Enhanced removal of VOCs from wood by coupling extraction with surfactant and, oxidation using ultrasound-activated persulfate

Abstract

Wood contains abundant extractives and volatile oils, which release strong odor and hazardous volatile organic compounds (VOCs). Free radicals generated by advanced oxidation processes (AOPs) can be used to efficiently destroy organic components in the aqueous phase. However, the limited water availability of hydrophobic extractives and non-water soluble volatile oils in wood may decrease the effectiveness of traditional in-situ chemical oxidation (ISCO). The poor permeability of wood-blocks, the limited of matter transmission, and the short half-life of radicals result in the low utilization of free radicals. To tackle this issue, surfactants can be combined with an ultrasound-activated persulfate (PS) process to construct a biphasic wood/water system to enhance the utilization of aqueous-phase radicals and the mass transfer of extractives and volatile oils. Various controlling factors were evaluated, including surfactant concentration, PS dosage and ultrasound temperature. The GC-MS analysis indicated that the removal rate of wood VOCs was ∼66.9 % without recycling treatment. The electron paramagnetic resonance (EPR) analysis further revealed that SO 4 •- and •OH as the main reactive species. The evaluation of wood characteristics shows that the process has no serious damage. The results demonstrate that the proposed method is effective for the oxidative removal of VOCs from wood. • VOCs source can be effectively oxidized in biphasic system. • C12-MADS surfactant was highly compatible with the ultrasound-activated persulfate. • Synergistic of ultrasonic irradiation and surfactant played a crucial role in the desorption of VOCs from wood. • The EPR analysis reveals that S O 4 - · and ·OH are the primary reactive species. • The key wood-VOCs was analyzed by the HS-SPME/GC-MS.