Dip-coating prepared nickel-foam composite cathodes with hydrophobic layer for atenolol elimination in electro-Fenton system

Abstract

The nickel ions (Ni2+) leaching is a crucial issue that must be considered when using nickel-foam (NF) as the electrode material. Here, the NF composite cathode (CNTs-nafion/NF/PTFE) was fabricated by the facile dip-coating process for the atenolol (ATL) elimination in electro-Fenton (EF) system. The preparation conditions and experimental variables were investigated and optimized. The introduction of PTFE hydrophobic layer not only greatly enhanced H2O2 electro-generation, but also effectively controlled the Ni2+ leaching under the acidic condition (pH = 3). Remarkably, CNTs-nafion/NF/PTFE exhibited a comparatively excellent stability and low Ni2+ leaching amount (0.035 ppm) after six consecutive cycles. And the composite cathode showed favorable performance in 20 mg L−1 ATL degradation using 0.4 mM Fe2+ under current density 9 mA cm−2 and initial pH 3.0, achieving 100% degradation efficiency within 30 min and 41.7% TOC removal rate within 120 min. Further, it was confirmed that hydroxyl radicals (OH) and superoxide anions (O2) were considered to be active substances in the EF system, and OH played the predominant role. Also, the reasonable degradation mechanism and reaction pathways of ATL in the EF process were proposed. Overall, the facile preparation procedure and the lower Ni2+ leaching amount make the NF composite cathode a practicable alternative to carbonaceous materials in the EF system.