Cu(II) and Au(III) recovery with electrospun lignosulfonate CO2-activated carbon fiber

Abstract

The objectives of this study were twofold: developing lignosulfonate activated carbon fibers (LACFs) and determining the corresponding metal recovery mechanisms with batch experiments and non-linear modeling. LACFs were developed through electrospinning, followed by CO₂-based physical activation. Physical and chemical characterizations revealed that the LACF sample that was activated for 60 min exhibited a higher specific surface area (376.54 m²/g), larger total pore volume (0.30 cm³/g), higher micropore ratio (32%), and more acidic and sulfur functional groups than did the other samples. Cu(II) and Au(III) adsorption behaviors on the LACF could be described with the Freundlich and Langmuir model, respectively. Both systems consist of physisorption and chemisorption, and the mechanisms include electrostatic forces, Van der Walls forces, cation exchange, surface complexation. In particular, Au(III) adsorption was faster, and LACF-Au bonds were stronger due to the additional microprecipitation. Furthermore, the LACF sample could regenerate after three adsorption-desorption cycles. Overall, this study provides the foundation for developing physically activated lignosulfonate carbon and its application in recovering valuable metal ions.

Keywords: Adsorption mechanism; Electrospun activated carbon fiber; Lignosulfonate; Metal ion.