The effects of different types of surfactants on the electrochemical degradation of PET microplastics

Abstract

Electrochemical advanced oxidation processes (EAOP) have demonstrated effective performance in removing microplastics (MPs) from water. Surfactant molecules are widely present as pollutants in water containing microplastics, alter the hydrophobicity of microplastic surfaces, facilitating the dispersion of plastic particles and forming stable suspensions. This study investigates without adding additional catalysts, the electrochemical degradation efficiency of PET MPs in the presence of different surfactants. Both cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), an anionic surfactant, enhance the electrochemical degradation efficiency of PET MPs, with the weight loss of PET MPs reaching 68 % and 58 %, respectively, after 6 h of electrolysis. The primary reactive species identified were ·OH and SO₄·⁻ radicals. Both electrodes contributed to the degradation, with the cathode playing a more significant role in the decomposition of PET MPs into water-soluble organic compounds, while the anode effectively removed these compounds from the solution. A quantitative analysis of the ability of the cathode and anode to generate H₂O₂, with and without surfactants, revealed that the addition of SDS and CTAB enhanced the redox reactions at the electrodes, increasing the yield of reactive species and improving the contact between PET MPs and these species, thereby further promoting the electrochemical degradation.