Synthesis and Characterization of Electrospun Carbon Quantum Dots – Polyacrylonitrile/Polycaprolactone Composite Nanofiber Membranes for Copper (II) Adsorption

Heavy metal adsorption (HMA) is one of the remediation techniques used to remove heavy metals from water/wastewater. Composite membranes with functionalized additives for selective adsorption are being investigated. In this study, Carbon Quantum Dots – Polyacrylonitrile/Polycaprolactone nanocomposite membranes are synthesized by electrospinning which is intended for HMA of Cu 2+ . The nanofiber mats were characterized using SEM, FTIR, and Contact Angle. Batch adsorption process were performed and to utilize the AAS for kinetic adsorption behavior analysis. SEM micrographs revealed the addition of CQD in PAN and PAN/PCL membrane matrix shifted the fiber size distribution from 50 – 100 nm to 150 – 250 nm indicates the decrease in effective surface area. FTIR analysis exhibited vibrational peaks and binding of distinct functional groups such as amine, nitrile, carboxylic, hydroxyl, and carbonyl for CQD, PAN and PCL, respectively. CQD in aqueous form further increases the hydrophilicity of PAN/PCL membrane matrix which is essential for HMA of Cu 2+ ions. The increase of nanofiber mat’s adsorption capacity with respect to contact time obtained a maximum at 63.45 mg/g with a maximum efficiency of adsorption at 90.74%. Kinetic adsorption studies show that the pseudo – first order kinetic model best fits the data for CQD – PAN/PCL nanofiber mat in Cu 2+ ions obtaining a correlation value of R 2 = 0.9418 and a rate constant k = 0.0172 min 1 indicating the adsorption behavior follows the physical adsorption process involving Van der Waals forces and hydrogen bonding between the adsorbent and adsorbate.