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• A metal-free graphitized carbon nitride (g-C 3 N 4) nanosheets was synthesized by gas template method. • The surface area and photocurrent of nanosheets was 6 and 3 times than that of bulk g-C 3 N 4 , respectively. • The nanosheets showed superior photodegradation ability towards cefixime. • 99% of cefixime could be removed within 30 min under the sunlight and persulfate addition. The removal and the treatment of antibiotics in environmental water by advanced oxidation process (AOP) has attracted much attention. In this paper, a metal-free graphitized carbon nitride nanosheets (g-C 3 N 4 -NS) was synthesized by gas template method. Cefixime in water was removed by direct photocatalysis and activation of persulfate (PS) under simulated sunlight. The flaky morphology made g-C 3 N 4 -NS's band gap narrow, charge separation enhanced, light absorption enhanced, and more active sites were exposed. The specific surface area of g-C 3 N 4 -NS was about 6 times than that of bulk g-C 3 N 4 , and its photocurrent was about 3 times. The effects of different PS concentrations and pH values on photocatalytic activation in two ways were studied. The influence of anions on the removal of cefixime was also studied. The synthesized g-C 3 N 4 -NS has good stability, and its performance is well maintained after continuous photocatalysis and photoactivation catalysis. The degradation rate of cefixime by g-C 3 N 4 -NS was three times than that of bulk g-C 3 N 4 , and the removal rate of cefixime by g-C 3 N 4 -NS /PS system was 30 times than that of PS. This work provides advanced idea for metal-free AOP in environmental chemistry. [ABSTRACT FROM AUTHOR]

Schematic diagram for efficiently removal of Pb (Ⅱ) based on UiO-67-Rhodanine-3-acetic acid (Rd) composites. [Display omitted] • A new UiO-67-Rhodanine-3-acetic Acid(Rd) composites was synthesized successfully. • The composites exhibited superfast removal efficiencies for Pb (II) with huge adsorption capacities of 309.8 mg g−1. • The proposed method provided a new, effective and straightforward method for rapid and superior trapping Pb (II). • The removal of Pb (II) by UiO-67-AC-Rd as advanced sorbents was presented and further provided a new pathway to application for wastewater. Metal organic frameworks (MOFs) have the advantages of large specific surface area, high porosity, controlled structures and strong stability, and were excellent adsorbents for the efficient trapping of heavy metals. In this work, two morphologies of Zr-MOF composites (UiO-67-AC-Rd and UiO-67-FA-Rd) under different solvent conditions were synthesized by a sequential solvothermal process. The properties of the composites were characterized by SEM, TEM, XRD, XPS, and BET, and the adsorption capacities of Pb (II) were investigated in detail. The excellent performance of UiO-67-AC-Rd exhibited superfast removal efficiencies for Pb (II), ascribing to its surface contains plentiful oxygen, nitrogen and sulfur functional groups and large specific surface area, which makes it have fascinating properties in removing Pb (II), and the maximum adsorption capacity of Pb (II) was 309.8 mg g−1. Chelation and electrostatic adsorption were considered as the main adsorption mechanisms. Adsorption isotherms were fitted well using the Langmuir and Freundlich model, and the adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous. The UiO-67-AC-Rd composites maintained excellent adsorption capacity for Pb (II) after four consecutive cycles, and the removal efficiency was above 74 %. The study will further provide a new pathway to the application of UiO-67-Rd composites in the adsorption of heavy metals in wastewater. [ABSTRACT FROM AUTHOR]

• An innovative MOFs@COFs-based molecular trap materials were successfully prepared. • The hierarchical core–shell composite was used as solid-phase microextraction (SPME) fiber coating. • The possible adsorption mechanism was systematically verified and explained. • The proposed method provided a new, effective and low-cost method for rapid and superior capture PAHs. In view of the serious carcinogenic, teratogenic and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs), which cause significant harm to human beings and the environment. Therefore, developing rapid adsorption and efficient analytical methods are research topic with practical significance. Herein, an innovative MOFs@COFs-based molecular trap materials were prepared with hierarchical porous core–shell structure and used as solid-phase microextraction (SPME) fiber coating, which combined with high performance liquid chromatography (HPLC) to achieve the efficient separation, capture, and detection for 7 PAHs in real samples. The possible adsorption mechanism was systematically verified and explained. Under the optimized conditions, the method developed in this experiment had a wide linear range (0.005–400 µg·L−1) with a good linear correlation coefficient (R2 > 0.9984), low detection limits (0.002–0.405 µg·L−1, S/N = 3) and low quantification limits (0.005–1.351 µg·L−1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.26–3.64% and 0.40–5.91%, respectively. Besides, the fiber showed higher enrichment capacity and extraction efficiency for PAHs compared to commercial SPME fibers and other material fibers, and exhibited excellent acid-base stability and reproducibility. This work provided a favorable synthetic pathway for the preparation of MOFs@COFs composites by layer-modified assembly synthesis strategy, showed excellent practical applicability as a SPME fiber coating combined with HPLC, and could be realized to provide technical support for future studies on the separation, adsorption, and analysis of PAHs in the petrochemical industrial zone of the Yellow River Basin. [ABSTRACT FROM AUTHOR]

• A new hollow NiO/Co@C magnetic nanocomposites derived from MOF were successfully prepared. • The carbonized bimetallic Ni-Co-MOF were transformed magnetic-carbon composites without the preparation of Fe 3 O 4. • The composite was used as magnetic solid-phase extraction and the removal of organic nitrogen pesticides for the first time. • The proposed method provided a new, effective and low-cost method for rapid and superior capture pesticides. The removal of pesticides is a prerequisite for reducing potential threat to environmental safety. It is significant to exploit some adsorbents with excellent adsorption performance, facile separation and recovery. Metal-organic framework (MOF)-based magnetic nanocomposites have received extensive attention in terms of pollutant adsorption. Thus, a new hollow NiO/Co@C magnetic nanocomposites derived from MOF was successfully assembled via simple solvothermal reaction, in which cobalt (Co) ions as inducers to conduct the formation of hollow MOFs by regulating the chemical transformation process, and benefiting from its coordination effect, the carbonized bimetallic Ni-Co-MOF were transformed into magnetic-carbon composites by maintaining its initial skeleton without the tedious preparation of Fe 3 O 4. The hollow structure can accelerate the mass transfer efficiency and the magnetism is conducive to rapid and convenient separation. The composite was used as magnetic solid-phase extraction (MSPE) adsorbent and the adsorption removal of organic nitrogen pesticides (ONPs) for the first time. NiO/Co@C contained hollow porous structure, resulting in high pesticides adsorption performance, as high as 62.2 mg g−1. Furthermore, the adsorption properties and mechanisms of ONPs had been discussed in detail including adsorption dynamics and thermodynamics. More importantly, NiO/Co@C could not only realize easy solid–liquid separation, but also demonstrate excellent reusability and stability. After nine cycles and the extraction recovery still retained higher than 90%. Therefore, NiO/Co@C has great promise as an effective adsorbent for pretreatment of aqueous samples and removal of hazardous pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-67 derived hollow double-shelled Co 3 O 4 /carbon (HoMS-Co 3 O 4) were successfully prepared. • A novel spiral-solid phase microextraction (S-SPME) fiber using HoMS-Co 3 O 4 as coating was designed. • Open a new way for the preparation of hollow multishelled structure using ligand conversion method. • The proposed method provided a new, effective and low-cost method for rapid and superior capture PAHs. Here, a unique spiral-solid phase microextraction (S-SPME) fiber using ZIF-67 derived hollow multishelled structures Co 3 O 4 /carbon nanomaterials (HoMS-Co 3 O 4 /C) as the coating was designed for superior capture of trace polycyclic aromatic hydrocarbons (PAHs). The ligand 2-methylimidazole of ZIF-67 was replaced twice with 2,5-dihydroxyterephthalic acid and followed by pyrolysis to obtain the material with an unique hollow double-shelled structure. The formation of the hollow structure can be explained by the Ostwald ripening. Fifteen PAHs, four brominated flame retardants (BFRs), and seven endocrine chemicals (EDCs) were used to investigate the extraction performance of HoMS-Co 3 O 4 /C coated S-SPME fiber. The spiral fiber displayed higher selectivity for PAHs compared with BFRs and EDCs. The methods had low detection limits (0.002–2.680 μg L−1), wide linear ranges (0.005–1000 μg L−1), and good reproducibility (0.7–10.7%, fiber to fiber). In addition, the S-SPME fiber demonstrated excellent enrichment ability and extraction efficiency for PAHs compared with commercial SPME fibers, it might since there were strong π-π stacking force, hydrophobic interaction between analytes and HoMS-Co 3 O 4 /C coating, also the HoMS coating and the spiral fiber could greatly increase the contact area between adsorbent and target compounds. Finally, the HoMS-Co 3 O 4 /C coated S-SPME fiber had been further adopted to detect fifteen PAHs in environmental water samples successfully. [ABSTRACT FROM AUTHOR]