Sustainable approach to recycle waste polystyrene to high-value submicron fibers using solution blow spinning and application towards oil-water separation

Polystyrene waste disposal is an environmental challenge and transforming it into value-added products such as submicron fibers is an attractive paradigm. In this work, we have reported a sustainable approach to deal with the twin issues of handling low-density polystyrene waste and its re-utilization. Using ethyl acetate as a cost-efficient environmentally preferable solvent, we have successfully demonstrated conversion of waste expanded polystyrene (WPS) into hydrophobic fibers via solution blow spinning technique and its application towards oil-water separation. The macroscale spray pattern analysis in combination with microscale analysis is reported as a facile tool for evaluating the effect of polymer solution properties and operating parameters on the spray morphology. Additionally, the fiber spinnability limits are identified that provide the operational parameters in which fibers without any undesirable structural features are obtained. Here, the lower fiber spinnability limits were identified as 6 wt% polymer concentration, 3 kg cm−2 gas pressure and 10 cm nozzle-to-target distance, below which excessive beads or film formation was observed. The upper fiber spinnability limits were 14 wt% polymer concentration and 5 kg cm−2 gas pressure beyond which the solution blow spinning was not feasible. Moreover, wettability studies showed the enhanced hydrophobic and superoleophilic behavior of the synthesized WPS fibrous mats with water contact angle as ∼138° and oil contact angle as ∼0°. The WPS fiber-coated membrane demonstrated a maximum separation efficiency of 97% for free oil (diesel)-water mixtures, indicating potential applications in oil recovery and treatment of oily wastewater.