The removal of Direct Yellow 12 from synthetic aqueous solution by a novel magnetic nanobioadsorbent

Abstract

In this study, a novel gelatin-based nanomaterial was produced through mixing a gelatin solution with nanoclay cloisite 30 B, iron salts and basic ammonium in a special setup. Characterization by Fourier transform infrared spectroscopy proved that the expected functional groups are present. From the Brunauer–Emmett–Teller analysis, surface area and total pore volume were 48 m2 g−1 and 0.06 cm3 g−1, respectively, showing appropriate textural properties of the sample. Field emission scanning electron microscopy not only showed the morphology of the surface but also visually allowed to estimate the mean diameter of nanoparticles of 14 nm. Further, energy-dispersive X-ray spectroscopy detected some elements, each referred to its source in the preliminary mixture. Among many different applications offered by this material and this technique, batch adsorption of Direct Yellow 12 was chosen and studied as a function of adsorbent mass, solution pH, contact time and initial concentration of the solution. Results demonstrated that acidic condition favors dye removal due to an upraised level of electrostatic attraction between the positively charged surface of nanobioadsorbent and anionic Direct Yellow 12 molecules. Pseudo-second-order model perfectly matched to the kinetics data in all initial concentrations. Adsorption equilibrium data well fitted to the Langmuir equation, giving the maximum capacity of adsorption of 476 mg g−1. Additionally, the nanobioadsorbent was regenerated and reused successfully with showing just a small decrease in capacity. Therefore, gelatin-nanobiocomposite is a promising agent to practically lower the hazardous dyestuff concentration.