Removal of hexavalent chromium ions and mixture dyes by electrospun PAN/graphene oxide nanofiber decorated with bimetallic nickel–iron LDH

Abstract

The network of electrospun nanofibers modified by layered double hydroxides (LDHs) still needs to be thoroughly investigated in the field of adsorption of toxic metal ions and dyes from its aqueous solution. In the present study, an innovative electrospun nanofiber membrane was fabricated, which was used to eliminate pollutants from water. Polyacrylonitrile/graphene oxide (PAN/GO) composite nanofibrous membranes were fabricated by the electrospinning technique first, and next bimetallic nickel iron layered double hydroxide/PAN/GO (NiFe LDH/PAN/GO) composite nanofibrous membranes were synthesized by via hydrothermal method. The characterizations of the prepared nanofibers membranes were analyzed using FE-SEM, EDS element mapping, XRD, FTIR, AFM, and WCA. The adsorption behavior of binary mixture of Rose Bengal (RB) and Brilliant Blue (BB) dyes and metal ions of hexavalent chromium (Cr(VI)) by NiFe LDH/PAN/GO nanofibers were investigated via batch experiments based on central composite design (CCD) method. According to the Langmuir model, the maximum adsorption capacity of the NiFe LDH/PAN/GO toward mixture of RB and BB dyes and Cr(VI) ions are 6.19, 7.74 and 13.1 mg g−1, respectively. In addition, the fabricated LDH composite membranes after five times sequential adsorption/desorption experiments. The adsorption kinetics of pollutants follows the pseudo-first-order model. The adsorption process is spontaneous, endothermic, and enhancement of randomness. In addition, NaCl salt decreased the mixture of RB and BB dyes and metal Cr(VI) ions removal by the composite membranes.