Highly efficient electro-catalysis activationof peroxymonosulfate by “used” As/Cr/Mo@FeOOH material for the degradation of metronidazole: Degradation mechanism and toxicity assessment

Abstract

Peroxymonosulfate (PMS) activation have provided a new direction to eliminate the organic pollutant. Current challenges that must be solved include secondary pollution by the metal ions and limitation in the recyclability of the catalysts. The waste 1D-FeOOH adsorbent with adsorption of metal elements (As, Cr or Mo ions) has been reused as an efficient electro-catalyst for PMS activation and used to metronidazole (MTD) degradation for the first time. The effects of current density, initial reaction pH, stirring rate, PMS dosage and solution temperature on MTD degradation was studied. The used 1D-FeOOH with adsorption of Mo ions showed the highest PMS activation ability and 99.6% MTD could be removed after 30 min degradation. The •OH and Found that SO4•− is the main free radical for MTD degradation. DFT calculation and characterization results were demonstrated that the high PMS electro-catalysis activation ability of the 1D-FeOOH@Mo has resulted from the special composition-dependent interactions among FeOOH@Mo and PMS, including stable adsorption properties, easy electron transfer and weak OO bond. The possible PMS electro-catalysis activation mechanism and MTD degradation pathway have been proposed. (ECOSAR) was used to evaluate the toxicity of metronidazole during degradation. The results showed that the toxicity of MTD and its intermediates could be effectively reduced by prolonging the degradation time in 1D-FeOOH@Mo solution. This work provides new insights for waste adsorbent disposal and gives a new perspective for PMS activation to degradation of antibiotics in water.