Fe encapsulated magnetic carbon gels for adsorption of methylene blue and catalytic reduction of p-nitrophenol

This paper documents the synthesis of magnetic carbon gels by encapsulating iron nanoparticles in porous carbon gel matrix and studying its application in dye adsorption and catalytic reduction reaction. The effects of magnetic nanoparticles under the purview of this study were investigated using X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer, Emmett and Teller (BET) surface area, Barrett-Joyner-Halenda (BJH) pore size distribution analysis, Raman spectroscopy and vibrating sample magnetometer. The adsorption capability of the magnetic gels in removing methylene blue dye pollutant from water was examined using different initial dye concentration (10-30 mg/L). The effect of pH, adsorbent dosage on adsorption and the kinetics, equilibrium and thermodynamics of the adsorption were investigated in detail. Spontaneous and favourable nature of the adsorption was confirmed with a maximum adsorption capacity of 67.75 mg/g. In addition, the catalytic properties of the gels were also probed using the model catalytic conversion of p-nitrophenol to p-aminophenol with NaBH4. The magnetic gels showed excellent activity towards the catalytic reduction of 60 ppm p-nitrophenol with a rate constant of 0.299 min(-1), that is comparable with several previously reported catalysts. The response of the gel to external magnetic field made the catalyst easily recoverable. The immobilization of Fe nanoparticles in the graphitic carbon matrix prevented the aggregation as well as oxidation problem making it reusable without any significant loss in its catalytic activity.