University of Kashan Journal of Nanostructures 2251-7871 15 4 2025 10 01 Adsorption of Methotrexate onto Rosemary-Loaded Chitosan-Poly (Acrylic Acid)/MWCNTs Nanocomposite 1667 1685 115015 10.22052/JNS.2025.04.011 EN Mohammed A. Kadhim Department of Science, College of Basic Education, Al-Muthanna University, Samawah, Iraq Zeina M. Kadam Department of Chemistry, College of Science, Al-Qadisiyah University, Diwaniyah, Iraq Journal Article 2025 08 01 In this work, a novel rosemary-loaded chitosan-poly (acrylic acid)/multi-walled carbon nanotube (MWCNTs) nanocomposite was synthesized via free radical polymerization and employed as an efficient adsorbent for the removal of methotrexate (MTX) from aqueous solutions. The integration of rosemary provided bioactive functionality and enhanced surface characteristics. The composite was comprehensively characterized using FTIR, XRD, SEM, TEM, EDX, and zeta potential (–46.5 mV), confirming successful synthesis, porosity, and structural stability. Batch adsorption experiments revealed optimal MTX uptake at pH 4 and 90 minutes, with rapid initial adsorption and high efficiency. Kinetic modeling showed that the process followed pseudo-second-order kinetics, indicating chemisorption. Isotherm analysis revealed that the Freundlich model best described the data (KF = 9.903, R² = 0.9942), suggesting multilayer adsorption on a heterogeneous surface. Thermodynamic parameters (ΔG = –2.37 kJ/mol, ΔH = –10.72 kJ/mol, ΔS = –28.5 J/mol·K) indicated that the adsorption is spontaneous and exothermic. The nanocomposite also showed partial reusability, retaining 78% adsorption efficiency after three cycles. These results highlight the potential of this eco-friendly, plant-based nanocomposite for applications in targeted drug delivery and environmental remediation of cytotoxic pharmaceuticals.   https://jns.kashanu.ac.ir/article_115015_b84a1acbedc1772170d5d9c7ebaa10e8.pdf