Allura Red dye sorption onto electrospun zirconia nanofibers

Abstract

Zirconia fibers were obtained by sol-gel and electrospinning techniques, using polyvinylpyrrolidone and zirconium butoxide as precursor. The as-spun fibers obtained from the precursor solutions were continuous and a mean diameter of 300±95 nm was observed in samples obtained using a high precursor molar ratio (Z1: 0.1 M). The fibers were treated at different temperatures, and characterizations by thermal analysis, FTIR, Raman Spectroscopy and XRD demonstrated that monoclinic and tetragonal phases of zirconia are present. The predominant phase is monoclinic with some crystalline peaks corresponding to tetragonal zirconia. The phase transition from tetragonal to monoclinic zirconium oxide was observed at 1000 ◦C. At 1200 ◦C, the fiber morphology was preserved, while diameter decreased to 130±39 nm due to the thermal decomposition of organic matter and sintering process. The adsorption behavior of the zirconia fibers was evaluated. Maximum adsorption capacity of Allura Red dye onto zirconia fibers was 0.895 mg/g. The data fitted better to pseudo-second order and Elovich kinetic models, while equilibrium data fitted to Freundlich and Temkin isotherms. The kinetic and equilibrium isotherm studies suggest that sorption of Allura Red dye on zirconia fibers takes place by a chemisorption process on a heterogeneous surface. The results showed that zirconia fibers can be used as an alternative adsorbent material for the effective removal of Allura Red dye from water. The manufacture of zirconia fibers by the electrospinning method offers an alternative to produce ceramics that can be used as adsorbent materials.