Superior membrane distillation by induction heating of 3D rGO/Nafion/Ni foam for water treatment

Abstract

Membrane distillation (MD) is a promising green technology that can harness waste or solar heat to treat water. Since such heat sources suffer from temporal variations, a complementary, efficient means is necessary. Induction heating is attractive in providing localized heating at the feed-membrane interface where the heat matters, but the typical conductive materials (e.g., metal, alloy) corrode readily in the high-salinity, high-temperature environment. In this work, a superior induction material was proposed, namely, reduced graphene oxides (rGO) coated onto a porous Nickel foam by Nafion (rGO/Nafion/Ni), which exhibited superior and sustained performance for membrane distillation. Results indicate that rGO/Nafion/Ni achieved up to 28.1% higher water flux (6.42 ± 0.36 Lm−2h−1) and 37.5% lower energy consumption (3.13 kWhL−1) compared to other carbon materials coated on Ni or the bare Ni foam. The mechanism underlying the enhanced MD performance was the higher absorption of the electromagnetic waves via multiple internal reflections and larger eddy currents generated by rGO, leading to higher temperatures at the feed-membrane interface that increased the driving force for distillation and thereby the energy efficiency of MD. Our work demonstrated that the induction heating of rGO has high potential for augmenting MD performance in water treatment.