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• A redesigned and novel two-chamber electrodeposition-electrodialysis combination craft was adopted. • The efficient recovery of Ni2+ and the synchronous removal of HPO 3 2- from spent bath was achieved in simple and rapid one-step purification. • The influence of current density, operation time, pH, dilution multiple, flow rate, and electrolyte concentration on craft performance were investigated. With the continuous promotion and application of electroless nickel plating technology, the environmental pollution caused by heavy metals nickel and phosphorus in the spent bath becomes more serious. It is challenging to develop a method for the treatment of a spent electroless nickel plating bath with the high-efficiency recovery of Ni2+ and synchronous removal of HPO 3 2-, no secondary pollution, and low energy consumption. Herein, a means that absolutely incorporates the ascendancy of two single treatment methods, called a combination of electrodialysis and electrodeposition, was used to treat the spent electroless nickel plating bath. The effects of current density, operation time, pH value of the spent bath, dilution multiple, flow rate, and electrolyte (Na 2 SO 4) concentration on the recovery, removal rate, and energy consumption were investigated. Then, the reusability of the ion-exchange membrane was studied. The experimental results indicated that the recovery of Ni2+ was 82.34%, the removal of HPO 3 2- was 51.61%, the energy consumption of this method was only 18.28 Wh/kg, and the stability of the anion exchange membrane was desirable. Overall, the study of this combined process provides a basis for the one-step treatment of spent electroless nickel plating bath by a comprehensive method and an idea for engineering the application of handling spent bath. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile dual physico-chemical activation strategy is proposed. • The synthesized NPHPC possesses high specific surface area, pore volume, specific capacitance and excellent hydrophilicity. • The NPHPC delivered a splendid desalination capacity and good cycling stability. The preparation of heteroatom-doped hierarchical porous carbons (HPCs) possessing both high-performance and cost-effective is advantageous for the advancement of capacitive deionization (CDI). Biomass, which is abundant and inexpensive, has been widely utilized as a precursor for carbon electrodes. However, the simple pyrolysis of a single biomass typically leads to insufficient porosity with narrow surface area, along with poor wettability and conductivity, thereby resulting in limited desalination performance. Therefore, we employ ammonium dihydrogen phosphate (NH 4 H 2 PO 4) and potassium carbonate (K 2 CO 3) as chemical and physical activators, respectively, to co-activate lotus petiole (LP) for the preparation of N/P co-doped hierarchical porous carbon (NPHPC). In comparison with conventional single K 2 CO 3 activation, NPHPC prepared through dual physico-chemical activation exhibits exceptional specific surface area (S BET , 2170.00 m2/g), excellent pore volume (V pore , 1.16 cm3/g), outstanding mesoporosity (V meso /V pore , 72.41 %), superior hydrophilic performance (contact angle: 39°), high specific capacitance (221.86F/g), moderate N-doping (3.1 %) and P-doping (0.4 %). When assembled for desalination, the synthesized materials demonstrate a fabulous electroadsorption capacity of 21.85 mg/g together with notable cycling stability, highlighting their excellent application prospects. In summary, this work presents innovative ideas in proposing a facile synthesis of high-performance heteroatom-doped HPCs for CDI desalination. [ABSTRACT FROM AUTHOR]

Highly efficient multifunctional adsorbent successfully realizes the removal of Cr ions from wastewater. The adsorbent is easily separated from the water to avoid secondary pollution. [Display omitted] • A novel 3D multifunctional composite magnetic adsorbent material has been successfully synthesized and applied for the removal of Cr(VI) from solution. • The composite adsorbent enables efficient capture and reduction of Cr(VI) under full light exclusion conditions. • The exceptional recyclability mitigates the issue of secondary contamination from the adsorbent. Designing a magnetic adsorbent material that is both reducible and has strong adsorption properties is significant in reducing Cr(VI) ion pollution. Herein, a 3D multifunctional composite adsorbent for Cr(VI) ions was obtained by using Fe 3 O 4 surface-arrayed magnesium iron layered double hydroxides (Mg/Fe-LDH) micro sheets as a substrate with in situ growth of Cu 2 O nanoparticles (Cu 2 O NPs) on their surfaces. Under dark conditions, adsorption capacity of the Cu 2 O@LDH@Fe 3 O 4 for Cr(VI) was up to 218.82 mg·g−1, surpassing that of Cu 2 O, Mg/Fe-LDH@Fe 3 O 4 , and Mg/Fe-LDH by factors of 1.39, 4.41, and 8.32 respectively. Surprisingly, the removal of Cr(VI) was as high as 76.16 % by the Cu 2 O@LDH@Fe 3 O 4 (C initial = 200 mg/L, pH = 3). Kinetic, isotherm, and thermodynamic results reveal that the removal of Cr(VI) by the Cu 2 O@LDH@Fe 3 O 4 is consistent with the pseudo-second-order kinetic model of spontaneous monomolecular layer chemisorption. Density functional theory (DFT) calculations show that HCrO 4 - has a lower energy band gap and is more easily reduced by Cu 2 O. Therefore, the reason for the adsorbent having more removal effect under acidic conditions was revealed. The XPS and FT-IR experimental mechanism analysis results indicated that Cr(VI) is immobilized on the Cu 2 O@LDH@Fe 3 O 4 surface through electrostatic interactions, followed by reduction to Cr(III) by Cu 2 O NPs, which is subsequently adsorbed on the surface of the Cu 2 O@LDH@Fe 3 O 4. This novel adsorbent structure and unique Cr(VI) removal mechanism provide new ideas for the design of future adsorbents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Green activation-self-activation strategy was proposed to prepare GO-inbuilt ENHPCs. • The splendid SAC of 17.86 mg/g and rapid ASAR of 0.99 mg/g/min for Ni2+ were gained. • The potential for eliminating NaCl, MgCl 2 , CaCl 2 and Ni2+ wastewater was evaluated. • Micro-mesoporous structure and copious active sites accelerated ion removal. Capacitive deionization (CDI) is considered a polar-promising technology to remove heavy-metal ions from wastewater. Herein, a green activation-self-activation strategy was exploited to build graphene (GO)-inbuilt mesopore-dominated N-doped hierarchical porous carbons (ENHPCs) using sodium lignosulfonate (SLS) as carbon sources/self-activators. Different from SLS self-activation and K 2 C 2 O 4 -SLS activation-self-activation, ENHPC LKG gained via GO-mediated K 2 C 2 O 4 -SLS activation-self-activation showed suitable mesopore-dominated micro-mesoporous structures with high surface area of 1795.5 m2/g, large mesoporous volume of 0.87 m3/g, 3.65 % N-doping and excellent conductivity. Its unique hierarchical porous structure and abundant active sites facilitated the ion rapid insertion and extraction. When utilized to capture low-concentration nickel (Ni2+) ions, ENHPC LKG delivered splendid salt removal capacity of 17.86 mg/g, rapid average salt removal rate of 0.99 mg/g/min and standout cycle stability. Meanwhile, ENHPC LKG was further extended to remove NaCl, MgCl 2 , CaCl 2 and Ni-containing wastewater, showing superior CDI property. Moreover, the recycled ENHPC LKG (10th) taken to eliminate indomethacin (IDM) depicted a splendid adsorption capacity. This work proved the significant applicant potential of the novel and green ENHPC LKG for disposing of Ni2+ ions via CDI technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doped La 2 CuO 4 had been synthesized using melamine as the N precursor. • N-doped La 2 CuO 4 showed enhanced catalytic activity and stability. • Density Functional Theory (DFT) calculations were performed to verify the results. • A mechanism of phenol degradation was proposed. • The toxicity of degradation intermediates was greatly reduced. Herein, N-doped perovskite La 2 CuO 4 (LCO) (N-LCO(M)) was fabricated by sol–gel rapid calcination method using melamine (M) as N source/ligand, and applied for the catalytic wet air oxidation (CWAO) to degrade high-concentration phenol-containing simulated wastewater. The experimental results exhibited that N-LCO(M) illustrated enhanced phenol degradation efficiency. Thereinto, 87.9% COD degradation efficiency was achieved in simulated wastewater containing 8000 mg/L phenol, while for undoped LCO prepared with citric acid (CA) as ligand (LCO(CA)) was only 43.8%. The systematic characterizations and density functional theory (DFT) calculations were utilized to verify the above results. The results revealed that N doping favored the formation of more oxygen vacancies (*) and facilitated the charge transfer between Cu and O. More oxygen vacancies (*) reinforced the ability of N-LCO(M) to adsorb O 2 to form reactive oxygen species (O*), and meanwhile, the charge transfer between Cu and O was manifested as the redox cycle of the catalytic active metal Cu2+/Cu1+. The redox cycle also promoted the formation of O 2 − and HO, making the more exhaustive degradation of phenol. This successfully proved that N doping was core to improving the activity and stability of N-LCO(M). Moreover, a possible mechanism of phenol degradation was proposed based on the experimental results and DFT calculations. Eventually, the toxicity of the intermediate products was further evaluated by quantitative structure–activity relationship (QSAR) analysis, showing the significantly reduced toxicity of the intermediate products. Overall, the proposed CWAO technique is a green and promising wastewater treatment method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic HAP doped with HDTMP was firstly prepared and remove Sr2+ and Co2+. • The adsorption capacity of 10HD-MHAP was more than 5 times that of MHAP. • IGMH and Hirshfeld surface was executed to reveal the interaction. • The coordination mechanism between HDTMP and Sr2+ or Co2+ was visualized. • The immobilization of 10HD-MHAP to Sr2+ or Co2+ was excellent. The magnetic Hexamethylene diamine tetramethylene phosphonic acid (HDTMP)-hydroxyapatite nanoparticles (HD-MHAP) were firstly prepared and applied for the immobilization of radioactive Sr2+ (Strontium ion) and Co2+ (Cobalt ion). The molar ratio of organic phosphine in HDTMP to total phosphorus was 10% (10HD-MHAP) and can also be easily separated from aqueous solution. At the equilibrium concentration of Sr2+ and Co2+ (200 mg/L), the adsorption capacity of MHAP and 10HD-MHAP on Co2+ was 28.4 mg/g and 172.3 mg/g, respectively and for Sr2+, the adsorption capacity was 54.9 mg/g and 320.7 mg/g. Additionally, the desorption percentage of Sr2+ (%) and Co2+ (%) was very low, which was 0.66 and 1.61, respectively. This is significant because the irreversible adsorption of HDTMP/Fe 3 O 4 /HAP composite for Sr2+ and Co2+ ensures the captured radionuclides will not be released back into the aquatic systems. Moreover, the affinity between HDTMP and HAP and the coordination of HDTMP and Sr2+ or Co2+ was probed by Multiwfn wavefunction analysis. The results indicated that the formation of a ternary surface complex of MHAP-HDTMP-M (Sr2+ or Co2+) was the key to the excellent immobilization performance of HD-MHAP composite for Sr2+ or Co2+. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sustainable and facile self-activation strategy is proposed to synthesize high N-doped hierarchical porous carbon (HNHPC) for CDI. • The synthesized HNHPC PUA possesses ultrahigh specific surface area (3280.16 m2/g), splendid pore volume (2.49 cm3/g), large mesopore ratio (57.83%) and high N content (6.4%). • The small hierarchical porous carbon nanogranlue structure of HNHPC PUA helps to expose more accessible and extra active sites, accelerating the ions insertion and extraction from the micropores. • The HNHPC PUA delivered a splendid desalination capacity of 24.86 mg/g and good cycling stability. High N-doped hierarchical porous carbon (HNHPC) with ultrahigh BET surface area (S BET) and pore volume (V pore) has attracted great attention in capacitive deionization (CDI) due to the copious active sites. However, the traditional methods often adopt strong corrosive activators and fail to achieve high N-doping, which are harmful for its practical application. Herein, we develop a sustainable CO(NH 2) 2 -C 6 H 5 O 7 (NH 4) 3 -co-assisted C 6 H 5 K 3 O 7 (U-A-co-assisted P) self-activation strategy to prepare ultrahigh S BET and V pore HNHPCs for CDI desalination. Compared to the single P self-activation and U/A-assisted P self-activation, HNHPC PUA acquired via U-A-co-assisted P self-activation possesses ultrahigh S BET (3280.16 m2/g), splendid V pore (2.49 cm3/g), high V meso /V pore (57.83%) and high N-doping (6.40%). Its small hierarchical porous carbon nanogranlue structure helps to expose more accessible S BET and extra active sites, accelerating the ions insertion and extraction from the micropores. The resultant HNHPC PUA delivers a high specific capacitance of 203.9F/g. In the assembled CDI setup, HNHPC PUA exhibits a superior salt adsorption capacity (SAC) of 24.86 mg/g, a rapid salt adsorption rate (SAR) of 8.29 mg/g/min and reaches 88.7% SAC retention after 50 cycles in 500 mg/L NaCl at 1.2 V, suggesting good application potential. Overall, this work provides new insight into rapidly preparing ultrahigh S BET and V pore HNHPCs for energy and environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel adsorbent of UiO-66-NH 2 @Mg(OH) 2 was prepared and characterized. • The adsorption capacity was improved significantly after modification. • Adsorption behavior and mechanism of phosphate on UNM were explored. • Multiwfn wave function methods were applied to interpret the adsorption mechanisms. • Phosphate was successfully recovered by the struvite-based method. Two serious challenges of water eutrophication and phosphorus resources exhaustion make the P recovery imperative. In this work, a novel phosphate adsorbent UiO-66-NH 2 @Mg(OH) 2 (UNM) has been synthesized by the in-situ growth of magnesium hydroxide nanosheets around UiO-66-NH 2. The batch adsorption experiments were carried out by controlling the single variate (such as pH, initial concentration, contact time, temperature and interfering anions) to explore the adsorption behaviors. And the adsorption dynamics and isotherms fit well with the pseudo-second-order (PSO) and Langmuir models, combined with the thermodynamics results, indicating a spontaneous and endothermic monolayer chemisorption process. Besides, the maximum phosphate adsorption capacity of UNM was calculated as 408.07 mg/g (≈130.39 mg P/g) at pH = 6.0, T = 298 K. A series of characterizations (XRD, FT-IR, SEM, EDS, BET, TGA, XPS, ICP-MS et. al) and quantum chemical analysis methods (ESP, ALIE and Hirshfeld surface) was applied to predict the reactive sites. The possible mechanism can be deduced as two continuous steps: the physical attraction by weak interactions and the chemical adsorption with an ion-exchange mechanism. The UNM also presented high removal efficiency in the environmental water samples and showed satisfactory reusability and excellent chemical stability in the recycling process. From the desorption effluents, we successfully recycled the struvite with 14.31% P content. Therefore, the UNM will be regarded as a promising phosphate adsorbent in practice and this work will provide inspiration and guidance for the design and preparation of high-efficiency P-removal adsorbents. [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]

[Display omitted] • Defect content and particle size of MOF-808 can be tuned using iron nitrate. • The modulating MOF-808 can achieve effective removal and recovery of phosphate. • Adsorption mechanisms involve electrostatic attractions and ligand exchange. In this work, a facile and green method is applied to synthesize hydrophilic MOF-808(Zr) and modulate its defect content and particle size using different amounts of iron nitrate (denoted as F) to obtain serial XF-MOF-808 ("X" implied the dosage of used F). The development of additional adsorption sites and the fine-tune of pore and particle size based on MOF-808 significantly improved phosphate adsorption performance. In particular, the 0.5F-MOF-808 shows excellent adsorption capacity (305.5 mg/g) and rapid diffusion rate (37.51 mg/g·min0.5) for phosphate at 298 K and initial pH = 6.5, outperforming pristine MOF-808 and most previously reported adsorbents. 0.5F-MOF-808 possesses a wide pH tolerance, outstanding reusability and excellent selectivity for phosphate adsorption from simulated wastewater, verified in environmental implication and regeneration experiments. Phosphate loaded on the adsorbent can be converted to struvite for agricultural fertilizer via a simple crystallization process. Compared to MOF-808, the exceptional sorption performance of 0.5F-MOF-808 is supported by decreased internal diffusion limitation, enlarged pore size and the development of new adsorption sites, which can be proved by advanced characterizations and batch adsorption experiments. This work presents a promising modification strategy of MOF materials for phosphate adsorption and recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel 3-CDI system with high desalination performance is designed. • Higher SAC and faster SAR are achieved in 3-CDI compared to FB CDI. • Higher Λ, lower energy consumption, shorter desorption time and good cyclic stability are realized in 3-CDI. • More FTE electrode mass is used for desalting compared to the reported value. • Analysis of pH fluctuations is used to explain the different adsorption processes in FB CDI and 3-CDI. Exploiting a high-performance capacitive deionization (CDI) system with both high salt adsorption capacity (SAC) and fast salt adsorption rate (SAR) is a challenge for desalination. Herein, a novel three-electrode CDI (3-CDI) with both flow-through (FTE) electrode and flow-by (FB) electrode is originally developed. Experimental results indicate that a higher SAC and faster SAR are realized in 3-CDI compared with FB CDI via using conventional symmetrical/ asymmetrical electrodes. Besides, 3-CDI achieves a higher charge efficiency (Λ), lower energy consumption, shorter desorption time and good cyclic stability. Further analysis shows more FTE electrode mass in 3-CDI can be used for desalting compared with the reported value. However, as the number of FTE electrodes increases, the electrode mass utilization rate will decrease in turn. Moreover, it is found that the deionization process of both CDI cells is different. pH fluctuations analysis reveals that 3-CDI can prolong the time required for the electrode to reach the desalination equilibrium and overtly delay the time for the conversion of desalination behavior to faradaic reactions. Overall, this work sheds light on the effective utilizing electrode mass for desalination and has a reference for designing high-performance CDI cells from the perspective of hybrid cell structure. [ABSTRACT FROM AUTHOR]