Efficient adsorption removal of organic nitrogen pesticides: Insight into a new hollow NiO/Co@C magnetic nanocomposites derived from metal-organic framework

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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 Fe3O4. 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.