Synthesis of pearl necklace-like ZIF-8@chitosan/PVA nanofiber with synergistic effect for recycling aqueous dye removal.

Recently, fabrication of MOF-based bionanocomposites for wastewater treatment applications is enjoying wide currency. Herein, zeolitic imidazolate framework-8 (ZIF-8) crystal was coated on chitosan/polyvinyl alcohol electrospun nanofiber (CS/PVA-ENF) to synthesize ZIF-8@CS/PVA-ENF. They were characterized, and their dye adsorption performances were studied in detail. The ZIF-8 was coated on CS/PVA-ENF for the first cycle (ZIF-8@CS/PVA-ENF(1)), second cycle (ZIF-8@CS/PVA-ENF(2)), and third cycle (ZIF-8@CS/PVA-ENF(3)). The impact of operational parameters including pH, the dose of adsorbent, and initial Malachite green (MG) concentration was evaluated and modeled by mostly-known statistical tools such as an artificial neural network (ANN) and response surface methodology (RSM). The mathematical calculation indicated that the obtained data were in high agreement with the Langmuir isotherm, and the kinetics data were well fitted to the pseudo-second-order model. The ZIF-8@CS/PVA-ENF(2) showed a higher Langmuir adsorption capacity (1000 mg/g) in comparison to other composites. Moreover, a cycling experiment shoed ZIF-8@CS/PVA-ENF(2) has high chemical stability.