A facile approach to synthesis of cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide for organic dye removal

Abstract Dispersions of surface capped ferrite nanoparticles have many practical applications in heat transfer, optics, memory devices, sensors and biomedicine. However, capping of ferrite nanoparticles with a stable ultrathin layer of organic or inorganic materials, without compromising magnetic properties, still remains a challenge. Here, we demonstrate, for the first time, a facile and rapid approach to cap cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide (~1.4 nm) by using an organosilica coating agent, dichlorodimethylsilane (DCDMSi), through sonochemical approach. The ultrasonic cavitation process is exploited for aiding the rapid and effective capping of SiC over CoFe2O4 through self-restrained condensation of silanol moieties. The synthesized silicon carbide coated CoFe2O4 nanoparticles (CFSi) and uncoated CoFe2O4 (CFUC) are characterized using Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analyzer with simultaneous differential scanning calorimetry (TGA-DSC), Vibrating sample magnetometer (VSM), X-ray diffractometer (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) and dynamic light scattering (DLS). The organic dye adsorption ability of capped particles was investigated using dyes with different functional moieties. The plausible mechanism of SiC capping, adsorption mechanism and the mode of interaction of different functional moieties are also elicited. The unique benefits of this approach include non-requirement of metal catalysts, hazardous chemicals, high temperature or pressure, long reaction time and exogenous initiators. Unlike the conventional approaches, this technique facilitates synthesis of fine magnetic nanoparticles with a uniform and robust ultrathin layer of silicon carbide. The results suggest that straight through channel dye removal by continuous feed through packed beds of CFSi particles under a magnetic field is possible without the need of centrifugation, precipitation, filtration, washing and ultrasonication.