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A new fluorescent labeling reagent, benzimidazo[2,1-<i>b</i>]quinazolin-12(6<i>H</i>)-one-5-ethyl-<i>p</i>-toluenesulfonate (BQETS) was designed and synthesized, and it was successfully applied to the determination of fatty acids with liquid chromatography. BQETS can easily and quickly label fatty acids within 20 min at 90 °C in dimethylformamide with K<sub>2</sub>CO<sub>3</sub> as catalyst. The derivatives exhibit high stability and strong fluorescence with excitation and emission wavelengths of 247 and 401 nm, respectively. The 24 derivatives of fatty acids were completely separated by gradient elution on a Hypersil GOLD C18 column. Excellent linear responses for all fatty acids were observed with correlation coefficients of >0.9991. The method also showed good sensitivity and precision, with limits of detection in the 0.0024-0.0206 μg g<sup>−1</sup> range and relative standard deviations ≤9.6 %. This is the first time that BQETS fluorescent probe and its applications for the determination of fatty acids have been reported. Moreover, this is the first report on the comparison of free fatty acids composition in the above-ground part of <i>Coriandrum sativum</i> L. from different habitats in China.

<br>Display Omitted<br>• Conversion of waste buckthorn branches to a value-added bio-carbon product. • Practical adsorbent for removal and destruction of DC contaminants. • Consecutive biosorption and heterogeneous Fenton oxidation regeneration cycles. • Composite biosorbent with β-FeOOH nanoparticles and in-situ catalytic regeneration properties.<br>Akaganeite (β-FeOOH) nanoparticles were successfully anchored on the surface of porous sea buckthorn biocarbon (SBC) via a simple low-temperature hydrothermal process without use of surfactants or external forces. The SBC@β-FeOOH composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). On the basis of characterization methods, a possible mechanism of formation of the SBC@β-FeOOH composite was discussed. The SBC@β-FeOOH composite was used in fixed-bed columns for the effective removal of doxycycline (DC) from an aqueous solution, by the synergistic effect of adsorption and subsequent Fenton-like oxidation reaction, which oxidized the sorbed DC. The effects of inlet DC concentration (22-32 mg/L) feed flow rate (1-3 mL/min) SBC@β-FeOOH bed depth (0.7-1.5 cm) and pH (2-11) on the adsorption breakthrough profiles were investigated. The adsorption process was controlled by the ionic speciation of the adsorbate DC and the available binding sites of SBC@β-FeOOH. It was simulated by the Thomas and Yoon-Nelson models under different conditions. The bed of SBC@β-FeOOH saturated with DC was readily regenerated, in situ, by a heterogeneous Fenton-like oxidation reaction. The synergistic effect resulting from the biosorption nature of SBC and the catalytic oxidation properties of the supported β-FeOOH nanoparticles results in a new promising composite material for water treatment and purification.