FeO@C Matrix with Tailorable Adsorption Capacities for Paracetamol and Acetylsalicylic Acid: Synthesis, Characterization, and Kinetic Modeling.

In this study FeO@C matrix was obtained by combustion method and used hereafter as adsorbent for paracetamol and acetylsalicylic acid removal from aqueous solutions. The FeO@C matrix was characterized by electronic microscopy, X-ray diffraction, thermal analysis, Fourier-transform infrared spectroscopy, and magnetic measurements. Two kinetic models of pseudo first-order and pseudo-second-order for both paracetamol and acetylsalicylic acid were studied. The experimental data were investigated by Langmuir, Freundlich, and Redlich-Peterson adsorption isotherm models. The adsorption followed the Redlich-Peterson and pseudo-second-order models with correlation coefficients R = 0.98593 and R = 0.99996, respectively, for the adsorption of paracetamol; for the acetylsalicylic acid, the adsorption followed the Freundlich and pseudo-second-order model, with correlation coefficients R = 0.99421 and R = 0.99977, respectively. The equilibrium was quickly reached after approximately 1h for the paracetamol adsorption and approximately 2h for acetylsalicylic acid adsorption. According to the Langmuir isotherm, the maximum adsorption capacity of the magnetic matrix was 142.01 mg·g for the retention of paracetamol and 234.01 mg·g for the retention of acetylsalicylic acid. The benefits of using the FeO@C matrix are the low cost of synthesis and its easy and fast separation from solution by using an NdBFe magnet.