Scalable Ir‑Doped NiFe_(2)O_(4)/TiO_(2) Heterojunction Anode for Decentralized Saline Wastewater Treatment and H_(2) Production

Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H_(2) production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study reports Ir-doped NiFe_(2)O_(4)(NFI,~5 at%Ir)spinel layer with TiO_(2) overlayer(NFI/TiO_(2)),as a scalable heterojunction anode for direct electrolysis of wastewater with circumneutral pH in a single-compartment cell.In dilute(0.1 M)NaCl solutions,the NFI/TiO_(2) marks superior activity and selectivity for chlorine evolution reaction,outperforming the benchmark IrO_(2).Robust operation in near-neutral pH was confirmed.Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO_(2) which serves both as the primary site for Cl−chemisorption and a protective layer for NFI as an ohmic contact.Galvanostatic electrolysis of NH4+-laden synthetic wastewater demonstrated that NFI/TiO_(2)not only achieves quasi-stoichiometric NH_(4)^(+)-to-N_(2)conversion,but also enhances H_(2)generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine.The scaled-up WEC with NFI/TiO_(2)was demonstrated for electrolysis of toilet wastewater.

The migration and transformation of dissolved organic matter during the freezing processes of water

This study investigated the partitioning behavior of dissolved organic matter（DOM） in liquid and ice phases, as well as the changes in the optical properties and chlorine reactivity of DOM during the freezing processes of water. DOM was rejected from the ice phase and accumulated in the remaining liquid phase during water freezing. Moreover, the decrease in freezing temperature, as well as the increase in dissolved organic carbon（DOC）concentration of feed water, caused an increase in DOM captured in the ice phase. The ultraviolet-absorbing compounds, trihalomethane precursors, as well as fulvic acid- and humic acid-like fluorescent materials, were more liable to be to be rejected from the ice phase and were more easily retained in the unfrozen liquid phase during water freezing, as compared with organics（on average） that comprise DOC. In addition, it was also found a higher accumulation of these organics in the unfrozen liquid phase during water freezing at higher temperature. The freeze/thaw processes altered the quantity, optical properties, and chlorine reactivity of DOM. The decrease in ultraviolet light at 254 nm as well as the production of aromatic protein- and soluble microbial byproduct-like fluorescent materials in DOM due to freeze/thaw were consistently observed. On the other hand, the changes in DOC, trihalomethane formation potential, and fulvic acid- and humic acid-like fluorescence caused by freeze/thaw varied significantly between samples.