Effective degradation of VOCs from wood by Fe2+ chelate activated dual oxidant (H2O2-PS)

Abstract

Wood is rich in extractives and volatile oils that emit unpleasant odors and some harmful volatile organic compounds (VOCs). Chemical oxidation technologies processes high efficiency on the destruction of aqueous organic components via oxidation by radicals, however, wood block treatment scenarios suffer from the low availability of radicals in aqueous conditions owing to the special structure of the wood blocks, limitations of mass transfer and the short life of free radicals. Herein, ethylenediaminetetraacetic acid (EDTA) is selected as a chelating agent to synthesize EDTA-Fe2+ chelate, thus introducing Fe2+ into the wood by vacuum impregnation. The Fe2+ is evenly distributed and immobilized in the wood to form a chemical oxidation system via in-situ activation of the dual oxidant (H2O2-PS), which truncates the contact distance between free radicals and extractives/volatile oils thus enhancing the removal efficiency. Various controlling factors, including EDTA/Fe2+ molar ratio, Fe2+dosage, PS/H2O2 molar ratio, and persulfate (PS) dosage are evaluated. The degradation products of VOCs by headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) indicate that the wood VOC removal rate is ∼80%. The Electron paramagnetic resonance (EPR) analysis further reveals that SO4−· and ·OH are the primary reactive species. The characterization of wood properties illustrates that the process has no destructive effect. The results of this work may provide a theoretical basis for feasibility of the practical application of the EDTA-Fe2+/H2O2-PS system.