RESUMEN
Electrochemical deionization (ECDI) has emerged as a promising technology for water treatment, with faradaic ECDI systems garnering significant attention due to their enhanced performance potential. This study focuses on the development of a highly stable and efficient, full-polymer (polypyrrole, PPy) ECDI system based on two key strategies. Firstly, dopant engineering, involving the design of dopants with a high charge/molecular weight (MW) ratio and structural complexity, facilitating their effective integration into the polymer backbone. This ensures sustained contribution of strong negative charges, enhancing system performance, while the bulky dopant structure promotes stability during extended operation cycles. Secondly, operating the system with well-balanced charges between deionization and concentration processes significantly reduces irreversible reactions on the polymer, thereby mitigating dopant leakage. Implementing these strategies, the PPy(PSS)//PPy(ClO4) (PSS: polystyrene sulfonate) system achieves a high salt removal capacity (SRC) of 48 mg g-1, an ultra-low energy consumption (EC) of 0.167 kW h kgNaCl-1, and remarkable stability, with 96% SRC retention after 104 cycles of operation. Additionally, this study provides a detailed degradation mechanism based on pre- and post-cycling analyses, offering valuable insights for the construction of highly stable ECDI systems with superior performance in water treatment applications.
RESUMEN
Aqueous zinc-based energy storage devices possess superior safety, cost-effectiveness, and high energy density; however, dendritic growth and side reactions on the zinc electrode curtail their widespread applications. In this study, these issues are mitigated by introducing a polyimide (PI) nanofabric interfacial layer onto the zinc substrate. Simulations reveal that the PI nanofabric promotes a pre-desolvation process, effectively desolvating hydrated zinc ions from Zn(H2O)6 2+ to Zn(H2O)4 2+ before approaching the zinc surface. The exposed zinc ion in Zn(H2O)4 2+ provides an accelerated charge transfer process and reduces the activation energy for zinc deposition from 40 to 21 kJ mol-1. The PI nanofabric also acts as a protective barrier, reducing side reactions at the electrode. As a result, the PI-Zn symmetric cell exhibits remarkable cycling stability over 1200 h, maintaining a dendrite-free morphology and minimal byproduct formation. Moreover, the cell exhibits high stability and low voltage hysteresis even under high current densities (20 mA cm-2, 10 mAh cm-2) thanks to the 3D porous structure of PI nanofabric. When integrated into full cells, the PI-Zn||AC hybrid zinc-ion capacitor and PI-Zn||MnVOH@SWCNT zinc-ion battery achieve impressive lifespans of 15000 and 600 cycles with outstanding capacitance retention. This approach paves a novel avenue for high-performance zinc metal electrodes.
RESUMEN
This study provides insights regarding the selective metal leaching of brass in various tap water conditions, which benefits water utilities to predict the potential of metal released from brass water meters. The long-term time-dependent selective metal dissolution of brass with various ß phase fractions have not previously been investigated. In this study, a 201-d immersion experiment was carried out in low and high conductivity tap water (LCTW and HCTW, respectively). Three commercialized brass samples in different ß phase fractions (ß = 51%, ß = 43%, ß = 39%), named brass 51, brass 43, and brass 39, respectively, were used. The results showed that brass 51 had the most negative corrosion potential (-0.17 V) and the lowest polarization resistance (8.5 kΩ) compared to brass 43 and brass 39 (-0.04 V and 10.1-14.7 kΩ, respectively) in LCTW. This trend was verified by the 201-d immersion experiment in which brass 51 exhibited the highest zinc leaching rate (21-30 µg L-1 cm-2 d-1), followed by brass 43 and brass 39 (16-23 µg L-1 cm-2 d-1) in both waters. The leaching amounts of lead and copper were extremely low compared to zinc. In LCTW, the uniform corrosion (UC) mechanism dominated from day 1 to day 120. Afterwards, UC was replaced by the galvanic corrosion (GC) mechanism, with the selective leaching coefficient of Zn over Cu (SZn/Cu) increasing from 10 to 25 to 40-80. In HCTW, however, the SZn/Cu reached 300-1000, and the transition of UC to GC occurred earlier on day 30 due to the rapid formation of the ZnO layer on the brass surface that hindered the ion attack.