Elaboration of magneto-thermally recyclable nanosorbents for remote removal of toluene in contaminated water using magnetic hyperthermia

Magnetic nanosorbents are novel materials that have been impacting various applications in environmental fields, including the detection of pollutants and remediation of polluted environments. In this work, the thermal heating effect caused by the interaction of nanoparticles’ magnetic moments with an alternating magnetic field (AMF) – magnetic hyperthermia – is proposed as proof of a concept to illustrate the remote controlled recycling of magnetic nanosorbents during the treatment of water containing toluene, a potentially toxic and volatile contaminant. Nanosorbents were synthesized by functionalization of ∼15 nm coprecipitated cobalt/manganese mixed ferrite with polydimethylsiloxane. Structural, chemical, and magnetic characteristics of the nanosized adsorbent were investigated by elemental analysis (ICP-OES), X-ray diffractometry (XRD), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM). Batch experiments indicated that nanoadsorbents, which can be magnetically recovered, exhibit high adsorption affinity for toluene in aqueous solution (∼325 mg/g) and that adsorption follows the Langmuir model. Moreover, application of AMF resulted in uniform heating within the nanosorbents (after being magnetically separated from the contaminated water) and triggered toluene desorption/evaporation, leading to accelerated release of pollutants from the nanosorbent, improving its reusability; even after seven cycles the removal efficiency was quite high (83%).