Magnetic attapulgite synthesized via Sonochemistry: an innovative strategy for efficient solid phase extraction of As³⁺ from simulated and unrefined crude oil samples

Magnetised attapulgite (ATP-Fe₃O₄) adsorbent was synthesised using a sonochemistry approach for the solid phase extraction of As³⁺ from stimulated and unrefined crude oil samples. The average size of the Fe₃O₄ nanoparticles estimated from the Transmission Electron Microscopy (TEM) image was 10 nm. The TEM analysis also showed that Fe₃O₄ nanoparticles agglomerated in the ATP’s tube and on its surface. The X-ray diffraction analysis (XRD) indicates that the crystallinity of the ATP reduced after the magnetisation process. The saturation magnetisation of the ATP-Fe₃O₄ was determined to be only 2.8 emu g^-1. Under the optimum conditions (pH = 7, adsorbent dosage = 0.6 g, contact time = 90 min and sample volume = 50 mL), the As³⁺ removal was more than 98% for both types of oil. The limits of detection (LOD) and relative standard deviations (RSD%) were 2.88 ng mL^-1 and 0.3423%, respectively. The adsorption process follows the pseudo-first-order kinetic model (R² = 0.9696) and adheres to the Langmuir isotherm model (R² = 0.9925). The reusability study showed that ATP-Fe₃O₄ is highly stable and can be reused five times with almost 100% removal efficiency. This research outcome aligns with the United Nations Sustainable Goal 7, Affordable and Clean Energy.