Advanced oxidation processes (AOPs, such as Fenton) coupled with wet scrubbers are powerful and eco–friendly for VOCs treatment. However, challenges remain in the efficient removal of hydrophobic VOCs due to the extremely high gas-liquid mass transfer resistance. Herein, we constructed a “gas-solid-liquid triple-phase interface” in a Fenton wet scrubber via fabricating a new amphiphilic catalyst (PAN@Fe 3 O 4 @Nafion), which allows to capture gas bubbles and directly convey the VOCs to catalytic active center through gas transport and bypass the gas-liquid mass transfer (rate–determining) step. Compared with system with the unmodulated catalyst, the removal efficiency of hydrophobic styrene in the triple-phase interface Fenton wet scrubber was improved by 69.0%, the intermediates were dominated by small–molecule fatty acids (98.0%), and the outlet CO 2 concentration and H 2 O 2 consumption increased by 22.1% and 19.6%, respectively. Notably, mechanism analysis via confocal laser scanning microscopy and contact angle measurements revealed the arrangement of hydrophilic and hydrophobic regions on the catalyst surface. Moreover, the affinity ability of bubbles was 2.5 times greater and the mass transfer enhancement factor reached 2.2 in the triple-phase interface Fenton wet scrubber system. This study provides a new avenue for overcoming the gas-liquid mass transfer resistance of hydrophobic VOCs in AOP wet scrubbers.
Volatile organic compound (VOC) emissions are a global environmental concern because of their potential health risks. The removal of refractory VOCs calls for advanced technologies with powerful oxidative ability and high mass transfer efficiency. In this study, a yolk-shell Fe 3 O 4 @C/Fenton system was designed to improve octane removal efficiency. The octane removal efficiency at equilibrium was increased by 24.7% relative to that of the Fe 3 O 4 /Fenton system, and the main intermediate or byproduct levels decreased by 89.4%. The yolk-shell Fe 3 O 4 @C displayed higher catalytic and mass transfer efficiencies for octane degradation than Fe 3 O 4 . A synergistic effect of mass transfer enhancement and catalytic oxidation was observed in the yolk-shell Fe 3 O 4 @C/Fenton system. The mechanism of the synergistic effect of mass transfer and octane degradation, a regional reaction theory for the yolk-shell structure, and octane removal pathways were proposed and supported by the octane removal results and byproducts detection and measurement. This yolk-shell Fe 3 O 4 @C/Fenton system provides an effective and advanced way to treat refractory and hydrophobic VOCs, and its preparation can be extended to other high-efficiency core-shell structure catalyst-carbon materials.
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