A highly dispersed Co–Fe bimetallic catalyst to activate peroxymonosulfate for VOC degradation in a wet scrubber

Abstract

Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are emerging methods for VOC waste gas treatment, but the activation of PMS via heterogeneous metal catalysts is greatly limited by the low dispersion of active components. In this work, a highly dispersed Co–Fe bimetallic catalyst using uncalcined SBA-15 as the support (CFS) was successfully prepared by a simple one-step calcination method. The abundant Si–OH groups and nanoconfined space provided by uncalcined SBA-15 were responsible for the dispersion behavior of Co–Fe species. Simultaneously, the doping of Fe in CFS can greatly enhance the Co stability in the channels of SBA-15 and prevent Co ion leaching in reaction media. The prepared CFS can be stored for 3 months with almost no loss of activity. Compared with CFS, the Co–Fe catalyst derived from template free SBA-15 (CFCS) showed aggregated particles with much lower dispersion. CFS showed superior catalytic activity towards PMS activation and VOC degradation in a wet scrubber. The toluene removal efficiency over CFS was kept above 95% while it was only 62%, 30% and 42% over CFCS, Co/SBA-15 and Fe/SBA-15, respectively. The powerful hydroxyl (HO˙) and sulfate (SO₄˙⁻) radicals were abundantly generated to oxidize toxic VOCs including toluene, styrene and chlorobenzene into soluble small molecules, which could be finally mineralized into CO₂. The highly dispersed Co–Fe nanoparticles developed in this study not only show outstanding activity for PMS activation in AOPs, but also greatly reduce the environmental risk from Co leaching and emission of toxic VOCs and their by-products.