Magnetic mesoporous silica composite (MNP@SiO2‐SBA) was obtained via embedding magnetite nanoparticles between SBA‐15 channels. It was silylated with N‐(3‐(trimethoxysilyl)propyl)picolinamide (TMS‐PCA) and then complexed with Pd(II). The obtained supported Pd(II) catalyst (MNP@SiO2‐SBA‐PCA) was characterized by conventional methods. The prepared magnetic catalyst showed high activity in the Heck and Hiyama reactions under optimal reaction conditions, including solvent, amount of catalyst, base, and temperature. Aryl bromides and iodides showed better results than aryl chlorides, and the catalyst exhibited noticeable stability and reused several times.

In this research, we synthesized and characterized a new acrylamide‐based monomer containing pyridine and 1,3,4‐oxadiazole moieties, N‐(4‐(5‐(pyridin‐2‐yl)‐1,3,4‐oxadiazol‐2‐yl)phenyl)acrylamide (POPA). Poly(POPA)‐grafted magnetite nanoparticles were then obtained via surface‐initiated atom transfer radical polymerization. The grafted nanoparticles were characterized by Fourier transform infrared analysis, scanning electron microscopy, wide angle X‐ray diffraction, and vibrating sample magnetometry. The amount of the grafted polymer was 126 mg/g, as calculated from thermo gravimetric analysis experiment. The capability of poly(POPA)‐g‐magnetite nanoparticles (MNPs) to remove Co(II) cations, under optimal time period, pH and adsorbent mass, was shown by atomic absorption. The adsorption kinetics obeyed the pseudo–second‐order kinetic equation, and the adsorption isotherm was best described by the Freundlich model with a maximum adsorption capacity of 59.90 mg/g. In addition, the poly(POPA)‐g‐MNPs were regenerated by simply washing with an aqueous 0.1M HCl solution, and no considerable decrease was observed in the extraction efficiency following the test of up to 7 cycles. These findings suggest that poly(POPA)‐g‐MNPs are stable and reusable adsorbent, and they could be potentially applied to water treatments for an efficient removal of Co(II) cations.

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