Evaluation of Electrospun Self-Supporting Paper-Like Fibrous Membranes as Oil Sorbents.

Adele Folino,Beatrix Petrovičová,Saveria Santangelo,Fabiolo Pantò,Demetrio A Zema,Claudia Triolo

doi:10.3390/membranes11070515

Abstract

Presently, adsorption/absorption is one of the most efficient and cost-effective methods to clean oil spill up. In this work, self-supporting paper-like fibrous membranes were prepared via electrospinning and carbonisation at different temperatures (500, 650 or 800 °C) by using polyacrylonitrile/polymethylmethacrylate blends with a different mass ratio of the two polymers (1:0, 6:1 or 2:1). After morphological and microstructural characterisation, the as-produced membranes were evaluated as sorbents by immersion in vegetable (sunflower seed or olive) and mineral (motor) oil or in 1:4 (v:v) oil/water mixture. Nitrogen-rich membrane carbonised at the lowest temperature behaves differently from the others, whose sorption capacity by immersion in oil, despite the great number of sorbent and oil properties involved, is mainly controlled by the fraction of micropores. The encapsulation of water nanodroplets by the oil occurring during the immersion in oil/water mixture causes the oil-from-water separation ability to show an opposite behaviour compared to the sorption capacity. Overall, among the investigated membranes, the support produced with 2:1 mass ratio of the polymers and carbonisation at 650 °C exhibits the best performance both in terms of sorption capacity (73.5, 54.8 and 12.5 g g−1 for olive, sunflower seed and motor oil, respectively) and oil-from-water separation ability (74, 69 and 16 for olive, sunflower seed and motor oil, respectively).

Highlights

Contamination by mineral and vegetable oils represents a serious environmental concern and a critical health hazard for ecosystems’ life in soils, freshwater and seawater [1,2,3]
Stabilisation in-air of as-spun membranes converts PAN to an infusible stable ladder polymer [51,52]. This happens through the cyclisation of nitrile groups (C≡N) and crosslinking of the chain molecules in the form of –C=N–C=N, which limits volatilisation and maximises the carbon yield, and at the same time prevents melting during the subsequent step at higher temperature
The carbonisation of the PAN-based membranes was accompanied by a mass loss roughly proportional to TC (Figure S5a), while during the carbonisation of the PAN/PMMA-derived membranes at 650 ◦C, the mass loss was roughly proportional to the relative amount of PMMA (Figure S5b), which completely degrades below this temperature via homolytic scission of the chain, side group scission and depolymerisation [54]

Summary

Introduction

Contamination by mineral and vegetable oils represents a serious environmental concern and a critical health hazard for ecosystems’ life in soils, freshwater and seawater [1,2,3] Organic compounds, such as polyphenols, hinder the treatment of water streams in the traditional depuration plants, due to the resistance of these molecules to biodegradation [4]. Compared to the low-cost melt-blown membranes [40], the electrospun supports show greater re-usability in filtration applications. Several polymers, such as polystyrene [10], polyimide [27] and polyvinylpyrrolidone [41], have been evaluated for the production of sorbent membranes

Methods

Results

Conclusion