Stable and effective super-hydrophilic polysulfone nanofiber mats for oil/water separation

•Super-hydrophilic membrane based on PSF nanofibers is introduced.•The membrane was modified using simple and effective heat treatment process.•The corresponding water flux is very high; 12.21 m3/m2 day.•The fabrication process is simple, cheap and applicable.

Hydrophobicity of polysulfone is the main constraint facing wide application in the most important field; water treatment, although this polymer shows promising characteristics to be used in different separation technologies. In this study, super-hydrophilic polysulfone nanofiber mats are introduced using novel modifications. The introduced nanofibers were synthesized by electrospinning of polysulfone/NaOH/DMF electrospun solution. The prepared electrospun nanofibers have been activated by deposition of a polyamide layer using interfacial polymerization (IP) reaction between m-phenylenediamine and 1,3,5-benzenetricarbonyl chloride. Three different heat treatment methodologies were investigated to enhance the characteristics of the activated nanofiber mats; normal drying at 70 °C, and soaking in boiled water followed by either normal drying at 70 °C or storing in the water. Investigation of the mechanical properties indicated that incorporation of NaOH improves the tensile stress by 40% compared to the pristine polysulfone nanofibers. Interestingly, treatment of the activated nanofiber mats in the boiled water followed by storing in water led to produce super-hydrophilic mats with water contact angle of 3° due to enhancing the IP reaction on the surface of the individual nanofibers. In oil/water separation process, the proposed heat treatment for the modified nanofiber mats resulted in increase the water flux from 8 to 12.21 m3/m2 day with oil rejection of 99.976%.

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