Removal of wood volatile organic compounds using ozone-activated persulfate system from China fir wood powder samples

Abstract

Wood contains abundant extractives and volatile oils, which release strong odors and hazardous volatile organic compounds (VOCs). The emission of VOCs can be minimized by degrading and mineralizing wood extractives. Wood powder is widely used as raw material for chemical industry, building materials, wood-based boards, and other products. In this study, China fir wood powder was used as object to remove wood VOCs by the ozonation and ozone-activated persulfate (O₃/PS) systems, and their VOC removal efficiencies were evaluated using gas chromatography–mass spectrometry (HS-SPME/GC–MS). The result showed O₃/PS system exhibited higher VOC removal efficiency. The mechanism of different ozone processes in wood treatment was explored, which contributed to the evaluation of the removal efficiency of VOCs and the degradation pathway of VOC components. The PS dosage, O₃ concentration, and pH had varying effects on the O₃/PS system. When the pH increased to 10, the removal rate of wood VOCs decreased. The VOC removal rate did not increase with the increasing free-radical concentration. When the PS concentration increased from 5 to 20 mM, the VOC removal efficiency gradually increased from 49.91 to 72.39%. However, when the PS concentration increased to 40 mM, the VOC removal efficiency of PS slightly decreased because the excess PS immediately produced a large amount of hydroxyl radical (·OH) and sulfate radical (SO₄^·−), which led to quenching reactions between radicals. The results revealed that the O₃/PS process promoted indirect oxidation. Under the synergistic effect of O₃, ·OH, and SO₄^·−, the VOC removal efficiency was significantly improved, the intermediate product was lower, and the total VOC removal rate VOCs by O₃/PS was more than 70%.