Synthesis of Triethanolamine Ionic Liquid Immobilized on Magnetic Mesoporous Silica as a Recyclable and Efficient Adsorbent and its Applications for the Removal of Acetaminophen from Aqueous Solutions

Abstract

Toxic pharmaceutical compounds are released into aquatic environments, posing risk to ecological sustainability. Therefore, it is essential to eliminate these toxic compounds. In this study, we synthesized a triethanolamine ionic liquid immobilized on magnetic mesoporous silica and assessed its effectiveness as a magnetic nanoadsorbent for removing acetaminophen from different water samples. The successful synthesis of the nanoadsorbent was confirmed through Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), vibrating sample magnetometer (VSM), and thermal gravimetric (TG) analyses. FT-IR analysis revealed characteristic bands for the functional groups of nanoadsorbent, while XRD confirmed the cubic spinel structure of magnetic nanoparticles, showing reduced crystallinity after modification. FE-SEM images showed spherical nanoparticles with diameters ranging from 40 to 72 nm, EDX verified the elemental composition, VSM indicated superparamagnetism, and TG analysis demonstrated thermal stability with approximately 40% total weight loss. Under optimal conditions-specifically a concentration of 20 mg L⁻¹, pH 6, a contact time of 45 min, and a temperature of 298 K, about 92% of the drug was removed. The isotherm and kinetic data confirm the applicability of the Langmuir and pseudo-second-order models, respectively, with a maximum monolayer sorption capacity of 97.67 mg g⁻¹ derived from the Langmuir model. Additionally, the data analysis indicated that adsorption process is endothermic and spontaneous. The nanoadsorbent maintained its removal efficiency after six reuse cycles. Across a concentration range of 0.01 to 500 mg L⁻¹, a linear calibration curve was obtained (R² = 0.9981), with limits of detection and quantification calculated at 3 µg mL⁻¹ and 30 µg mL⁻¹, respectively. Consequently, the nanoadsorbent can effectively remove the drug from various water samples obtained from medical plants achieving analyte recovery values between 91.30% and 91.70%, with a precision indicated by a relative standard deviation of less than 1.12%.