PAMAM grafted α-Fe2O3 nanofiber: Preparation and dye removal ability from binary system

Abstract In this paper, polyamidoamine (PAMAM) grafted α-Fe 2 O 3 nanofiber as a new adsorbent was prepared by a three-step method. (1): preparation of α-Fe 2 O 3 nanofiber by electrospinning technique, (2): incorporation of vinyl group on the nanofiber surface by vinyltriethoxysilane (VTES) and (3): grafting of PAMAM dendrimer onto the nanofiber surface. For the first time, the possibility of reaction between the vinyl group of VTES and the amine group of PAMAM was evaluated and the optimum condition was reported. Characterization by Fourier transform infrared spectroscopy (FTIR) showed that the PAMAM molecules were covalently grafted to the surface through the formation of C N group. The diameter of nanofibers was increased after the grafting process, confirming the deposition of a layer containing silica and PAMAM molecules on the surface. Decreasing in the total surface area values of nanofibers after the grafting process was detected by Brunauer–Emmett–Teller (BET) analysis. Moreover, dye removal ability of prepared nanofibers in single and binary systems were investigated. It was found that the number of functional group and size of dye molecule play important roles in selective adsorption in binary system. Adsorption of dyes in single and binary systems followed the Langmuir isotherm and pseudo-second order kinetics confirming monolayer and chemical adsorption, respectively. The maximum adsorption capacity of PAMAM grafted nanofiber was 1428.57 and 1250 mg/g for Direct Red 80 and Acid Red 18 at pH 3, respectively. It was concluded that the prepared nanofiber with a relatively large adsorption capacity can be a suitable alternative for elimination of dyes from aqueous media.