K Govind Raj

An efficient magnetic adsorbent nanocomposite material is prepared by simple chemical methods using coconut shell based activated carbon and iron oxide nanoparticles. The composite material shows good oil retention capacity with fast kinetics and can be recovered along with the adsorbed oil by using an external magnet. The adsorbent material can be reused after recovering either by heat treatment of by solvent extraction. Hence, the magnetic nanocomposite is shown to be an efficient and recyclable potential candidate for removal of oil spills by magnetic separation.

The changes in the electrical transport properties and mechanism of conduction in disordered carbon,
with the extent of graphitization, are studied and discussed. With heat treatment induced graphitic
ordering, the electrical properties are considerably modified, inducing a crossover from strong
localization to weak localization behavior. Accordingly, the conduction mechanism is modified from the
3-dimensional variable range hopping (3D VRH) model to the 2-dimensional weak localization (2D WL)
model. Results show that carrier–carrier and carrier–phonon interactions play major roles in developing
the weak localization behavior with the extent of graphitization

ABSTRACT High room temperature ferromagnetic moment with high Curie temperature (>>700 K) for graphene oxide (GO) is obtained by a simple chemical activation using phosphoric acid followed by heat treatment at 800 °C. The field and temperature variations of the magnetization data indicate ferromagnetic, paramagnetic and diamagnetic contributions in the acid/heat treated sample. IR spectroscopic studies suggest hydrogenation (reduction) of GO after the acid and heat treatments. The results point to the role of defects, extent of hydrogenation, changes in the bonding characteristics and the nature of the functional groups in determining the different magnetic contributions.