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The alternative desalination technique of membrane capacitive deionization (MCDI) has emerged in the last 15 years and received a lot of research attention since then. By using a voltage applied between two electrodes covered with ion-exchange membranes, MCDI has attempted to challenge established methods such as reverse osmosis or electrodialysis. In this study, through the crosslinking of sulfosuccinic acid (SSA) and glutaric acid (GA) with polyvinyl alcohol (PVA), cation exchange membrane preparation and characterization were introduced. For the CDI system, membranes were chosen based on their water absorption and ion exchange properties. The PVA/SSA/GA composite (mass ratio of 100:5:5) had the best water adsorption and charge efficiencies that could be utilized for CDI application. The membrane’s ability to desalinate water was assessed using electrical properties such as total resistance, specific capacitance, and electro adsorption coated with the best ratio composite CEM. The salt absorption capacity of 19.06 mg·g−1 with stable performance was found to be encouraging.

This study reported the synthesis, characterization, and electrochemical performance of sea-urchins γ-MnO2 structure and its composites with carbon aerogel (CA) derived from Waste-corn-stalk for capacitive deionization (CDI) application. Scanning electron microscopy revealed distinct sea-urchin morphologies where γ-MnO2 exhibited a fibrous, porous structure, and its integration with CA resulted in composites with varied porosity and particle size distributions; X-ray diffraction analysis confirmed the crystalline nature of γ-MnO2. It indicated a successful composite formation with CA, which was observed to enhance the electrochemical performance via the synergistic charge storage effect. Cyclic voltammetry and charge-discharge tests showed that the composites, particularly CA/γ-MnO2-30, had superior electrochemical performance compared to γ-MnO2 pristine, with improved capacitance and rate capabilities. CDI performance assessments demonstrated that the composite CA/γ-MnO2-30 significantly outperformed in salt adsorption capacity of 32.7 mg/g, highlighting the potential of these materials for efficient water desalination. The electrosorption kinetic process of CA/γ-MnO2 composites is suitable for the pseudo-second-order (PSO) model by combining the double-layer adsorption and the pseudo-capacitance process. [ABSTRACT FROM AUTHOR]

Capacity deionization (CDI), which combines capacitive carbon electrodes and redox-active electrodes, has emerged as a promising method for water desalination. It enables higher ion removal capacity than CDI-containing carbonaceous electrodes. Our work aimed to synthesize layered structure δ-MnO2/CNTs composites via the sol-gel method, examining their suitability for hybrid capacitive deionization (HCDI). The XRD results showed a layered structure birnessite for all composites with a distance interlayer over 7.0 Å, while the SEM images confirmed the intercopration of MnO2 particles and CNT fibers. The electrochemical evaluations evidenced the role of CNTs in enhancing the charge transfer and ionic diffusion in composites. Composite δ-MnO2/CNTs presented a specific capacitance of 160 F g−1 at a charge-discharge rate of 1 A g-1 upon 1600 cycles. In salt removal performance, the asymmetric cell AC||δ-MnO2/CNTs-1 showed the highest salt adsorption capacity (SAC) of 30.2 mg g−1 and fast average salt adsorption rate (ASAR) of 3 mg g−1 s−1 under a constant applied potential 1.4 V in 200 ppm NaCl, rendering it a promising candidate for efficient and sustainable desalination technology. [ABSTRACT FROM AUTHOR]

In the recent years, piezocatalysis process is attracting extensive attention as an emerging technology to remove persistent organic pollutants. Its advantage is that it relies on mechanical energy and is independent of electricity and light source, unlike electrocatalysis or photocatalysis processes. In this research, 2H-MoS2/g-C3N4 heterojunction materials were successfully fabricated via the hydrothermal method and utilized as piezocatalyst in the treatment of Rhodamine B. This material exhibited a highly efficient piezo-catalyst effect, with the piezo-response amplitudes of 78.8 mV, almost doubled compared to 39.8 mV of 2H-MoS2. The degradation of Rhodamine B by ultrasonic irradiation could reach 75.4% only after 5 s and then 94.9% in 60 s without light assistance. This ultra-rapid degradation rate is attributed to the electron–hole pairs and transfer of the charge-carriers on the surface of 2H-MoS2 and g-C3N4 via S-scheme heterojunction model, which was confirmed by density functional theory study. The piezo-catalytic ability of the material can still be improved for better treatment of other organic pollutants in aqueous environment. [ABSTRACT FROM AUTHOR]

This work was aimed at preparing the composites TiO2@CNTs via facile sol-gel route and investigating the electrochemical performance in neutral aqueous electrolyte 1 M Na2SO4 with a high voltage of 1.8 V The synergistic effects between TiO2 and CNTs in composite electrode were offered a significantly high specific capacitance of 227 F·g−1 at a scan rate of 10 mV·s−1. The EIS analysis evidenced not only the pseudocapacitance process of composite TiO2@CNTs with the combination of non-Faraday and Faraday process but also the superior electrochemical performance of TiO2@CNTs-5%. The ionic diffusion coefficients of TiO2@CNTs-5%, TiO2@CNTs-3%, and TiO2@CNTs-1% were calculated 1.47 × 10−17 cm2·s−1, 1.12 × 10−17 cm2·s−1, and 0.71 × 10−17 cm2·s−1, respectively. Moreover, TiO2@CNT electrodes have been utilized to assemble a symmetrical supercapacitor which has delivered an excellent capacitance of 97.3 F·g−1 at a current rate of 1 A·g−1. The device shows a long-term stability upon 5000 cycles without degradation, and the energy density of TiO2@CNTs was 15–43.8 Wh·kg−1 in the power density range of 1800–18,000 W·kg−1. [ABSTRACT FROM AUTHOR]