Eco-friendly nanoadsorbent for sustainable removal of cefixime from water: Dendrimer-modified graphene quantum dots with response surface optimization

The growing prevalence of antibiotic resistance, driven by improper antibiotic use and their release into wastewater and ecosystems, has become a global public health crisis. This work introduces a novel approach using dendrimer-grafted silica-coated graphene quantum dots, specifically employing a unique cyanuric chloride-phloroglucinol combination as a nanoadsorbent for the efficient removal of cefixime. The response surface methodology-central composite design was used to evaluate the effects of various experimental factors on drug elimination. The optimized parameters (pH 6, temperature of 35 °C, and contact time of 45 min) achieved a 96 % drug removal efficiency. Statistical evaluations confirmed the model's reliability in predicting adsorption performance. The experimental adsorption data were accurately described by the pseudo-second-order kinetic and Langmuir isotherm models. Thermodynamic studies confirmed the spontaneous and exothermic nature of the adsorption process. This novel nanoadsorbent demonstrates superior adsorption efficiency and precision compared to unmodified graphene quantum dots across diverse water samples. Furthermore, it combines high removal capacity with exceptional cyclic stability, maintaining 85 % efficiency after five regeneration cycles. The results highlight the promising role of this nanoadsorbent as an eco-friendly, economical, and efficient approach for removing pharmaceutical contaminants. Its application could revolutionize water treatment methods while supporting environmental conservation efforts. • GQDs@mSiO 2 @CC-PG/G 3 was prepared for efficient cefexime removal. • Structural and morphological characteristics were analyzed using various methods. • RSM-CCD was used to evaluate the effects of different factors on drug elimination. • The drug removal efficiency remained as high as 85 % after five cycles. • GQDs@mSiO 2 @CC-PG/G 3 demonstrated a higher drug removal efficiency compared to GQDs.