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Sodium iron dioxide (NaFeO2) with high specific capacity, has been widely used as a kind of electrode materials for Na-ion batteries. When NaFeO2is used as the battery-type electrode for aqueous Na-ion hybrid capacitors, there are a lot of technical challenges to meet, especially the narrow voltage window limited by the thermodynamic decomposition of water. We propose a novel decoupling electrolyte strategy to suppress the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) on the NaFeO2anode and the activated carbon (AC) cathode respectively, in order to expand the voltage window of the aqueous AC//NaFeO2Na-ion hybrid capacitor. The alkaline anolyte (2 M NaOH) and the neutral catholyte (1 M Na2SO4) can be decoupled by the cation exchange membrane, which selectively allows the Na+ions through the membrane to carry the electric currents in the charge/discharge process. The NaFeO2sample with the stable crystal structure and oxygen vacancy defects, can provide a gravimetric specific capacitance of 101.1 F g−1at 1 A g−1. Electrochemical kinetic analysis indicates that the capacitor-type behaviour is predominant in the electrochemical energy storage process of the AC//NaFeO2Na-ion capacitor at the scan rates higher than 40 mV s−1. The AC//NaFeO2Na-ion capacitor with the stable voltage window of 2 V, can provide an energy density of 12.6 Wh kg−1at 1 kW kg−1. Due to its inhibiting effects on HER and OER, this decoupling electrolyte strategy holds great potential for constructing high-voltage aqueous energy storage devices.

AgCl/PES hybrid membrane adsorbents with different AgCl contents for iodide ion were prepared by in situ synthesized phase inversion method. Scanning electron microscopy and X-ray diffraction (XRD) analysis confirmed the presence of silver chloride on the hybrid membrane adsorbent. Brunauer, Emmett, and Teller adsorption/desorption found that the membranes have the same isotherm type, but the adsorbed quantity increased with the content of the AgCl. The kinetics of iodide adsorption exhibited that the rate-limiting step may be chemical sorption between sorbent and sorbate. The composite adsorbents used in this study have been proved to be an effective iodide adsorbent with a biggest adsorption capacity of 551 mg g-1. Fourier transform infrared spectroscopy and XRD analyses for the membrane after reaction with iodide confirmed that chloride was exchanged with iodide to form AgI(s). This study can provide a promising method to address radioactive I–pollution in water.

Magnesium silicate (MgSiO)/polyethersulfone (PES) hybrid membranes were prepared by phase inversion method, in which MgSiO particles were in-situ synthesized during the formation of membrane. Energy dispersive X-ray spectrometry (EDS), scanning electron microscopy (SEM) and atomic force microscope (AFM) measurements were performed to characterize the component and morphology of membranes, while X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR) were conducted to characterize MgSiO particles morphology as well as its structural properties and the presence of functional groups. What’s more, the properties of membranes were investigated. Results showed that MgSiO particles were formed in a Mg/Si ratio of 1.36, and dispersed uniformly both on the membrane surface as well as matrix. The porosity and permeation of hybrid membranes were found a decrease and then an overall increase, along with the increased MgSiO content. Compared with the PES membrane, the hydrophilicity, separation performance and antifouling property of the hybrid membranes were enhanced due to the existence of MgSiO. Moreover, the hybrid membranes present both a higher BSA (bovine serum albumen) rejection, and a higher rejection towards MB (methylene blue) solution.

In this study, an anion exchange resin/polyethersulfone (PES) blend flat sheet membrane was prepared, using anion exchange resin 201×7 as function particle and PES as matrix material. The highlight of this membrane is to combine strong enrichment of bromine by resin and stable mechanical properties by PES, obtaining a new material with stronger practicability than traditional materials. The membrane adsorbents were characterized by scanning electron microscope (SEM), nitrogen adsorption (Brunauer, Emmett and Teller) and Fourier transform infrared spectroscopy. The batch adsorption experiments demonstrated that the membrane effectively enriched bromine in a wide optimal pH ranging from 3 to 9. The adsorption equilibrium could be established in 2 h, and the maximum adsorption capacity was 145.35 mg/g. The adsorption data were well described by the pseudo-second-order rate model and the Langmuir isotherm model. The adsorption process was endothermic and spontaneous. In addition, the effects of coexisting anions on the adsorption capacity declined with the following order: SO42–> Cl–> NO3–. The membrane saturated by bromine could be easily regenerated using trisodium citrate dehydrate (1 mol/L) with a high recovery rate of 97.77%. Compared with other adsorbents, the resin/PES membrane shows high adsorption capacity.

Carbon nanomaterials with large specific surface area and high electronic conductivity, have been widely used as capacitive cathode materials for Zn-ion hybrid supercapacitors. Doping of heteroatoms and regulation of pore structure are crucial for boosting the energy storage performances of the carbon-based cathodes. We propose a N-doped carbon nanosheet aerogel (N-CNAG) with high active N content and hierarchically porous structure, which can be prepared by the bubble-templated polymerization of Py and the carbonization of the PPy nanosheet hydrogel (PPyNHG). The high active N content of N-CNAG can produce high pseudocapacitance through the N-dependent electrochemical redox reactions. The hierarchically porous structure of N-CNAG can facilitate fast electrolyte ion diffusion. Based on the Zn anode and the N-CNAG cathode, the Zn-ion hybrid supercapacitor can provide a remarkable specific capacitance of 706 F g−1at 1 A g−1and the rate capability of 50 % from 1 A g−1to 5 A g−1, mainly attributed to the high active N content and the hierarchically porous structure of N-CNAG. Additionally, this Zn-ion hybrid supercapacitor provides the superhigh energy density of 392 Wh kg−1at 1 kW kg−1and the cycling stability of 87.4 % after 10,000 cycles, holding great potential for developing high-energy-density Zn-ion hybrid supercapacitors.

AbstractAdsorption of fluoride by PES/LDH (layered double hydroxide) blend flat-sheet membrane was investigated. The SEM, AFM, and fluoride adsorption capacity of the membrane were evaluated. The addition of LDH led to a significant enhancement in the adsorption capacity of the membrane. The batch adsorption experiments demonstrated that the membrane effectively removed fluoride in a wide pH ranging from 2–10. The adsorption equilibrium could be established in 30 min, and the maximum adsorption capacity was 2.63 mg/g. The pseudo-second-order kinetics was observed for the adsorption process which followed the Langmuir-type adsorption isotherm. The membrane can be regenerated with 0.1 M NaOH. This work provides a new method to the adsorptive removal of hazardous substance in aqueous solutions.

Adsorption of fluoride by PES/LDH (layered double hydroxide) blend flat-sheet membrane was investigated. The SEM, AFM, and fluoride adsorption capacity of the membrane were evaluated. The addition of LDH led to a significant enhancement in the adsorption capacity of the membrane. The batch adsorption experiments demonstrated that the membrane effectively removed fluoride in a wide pH ranging from 2–10. The adsorption equilibrium could be established in 30 min, and the maximum adsorption capacity was 2.63 mg/g. The pseudo-second-order kinetics was observed for the adsorption process which followed the Langmuir-type adsorption isotherm. The membrane can be regenerated with 0.1 M NaOH. This work provides a new method to the adsorptive removal of hazardous substance in aqueous solutions.

AbstractMesoporous magnesium silicate gel was successfully synthesized and characterized by N2adsorption/desorption technique and FT-IR. The adsorption experiments of anionic dye (weak acid red 2R) onto prepared magnesium silicate gel were studied by varying mass of adsorbent, dye concentration, pH, temperature, and contact time. The results showed magnesium silicate gel had high surface area, 277.37 m2 g−1. The adsorption capacity increases with increasing initial dye concentration, adsorption temperature, and contact time. The experimental data were applied to three adsorption kinetic models and the results indicated that the adsorption behavior was described very well by the second-order kinetics model with the high correlation coefficients (R2 > 0.99). Intra-particle diffusion was performed in three different stages. The activated energy obtained was 127.6 kJ mol−1and the enthalpy, entropy, and standard free energy were calculated and given that ΔHоwas 80.1 kJ mol−1, ΔSоwas 300.1 J mol−1, and ΔGоwere negative values at the different temperatures. The adsorption process is rapid and physisorption in nature. Therefore, magnesium silicate gel would be used in the industrial wastewater treatment as a potential adsorbent.

Mesoporous magnesium silicate gel was successfully synthesized and characterized by N2adsorption/desorption technique and FT-IR. The adsorption experiments of anionic dye (weak acid red 2R) onto prepared magnesium silicate gel were studied by varying mass of adsorbent, dye concentration, pH, temperature, and contact time. The results showed magnesium silicate gel had high surface area, 277.37 m2 g−1. The adsorption capacity increases with increasing initial dye concentration, adsorption temperature, and contact time. The experimental data were applied to three adsorption kinetic models and the results indicated that the adsorption behavior was described very well by the second-order kinetics model with the high correlation coefficients (R2 ##xgt; 0.99). Intra-particle diffusion was performed in three different stages. The activated energy obtained was 127.6 kJ mol−1and the enthalpy, entropy, and standard free energy were calculated and given that ΔHоwas 80.1 kJ mol−1, ΔSоwas 300.1 J mol−1, and ΔGоwere negative values at the different temperatures. The adsorption process is rapid and physisorption in nature. Therefore, magnesium silicate gel would be used in the industrial wastewater treatment as a potential adsorbent.

A mild hydrothermal route for preparing highly photocatalytic activity (I2)nsensitized and I(V) doped TiO2supported on SiO2(ITS) materials was developed. The ITS was characterized by X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area, TG-DTA, X-ray diffraction, UV-vis diffuse reflectance spectra and transmission electron microscopy. Concentration of TiO2in the ITS was 287.8 mg/g. The presence of iodine and hydrogen iodate in the ITS was established through the results of XRD and XPS. ITS is very stable under 750 K and shows a drastic photoabsorption in the range of wavelength from 384 to 700 nm for the iodine sensitization. The photocatalytic activity was evaluated by the photocatalytic oxidation of phenol under dysprosium lamp light illumination. ITS exhibited highly photocatalytic activity.