Design and synthesis of a new chitosan derivative for the removal of Congo Red from aqueous solutions via non-electrostatic interactions
2025
Aqeel H. Al Sayyad | Hamida Idan Salman | Asim A. Balakit
This paper presents the design, synthesis and identification of a new chitosan- derivative (CTAP) as an efficient adsorbent to remove Congo Red (CR) dye from aqueous solutions. CTAP was synthesized via the reaction of chitosan with 4-aminoantipyrine and terephthaldehyde, resulting in a stable polymer rich in aromatic rings, π-electron systems, and heteroatoms. These structural features facilitate dominant non-electrostatic interactions such as hydrophobic forces, π–π stacking, and hydrogen bonding, enabling CR adsorption across a wide pH range (4–10) without relying on electrostatic forces. CTAP was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller analysis (BET), and thermal analysis. Adsorption studies demonstrated a high removal efficiency (93 %) and maximum adsorption capacity of 20.63 mg/g, following the Langmuir isotherm model. Density functional theory (DFT) studies were also performed to support the experimental results, demonstrating the predominance of non-electrostatic interactions between CTAP and CR. The material exhibited excellent reusability over five cycles and retained 80 % efficiency.
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