The design of coal-based carbon membrane coupled with the electric field and its application on the treatment of malachite green (MG) aqueous solution

Abstract

The wastewater treatment system, where coal-based carbon membrane is adopted as the anode and coupled with an electric field for the removal of malachite green (MG) from aqueous solution, is designed. Effects of electric field intensity, MG concentration, and initial pH of solution on separation performance of carbon membrane are investigated. The morphology of carbon membrane is observed using scanning electron microscope (SEM). The electrochemical degradation intermediates of the MG solution are identified by high-performance liquid chromatography/mass spectrometry (HPLC/MS). The results show that the treatment system demonstrates improved permeate flux and removal efficiency for MG solution due to electrochemical anodic oxidation. High MG concentration produces low final permeate flux due to excessive MG molecules, which exceed the degradation ability of the treatment system. High initial pH favors the enhancement of the antifouling ability of carbon membrane, and thus improves its separation performance. During electrochemical degradation of MG, N-demethylation and decomposition of conjugated structure by the cleavage of central carbon structure are the main reaction routes. Afterwards, these intermediates are further degraded into small molecular intermediates, which are oxidized into CO2 and H2O eventually.