Synthesis and characterization of rosin-modified chitosan/polylactic acid (CS/PLA) composite

This study aimed to develop a biodegradable and environmentally friendly composite material for the removal of ketoprofen, a persistent and toxic pharmaceutical contaminant, from aqueous environments. Within this scope, a rosin-modified chitosan/polylactic acid-based hybrid structure was synthesized and characterized. The main motivation for the study was to overcome the inadequacy of traditional water treatment methods for micropollutants and to offer a sustainable alternative. During the synthesis process, chitosan was first protected with phthalic anhydride, then chemically modified with gum rosin, and finally, a composite film form was obtained with the PLA matrix. The products were structurally and morphologically examined using FT-IR, ¹H NMR, and SEM analyses. FT-IR and ¹H NMR results demonstrated the success of rosin modification and PLA integration. SEM images revealed the homogeneous distribution of R-CS particles within the PLA matrix and the formation of a porous structure. The KTP (ketoprofen) removal performance of the composites was evaluated via reduction testing in the presence of NaBH₄ using UV-Vis spectroscopy. After a 60-minute reaction, the R-CS/PLA composite exhibited the highest performance with a removal efficiency of 93.29%; R-CS achieved over 80%, while pure chitosan and PHCS provided approximately 49% removal. The study also included kinetic analyses of the catalytic reduction processes for CS, R-PHCS, R-CS, and R-CS/PLA composites. While the zero- and first-order models showed poor fit, the highest correlation coefficients were obtained in the second-order kinetic model (R²>0.95). In particular, the rate constant of R-CS/PLA (k₂ = 0.08091 1/(Abs·min)) was found to be significantly higher than that of other compounds, demonstrating that this composite offers the most effective performance in terms of both yield and kinetics. These results demonstrate that rosin modification and PLA integration synergistically enhance adsorption and catalytic activity. The study reveals that biopolymer-based hybrid materials offer an effective and environmentally friendly alternative for the removal of pharmaceutical contaminants.