Hyperbranched Polymer-Functionalized Reduced Graphene Oxide Composite for Ciprofloxacin and Telmisartan Removal: Molecular Insights

Abstract

Abstract The persistent occurrence of pharmaceutical pollutants in water bodies poses a significant threat to human health and aquatic life, which necessitates the advancement of efficient and sustainable removal methods. Herein, a thiol-amine hyperbranched polymer functionalized reduced graphene oxide composite (ATT-Hyp/rGO) was prepared and applied for the remediation of ciprofloxacin (CIP) and telmisartan (TEL). Thorough physicochemical characterization confirmed the successful functionalization of rGO, revealing the mesoporous property enriched with thiol and amine functionalities and good thermal stability. However, the optimization was performed using Central Composite Design (CCD) under Response Surface Methodology (RSM), which achieved 91.84% and 98.90% removal efficiency for CIP and TEL, respectively. Equilibrium studies employed isotherm modeling using classical and advanced statistical physics models, which revealed a multilayer adsorption process on a heterogeneous surface. Kinetic investigation revealed a diffusion-controlled adsorption process, while fractal-like modeling revealed the heterogeneous nature of the adsorbent surface. Thermodynamic study highlighted the spontaneous (ΔG° < 0) and exothermic (ΔH° < 0) nature of the adsorption process. The mechanistic investigations suggested that the adsorption process was mainly governed by hydrogen bonding, π–π stacking interactions, hydrophobic interactions, pore diffusion, and weak electrostatic interactions. Moreover, the composite ATT-Hyp/rGO exhibited excellent reusability over 6 adsorption–desorption cycles and maintained high removal efficiency in the presence of competing ions and real water matrices, which supports real-world environmental applicability. The detailed mechanistic elucidation presented that the ATT-Hyp/rGO composite is a robust and potential adsorbent for the uptake of CIP and TEL from complex aqueous media, with favorable reusability for real-world applications.