Dye Adsorption Capacity of MoS2 Nanoflakes Immobilized on Poly(lactic acid) Fibrous Membranes

The increasing concern about water contamination has led to the search for easy, low-cost, and efficient approaches for wastewater treatment. In this regard, the precise preparation and proper utilization of emerging nanomaterials can be key in achieving technologies with superior performance for pollutant adsorption and filtration systems. Herein, poly­(lactic acid) (PLA) membranes fabricated by solution blow spinning (SBS) technique were coated with Zein (sample PLA-Zein) and then sprayed-modified with molybdenum disulfide (MoS2), yielding the nanocomposite PLA-Zein/MoS2. A post-modification method using spraying was preferred because it is a simple, low-cost, and rapid strategy to modify the surface of the SBS fibers. Specifically, distinct morphologies of MoS2 were obtained using bulk (no treatment), top-down (TD; milling and ultrasonic processing), and bottom-up (BU; hydrothermal synthesis) routes. A detailed morphological and physical–chemical characterization of MoS2 nanoflakes and composite membranes was carried out, confirming successful modification of the PLA fiber surface. The different morphologies of MoS2 (obtained by bulk, TD, and BU routes) led to different kinetics, isotherm, and adsorption capacity toward methylene blue (MB; used as a model). The removal efficiencies of composite membranes were 19.7% for PLA, 34.5% for PLA-Zein, 39.8% for PLA-Zein/TD, and 98.2% for PLA-Zein/BU. The obtained results indicated that BU MoS2 nanoflakes used to modify the submicrometric fibers reached an MB adsorption capacity of 111.2 mg g–1. The MoS2 high adsorption capacity combined with the fiber membranes’ interconnected pores and facile modification strategy make the PLA-Zein/MoS2 fiber composites particularly suitable for high-performance adsorbent membranes to be employed in filtration systems for water pollutant remediation.