Construction of 3D ternary layered double hydroxides on nickel foam for enhancing dielectric barrier discharge plasma to degrade DUR: Performance, mechanism and energy efficiency

Abstract

Dielectric barrier discharge plasma (DBDP) has attracted much attention because of its energy saving, high efficiency, and simultaneous production of various active substances. In this work, a three-dimensional (3D) ZnFe-layered double hydroxides (LDH)/nickel foam (NiF) was rationally engineered and synthesized to overcome the problem of active substances insufficient use and clogged pipes in DBDP. With the assistance of ZnFe-LDH/NiF, the removal efficiency of diuron (DUR) increased from 85.98 % to 96.52 %, and the energy efficiency increased from 1074 mg·kWh−1 to 1281 mg·kWh−1. In various circumstances, the DBDP + ZnFe-LDH/NiF process performed a strong anti-interference ability, high stability, and reusability. The improvement of catalytic degradation ability could be attributed to the combined action of the Fenton-like process and O3 catalysis, all three elements participating in the electron transfer. With the help of quenching experiments, reactive oxygen species (ROS, including OH, 1O2, and O2−) were identified as the dominant active substance, significantly contributing to DUR elimination. Density functional theory calculation (DFT) and quadrupole-time of flight-liquid chromatography/mass spectrometry (Q-TOF-LC/MS) reached the same conclusion that CN and C−Cl were the main sites attacked by electrophiles and radicals. In summary, the combination of DBDP and ZnFe-LDH/NiF sheds new light on catalyst design and DBDP application.