Hierarchically porous electrospun nanofibrous mats produced from intrinsically microporous fluorinated polyimide for the removal of oils and non-polar solvents

Abstract

Oil spills impose serious ecological threats to the environment and are of international concern. Novel approaches and materials are continuously being sought to improve the cleanup of oil spills. In widespread oil spills, the performance of many materials used as oil sorbents is limited by their low surface area. Here, we describe a novel nanofibrous oil sorbent composed of a fluorinated polyimide of intrinsic microporosity (PIM-PI) with a high Brunauer–Emmett–Teller (BET) surface area of 565 m² g⁻¹. The nanofibrous sorbent was produced by electrospinning of PIM-PI (6FDA–TrMPD), which was synthesized by a one-pot, high-temperature polycondensation reaction between 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,4,6-trimethyl-m-phenylenediamine (TrMPD). Electrospinning of 6FDA–TrMPD from a solution of DMF with a concentration of 10% (w/v) produced ultrafine nanofibers, whereas at lower concentrations, beaded-fibers were obtained. The adsorption performance of the nanofibrous sorbent using several oils (i.e. crude oil, silicone oil, gasoline, and diesel) and non-polar organic solvents (i.e. toluene and m-xylene) was explored. The developed sorbent showed high sorption capacities in the range of 25–56 g g⁻¹, along with a rapid removal performance; the sorbent reached the equilibrium sorption capacity within a few minutes for oils and organic solvents. The feasibility of the designed hierarchically porous mat for oil spill cleanup was demonstrated by the treatment of real seawater and crude oil. The robustness and reusability of the sorbent were demonstrated through its regeneration by both mechanical recovery and toluene treatment.