Abstract
This study investigates the removal efficiency of Cu(2+) from wastewater using a composite hydrogel made of carbon nanotubes (CNTs), sodium alginate (SA), and polyacrylic acid (PAA) prepared by free radical polymerization. The CNTs@SA/PAA hydrogel's structure and properties were characterized using SEM, TEM, FTIR, XRD, rheology, DSC, EDS, elemental mapping analysis, and swelling. The adsorption performance for Cu(2+) was tested in batch adsorption experiments, considering the pH, dosage, initial concentration, and contact time. The optimal conditions for Cu(2+) removal were pH 5.0, an adsorbent dosage of 500 mg/L, and a contact time of 360 min. The adsorption followed pseudo-second order kinetics. Isotherm analyses (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Sips, Toth, and Khan) revealed that the Freundlich isotherm best described the adsorption, with a maximum capacity of 358.52 mg/g. A thermodynamic analysis indicated that physical adsorption was the main interaction, with the spontaneity of the process also demonstrated. This study highlights the high efficiency and environmental friendliness of CNT@SA/PAA composites for Cu(2+) removal from wastewater, offering a promising approach for water treatment.