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Abstract Major challenges for effective implementation of the Electro-Fenton (EF) water treatment process are that conventional efficient cathodes are relatively expensive, and H 2 O 2 activation by Fe2+ may cause secondary pollution. Herein, we propose a low-cost activated carbon/stainless steel mesh (ACSS) composite cathode, where the SS mesh distributes the current and the AC simultaneously supports H 2 O 2 electrogeneration, H 2 O 2 activation, and organic compounds (OCs) adsorption. The oxygen-containing groups on the AC function as oxygen reduction reaction (ORR) sites for H 2 O 2 electrogeneration; while the porous configuration supply sufficient reactive surface area for ORR. 8.9 mg/L H 2 O 2 was obtained with 1.5 g AC at 100 mA under neutral pH without external O 2 supply. The ACSS electrode is also effective for H 2 O 2 activation to generate OH, especially under neutral pH. Adsorption shows limited influence on both H 2 O 2 electrogeneration and activation. The iron-free EF process enabled by the ACSS cathode is effective for reactive blue 19 (RB19) degradation. 61.5% RB19 was removed after 90 min and 74.3% TOC was removed after 720 min. Moreover, long-term stability test proved its relatively stable performance. Thus, the ACSS electrode configuration is promising for practical and cost-effective EF process for transformation of OCs in water. Graphical abstract Image 1 Highlights • A novel iron-free Electro-Fenton process is proposed for oxidation of chemicals in water. • A low-cost granular activated carbon/stainless steel mesh electrode is used for the process. • Effect of electrolyte pH and current on H 2 O 2 production are investigated. • Neutral pH could supported effective H 2 O 2 electrogeneration and H 2 O 2 activation. • Long-term stability for H 2 O 2 production, H 2 O 2 activation, OH production is verified. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) has been widely used to prepare electrode sheet for capacitive deionization (CDI) owing to its high surface area for ionic adsorption. However, further modification of the AC electrode is still necessary to improve the CDI performance by enhancing the ionic transportation inside the electrode. Here, an asymmetric CDI cell was prepared using Nafion-AC composite with low PTFE content (3.5%) as the negative electrode and AC as the positive electrode. Nafion functions not only as a binder to improve the adhesion of electrode sheet, but also as a mediator to provide an ion conductive pathway for counterions. The morphology and elemental analysis of Nafion-AC were investigated via scanning electron microscopy (SEM) and elemental mapping. The electrochemical capacitance property of the Nafion-AC electrode was studied by cyclic voltammetry (CV). The desalination capacity of the asymmetric CDI cell arrived at 10.8 mg/g, compared with the symmetric AC-based cell (6.9 mg/g). Contribution of Nafion and the corresponding mechanism were analyzed by differential capacitance tests and inverse charging. It demonstrates that in the Nafion-AC composite containing low PTFE content, the co-ion repulsion was reduced and the electrode adhesion was improved. The electrode performance has been conveniently evaluated by monitoring the variation of the charging efficiency and desalination amount with time under an appropriate charge input, which is much helpful to guide the operation process in practical CDI applications. [ABSTRACT FROM AUTHOR]