Synthesis of antibacterial, antioxidant and magnetic Nigella sativa-graphene oxide based nanocomposite BC-GO@Fe3O4 for water treatment

The multifunctional nanocomposite BC-GO@Fe3O4 was prepared by incorporating magnetic Fe3O4 nanoparticles in cellulosic Black cumin seed powder which was functionalized with graphene oxide following co-precipitation method. The prepared BC-GO@Fe3O4 was characterized by employing thermal, spectroscopic and microscopic techniques that showed high thermal stability, magnetic behaviour, and the presence of large numbers of hydroxyl and carbonyl functional groups at the surface. The in vitro investigation has shown that BC-GO@Fe3O4 possesses significant antibacterial activities against Gram-negative and Gram-positive bacterial strains, and antioxidant capability. Thus the prepared nanocomposite is biologically safe and beneficial; therefore was tested for adsorptive removal of both cationic and anionic representative water pollutants, namely, methylene blue and arsenic from their aqueous solutions. The removal was carried out under variable conditions and the process has been investigated thoroughly. The adsorption data for both methylene blue and arsenic fitted well to the Freundlich isotherm and pseudo-second order kinetics which suggested that both these pollutants, during adsorption, bound specifically to the chemically active sites on the surface of BC-GO@Fe3O4. However, for comparison purpose the Langmuir capacity was determined at equilibrium which was found to be approximately 10.0 mg g(-1) for methylene blue and 1.0 mg g(-1) for arsenic at optimum conditions (Adsorbent dose: 1.0 g L-1 for both methylene and arsenic; initial concentration: 10.0 and 1.0 mg L-1, and pH: 7.0 for methylene blue and arsenic, respectively). The obtained adsorption capacities were compared with previously reported adsorption capacities for various adsorbents for methylene blue and arsenic which proved the better adsorption capacities of BC-GO@Fe3O4 for the present study. Therefore, BC-GO@Fe3O4, a biologically safe and beneficial material, can be employed for adsorptive removal of dyes and arsenic from water while controlling the bacterial growth and acting as antioxidant.