electronic conductivity. Additionally, the physical properties of activated carbon was characterized. The apparent morphology of activated carbon was observed by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The nitrogen adsorption-desorption was conducted to investigate the pore structure of the carbon material. The results showed that: sword shell-based activated carbons possess a large number of nanopores, which distributed on the surface of the material, and the maximum specific surface area, total pore volume and micropore volume can up to 3 129 m2/g, 1.68 cm3/g and 0.96 cm3/g, which is conducive to electrolyte circulation and electrolyte ion adsorption [ABSTRACT FROM AUTHOR]

In order to improve the desalination efficiency of the polypyrrole/activated carbon(PPy/AC)electro-adsorption electrode in salty wastewater,the Box-Behnken response surface method was used to optimize the preparation conditions of PPy/AC, specific surface area testing,scanning electron microscope and electrochemical testing were used to characterize the performance of electrode materials.The results show that the optimal process conditions for the preparation of PPy/AC were pyrrole concentration 2.02 mol/L, sodium benzenesulfonate concentration 0.10 mol/L, ferric chloride concentration 2.15 mol/L,and activated carbon quality 2.12 g; the specific surface area of PPy/AC is 499.64 m2/g,polypyrrole is successfully loaded on activated carbon and is flocked,the PPy/AC electrode has a lower transfer impedance,and the specific capacitance of the electrode increased from 89.66 F/g to 276.83 F/g [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]