Joule-heating electrospun reduced-graphene oxide nanoribbon-coated reusable polymeric sorbent with an excellent sorption/desorption of high-viscosity oils

Abstract

Reusable oil sorbents for oil/water separation have been extensively researched due to their environmentally friendly applications. While reusing sorbents that have removed low-viscosity oils was relatively straightforward, the challenge arose with high-viscosity oils. Consequently, this study fabricated a Joule-heated reduced-graphene oxide nanoribbon-coated polyvinylidene fluoride (r-GONR-coated PVDF) oil sorbent to enhance the sorption/desorption (reusability) performance of highly viscous oils. Joule heating was employed as a novel oil desorption technique to decrease the viscosities of oils and enhance oil desorption performance from the sorbent. The r-GONR-coated PVDF oil sorbents significantly increased surface temperatures through Joule heating, reaching up to 160 °C at a low voltage (20 V). Owing to comparable porosity and water contact angle, the oil sorption capacity was similar between PVDF and r-GONR-coated PVDF oil sorbents (19 g/g for motor oils and 12 g/g for diesel oil). However, the highest oil desorption efficiencies with highly viscous oils were achieved with the r-GONR5 oil sorbent (∼50 % within 5 min) using Joule-heating, compared to the PVDF oil sorbent (≤10 %). Furthermore, this sorbent demonstrated reusability for up to the 5th sorption/desorption cycle, with a recovery efficiency of approximately 50 %. In comparison to the PVDF oil sorbent, therefore, the Joule-heated oil sorbent is expected to reduce the cost of spilled oil clean-up by approximately 3.24 times. This study introduces a novel material with high reusability and a new method for the desorption of oil sorbents in practical applications. Specifically, it provides a cost-effective and sustainable clean-up method for spilled oils with high viscosity.