Sulfonic acid-grafted polyvinylidene fluoride electrospun mats as electro-Fenton reactor membrane components

Abstract

Electro-Fenton (EF) reactors, involving in situ generation of H₂O₂ by reaction of O₂ in aqueous Na₂SO₄ upon applying voltage, show a number of advantages for organic pollutants degradation. The membrane, a key component of EF reactors, prevents H₂O₂ from being consumed in the anode. Recently, polyvinylidene fluoride (PVDF) nanofibers have emerged as promising membrane components, although the high interface impedance and low conductivity of these materials are serious drawbacks. Sulfonic acid-grafted PVDF nanofiber membranes can overcome these limitations. In this work, nanofiber PVDF membranes were prepared from electrospun single-fiber mats loaded on non-woven fabrics. In these fibers, the PVDF polymer was functionalized with sulfonic acid via covalent (3-mercaptopropyl)trimethoxysilane (MPS) bonding. These sulfonic acid-grafted PVDF nanofiber membranes showed a remarkable decrease in the water contact angle (WCA, from 120 to 6°), thereby greatly improving the hydrophilicity while reducing the membrane impedance (from 21.9 Ω for the unmodified membrane to 15.7 Ω for the acid-grafted material). Methyl orange (MO), a model pollutant, was completely EF removed within 30 min using the modified membrane. The modified membrane allowed a decrease of the electric energy consumption (EEC) from 76.8 to 65.0 kW h kg_TOC⁻¹, thereby suggesting that this novel material can provide an effective approach to improve the EF performance.