Structural insights and comparative electrocatalytic performance of citric acid-functionalized Luffa aegyptiaca and Pt-Pd/MWCNT-Luffa composites for the degradation of acetaminophen in aqueous media

Abstract

Emerging contaminants, such as acetaminophen, pose a critical threat to aquatic ecosystems and human health due to their persistence in water and the difficulty of their removal using conventional methods. In this work, Luffa aegyptiaca biomass was valorized via citric acid functionalization to develop a sustainable catalyst for the electrochemical degradation of acetaminophen in aqueous solution. The electrocatalytic performance of the citric acid-functionalized biomass was systematically compared (using a Box-Behnken design) with that of the same support further modified with Pt-Pd/MWCNT nanostructures. Structural, morphological, and physicochemical characterization (XRD, XPS, SEM, elemental mapping, and Raman spectroscopy) confirmed the successful functionalization and incorporation of the catalytic materials. High-performance liquid chromatography (HPLC) validated the rapid degradation kinetics, attributed to the functionalization of the lignocellulosic support. Kinetic tests demonstrated that the catalysts achieved degradation efficiencies exceeding 99% for acetaminophen in 5 min (20 mg/L acetaminophen, 12 V, pH 3, 20 mg of composite). Despite variations in pH, NaCl concentration, voltage, and composite mass, the developed material achieved degradation performance exceeding 90% in most scenarios. The degradation kinetics improved between 160 and 300% when the operating parameters were optimized in comparison with the initial set of operating parameters. This work underscores the potential of supports derived from functionalized biomass for the rapid and efficient degradation of pharmaceutical contaminants in aqueous systems.