Removal of emerging contaminants from water using novel electroconductive membranes in a hybrid membrane distillation and electro-Fenton process
Farah Rahman Omi, Masoud Rastgar, Mojtaba Mohseni, Upasana Singh, Waralee Dilokekunakul, Robert Keller, David A. Wishart, Matthias Weßling, Chad D. Vecitis, Mohtada Sadrzadeh
Abstract
• Membrane distillation (MD) was integrated with electro-Fenton (EF) using a dual-functionality membrane. • Coupled EF-MD achieved an 81% degradation of ibuprofen in a 2-hr operation time. • Hybrid EF-MD exhibited excellent dye removal and TOC decay: about 3-fold more than solo EF. • Electroconductive membranes were developed by a facile “spray and cure” method. • For the first time, larger Ag-PTFE surface area (140 cm 2 ) was used, showing the stability of the electroconductive membrane. The treatment of emerging contaminants (ECs) with extremely low concentrations presents a significant challenge in advanced oxidation processes (AOPs) like electro-Fenton (EF). Combining EF with membrane distillation (MD) can concentrate the feed solution, thereby improving the reaction kinetics. Our innovation integrates MD with EF using a hydrophobic, electrically conductive membrane, offering a sustainable solution for continuous dewatering while simultaneously facilitating the EF reaction. The electroactive membrane, fabricated via a simple “spray and cure” method with Ag ink on polytetrafluoroethylene (PTFE) membrane, exhibited high electrical conductivity (60000 S/cm) and underwater oleophobicity. The hybrid EF-MD showed a 2.5-fold increase in methyl orange (MO) degradation and a 3.4-fold reduction in the total organic carbon (TOC) compared to EF alone at room temperature. Testing ibuprofen removal at 350 ppb, EF-MD achieved 81 % degradation within a 2-hour operation time in a temperature range of 20–60 °C. In comparison, EF alone required over 6 h at 60 °C to achieve a similar level of ibuprofen degradation. The fabricated Ag-PTFE membrane can be operated at low electric potential (−1 V), maintaining a steady state of 10 mA current, making it an energy-efficient technology for EC removal. Moreover, it shows exceptional antibiofouling characteristics as it completely deactivates E. coli by > 99 % at 1 V. The Ag-PTFE membrane can be fabricated at larger scales and can actively capture and degrade harmful micropollutants that are often resistant to conventional treatment methods. This results in cleaner, safer water for both consumption and environmental discharge.