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In this work, nanoscale zero-valent iron (NZVI) was synthesized via liquid phase reduction method with surfactant polyethylene glycol (PEG-4000) modified and supported onto zeolite to prepare PZ-NZVI composite. SEM-EDS, XPS, BET.etc. characterizations indicated that the sphere NZVI particles were loaded on the zeolite successfully and the aggregation was restrained. The adsorption performance of PZ-NZVI for norfloxacin (NOR) or ofloxacin (OFL), two typical fluoroquinolones (FQs), from water was conducted. The equilibrium studies were demonstrated using Langmuir, Freundlich, Temkin and Elovich isotherms and better agreement was attained with the Temkin model. Compared with NZVI and zeolite, PZ-NZVI had higher FQs removal efficiency, and the Langmuir maximum adsorption capacity was 54.67 mg g−1 (NOR) and 48.88 mg g−1 (OFL). The kinetic parameters displayed that two FQs adsorption onto PZ-NZVI followed pseudo-second-order kinetic model. The thermodynamic analysis suggested the adsorption process was spontaneous and exothermic. In addition, the adsorption tests were executed at different influence factors and the adsorbent PZ-NZVI was suitable for a wide pH range (4–10) with the FQs (10 mg L−1) removal efficiency above 90% in 1 h. Furthermore, it was found that PZ-NZVI can be effortlessly separated from mixed solutions using external magnetic field. Finally, the process of FQs adsorbed onto PZ-NZVI was attributed to the surface complexion (forming bidentate complexes), hydrophobic interaction, pore filling and electrostatic interaction. Unlabelled Image • PZ-NZVI composite was prepared and well applied for two FQs removal in water. • Coating PEG-4000 and supported on zeolite enhanced the dispersity of NZVI. • Temkin isotherm and pseudo-second-order kinetic models best fitted experimental data. • Electrostatic, hydrophobic interactions and complexation were the main mechanisms. [ABSTRACT FROM AUTHOR]

Three adsorbents, namely, original biochar (CLB), montmorillonite (MMT)-biochar composite (MBC), and magnetic MMT-biochar composite (MMBC) were successfully fabricated by one step pyrolysis of original cauliflower (Brassica oleracea L.) leaves, mixture of cauliflower leaves and MMT, and FeCl 3 -laden mixture of cauliflower leaves and MMT under limited oxygen atmosphere, respectively. The characterizations of samples indicated that substantial MMT mineral particles and Fe 3 O 4 nanoparticle were dispersed on the surface of MMBC. Due to the introduction of Fe 3 O 4 , MMBC performed excellent magnetization property. The adsorption experiments of oxytetracycline (OTC) indicated that the maximum adsorption ability of MMBC was 58.85 mg·g−1, which was 2.63 times as large as CLB, also, larger than that of MBC. Meanwhile, pH, ionic strength, and humic acid (HA) performed slight effects for adsorption of OTC on MMBC. In addition, MMBC still removed 92% OTC after five regeneration cycles. Finally, primary mechanisms of OTC adsorption onto MMBC were attributed to hydrogen bonding and π-π reaction, and ion exchange reaction was considered to exist. Meanwhile, functional groups including Si-O-Al, Si-O-Si, Si-O, and Fe 3 O 4 nanoparticles would provide extra binding sites for OTC adsorption. Therefore, MMBC had an obvious potential to apply into water purification as a reliable, low-cost, and environmentally friendly adsorbent. Unlabelled Image • Magnetic montmorillonite biochar material is first prepared by one step pyrolysis. • The composite performs excellent adsorption capacity for oxytetracycline. • Adsorption is mainly controlled by hydrogen bond, π-π and ion exchange reactions. • Fe 3 O 4 nanoparticles on composite provide extra adsorption sites. • The spent composite is successfully regenerated and collected by magnet. [ABSTRACT FROM AUTHOR]