Pilot scale catalytic ozonation with wet scrubbing enhanced by PAC for treating automotive electrophoretic VOCs: performance and environmental-economic advantages

Abstract

Automotive electrophoretic coating volatile organic compounds (VOCs) exhibit complex compositions that pose significant atmospheric and human health risks. These emissions are characterized by low concentrations (average 7.67 mg/m³) and a high proportion of oxygenated VOCs (OVOCs, 82.94%), making them poorly amenable to conventional treatment methods, with activated carbon adsorption achieving only 9.0% removal efficiency. This study presents a pilot-scale evaluation of a powdered activated carbon–enhanced wet catalytic ozonation (PAC+WCO) system for treating such exhausts. Over 15 d of continuous operation, the system achieved an average VOC removal efficiency of 85.0%, with removal efficiencies of 97.7% for OVOCs, 85.1% for alkanes, 92.0% for olefins, 75.8% for aromatics, and 31.1% for halocarbons. The absorption solution maintained low chemical oxygen demand (COD, 178.4 mg/L) and total organic carbon (TOC, 107.4 mg/L) levels, with three-dimensional fluorescence spectroscopy confirming negligible pollutant accumulation. Mechanistic analysis revealed that the hydrophilicity of OVOCs, the “particle effect” of PAC, and the adsorption of small oxygen-containing molecules onto PAC surfaces collectively enhanced the mass transfer of hydrophobic VOCs, while efficient catalytic oxidation ensured stable system performance. The system significantly reduced ozone formation potential (OFP) from 25.3 to 0.79 mg/m³ and mitigated associated non-carcinogenic and carcinogenic health risks. An economic assessment indicated competitive operating costs attributable to low PAC consumption and the elimination of hazardous waste disposal. Overall, these findings validate the PAC+WCO system as an efficient, stable, and economically viable technology for controlling challenging VOC emissions from automotive water-based painting processes.

Graphical abstract

Keywords

Volatile organic compounds (VOCs) / Automotive electrophoretic coating / Powdered activated carbon (PAC) / Wet catalytic ozonation (WCO) / Environmental-economic advantages

Highlight

	● Pilot-scale PAC+WCO system achieved 85.0% average VOCs removal.
	● PAC enhanced mass transfer and catalytic ozonation.
	● Adsorption liquid maintained low secondary pollution.
	● OFP and health risks have been reduced with competitive operational costs.

References

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