Biomimetic fabrication of hierarchically structured LDHs/ZnO composites for the separation of bovine serum albumin

Hierarchically structured layered double hydroxides (LDHs), with special surface structural and positively charged layer, are of great interest due to their potential applications in bioseparation and catalysis. Herein this work presents a novel method for fabricating Zn-Al LDHs/ZnO composites derived from cotton fibers, as well as its application in bovine serum albumin (BSA) separation. The morphology and structure of as-prepared samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. It is found that the fibrous morphologies are retained in inorganic replicas, and the surface of composites is composed of many small nanosheets. Batch adsorption results indicated that the prepared samples were very effective in adsorbing BSA. Effects of solution pH, adsorbent dose, adsorption time, and adsorption temperature were investigated in detail. The equilibrium data were found to be well described by Dubinin-Radushkevich model, while the kinetic data were well-fitted to the intraparticle diffusion model. Based on the mechanism of adsorption, the adsorption sites of composites can be easily occupied by adsorbed high negative charge anions through electrostatic interactions. The BSA desorption can be controlled via the addition of salt solution. (C) 2013 Elsevier B.V. All rights reserved.