Microwave-assisted pyrolysis of fish-scale biochar by magnetic ionic liquid activation for the soild phase extraction of benzophenones ultraviolet filters from sludge-amended soil

The magnetic ionic liquid-modified fish-scale biochar (MIL/FSBC) was prepared via microwave-assisted pyrolysis (MWP) processes. The hydroxyapatite (HAP) were efficiently separated from the interior of collagen fibrils with magnetic ionic liquid [C 4 min]FeCl 4 . The synergistic activation of HAP liberation combined with MIL process significantly increased the MWP efficiency of fish scale biomass. The morphology and texture properties of MIL/FSBC magnetic nanoparticles (MNPs) were analyzed using SEM, TEM, XRD, XPS, VSM and BET/BJH. The MIL/FSBC MNPs were employed to extract and enrich the benzophenone (BP-1, BP-3 and BP-12) ultraviolet filters from sludge-amended soil sample using magnetic dispersive solid phase extraction (MDSPE) coupled with microwave assisted extraction (MAE) technique. The important parameters influencing the extraction efficiency of the target analytes were investigated, including the amount of adsorbent, pH, microwave extraction temperature and time, NaCl concentration and desorption conditions. The average relative recoveries of BPs exceeded 90.5% using 20.0 mg of MIL/FSBC for extraction over 20.0 min at 35 °C. The matrix effect ranges from −11.42% to 6.2%, and it is slight at low concentrations. The limits of detection (LODs) and limits of quantification (LOQs) for the calibration curve were in a range of 4.3–14.3 ng/kg and 14.9–47.1 ng/kg, respectively. The monitored stability (79.7–106.3%) in soil samples over 90 days confirmed the environmental persistence of BPs in the soil. The developed method was applied to determine BPs in sludge-amended soil and sediment samples, with acceptable recoveries (84.2–102.6%). The typical chemisorption with a heterogeneous multilayer adsorption mechanism was confirmed using the quasi-secondary kinetic model and the Freundlich adsorption isotherm model. The results confirmed that the proposed method was practicable for the analysis of ultraviolet filters pollutant in actual soil samples.