Biofabricated graphene-magnetite nanobioaerogel with antibiofilm property: Response surface methodology based optimization for effective removal of heavy metal ions and killing of bacterial pathogens

Fabrication of mechanically stable porous materials with excellent adsorption capacity for different types of heavy metal ions simultaneously is still scientifically and technically challenging. Herein, the Response Surface Methodology (RSM) was employed to statistically fabricate the biological materials (collagen, chitosan) functionalized graphene–magnetite (BGM) hybrid nanobioaerogel. RSM statistically predicted the concentration of GO, Fe2+, collagen–chitosan mixture and glutaraldehyde as 6.78 mg/mL, 0.20 M, 61.39 mg/mL and 68.63 µM, respectively, for the maximum responses of Young’s modulus (5.26 kPa) and adsorption capacity. Various spectroscopic and microscopic techniques demonstrated the porous interconnected network structure and superparamagnetic behavior of BGM hybrid nanobioaerogel with a saturation magnetization value of 19.34 emu/g. The nanobioaerogel exhibited fast and high adsorption for Cu(II) (183.96±5.68 mg/g, 29 min), Cd(II) (67.04±1.53 mg/g, 36 min), Cr(VI) (134.49±5.21 mg/g, 45 min) and As(III) (64.62±2.40 mg/g, 40 min) at optimum pH 5.0 and 60 °C in multicomponent system, which is almost four times higher than commercially available activated carbon and other reported literatures. The adsorption process follows the Langmuir isotherm suggesting the monolayer chemisorption, follows pseudo–second order (Cu(II)) and intraparticle diffusion (Cd(II), Cr(VI) and As(III)) models and suggesting rate–limiting step is surface binding and internal pores. ATR–FTIR spectrum revealed that hydroxyl, amine, carboxylate, carbohydrate and iron functional groups in hybrid BGM nanobioaerogel interacted with the heavy metals in a multicomplex manner. It was easily regenerated and reused for multiple adsorptions–desorption cycles. In addition, it also showed >5 log reduction in 4 h against different pathogens and antibiofouling agents.