Electrospun chitosan/baker's yeast nanofibre adsorbent: preparation, characterization and application in heavy metal adsorption

In this study, chitosan/baker's yeast nanofibre was synthesized by electrospinning method and subsequently, the performance of the prepared nanofibre for removal of uranium(VI) and thorium(IV) ions from aqueous solutions was investigated. The prepared adsorbent was characterized by Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The influences of experimental parameters on the chitosan/baker's yeast nanofibre such as contact time, pH, temperature and initial concentration were studied in a batch system. The adsorption kinetics was studied by the pseudo-first order, pseudo-second-order, double-exponential and intra-particle kinetic models. Three isotherm models, namely Langmuir, Freundlich and Dubinin-Radushkevich (D-R) were used for analysis of equilibrium data of heavy metals. The maximum adsorption capacities of U(VI) and Th(IV) were estimated by Langmuir model to be 219 and 131.9 mg g(-1) at optimum conditions, respectively. The positive values of the enthalpy changes and negative values of Gibbs free energy changes showed that U(VI) and Th(IV) adsorption process was endothermic and spontaneous. Also, the inhibitory effect of Co(II), Cu(II), Cd(II), Fe(II) and Ni(II) metal ions on U(VI) and Th(IV) adsorption was investigated. The reusability of chitosan/baker's yeast nanofibre was determined after five adsorption-desorption cycles.