Green Pomegranate Peel and Potato Peel Starch-Derived Magnetic Nanocomposite as Efficient Sorbent of Ascorbic Acid Extracted from Fruit Juices

This study aims to investigate a newly designed magnetic nanocomposite based on pomegranate peels@starch@Fe₃O₄ nanoparticles for dual applications, extraction of ascorbic acid from fruit juices using magnetic solid phase extraction, and hyperthermia. The physicochemical characterizations of the magnetic nanocomposite by SEM and EDX-Map, IR, XRD, and VSM manifest interesting properties making it a potential candidate as a sorbent and hyperthermia. Several critical parameters influencing the performance of the MSPE procedure are thoroughly investigated, including elution solvent type and volume, elution time, sorbent amount, and extraction time. Measurements performed using high-performance liquid chromatography demonstrate linearity (R² ≥ 0.9996) over the concentration range of 0.01 – 10 µg/L for ascorbic acid, with LOD values ranging from 0.0014 to 0.012 µg/L. Furthermore, the developed method successfully analyzed real samples of four fruit juices, achieving satisfactory recovery ranging from 92.48% to 103.76% and RSDs of ≤ 5.71%. Finally, the magnetic nanocomposite reveals superparamagnetic behavior, reaching 42 °C in a relatively short time of min with relatively good heating ability (SAR of 35 W/g) under an alternating magnetic field of 17 mT and a frequency of 332 kHz for promising use in magnetic hyperthermia. Furthermore, density functional theory (DFT) calculations were performed to evidence the electrostatic interaction between BPO@starch@Fe₃O₄ and AA. The most significant likelihood of attraction between BPO@starch@Fe₃O₄ and MB lies between the -Fe²⁺ and -OH groups in BPO@starch@Fe₃O₄ and the -OH groups in AA. This research enhances our comprehension of the mechanism behind AA adsorption on modified biochar and offers a combined experimental and computational approach to designing novel adsorbents with a high capacity for ascorbic acid adsorption.