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Polysaccharide-based hydrogel adsorbents become popular because of their high adsorption capacity and fast adsorption rate, but their low removal rate and poor pH resistance have always been fatal shortcomings. Herein, a feasible strategy was proposed to strengthen the ability of hydrogel adsorbent to remove organic pollutants (i.e., dye) by incorporating natural rectorite (REC) into chitosan- g -poly (2-acrylamido-2-methyl-propane-sulfonic-acid) hydrogel network to form a rectorite-in-polymer network structure. The introduction of less dosage of REC (1.2 wt%) into the hydrogel facilitates to improve its adsorption capacities toward methylene blue (MB) in deionized water, tap water, seawater, Yangtze River water, and Yellow River water (1083.39–1303.49 mg/g); while incorporating higher content of REC (15.8 wt% REC) helps to improve the removal rate (99.6% for MB in real waters), which are greatly superior to commercial activated carbons. The adsorbent keeps high adsorption efficiency in a broad pH range (2–11), and can be reused for >4 times. [Display omitted] • Synthesized chitosan-based hydrogel has a rectorite-in-polymer composite network. • The hydrogel shows high adsorption capacity (1303.49 mg/g) and removal rate (99.6 %). • Removal efficiency keeps high in real waters (Yangtze River, Yellow River, seawater). • The hydrogel's adsorption capacity far exceeds that of commercial activated carbon. • This method is universal to enhance the removal efficiency of hydrogel adsorbent. [ABSTRACT FROM AUTHOR]

• Novel MoSe 2 /MCHS composite with unique 2D/3D interconnected structure was synthesized. • The MoSe 2 /MCHS electrode exhibited excellent HCDI water desalination performance. • Excellent performance came from synergy of intercalation pseudocapacitance and EDLC. • The MoSe 2 /MCHS electrode exhibited great recyclability and low energy consumption. Transition-metal dichalcogenides can be used for capacitive deionization (CDI) via pseudocapacitive ion intercalation/de-intercalation due to their unique two-dimensional (2D) laminar structure. MoS 2 has been extensively studied in the hybrid capacitive deionization (HCDI), but the desalination performance of MoS 2 -based electrodes remains only 20–35 mg g−1 on average. Benefiting from the higher conductivity and larger layer spacing of MoSe 2 than MoS 2 , it is expected that MoSe 2 would exhibit a superior HCDI desalination performance. Herein, for the first time, we explored the use of MoSe 2 in HCDI and synthesized a novel MoSe 2 /MCHS composite material by utilizing mesoporous carbon hollow spheres (MCHS) as the growth substrate to inhibit the aggregation and improve the conductivity of MoSe 2. The as-obtained MoSe 2 /MCHS presented unique 2D/3D interconnected architectures, allowing for synergistic effects of intercalation pseudocapacitance and electrical double layer capacitance (EDLC). An excellent salt adsorption capacity of 45.25 mg g−1 and a high salt removal rate of 7.75 mg g−1 min−1 were achieved in 500 mg L−1 NaCl feed solution at an applied voltage of 1.2 V in batch-mode tests. Moreover, the MoSe 2 /MCHS electrode exhibited outstanding cycling performance and low energy consumption, making it suitable for practical applications. This work demonstrates the promising application of selenides in CDI and provides new insights for ration design of high-performance composite electrode materials. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, active carbon nanofibers (ACFs) and reduced graphite oxidate (RGO) nanocomposites were facilely synthesized and proposed as capacitive deionization (CDI) electrodes for removal of different salty ions. According to this study, the dosage of ACFs has a great effect on the CDI performance of these electrode materials. Cyclic voltammetry results illustrated that sample RGO-ACF 20 (RGO with 20 wt% ACFs) showed the best CDI performance among the all RGO-ACF x samples. The electro-adsorptive capacity of RGO-ACF 20 electrode was 2.99 mg/g with electrical voltage of 2.0 V in about 20 min. Furthermore, the electrosorption of salty ions onto RGO-ACF x follows the Langmuir isotherm, implying the monolayer adsorption. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is a promising technology for the desalination of brackish water due to its potentially high energy efficiency and its relatively low costs. One of the most challenging issues limiting current CDI cell performance is poor cycling stability. CDI can show highly reproducible salt adsorption capacities (SACs) for hundreds of cycles in oxygen-free electrolyte, but by contrast poor stability when oxygen is present due to a gradual oxidation of the carbon anode. This oxidation leads to increased concentration of oxygen-containing surface functional groups within the micropores of the carbon anode, increasing parasitic co-ion current and decreasing SAC. In this work, activated carbon (AC) was chemically modified with titania to achieve additional catalytic activity for oxygen-reduction reactions on the electrodes, preventing oxygen from participating in carbon oxidation. Using this approach, we show that the SAC can be increased and the cycling stability prolonged in electrochemically highly demanding oxygen-saturated saline media (5 mM NaCl). The electrochemical oxygen reduction reaction (ORR) occurring in our CDI cell was evaluated by the number of electron transfers during charging and discharging. It was found that, depending on the amount of titania, different ORR pathways take place. A loading of 15 mass% titania presents the best CDI performance and also demonstrates a favorable three-electron transfer ORR. [ABSTRACT FROM AUTHOR]

As an indispensable element in the field of nuclear energy, uranium (U (VI)) is widely concerned because it is abundant and easy to obtain from seawater. Herein, we report a promising dual-template strategy to prepare heteroatom-doped carbon materials with hierarchical micro−/ meso −/macroporous from low-cost biomass precursors. The carbon materials with hierarchical porosity nitrogen/oxygen are synthesized through freeze-drying, high-temperature thermal treatment and subsequent HF etching treatment by in-situ growth of SiO 2 on the precursor with ethyl silicate as silicon source and introduction of ZnCl 2 as hard template and starch/ammonia as carbon and nitrogen source. Based on the advantages of three-dimensional interconnected hierarchical porous heteroatom doping, the electrosorption capacity reaches 67.25 mg/g, and the removal efficiency is as high as 98.45%, when the initial UO 2 (NO 3) 2 concentration is 80 mg/L in capacitive deionization. The isothermal adsorption of nitrogen doped hierarchical porous carbon (NHPC) is consistent with the Langmuir model, with a maximum electrosorption capacity of 152.43 mg/g, good cycle stability and high charge efficiency (energy consumption is only 0.77 kg-U kWh−1). Fascinatingly, the initial UO 2 (NO 3) 2 concentration is 80 mg/L and it also has a high adsorption capacity in 3.5 wt% NaCl solution, and the U (VI) removal efficiency could reach 42.5% after 8 h of continuous adsorption, with high selectivity. The prepared adsorbent NHPC shows good selectivity for U (VI) in the solution of 11 metal ions co-existing, and the effective selectivity K d value of U (VI) is 1620.84 mL/g. Finally, X-ray photoelectron spectroscopy analysis reveals that in addition to Coulomb interaction and chelation during the adsorption process, there is also a synergistic effect of the conversion of U (VI) to UO 2 under electric drive to improve the adsorption capacity of U (VI). • Dual-template synthesis of biomass-derived hierarchical porous heteroatom-doped carbon materials. • The removal efficiency of the NHPC electrode for U (VI) in 3.5 wt% NaCl solution is 42.5%. • The synergistic effect between UO 2 2+ and NHPC through coulomb interaction and reduction reaction makes it selective for UO 2 2+. [ABSTRACT FROM AUTHOR]

Prussian blue analogue (PBA) as a typical Faraday electrode material has important application value in capacitive deionization (CDI) for its rigid open framework and unique ion storage properties. But poor electrical conductivity and deformation of crystal structure during the desalination process restrict its development. To enhance the stability of PBA and provide rapid charge transfer, a new composite hollow core-shell polyaniline-encapsuled Ni-Prussian blue analogue (H-NP@PANI) is constructed. Experiments illustrate that PANI formed an omnidirectional uniform and highly conductive layer on the crystal surface, which tremendously improved the electrochemical capacity of H-NP@PANI (242.24 F·g−1). In constant voltage mode, the adsorption capacity of AC║H-NP@PANI cell is 35.86 mg·g−1, which was the highest to H-NP (20.82 mg·g−1) and pure Ni-PBA (16.08 mg·g−1). The retention rate remains 96.1 % after 50 cycles. XRD tests show that superior cycle stability is due to the hollow structure and buffer space provided by PANI shell, which can effectively inhibit the degree of crystal transformation. Furthermore, DFT calculation confirms the existence of a highly stable tight electron coupling between H-NP and PANI, and the electron aggregation center around Fe atom facilitates the Fe3+/Fe2+ redox cycle. Hence, this work can provide a feasible strategy for designing stable and efficient electrodes. [Display omitted] • Hollow core-shell PANI-encapsuled Ni-PBA (H-NP@PANI) with omni-directional conductive layer was constructed. • H-NP@PANI electrode showed superior electrochemical performance with high specific capacity of 242.24 F·g-1. • H-NP@PANI electrode had remarkable desalination performance of 35.86 mg·g-1 with superior desalination cycle stability. • Both DFT calculation and experimental analysis revealed the synergistic effect between PANI shell and H-NP in CDI process. [ABSTRACT FROM AUTHOR]

[Display omitted] • A low-carbon strategy was proposed for discarded mask recycling. • High Cr(VI) removal (358.68 mg g−1) was achieved using low-cost CPM/PDA/PPy. • Excellent desalination performance was obtained via capacitive deionization. • It has shown excellent reusability in Cr(VI) adsorption and desalination. The global mask consumption has been exacerbated because of the coronavirus disease 2019 (COVID-19) pandemic. Simultaneously, the traditional mask disposal methods (incineration and landfill) have caused serious environmental pollution and waste of resources. Herein, a simple and green mass-production method has been proposed to recycle carbon protective mask (CPM) into the carbon protective mask/polydopamine/polypyrrole (CPM/PDA/PPy) composite by in situ polymerization of PPy. The CPM/PDA/PPy composite was used for the removal of Cr(VI) and salt ions to produce clean water. The synergistic effect of PPy and the CPM improved the removal capability of Cr(VI). The CPM/PDA/PPy composite provided high adsorption capacity (358.68 mg g−1) and economic value (811.42 mg $−1). Consequently, the CPM/PDA/PPy (cathode) was combined with MnO 2 (anode) for desalination in CDI cells, demonstrated excellent desalination capacity (26.65 mg g−1) and ultrafast salt adsorption rate (6.96 mg g−1 min−1), which was higher than conventional CDI cells. Our work proposes a new low-carbon strategy to recycle discarded masks and demonstrates their utilization in Cr(VI) removal and seawater desalination. [ABSTRACT FROM AUTHOR]

Polyethersulfone (PES) is a widely used polymer for ultrafiltration (UF) membrane fabrication. In the current study, carbide-derived carbon (CDC) oxidized by acid treatment was utilized as a filler to fabricate a novel PES composites UF membranes. The successful oxidation of CDC was validated from presence of oxygen containing functional groups and improved oxygen content, from 5.08 at.% for CDC to 26.22 at.% for oxidized CDC (OCDC). The OCDC PES UF membranes were prepared at different loadings of OCDC between 0.5 and 3.0 wt%. The membrane porosity, pore size and surface free energy found to be improved while a noticeable reduction in water contact angle was observed with OCDC loading implying the improved hydrophilicity of PES membranes. Consequently, the pure water flux found to improve from 151.6 to 569.6 (L/(m2. h)) for the 3.0 wt% modified OCDC membrane (M−3) which is 3.8 folds of the bare PES membrane. The antifouling characteristics were evaluated by humic acid (HA) filtration. The results revealed a significant enhancement in HA rejection with OCDC loading, the highest rejection was 96.8% for M−3 membrane. Additionally, the adsorption capacity of OCDC modified membranes found to decrease with OCDC loading indicating improved rejection of HA from the membrane surface. Moreover, M−3 demonstrated the maximum flux recovery ratio (FRR) of 92.3%. Reusability of the fabricated membranes was evaluated by deionized water/humic acid cycling filtration. The FRR was higher than 86.7% over three cycles of pure water/HA filtration for 140 min, indicated the excellent stability and reusability of the membranes. Overall, the OCDC was an effective filler for enhancing the PES UF membranes antifouling and permeability properties. [Display omitted] • Oxidized carbide-derived carbon (OCDC) was synthesized by acid treatment. • PES UF membrane porosity, contact angle and hydrophilicity were improved with OCDC addition. • Humic acid rejection and antifouling properties were improved with OCDC loading. • Long term filtration experiments of pure water and humic acid were considered. • The OCDC found to be an effective and compatible filler for PES UF membranes. [ABSTRACT FROM AUTHOR]

Fluorine pollution has been recognized as one of the major problems of global concern. Metal-organic frameworks (MOFs), as potential fluoride adsorbents, possess unique chemical reactivity and broad functionalities. However, their application is restricted by instability in fluoride or acid/base solution and difficult separation. Here, lotus flower-like Al/N-doped porous carbon composite was prepared by a simple pyrolysis method using Al-based MOF as a precursor and used for capacitive deionization (CDI) defluorination. Through pyrolysis, MOF-derived carbon not only obtained a larger specific surface area and N-rich structure, but also possessed multiple F− capture sites. These carbon substrate enabled the metal centers to be uniformly dispersed and contributed to enhanced electrical conductivity and chemical stability of electrode material. Through the CDI defluorination system, F− migrate rapidly with the aid of the electric field and was captured under the synergistic effect of metal sites and carbon substrate. According to the Langmuir isotherm, the maximum F− removal capacity was 76.28 mg g−1 at 1.2 V, and the adsorption kinetics followed pseudo-second-order model. The electroenhanced adsorption method exhibits high adsorption capacity and selectivity for F− due to combining the advantages of adsorbent adsorption and electrosorption, which already exceeds the capacities of most electrode material. [Display omitted] • MOF-derived Al/N-doped porous carbon composite (AlNC) is firstly proposed in Capacitive deionization defluorination. • The F− removal capacity reached 76.28 mg g-1 at 1.2 V. • Presented a possible mechanism for the elctrosorption of F- on AlNC. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) has been considered as the most promising and environmentally friendly electrical desalination technology owing to its low energy consumption and no secondary pollution. CDI is based on the principle of electric double layer for salt ion adsorption, but the existence of co-ions repulsion reduce the charge efficiency, leading to the low salt adsorption capacity. To prevent the intrinsic "co-ion effect" inside the porous carbon electrodes, membrane capacitive deionization (MCDI) by applying an ion-exchange membrane (IEM) to the surface of electrode is of increasing interest. However, MCDI brings various resistances, such as the internal and interface resistances of membrane, as well as the contact resistance between membrane and carbon electrode. More recently, by integrating "membrane" with carbon electrode without the introduction of free-standing IEM, integrated-MCDI has shown great merits to enhance counter-ion selectivity of electrode and decrease resistance, resulting in improving adsorption rate and reducing energy consumption. In this review, the preparation methods of innovative electrodes, the working mechanisms and performances of integrated-MCDIs, and the advanced advantages are summarized. It is hoped that this work will provide insight into integrated-MCDI and shed light on the future direction of water desalination based on CDI technology. [Display omitted] • Integrated-MCDI has been developed without using free-standing IEM on electrode. • Integrated-MCDI outperforms MCDI on energy consumption, cost, and kinetic rate. • Integrated-MCDI has the potential of anti-organic pollution and ion-selective removal. • Review summarized current status of integrated-MCDI for water desalination. • The mechanisms of integrated-MCDI with different fabrication methods are analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The universal low carbon mass loading was used in capacitive deionization (CDI) for efficient deionized (DI) water production. • Partial desalination performance weakened with increasing carbon mass loading. • CDI cells using YEC-8–5.81 as electrodes produced DI water with a low conductivity of 1.89 μS/cm. • Carbons with a suitable micro- meso pore distribution and high specific capacitance may be a better choice. • 82.2% DI water recovery was achieved under stopped flow (SF) discharge mode. High-purity deionized (DI) water can be widely used in high-end manufacturing fields, but its efficient and energy-saving production is a huge challenge. Here, simple carbon mass loading control was developed for efficient DI water production via advanced capacitive deionization (CDI). Supercapacitor carbon (YEC-8) electrodes with diverse mass loading of 2.50, 5.81, 12.63 and 24.72 mg/cm2 were prepared for desalination. As expected, YEC-8–2.50 acquired the optimal CDI performance. High mass loading of 12.63 and 24.72 mg/cm2 not only caused an overt property drop but also serious wasted materials. Competitively, YEC-8–5.81 achieved a similar volumetric adsorption capacity (VAC) to YEC-8–2.50 as well as made up for the lack of total mass of YEC-8–2.50 and the resultant solution conductivity was as low as 1.89 μS/cm (grade III DI water). This strategy has been successfully extended to other carbon materials and carbons with suitable micro- meso pore distribution and high specific capacitance may be a better choice. Besides, the reverse effect of acetylene black (AB) mass on desalination was verified. To gain a high water recovery (W R), stopped flow (SF) discharge was introduced and realized a high W R of 82.2 %. Meanwhile, cycling tests indicated its splendid cycling stability. This study provides a universal direction for using low mass loading strategy for efficient DI water production. [ABSTRACT FROM AUTHOR]

Flow electrode capacitive deionization (FCDI) has great advantages in high salinity wastewater desalination. However, due to the limited adsorption capacity of electrode material, membrane concentration polarization would form and increase energy consumption, and affect the continuity of desalination. In this work, milling technology was used to modify original activated carbon (AC), the obtained ball milled activated carbon (BAC) was used as FCDI electrode material. The milling process modified multiple physical and electrochemical characteristics of original AC. The highest average salt removal rate (ASRR) of BAC was 2.2 times of that of AC, which was attributed to the modified surface properties including more oxygenated functional group, larger electrostatic gravitation characteristics and better hydrophilicity. The reduced concentration polarization during the desalination was responsible for the increased adsorption capacity, which was due to larger electrolyte contact area, enhanced ions capacity by more suitable pore structures, and 5 times higher energy normalized removal salt (ENRS) of BAC flow electrode than that of AC. Because of its simple operation and remarkable modification effect, ball milling technology shows great potential in large scale modification of electrode materials. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is attracting increasing attention as an emerging technology for the facile removal of ionic species from water. In this work, the feasibility of fluoride removal from low-salinity groundwaters by single-pass constant-voltage CDI was investigated and a model developed to describe the dynamic fluoride electrosorption behavior. Effects of operating parameters including charging voltage and pump flow rate as well as impact of fluoride and chloride feed concentrations on the effluent fluoride concentration and equilibrium fluoride adsorption capacity were studied and the obtained data used to validate the model. Using the validated model, the effects of various design parameters, including arrangement of multiple CDI cells, on fluoride removal were assessed. Single-pass constant-voltage CDI was found to be effective in removing fluoride from low-salinity groundwaters but, as expected, removal efficiency was compromised in waters of high salinity. The relatively simple electrosorption model developed here provided a satisfactory description of both fluoride removal and current evolution and would appear to be a useful tool for prediction of CDI performance over a range of operating conditions, cell arrangements and feed water compositions though scope for model improvement exists. [ABSTRACT FROM AUTHOR]

Six water-tolerable metal-organic frameworks (MIL-101(Cr), MIL-100(Fe), MIL-100(Cr), MIL-53(Cr), MIL-96(Al), and UiO-66) were employed for the adsorptive removal of acetic acid from water. UiO-66 exhibited more potential as an acetic acid adsorbent than other five MOFs. UiO-66 was further investigated in the view of adsorption kinetics, isotherm, thermodynamics, and regeneration of the adsorbent. The analysis of film diffusion and intraparticle diffusion model suggested that larger acetic acid concentrations would cause higher effects of boundary layer, and the adsorption process was multiple steps. The kinetic results show that adsorption of acetic acid on UiO-66 fitted to pseudo-second-order model and was controlled by chemical adsorption. The adsorption isotherm of acetic acid on UiO-66 followed Freundlich isotherm, which indicated the presence of heterogeneous surface on UiO-66. The thermodynamic parameters (Δ G , Δ H and Δ S ) were also calculated, confirming that the adsorption of acetic acid on UiO-66 was spontaneously exothermic and decrease of disorder. The regeneration of UiO-66 was also demonstrated by washing with deionized water and ethanol. The adsorption capacity and XRD of UiO-66 did not change significantly even after three cycles. Therefore, UiO-66 can be a promising adsorbent for adsorptive removal of acetic acid from wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen-doped porous carbon is synthesized via a dual-salt template approach. • The carbon exhibits high ion adsorption capacity and ultrafast adsorption rate. • Ion adsorption proceeds via electrocapacitive and pseudocapacitive mechanisms. • The electrocapacitive mechanism plays a dominant role in the ion adsorption. Porous carbon materials hold tremendous potential for capacitive deionization (CDI). However, realizing high specific surface area (SSA), suitable pore size distribution, and hierarchical porosity in carbons with facile and sustainable techniques is still challenging. In this work, we prepare hierarchical porous carbons (HPCs) with high SSA, abundant pore structures, and N-self doping via a versatile and sustainable modified salt-template approach. The optimized electrode gives a high SSA of 1639.9 m2/g, a large pore volume (2.7 cm3/g), and hierarchical porous structures (micro-meso-macro pores). For applications, the symmetric CDI electrode assembly delivers a salt adsorption capacity (SAC) of up to 17.67 mg/g in a 500 mg/L NaCl at 1.2 V together with ultrafast salt adsorption kinetics. We systematically study their associated desalination mechanism by combining several electrochemical experiments with the in-situ Raman spectroscopy technique, which revealed that the total salt storage is from the synergistic effect of both electrical double-layer (EDL) storage and pseudocapacitive mechanisms, with the EDL storage being dominant. This work paves the way to design economical and eco-friendly porous carbon materials for high-performance CDI desalination. [ABSTRACT FROM AUTHOR]

Integration of membrane and nanomaterial is a forward-looking research orientation, which can effectively overcome the permeability-selectivity trade-off relationship and improve anti-fouling performance. However, the current combination methods usually suffer from defects due to the aggregation and embedding of nanomaterials, resulting in serious performance deterioration of membrane during continuous operation process. Herein, "graphdiyne-like" Tetrabromobisphenol A molecularly imprinted membranes with uniform and dense SiO 2 layer, namely TB-MIMs, are successfully prepared by delayed phase inversion method (DPIM). We found that the membrane prepared by DPIM exhibits both promoted pure water flux (405 L m−2 h−1) and enhanced adsorption capacity (83.476 mg g−1) by comparing with the membranes prepared by blending and grafting methods. The role of molecularly imprinting technique contributes to improving the selectivity of TB-MIMs toward TBBPA, leading to a high selectivity factor of 3.39, 3.27 and 3.05 for bisphenol A, paratert-butyl phenol and 4, 4'-dihydroxybiphenyl, respectively. Moreover, the flux of TB-MIMs is nearly recovered to an original level after washing the bovine serum albumin fouled membrane surface with deionized water. Notably, the TB-MIMs presents a high rejection rate for bovine serum albumin (94%), humic acid (92%) and alginic acid (91%) in natural water, indicating its bright actual application value. These superior performances highlight the advantage of DPIM strategy over traditional methods in terms of combination between membrane and nanomaterials. A "graphdiyne-like" molecularly imprinted membrane with high selectivity and lasting anti-fouling performance was first proposed and developed by delayed phase inversion method for selective recognition and separation of Tetrabromobisphenol A. [Display omitted] • A"graphdiyne-like" membrane was synthesized by delayed phase inversion method. • The SiO 2 sphere had a dense and uniform distribution on the membrane surface. • The TB-MIMs possessed a superior selectivity and water permeability. • A lasting anti-fouling stability was realized. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is an emerging technology in brackish water desalination. Several types of CDI electrodes have been fabricated and tested throughout the years and most, if not all, require hours of CDI performance testing to assess their capability. In this study, a model was created to predict the salt adsorption capacity of different carbon-based CDI electrodes. Random forest, a statistical classification method, was utilized in the making of the model. Based on the results, the generated models had high accuracy and precision in estimating the salt adsorption capacity, representing R2 values mostly over 0.9. Furthermore, feature importance analysis showed that specific capacitance at higher scan rates can reduce the performance of the model. Therefore, it is recommended that low scan rate specific capacitance be used in creating any kind of CDI model. This study also illustrated that a universal model is possible for CDI with a minor sacrifice in precision. Depending on the goal of the end user, individual and universal models can be used in the prediction of salt adsorption capacity of various CDI electrodes. • The SAC of different CDI electrodes was predicted by the RF model. • Carbon electrodes doped with heteroatom and metal/metal-heteroatom were examined. • Variable importance of operational condition and electrode property was explored. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ppy grafted CMC carbon aerogels are applied in CDI for the first time. • Ppy/CA-2 shows excellent electrochemical and electrosorption performance. • The salt adsorption capacity of Ppy/CA-2 reaches 34.03 mg g−1. • Ppy could capture Cl− via surface redox reaction during CDI. Capacitive deionization (CDI) has been identified as a prospective desalination technology. There has been increasing interest in the exploration of electrodes with high electrochemical properties and salt adsorption capacity. Here, polypyrrole (Ppy)/CA electrodes were prepared by grafting Ppy on carbon aerogel (CA) via in-situ polymerization and applied in CDI desalination. Compared with CA, the Ppy/CA samples display higher specific capacitance, lower charge transfer resistance as well as enhanced ion diffusion rate. Particularly, Ppy/CA shows enhanced pseudocapacitance generation and the synergistic effect of the diffusion-controlled dominating process and capacitive process by Ppy introduction, conducive to the desalination performance. The optimal Ppy/CA-2 CDI system exhibits high adsorption capacity (34.03 mg g−1 with 500 mg L−1 solution), fast salt adsorption rate (0.053 mg g−1 s−1 with 500 mg L−1 solution) together with reasonable long-term stability. The outstanding desalination performance is principally on account of the positively charged nitrogen atoms of Ppy could capture Cl− well through the surface redox reaction in CDI and the most positively charged nitrogen in Ppy/CA-2 contribute its best adsorption capacity. The simple preparation method, excellent electrochemical properties, outstanding adsorption performance, and good cycling stability render Ppy/CA-2 a potential CDI electrode material. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-doped ultra-microporous wood carbon (SUMW) composite was prepared by one-step chemical activation. • We proposed E pzc -based ion-selective electro-adsorption mechanism. • The selective coefficient of SUMW electrode of NO 3 – over SO 4 2− was reached 32, • The adsorption capacity of the designed material reached up to 637 μmol/g. Capacitive deionization (CDI) technology is promising for selective removal of target ions from various sewages. However, the low electro-adsorption capacity and poor selectivity in the complex sewage system highly restrict its practical application. Potential of zero charge (E pzc) is the external circuit applied potential as the electrode material exhibiting no ion electro-adsorption from the electrolyte. Although E pzc shows a great prospect for regulating the electro-adsorption performance of the electrode, how to use it to achieve selective electro-sorption remains challenging. Herein, we demonstrate a Sulphur (S) doped ultra-microporous (∼0.7 nm) free-standing wood carbon electrode by one step chemical activation, which exhibits different E pzc values in nitrate or sulphate solution due to the unique S-doped ultra-microporous structure. Accordingly, a fantastic selectivity for NO 3 – over SO 4 2− (S N O 3 - / SO 4 2 - =32) was achieved as the applied voltage window ranges from 0.12 V (E pzc -NO 3 –) to 0.43 V (E pzc -SO 4 2−). In addition, the adsorption capacity of the designed material reached up to 637 μmol/g, which is much higher than the maximum value ever reported (∼200 μmol/g). 2000 mL Yellow River water was treated by our tandem CDI cell device through recycling charge and discharge ten times. As expected, the concentrations of NO 3 – ions in the Yellow River water were dramatically reduced from 152 mg/L to about ∼ 35 mg/L after treated with the tandem CDI cell device, which demonstrates the excellent practical application prospect. [ABSTRACT FROM AUTHOR]

Given that carbon-based electrodes suffer from poor long-term stabilities and limited desalination capacity, the optimized charge storage mechanism used for improving desalination performance remains requisite. In this work, the KC-pre-intercalated carbon nanosheets (PCNs) with abundant conjugated carbonyl groups were designed via a one-step smelting method for the first time as a novel intercalation electrode in the symmetric capacitive deionization. Interestingly, below 500 mg/L, the physical electrical double-layer mechanism is mainly influential. Benefitting from the proposed dynamic intercalation mechanism, a remarkable ion removal capacity of 1.65 g g−1 and impressive cyclability of 300 cycles (97.96%) were observed in the high salt concentrations (>1000 mg/L) and simulated seawater system rather than pure NaCl solution. The ultrahigh adsorption capacity and prominent cycling stability make the PCNs-based device rank top three among these of all the symmetric CDI systems reported in the literatures so far. The Na+ ions are intercalated in the enlarged interlayer spacing without a host structure deformation, thus offering a high ion removal rate (2.04 mg g−1 min−1) and a low energy consumption (0.28 Wh g−1). Our work exemplifies the importance of engineering conjugated carbonyl groups and pre-intercalated structure to capacitive deionization for brine. [Display omitted] • A novel dynamic intercalation mechanism leads to a remarkable SAC of 1.65 g g−1 in the simulated seawater system. • Pre-intercalation carbon nanosheets deliver superior SAC (40.72 mg g−1) as well as life-span (300 cycles) in 500 mg/L NaCl. • Engineering conjugated carbonyl groups and pre-intercalated structure to capacitive deionization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cyclic voltammetry (CV) measurements were performed for the MCDI cell. • The potential of minimum charge (PMC) of the MCDI cell was measured as −0.22 V. • The desorption rate was not significantly affected by the desorption potential. • The water splitting reaction occurred at a desorption potential below the PMC value. • The optimal desorption potential was equivalent to the PMC value for stable and effective operation of the MCDI cell. The optimal desorption potential (DP) for maximizing the salt adsorption capacity of a carbon electrode while maintaining the stable operation of a membrane capacitive deionization (MCDI) cell was studied. Cyclic voltammetry (CV) measurements were performed for the MCDI unit cell. Additionally, the adsorption and desorption characteristics of the MCDI cell were analyzed while changing the DP. The potential at which the charges of the carbon electrode become the minimum was defined as the potential of minimum charge (PMC). The PMC value was measured as −0.22 V from the cyclic voltammogram. In addition, as the cell potential increased, the adsorption capacity of the carbon electrode increased. However, the effect of the DP on the desorption rate was negligible. In DPs below the PMC value, all adsorbed ions were desorbed, but the effluent pH rapidly decreased due to the occurrence of a water splitting reaction at the interface between the carbon electrode and the ion exchange membrane. When the DP was set as greater than the PMC value, some ions remained on the carbon electrode, resulting in a decrease in the amount of adsorbed ions during the subsequent adsorption process. When the DP was equivalent to the PMC value, the adsorption capacity of the carbon electrode was maximally utilized, and the pH of the effluent was maintained in a stable state. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is an electrochemically controlled desalination technology based on applying a non-faradaic process in the electrical double layer region. Because CDI performance is affected by the type of operational mode, this study examined salt adsorption capacity (deionization capacity) and energy consumption of two CDI operational modes, constant voltage (CV) and constant current (CC). The use of higher cell voltage in CV mode resulted in faster salt adsorption under a given charging time due to stronger electrostatic attraction than CC mode. However, despite of the faster salt adsorption of CV mode, CC mode showed much lower energy consumption than CV mode by 26%–30% as an identical electrical charge was consumed or an identical amount of ion removal was considered. This lower energy consumption is due to the overall lower cell voltage used in CC mode than in CV mode. This study suggests that better salt adsorption capacity and energy consumption in CDI operation may be achieved by applying appropriate CV and CC modes. [ABSTRACT FROM AUTHOR]

Cadmium (Cd2+) is the main toxic heavy metal in desulphurisation wastewater for coal-fired power plants. Here, a novel carbon skeleton/molybdenum disulphide composite material (MoS 2 /AC) with expanded layer spacing was synthetized in one step for Cd2+ removal through the capacitive deionization method. As the results showed, the Cd2+ removal capacity of the MoS 2 /AC cell was 22.15 mg g−1, and the concentration of Cd2+ in the simulated wastewater was effectively reduced from 10 ppm to <0.1 ppm. According to the characterisation, the layer spacing of MoS 2 nanosheets in MoS 2 /AC increased by 58.06% compared with the original commercial MoS 2 , which could provide more active sites for Cd2+ adsorption. Moreover, the XPS results showed that electrosorption and complexation on the surface of MoS 2 /AC were the main routes for Cd2+ removal, especially the complexation between Cd2+ and metal-sulphur. In addition, the selective adsorption efficiency of MoS 2 /AC was more than 98% under the coexistence of other ions, such as Na+, Mg2+, and Ca2+. The regenerated MoS 2 /AC also had a high adsorption capacity for Cd2+ even after 5 cycles. The MoS 2 /AC material also exhibited excellent removal capability for heavy metal ions in the actual desulphurisation wastewater from coal-fired power plants (<1 ppb). The results indicated that MoS 2 /AC may be a prospective material for heavy metal ion removal from wastewater. [Display omitted] • MoS 2 /AC was developed as an effective CDI electrode material. • High Cd2+ absorption capacity of 22.15 mg g−1 and excellent recyclability. • The obtained MoS 2 /AC possess enlarged interlayer spacing to expose S adsorption sites. • The exposed sulphur atoms complexed with cadmium ions to remove Cd2+. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) technology is a high-efficiency, energy-saving, green and environmentally friendly new water treatment technology, which will have potential in the field of low-salinity seawater desalination. Current carbon-based electrode materials have limited desalination capacity and rate due to insufficient ion-accessible specific surface area and slow ion transmission rate. Here, we demonstrate layered porous carbon (CHPC) derived from Chitosan, colloidal SiO 2 and polytetrafluoroethylene (PTFE) mixed carbonization for efficient CDI desalination. CHPC has abundant macropores that are connected with mesopores. This layered porous structure enables CHPC to have a faster ion migration rate. The salt removal capacity of CHPC reaches 26.5 ± 1.5 mg/g, and the average adsorption rate is 8.8 ± 0.5 mg/g/min, which are about 1.6 and 10 times than that of commercial activated carbon, respectively. In addition, CHPC has extremely strong anti-interference performance against organic macromolecules, which could maintain more than 95% adsorption capacity after 30 cycles. Our work helps to promote the practical application of hierarchical porous structures based on typical biomass in large-capacity and fast-rate CDI desalination technology. [Display omitted] • CHPC forms a macroporous-mesoporous hierarchical carbon network framework through a multi-step etching reaction. • CHPC achieves an ultra-fast adsorption efficiency of 8.8 ± 0.5 mg/g/min due to fast ion/electron transport. • CHPC has excellent cycle stability and resistance to interference from macromolecular substances. [ABSTRACT FROM AUTHOR]

• The presence of coordinated water was beneficial for ion diffusion within CuHCF. • Chelators and Na+ in precursors reduced zeolitic and/or coordinated water in CuHCF. • Lower water content increased Na+ removal capacity but sacrificed stability. • CuII/CuI redox couple activation increases when controlling chelators in precursors. • Activation of reversible CuII/CuI redox couple contributed to BDI cycling stability. Prussian blue analogues are being explored as electrode materials for electrochemical desalination of saline water in battery-type electrode deionization systems and hybrid capacitive deionization systems due to their open framework crystal structure that provides selective adsorption of multiple cations, high theoretical sodium adsorption capacities, and low costs. However, poor electronic conductivity and instability (dissolution) prevents the use of these materials for long-term desalination applications. To understand how synthesis conditions might improve the properties of copper hexacyanoferrate (CuHCF) powders relative to sodium ion adsorption capacity and cycle life, the co-precipitation process was investigated using multiple common synthesis strategies that included addition of chelators and sodium salts as well as different concentrations and oxidation states of precursors. Smaller crystallite sizes (<35 nm) and lower structural water contents increased the initial sodium removal capacity to 53.2 mAh/g from 40.4 mAh/g (control), but also reduced cycling stability in long-term operation (20–55% retention over 100 cycles). The trade-off in stability is thought to be a consequence of structural water facilitating ion diffusion within the material. Adding chelators as precursors led to a highly reversible CuII/CuI redox couple that increased the stability of the FeIII/FeII redox couple in BDI cycling performance (79.4% retention over 100 cycles). [ABSTRACT FROM AUTHOR]

Activated-carbon-electrodes are widely used in capacitive deionization (CDI). However, the desalination capacity of most activated carbons remains to be improved, which makes it necessary to explore activated carbons with special structure and improved desalination capacity. In this context, we studied the desalination performance of super activated carbons with ultra-high total pore volume (V Tot). This carbon showed a salt adsorption capacity of 27.2 mg/g in 500 mg/L NaCl solution at 1.2 V, which ranked among the highest value ever reported for activated carbons. The high adsorption capacity was due to the large V Tot caused by the abundant presence of both micropores and mesopores in the material. The adsorption capacity of the carbon after 10 adsorption-desorption cycles (saturated adsorption capacity) was as high as 67.6 mg/g, which was dominated by V Tot and water contact angle. The sample also showed excellent desalination rate and superior charge efficiency (76.5%). This study indicated that superior desalination performance could be obtained by using super activated carbon with high pore volume as a CDI electrode material. [Display omitted] • SAC with high pore volume (AC-P-CO 2) showed excellent desalination performance. • The salt adsorption capacity of AC-P-CO 2 was 27.2 mg/g. • The salt adsorption capacity ranked among the highest values for activated carbons. • The salt adsorption capacity after 10 cycles of AC-P-CO 2 was 67.6 mg/g. • AC-P-CO 2 showed superior desalination rate and charge efficiency (76.5%). [ABSTRACT FROM AUTHOR]

• A porous nanofiber membrane with dense distribution of La nanorods was prepared. • Exceptional high utilization ratio of La (0.98). • LPS was easily separated from solution. • The LPS can reduce total phosphorus to less than 10 μg/L in natural lake water. • Phosphate was effectively captured in a wide pH range of 4–10. As phosphate is one of the key causes of water eutrophication, its removal from aquatic ecosystems is essential. Adsorption methods have been widely used to remove phosphate from water bodies. However, most of the adsorbents are unstable and difficult to separate from solution. In this paper, we used a simple electrospinning method to prepare a new, well-dispersed, lanthanum (La)-based porous polyacrylonitrile nanofiber (LPS) with more active sites, which improve its phosphate removal efficiency. The maximum phosphate adsorption capacity on LPS was 218.5 mg P/g (La) (50.4 mg P/g). After complete adsorption, the P/La molar ratio on LPS was 0.98. After 48 h of oscillation, the leakage of La from LPS in deionized water was only 74 μg/L, effectively ruling out secondary pollution of the water-body. Moreover, unlike most adsorbents, LPS has the advantage that it can be readily isolated from water. After treatment with LPS, the total phosphorus (TP) of a water sample from Yangzonghai Lake (Yunnan, China) was reduced to 4.2 μg/L, a value lower than the concentration threshold of eutrophication (10 μg/L) set by the United States Environmental Protection Agency (USEPA) and the first category of the surface water environmental quality standard (10 μg/L) set by China for lakes and reservoirs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A pilot-scale MCDI system was designed for ammonia recovery from municipal wastewater. • Different working conditions were optimized for ammonia recovery. • Competitive adsorption between Ca2+, Mg2+ and NH 4 + were discussed. • The MCDI system showed high stability in long-term operation. • MCDI showed preferential electrosorption of NH 4 + in short adsorption periods. With the depletion of energy, renovation of wastewater has attracted wide attention around the world, among which the recovery of ammonia has also been an ongoing topic. Membrane capacitive deionization (MCDI) has emerged as a promising technology for nutrient removal and recovery. However, limitations of both scale-up and treatment of practical wastewater still restrict its real application. This study aims to investigate the feasibility of ammonia removal from real wastewater by MCDI on a pilot scale. The MCDI module used in this study was expanded to a 2-unit facility (15 pairs of electrodes per unit). Firstly, synthetic wastewater was used as feed water to optimize different kinds of operating parameters, including applied voltage (0–2.5 V), flow rate (7–30 L/h), and initial concentration (20–100 mg/L). Further experiments investigated the competitive adsorption performance under complex inflow conditions. Results indicated that the presence of co-existing cations significantly reduced the removal efficiency and adsorption capacity of ammonia. With the same inflow concentration, the removal efficiency of NH 4 +, Mg2+, and Ca2+ was 39.12 ± 5.31%, 47.56 ± 2.68%, and 33.33 ± 1.90% respectively. The interplay of initial ion concentration, charge valence, and hydrated radii led to the different electro-sorption performances. Subsequently, practical municipal wastewater after the up-concentration of organics was used as feed water to evaluate the feasibility of the pilot-scale MCDI. Under the optimized condition, a long-term experiment was carried out for 15-day to deal with actual wastewater. Besides, ion removal performance, the energy consumption, and desorption efficiency were also analyzed. The system maintains a stable removal efficiency for all cations, with low energy consumption (1.16 kWh/m3) and high desorption efficiency (around 90%). Overall, the results of this study posed the MCDI process as a potential approach to ammonia removal and recovery from municipal wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed a carbonized MIP-202/MXene (CMM) for selective electrosorption of U(VI). • MXene provides pseudocapacitance/intercalation effect and conductive base. • Two composite structures were observed during preparation of CMMs. • The CMM electrode exhibited excellent adsorption capacity and selectivity for U(Ⅵ). As the key element in the nuclear industry, uranium (U) has been widely concerned for its stable acquisition and efficient recycling. Capacitive deionization (CDI), which known as a seawater desalination technology, has shown great potential for uranium-adsorption. However, the poor selectivity restricts the application of CDI in uranium extraction. In this work, a carbonized MIP-202/MXene (CMM) composite was developed for highly efficient selective electrosorption of U(VI) from multi-ionic water. The uniformly decorated MIP-202 can prevent MXene from aggregation and provide rich pore structures, large specific surface area and additional nitrogen source for the efficient electrosorption of U(VI). With the addition of MXene nanosheets, a conductive network was introduced into the CMM and improved mechanical robustness of material to facilitate rapid charge transfer at the interface. As a result, the CMM electrode exhibited a maximum adsorption capacity of 582.46 mg g−1 calculated from Langmuir model and a removal ratio of 89.1% at 1.2 V in UO 2 2+ solution. The selectivity adsorption of CMM for UO 2 2+ can reach 92.3% when treated with multi-ionic solution. Besides, there is an interesting fact that the decreased ratio of added MXene can got a higher adsorption capacity, which may cause by the two composite structures formed when the mixing ratio changed. Overall, the excellent conductivity, high adsorption capacity and selectivity make CMM a promising electrode in CDI for efficient extraction of uranium from water. [ABSTRACT FROM AUTHOR]

• The first high entropy oxides based multifunctional electrode material is synthesized by simple grinding technique. • Nano-sized (< 10 nm) high entropy oxides are incorporated in surface functionalized biowaste derived activated carbon. • High salt adsorption capacity of 241 mg g−1 and cycle repeatability upto 20 cycles is demonstrated. • The excellent desalination capacity is attributed to the combined electric-double layer and pseudocapacitive mechanism. Nano-sized high entropy oxides (particle size < 10 nm) are expected to possess enhanced stability, electrochemical properties and increased potential in versatile applications than bulk metal oxides. In this study, nano-sized high entropy oxides incorporated surface functionalized coconut shell derived activated carbon (HEO/f-CSAC) is synthesized, characterised and used as an advanced multifunctional material for electrochemical energy storage and desalination. Attributed to its unique microstructure and extraordinary properties, HEO/f-CSAC shows an excellent salt adsorption capacity of 241 mg g−1 at 1.2 V in 500 mg L−1 concentration of NaCl solution, which is very high as compared to previous reports. The reason behind high salt adsorption capacity is its outstanding specific capacitance of 147.5 F g−1 at current density 1 A g−1. Moreover, the assembled lab-scale CDI unit demonstrates extremely good performance upto 20 adsorption-desorption cycles due to the long cycle life with good capacitance retention of fabricated HEO/f-CSAC based two-electrode supercapacitor. Additionally, a red light-emitting diode illumination by connecting three supercapacitors in series, indicates the high efficiency and potential of HEO/f-CSAC for real life energy-related application. These results prove that HEO/f-CSAC can be implemented for water desalination with enhanced supercapacitive performance manifesting its multifunctionality for energy and environmental applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A self-supported MoS 2 /CoS 2 @TiO 2 nanotube (TNT) hybrid electrode was fabricated by an in-situ hydrothermal process-assisted growth strategy, which achieved a significantly high gravimetric Na+ adsorption capacity and excellent regeneration performance. It also demonstrated amazing removal efficiencies close to 90% for various heavy metal ions (i.e., Fe3+, Cr3+, Cd2+, Pb2+, Cu2+ and Ni2+), revealing its great potential for wastewater purification. [Display omitted] • A self-supported MoS 2 /CoS 2 @TNT hybrid electrode was constructed. • The electrode achieved a gravimetric Na+ adsorption capacity of 44.22 mg g−1. • The electrode exhibited excellent regeneration performance and removal rates. • The electrode also realized removal efficiencies up to 90% for heavy metal ions. Recently, the rational design and construction of graphene-like layered transition-metal disulfides (TMDs) with chemical and physical superiorities to act as capacitive desalination (CDI) electrodes for water purification have attracted increasing interest worldwide. Herein, an advanced self-supported MoS 2 /CoS 2 @TiO 2 nanotube (TNT) hybrid electrode was grown on a TNT scaffold by a hydrothermal process-assisted in-situ growth strategy, and an asymmetric CDI cell was constructed with the as-fabricated MoS 2 /CoS 2 @TNT and commercial AC electrodes as cathode and anode, respectively. Benefiting from the effective structural feature (i.e., fully open nanosheet-assembled flowers and hierarchical pore alignment) and synergy effect of metal-like CoS 2 , state-of-the-art MoS 2 and TNTs with an efficient charge "superhighway", the MoS 2 /CoS 2 @TNT electrode achieved a significantly high gravimetric Na+ adsorption capacity of 44.22 mg g−1 in a 600 mg L−1 NaCl solution at 1.2 V. Moreover, the hybrid electrode possessed excellent regeneration performance with a capacity retention of nearly 100% even after 20 cycles. Most notably, such electrode also demonstrated amazing removal efficiencies close to 90% for various heavy metal ions (i.e., Fe3+, Cr3+, Cd2+, Pb2+, Cu2+ and Ni2+), revealing its great potential for wastewater purification. [ABSTRACT FROM AUTHOR]

A promising electrode material, manganese dioxide (MnO 2), has been widely studied for capacitive deionization (CDI) desalination and recently researched for heavy metal removal. However, there are significant differences in the performance of MnO 2 in applications for heavy metal removal and desalination. In this paper, the mechanism for different electrochemical processes of Cd2+/Na+ ions on MnO 2 electrodes was comprehensively studied. MD simulations show that the diffusion performance of Cd2+ is much slower than that of Na+ in the presence of CdCl−, leading to a lower adsorption rate of Cd2+. Of the two ion storage mechanisms (capacitive and diffusion-controlled progress), capacitance contributions provided 65.6% of the total in the Na+ electrolyte, while diffusion-controlled progress contributed 55.2% in the Cd2+ electrolyte. For diffusion, tunnelling is the main storage mechanism for Na+; instead, Cd2+ undergoes a sequential surface redox process: (1) the combination of Cd2+ and O atoms from Mn-O-Mn results in the transition from Mn4+ to Mn3+, and (2) the H substitution reaction on Mn-O-H is generated from (1). Therefore, the adsorption capacity of Cd2+ is closely related to the chemical state of MnO 2 on the surface, which results in worse cycling stability than Na+. • The presence of CdCl+ reduces the migration of Cd2+ on the electrode surface. • Different faradaic processes are responsible for differences in the adsorption of Cd2+ and Na+. • The surface redox mechanism for Cd2+ in MnO 2 involves two processes. • The results of this study provide significant insights into the cation storage mechanism of MnO 2. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) has aroused significant concern for its application in treating low-concentration brackish water. However, some carbonaceous materials suffer from the limited salt adsorption capacity (SAC), sluggish adsorption kinetics, and inferior selectivity to particular ions. Hence, we develop the well-dispersed few-layered two-dimensional pseudocapacitive material MoS 2 connected with a robust 3D conductive architecture constructed by carbon nanotubes (CNT) and carbon spheres (CS) (MoS 2 @CNT-CS). The enhanced dispersibility and expanded interlayer of MoS 2 nanosheets provide sufficient faradic effective sites for ion storage and transfer, while the interlaced carbonaceous network affords improved hydrophilicity, convenient electron transport path, and low charge transfer resistance for fast charge transportation and permeation. Therefore, the asymmetric hybrid CDI cell (CNT-CS for anode and MoS 2 @CNT-CS for cathode) delivers a prominent SAC (25.35 mg g−1), fast SAR (3.9 mg g−1 min−1), enhanced desalination kinetics, and favorable cycling stability. In addition, the specific ion selectivity of MoS 2 @CNT-CS electrode was evaluated systematically in the equimolar multi-salt solutions, and a selectivity order of Ca2+ > Na+ > Mg2+ > K+ was obtained. The molecular dynamic (MD) calculation provides the lowest intercalation energy for Ca2+ (−2.55 eV), further confirming the strong interaction and preferable pseudocapacitive deionization of MoS 2 @CNT-CS electrode to Ca2+ over other cations. [Display omitted] • Few-layered MoS 2 is dispersed in a robust 3D carbonaceous CNT-CS architecture. • MoS 2 @CNT-CS has improved active sites, conductivity, and hydrophilicity. • MoS 2 @CNT-CS electrode shows a prominent salt adsorption capacity and rate. • MoS 2 @CNT-CS has an ion selectivity of Ca2+ > Na+ > Mg2+ > K+. [ABSTRACT FROM AUTHOR]

[Display omitted] • HBC was synthesized via a "sacrifice template" method and applied in CDI. • The salt adsorption capacity was 28.06 mg g−1, the ASAR was 1.56 mg g−1 min−1. • Hollow bowl-like structure and N-doped 3D carbon reached high ion removal capacity. As a bright technology for desalinating brackish water, the desalination ability of capacitive deionization (CDI) has been limited by the electrode materials. However, it was still a challenge to adjust the construction of CDI electrode material to improve the salt removal ability. Here, nitrogen-doped hollow bowl-like carbon (HBC) has been successfully constructed in ZIF-8 by facile templating approaches. Physical measurements displayed that HBC had a hollow bowl-like structure, a certain number of nitrogen-containing groups and high specific surface area (1244 m2 g−1). These unique features made HBC have high capacitance (210.7F g−1), remarkable cycle stability and low charge transfer resistance in electrochemical double layer capacitors, indicating its promising application in CDI desalination. Due to the abundant ion accumulation active sites and rapid ion diffusion of HBC materials, provided by unique characteristics of regular hollow bowl-like structure, microporous dominated structure, interconnected channels and nano-scale wall thickness, HBC showed high salt removal ability of 28.06 mg g−1 with 1.2 V in 0.5 g L-1 NaCl solution. Besides, HBC exhibited excellent average salt ion adsorption rate (1.56 mg g−1 min−1) and initial salt adsorption capacity of 90% after 20 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • QRAC electrodes selectively adsorb NO 3 – due to the difference in binding energy. • The selectivity coefficient of QRAC-5 to NO 3 – reaches 2.7 at 0.4 V. • The electrosorption behavior of QRAC depends on physical adsorption and ion exchange adsorption. Nitrate pollution has become an increasingly serious water pollution problem worldwide. Capacitive deionization (CDI) technology is an emerging water treatment technology that can efficiently remove nitrate in water with advantages of simple process, high water recovery rate, low cost and energy consumption. In this work, we engineer a covalently bonded quaternized activated carbon (QRAC) material by silanization and investigate its selective adsorption of nitrate in mixed solution with extended voltage capacitive deionization (eV-CDI) mode. The results show that (1) the QRAC electrodes achieve selective adsorption due to the different adsorption binding energies of the quaternary ammonium group with Cl- and NO 3 –. The selectivity coefficient of QRAC-5 to NO 3 – reaches 2.7 at 0.4 V and the electrosorption capacity is 140% higher than that of AC in 5/5 mM KCl/KNO 3 solution. (2) The electrosorption of QRAC electrodes are dominated by two aspects: physical adsorption by external electric field which occurs in the incipient stage and ion exchange adsorption by quaternary ammonium groups occurring in the following stage. (3) CDI experiments in simulated municipal wastewater show that SO 4 2- had a negative effect on the adsorption capacity of NO 3 –, but QRAC electrode can still achieve separation effect in Cl-/NO 3 – solution system. These results show that covalently bonded quaternized activated carbon can achieve the effective separation and removal of NO 3 – in polluted water, and our work provides new insights into the selective electrosorption of CDI technology. [ABSTRACT FROM AUTHOR]

• Methyl Red (MR) was adsorbed from wastewater and the residual amount of MR was detected simultaneously. • The synthesized MR-MIP has a specific adsorption capacity for MR. • The MR-MIP has a large adsorption capacity (C p = 264.20 mg g−1). • Graphite in the normal carbon paste electrode was replaced by Co-FeC for improved conductivity. In this paper, an integrated system for specific adsorption of methyl red (MR) and sensitive detection of the residual amount of this dye in printing and dyeing wastewater is proposed. A molecularly imprinted polymer using MR as the template molecule (MR-MIP) was prepared for specific adsorption of MR from printing and dyeing wastewater. A solid-phase extraction column was filled with a paste of MR-MIP and cobalt-doped iron carbide nanoparticles as the working electrode to construct a highly sensitive sensor for MR detection. The distillation–precipitation approach was used to fabricate microspheres with molecularly imprinted surfaces using cellulose as the carbon source and methyl red (MR) as the template. Not only do the molecularly imprinted microspheres have a satisfactory adsorption performance for the template molecule MR, with a dynamic adsorption capacity up to 264.2 mg g−1, but also the electrochemical sensor built from the molecularly imprinted polymer and iron paste electrode, co-modified with nitrogen-doped carbonized iron nanoparticles, has great sensitivity for MR detection. It is very important to develop an integrated platform for dye treatment and residue detection in wastewater. This technique has a low detection limit and a broad linear range compared to other approaches. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical capture and release of Cd2+ were conducted using Cu-MOF-74. • Selective removal of Cd2+ (>95%) was feasible under Na/Cd ~ 2 × 104 in molar ratio. • Redox of Cu within the MOF enables energy-efficient electrosorption/regeneration. • Excellent electrosorption (>100 mg/g) and regeneration (>90%) were achieved. An electrochemically-assisted wastewater treatment using Faradaic materials offers a promising technique for the selective removal of hazardous substances. Here, we demonstrate the reversible capture and release of cadmium ions in aqueous solutions, using a redox-active metal-organic framework (MOF) electrode. As-synthesized copper-based MOF (Cu-MOF-74; copper 2,5-dihydroxyterephthalate) is a highly attractive candidate for Faradaic electrosorption due to its large surface area, water stability, and redox-active metal nodes. Our work demonstrates the reversible capture and release of Cd2+ ions assisted by the electrochemical redox reaction of Cu2+/Cu+ within the MOF structure. Combined material characterization and electrosorption tests were carried out to determine the operational conditions for maximizing adsorption capacity, energy efficiency, and material stability, thus leading to excellent electrosorption (>100 mg g−1) and regeneration efficiency (>90%). This study demonstrates the feasibility of leveraging MOFs containing redox-active metal nodes for the selective separation of toxic cations, and paves the way for promising future applications of these 3-D porous structures for wastewater treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

Arsenite (As(III)) is more toxic and difficult to remove than arsenate (As(V)). In this study, an S-doped Cu-La bimetallic oxide (S-CuLaO) decorated with metal-organic framework (MOF) composite (S-CuLaO@UIO-66) was synthesized and applied for the adsorption of As(III). The maximum adsorption capacity of As(III) by S-CuLaO@UIO-66 was as high as 171 mg/g, which was much higher compared with other MOF compounds reported to date. The UIO-66 support improved the dispersion and reduced the size of the S-CuLaO particles, which increased the number of exposed adsorption reactive sites. Study of the mechanism revealed that the synchronous oxidation and adsorption significantly increased the removal of As(III). O 2 ∙ - was produced by the receiving electron from the dissolved oxygen from Cu(I) in S-CuLaO, which converted As(III) to As(V). Furthermore, the stability and reusability S-CuLaO@UIO-66 (without regeneration) was investigated at a low As(III) concentration (approximately 1000 µg/L) in deionized water and well water. The residual arsenic concentration ranged from 0.8 to 2.8 μg/L in deionized water and 3–58.2 μg/L in well water within 240 min during three cycles. Generally, this study suggests that combining an optimal oxide with a stable MOF is a promising approach for the fabrication of composite adsorbents. [Display omitted] • S-CuLaO@UIO-66 was successfully fabricated via decorating S-CuLaO to MOF (UIO-66). • S-CuLaO@UIO-66 was used for As(III) removal via simultaneous oxidation and adsorption. • O 2 ∙- resulted from the interaction of O 2 with Cu(I) was responsible for the oxidation of As(III). • Maximum adsorption capacity of S-CuLaO@UIO-66 towards As(III) was up to 171 mg/g. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is a feasible low-cost desalination technique for low-to-medium (brackish) salinity water. However, cycling stability and regeneration of the CDI electrodes are the bottlenecks hindering the practical application of the technology on large scale. Oxidation of the electrodes during the sequential adsorption-desorption processes is one of the most challenging problems hindering their long-term cycling performance. Herein, we demonstrated the ability to design and fabricate exceptionally stable CDI electrodes via a one-pot pyrolysis protocol. The optimized pyrolysis of nitrogen‑carbon precursors at different temperatures enabled the fabrication of carbon materials with a controlled amount nitrogen dopant (NDCs) with exceptional cycling stability. The NDCs showed high specific capacitance and dual meso /microporous structures with high salt adsorption capacity (SAC), reaching 26.5 mg·g−1 in a single-pass desalination mode. Moreover, all NDC electrodes exhibited exceptional desalination stability performance over 150 successive charging/discharging cycles with 100% retention in aerated and deaerated solutions under harsh 1.4 V as the charging voltage. Moreover, all NDCs cells demonstrated charge efficiencies in the range from ~40 to 60%. The potential of zero charge (PZC) was determined for the tested NDC electrodes to elucidate their oxidation resistance (EOR). The electrodes exhibited a minimal shift in potential after the entire desalination stability tests, revealing minor electrode oxidation. The performance of our NDC-electrodes was compared against that of the commercially available activated carbon (AC) under the same experimental conditions, with the latter showing a server decrease in the SAC retention within the first few cycles. [Display omitted] • Synthesis of meso/microporous carbon electrodes with a controlled nitrogen content • The electrodes showed a salt adsorption capacity of 26.5 mg·g−1 in a single-pass desalination mode. • The electrodes showed exceptional cycling stability over 150 successive cycles. • The electrodes showed 100% retention in aerated and deaerated solutions under harsh 1.4 V. • The potential of zero charge (PZC) showed very high oxidation resistance. [ABSTRACT FROM AUTHOR]

Rocking-chair capacitive deionization (RCDI) is a semi-continuous desalination technology, however, suffering from issues pertaining to effluent salinity and pH. We thoroughly investigated the composition evolution and pH-related behavior in RCDI and disclosed the underlying causes for quality decay. RCDI concomitantly produces two streams: the desalted cathodic effluent becomes basic, whereas the brine anodic stream becomes acidic. These pH-related species deteriorate the outflow quality and distort conductivity profiles. Under variation in dissolved oxygen and potential distribution, we verified the carbon oxidation and oxygen evolution reactions as causes for the acidic anode and oxygen reduction as the cause for the basic cathode. Faradaic reactions and resultant pH fluctuation were exacerbated with increasing charging voltages, even at 0.9 V, whereas they were negligibly affected by the resembling potential distribution at different flowrates. To improve pH stability and water recovery, we integrated the ion exchange and flowrate adjustment procedures; consequently, water recovery increased to 71.43% and pH was stabilized at 5–6.5 for over 80 cycles, with significant adsorption capacity enhancement owing to the ion exchange with pH-related species. Thus, with a better understanding of pH-related behaviors, RCDI can be optimized and extended more specifically for demands such as acid/base production and resource enrichment. • RCDI with semi-continuity and high capacity was thoroughly investigated. • Evolution of pH and mechanism for performance variation was disclosed fundamentally. • The effect of voltage and flowrates on pH and RCDI behavior was expounded. • Facile modification for stable outflow composition and high efficiency were proposed. [ABSTRACT FROM AUTHOR]

The performance of the membrane capacitive deionization (MCDI) system was evaluated during the removal of three selected pharmaceuticals, neutral acetaminophen (APAP), cationic atenolol (ATN), and anionic sulfamethoxazole (SMX), in batch experiments (feed solution: 2 mM NaCl and 0.01 mM of each pharmaceutical). Upon charging, the cationic ATN showed the highest removal rate of 97.65 ± 1.71%, followed by anionic SMX (93.22 ± 1.66%) and neutral APAP (68.08 ± 5.24%) due to the difference in electrostatic charge and hydrophobicity. The performance parameters (salt adsorption capacity, specific capacity, and cycling efficiency) and energy factors (specific energy consumption and recoverable energy) were further evaluated over ten consecutive cycles depending on the pharmaceutical addition. A significant decrease in the specific adsorption capacity (from 24.6 to ∼3 mg−NaCl g−1) and specific capacity (from 17.6 to ∼2.5 mAh g−1) were observed mainly due to the shortened charging and discharging time by pharmaceutical adsorption onto the electrode. This shortened charging time also led to an immediate drop in specific energy consumption from 0.41 to 0.04 Wh L−1. Collectively, these findings suggest that MCDI can efficiently remove pharmaceuticals at a low energy demand; however, its performance changes dramatically as the pharmaceuticals are present in the target water. [Display omitted] • The performances of the MCDI system were evaluated during pharmaceutical removal. • Neutral APAP, cationic ATN, and anionic SMX were tested. • Neutral APAP was removed ∼68% while ionic ATN and SMX were removed >93%. • A significant decrease in SAC and SC were observed. • The shorter operation time of the pharmaceutical addition led to lower SEC and E R. [ABSTRACT FROM AUTHOR]

• Faradic deionization (FDI) with the outstanding desalination capacity and high feed salt concentration is emerging as a promising desalination technology. • A carbon-embedded hierarchical and dual-anion C@MoSP heterostructure was synthesized by a facile hydrothermal method accompanied by the phosphorization treatment. • The C@MoSP electrode realized an outstanding adsorption capacity of 25.43 mg/g, excellent adsorption rate, and good durability. • The strong synergy of highly conductive carbon and dual anions boosted the CDI performance of pristine MoS 2. Recently, two-dimensional transition-metal disulfides (TMDs) with amazing chemical and physical superiorities are emerging as promising faradic ion intercalation materials for effective capacitive deionization (CDI) application. Herein, a carbon-embedded hierarchical and dual-anion C@MoSP nanoflowers was synthesized by a facile hydrothermal reaction accompanied by the phosphorization treatment, and explored as an advanced CDI electrode material. Benefiting from the specific microstructure (e.g., hierarchically porous arrangement, enriched porosity and highly open pore network) and the strong synergistic effect of highly conductive carbon and low-electronegativity P dopant, the C@MoSP electrode demonstrated high surface area, enrich accessible interlayer, superior ion diffusion pathway and good electric conductivity for effective salty ion intercalation/deintercalation; Accordingly, the C@MoSP electrode realized an outstanding gravimetric adsorption capacity of 25.43 mg/g, excellent intercalation rate, and good durability in a NaCl aqueous solution with an initial concentration of 500 mg/L at an operation voltage of 1.2 V, which were evidently enhanced in comparison to MoSP and pristine MoS 2 ones. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the activated graphene (AG) was applied to remove a malachite green (MG) as an adsorbent. The AG with fractal structure was synthesized at high temperature under a nitrogen (N 2) environment. The fractal structure is shaped like a branch that extends apart because the AG is created by the rGO with a thin sheet. The fractal structure allows AG to have a high surface area. The surface area of AG was found to be 1885.7 m2 g−1. Also, it makes many pores of micro, meso-size which improves the quality as compared to traditional activated carbon (AC). Due to these features, the maximum MG adsorption capacity was 791.27 mg L−1 within the contact time at 40 min. Freundlich isotherm and pseudo-second-order were fitted to AG. Moreover, after cleaning with ethanol and deionized water, the recycled AG maintained a 99.44% removal efficiency which suggesting a good reusability. The AG showed better adsorption capacity than commercial AC showing that AG could be utilized as an excellent adsorbent for next-generation owing to its high removal efficiency, eco-friendly nature, and the long-lasting ability for adsorption of MG. [Display omitted] • Activated graphene (AG) was successfully synthesized under N 2 atmosphere. • The AG has the fractal structure owing to the edge. • The fractal structure of AG has micro, meso-size pores with high surface area. • The maximum adsorption capacity of AG is 791.27 mg L−1 for malachite green. [ABSTRACT FROM AUTHOR]

• A novel core-shell LiX@ZIF-8 composite has been constructed. • Single layer showed the highest CO 2 adsorption capacity in highly humid flue gas. • The whole synthesis is conducted in a green, energy-saving and economical way. • LiX@ZIF-8-I could maintain excellent cycle hydrothermal stability in humid flue gas. Decreased adsorption capacity and complicated synthetic procedures with expensive or toxic raw chemicals are two major challenges faced by physical adsorbents for carbon capture in highly humid flue gas. In this study, a novel core-shell composite using LiX with high CO 2 adsorption capacity as core and superior hydrophobic ZIF-8 as shell is proposed. The overall synthesis process is conducted under ambient temperature and pressure by adopting deionized water as green solvent. Experimental results show that the adsorption performance of the core-shell structure is enhanced along with the improvement of hydrophobic performance in highly humid flue gas. The performance of ZIF-8 shells from monolayer to multilayers (up to three layers) are investigated. In particular, LiX@ZIF-8-I with single layer of ZIF-8 exhibit the highest CO 2 adsorption capacity of 1.73 mmol/g in humid flue gas. The monolayered adsorbent not only exhibit superior hydrophobicity and CO 2 adsorption capacity but also maintain excellent hydrothermal stability in humid flue gas over 50 adsorption/desorption cycles, which promote its application to practical in a green, energy-saving and economical way. [ABSTRACT FROM AUTHOR]

Here a strategy by designing a series of hyper-cross-linked polystyrene resins ( HCLR s) with highly selective adsorption ability toward hazardous 2,4-dinitrotoluene from nitrophenol sodium salt-rich real industrial wastewater was reported. Macroporous cross-linked chloromethylated polystyrene was self-crosslinked or crosslinked with ligands, i.e. toluene, aniline, and phenol to produce 2,4-dinitrotoluene affinitic HCLR-0 , HCLR-T , HCLR-A and HCLR-P , respectively. The ultrahigh affinity through the like dissolves like mechanism toward 2,4-dinitrotoluene was validated by adsorption experiments, i.e. isotherm, kinetics, thermodynamics, effect of pH & 2-nitrophenol sodium salt and dynamic column adsorption-desorption investigations. They showed ultrahigh adsorption capacities toward 2,4-dinitrotoluene, reaching 628.9, 621.1, 657.9 and 641.0 mg/g for HCLR-0 , HCLR-T , HCLR-A and HCLR-P at 303 K, outperforming their matrix cross-linked chloromethylated polystyrene of 79.2 mg/g and XAD-4 of 286 mg/g very much. This advantage was also reflected in the dynamic adsorption study with promising breakthrough and saturated capacities of 195.8 and 334.4 mg/mL wet HCLR-A s, respectively. The HCLR s also featured interesting impurity affectless properties, in which 2-nitrophenol sodium salt showed no influence on the 2,4-dinitrotoluene capture even in high concentration. With the interesting properties shown above, the HCLR-A column worked very well in the large-scale real industrial wastewater, and could also be fully recycling used through simple low-cost treatment. Image 1 • HCLR s with highly selective adsorption affinity toward DNT were synthesized. • Ultrahigh adsorption capacity of 657.9 mg/g for DNT was reached by HCLR-A. • 2-nitrophenol sodium salt showed no influence on the adsorption of DNT onto HCLR s. • HCLR-A column shows stable adsorption in large-scale real industrial wastewater. • HCLR column could be fully recycling used through simple treatment of toluene. [ABSTRACT FROM AUTHOR]

• The adsorption of diclofenac potassium onto modified soybean hulls was evaluated. • The thermal treatment was studied by thermogravimetric analysis and residence time. • The experimental data fitted pseudo-first order and Sips models. • The adsorption mechanism occurs through hydrogen bonds and π-π interactions. • The modified soybean hulls presented a maximum adsorption capacity of 96.88 mg g−1. Because Diclofenac potassium (DCF-p) is a drug that is easily accessible and widely consumed worldwide, it is often identified in water monitoring samples. Wastewater treatment has not been able to remove it completely, and for this reason traces reach the surface and groundwater, causing an impact on non-target organisms. In this sense, adsorption is highlighted as a simple and usually efficient process. Soybean hulls are residues generated in large quantities, often disposed of in landfills. For this reason, their use as adsorbent becomes interesting. However, no study to date has evaluated modifications of such residue in order to remove drugs from water. Thus, the objective of this study was to evaluate the adsorption capacity of the soybean hulls after chemical and thermal treatment in the removal of DCF-p. In the adsorption tests, it was found that the increase in pH from 5 to 9 caused a small reduction in the adsorption capacity, however the effect of the ionic strength showed that the dissolved salt ions acted as co-adsorbents, favoring adsorption. Kinetic data demonstrated rapid adsorption, with equilibrium at 180 min and adsorption capacity of 17.27 mg g−1. The experimental data adjusted to the pseudo-first-order model, and the intraparticle diffusion model suggested a multi-stage process. The adsorption isotherms were adjusted to the Sips model, revealing a maximum adsorption capacity of 96.88 mg g−1 at 308 K. The thermodynamic parameters indicated a spontaneous and favorable process for all temperatures studied, with an exothermic reaction controlled by physisorption. Lastly, it was found that the adsorption of DCF-p occurred by π-π interaction and hydrogen bonds. [ABSTRACT FROM AUTHOR]

• Adsorption mechanisms were found to be both ion exchange and surface adsorption. • The isotherms were better fitted using Freundlich model. • KZTS-NS showed fast kinetics and high adsorption capacity and selectivity for Co2+. • A DF of Co2+ as high as 1176 was obtained in tap water using a CTA-F-MF process. The removal of radioactive Co2+ from aqueous solutions is a critical issue because it is highly toxic and hazardous to humans. Metal sulfides are promising materials for the removal of toxic ions; however, studies on the adsorption of Co2+ by this class of adsorbents as well as their adsorption mechanisms and practical application in complex natural water matrixes are limited. To fill this knowledge gap, in this study, a layered K/Zn/Sn/S metal sulfide nanosheet (KZTS-NS) was employed as an adsorbent for Co2+ removal from aqueous solutions. Besides ion exchange, the mechanism of surface adsorption by forming a Zn 0.76 Co 0.24 S composite was found when initial Co2+ concentration was higher than 20 mg/L, which was reported for the first time in layered metal sulfides. The Co2+ adsorption performance of KZTS-NS was systematically studied using batch methods in deionized water, including isotherms, kinetics, influential factors, and selectivity. The results indicated that KZTS-NS exhibited a high adsorption capacity, rapid kinetics, and strong selectivity in a wide pH range. Furthermore, tap water was used as a complex natural water matrix, and the practical application of KZTS-NS in a bench-scale countercurrent two-stage adsorption-flocculation-microfiltration (CTA-F-MF) process for Co2+ removal from tap water matrix was demonstrated. The CTA-F-MF process significantly enhanced the performance of the adsorbent, thereby achieving ultrahigh Co2+ removal (decontamination factor of up to 1176). This study not only provides a new insight into the adsorption of Co2+ by layered metal sulfides, but also forms the basis to enable the practical application of metal sulfides in the field of radioactive wastewater treatment. [ABSTRACT FROM AUTHOR]

• Porous carbon nanoflakes were prepared by carbonizing xylose with KHCO 3. • Porous carbon nanoflakes exhibited a satisfactory salt adsorption capacity. • Porous carbon nanoflakes have great potential for large-scale application. Capacitive deionization (CDI) works by using the electrical double layer on various materials including nanoporous carbons to separate ions from saline water. To help realize industrial application, there has been an increasing interest in the exploration of carbon materials from low cost, eco-friendly and abundant biomass for CDI to align with the demands of sustainable development strategies. Herein we report pyrolysis of xylose with KHCO 3 to prepare hierarchically porous carbon nanoflakes which display a satisfactory salt adsorption capacity of 16.29 mg g−1. This novel strategy can design highly efficient carbon materials from naturally-developed biomass materials with its low preparation cost, environmentally friendliness and superior desalination performance. Our xylose-derived hierarchically porous carbon nanoflakes are promising for potential industrial application for CDI. [ABSTRACT FROM AUTHOR]

Pb2+ adsorption onto activated carbon was studied as a function of the different liquid medium during batch adsorption process without shaking/agitation of flasks (where adsorbate and adsorbent coexist). As liquid medium deionized water (DW) enhanced with gases bulk nanobubbles (bNBs) was used. The adsorbent material used was activated carbon from potato peels. The maximum Pb2+ adsorption capacity (Q m) was 9 mg/g in the case of adsorption process in DW without agitation, whereas the respective Q m was 94 mg/g by using DW-bNBs as medium without agitation. It was also found that Q m increased to 171 mg/g in the adsorption process with DW-bNBs and agitation (150 rpm). This finding was the start point of a new experimental design where after re-agitation (intense shaking of 225 rpm) of the respective experimental case (94 mg/g), the final Q m was 163 mg/g i.e. very close to the one corresponding to simultaneous adsorption and agitation from the beginning. The results are analyzed and discussed intensively to lead in several important implications on the influence of bNBs to the bulk solute mass transfer. Based on our experimental equilibrium data a modified-Langmuir equation was developed, applied and proposed so as to better simulate the whole (complicated) process. [ABSTRACT FROM AUTHOR]

Electrosorptive desalination is a very simple and appealing approach to satisfy the increasing demand for drinking water. The large-scale application of this technology calls for the development of easy-to-produce, cheap and highly performing electrode materials and for the identification and tailoring of their most influential properties, as well. Here, biosynthesised bacterial cellulose is used as a carbon precursor for the production of three-dimensional nanostructures endowed with hierarchically porous architecture and different density and type of intrinsic and hetero-atom induced lattice defects. The produced materials exhibit unprecedented desalination capacities for carbon-based electrodes. At an initial concentration of 585 mg L−1 (10 mmol L−1), they are able to remove from 55 to 79 mg g−1 of salt; as the initial concentration rises to 11.7 g L−1 (200 mmol L−1), their salt adsorption capacity reaches values ranging between 1.03 and 1.35 g g−1. The results of the thorough material characterisation by complementary techniques evidence that the relative amount of oxygenated surface functional species enhancing the electrode wettability play a crucial role at lower NaCl concentrations, whereas the availability of active non- sp 2 defect sites for adsorption is mainly influential at higher salt concentrations. • Bacterial-cellulose (BC) is biosynthesised by using Gluconacetobacter medellinensis as a strain. • By carbonising BC, microporous nanocarbons with different amount and type of defects are produced. • BC-derived nanocarbons are tested as electrodes for the capacitive deionization of water. • The BC-based electrodes remove 55–79 mg g−1 of NaCl from a solution with a 585 mg L−1 initial concentration. • The C network defectiveness plays a key role in the electrode capacitive and electrosorptive behaviour. [ABSTRACT FROM AUTHOR]