Copper Recovery from Mobile Phone Printed Circuit Board E-Waste and Transforming into CuO@C for Electrode Material in Extended Gate Field-Effect Transistors Facilitating Non-Enzymatic Ascorbic Acid Detection

Abstract

This study presents a new approach for the simultaneous leaching and sorption of Cu(II) from waste printed circuit board (PCB) flakes using phosphorylated cellulose (P(O)-cellulose). The leaching-sorption experiments were conducted at various temperatures (25, 45, and 60 °C) and pH values (4, 7, and 10). Phosphorylated cellulose successfully facilitated the recovery of Cu(II) under optimal conditions identified at pH 7 and 60 °C, achieving a recovery efficiency of 35.9 mg/g. Further, the recovered Cu(II)-P(O)-cellulose was treated with glycine to form copper-glycinate for quantification. Cu(II)-P(O)-cellulose was then used to synthesize Cu/CuO and CuO nanoparticles supported on carbon (Cu/CuO@C and CuO@C) through calcination at 400 and 700 °C, respectively. The synthesized CuO@C material exhibited remarkable performance as an electrode for ascorbic acid biosensing via the EGFET configuration. The dynamic study demonstrated its superior response to ascorbic acid in the concentration range of 20–2300 μM, with a response time of less than 6 s in 1× PBS, which mimics the physiological condition of body fluids. The CuO@C electrode displayed high sensitivity (821.94 μA·dec –1 ·cm –2 ) with a low detection limit of 0.047 μM, showcasing its potential for sensitive and selective ascorbic acid detection. Utilizing a sustainable cellulose functionalized derivative, copper was extracted from e-waste PCBs and repurposed for biosensing applications.