title: Polyaniline nanofibers as highly effective re-usable adsorbent for removal of reactive black 5 from aqueous solutions.
abstract: Polyaniline nanofibers (PANI NFs) with 50-80 nm in diameter were successfully prepared at room temperature (22 °C) using ferric chloride (FeCl3) as an oxidant via a simple rapid mixing polymerization method. The prepared PANI NFs were characterized by FE-SEM, HR-TEM, BET, ATR-FTIR and by Zeta potential measurement method. The adsorption of azo dye Reactive Black 5 (RB5) onto PANI NFs from aqueous solutions was investigated. Adsorption studies were carried out at different initial dye concentrations, initial solution pH and adsorbent doses. The kinetic data fitted well with the pseudo-second-order model while the equilibrium data were satisfactorily described by the Langmuir isotherm model. The Langmuir maximum adsorption capacity of RB5 at pH 6.0 was found to be 312.5, 389.1 and 434.7 mg/g at 25 °C, 35 °C and 45 °C, respectively. Thermodynamic parameters including the Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes indicated that the adsorption of RB5 onto PANI NFs was feasible, spontaneous, and endothermic. Moreover, desorption experiments revealed that the PANI NFs can be reused effectively for five consecutive adsorption-desorption cycles without any loss of its original capacity.
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa.
authors.forename: Madhumita
authors.initials: M
authors.lastname: Bhaumik
authors.affiliation: Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria, South Africa.
authors.forename: Rob I
authors.initials: RI
authors.lastname: McCrindle
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa; DST/CSIR National Centre for Nanostructured Materials, Materials Science and Manufacturing, Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa. Electronic address: amaity@csir.co.za.
authors.forename: Arjun
authors.initials: A
authors.lastname: Maity
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa.
authors.forename: Shilpi
authors.initials: S
authors.lastname: Agarwal
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa; Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India. Electronic address: vinodfcy@gmail.com.
authors.forename: Vinod Kumar
authors.initials: VK
authors.lastname: Gupta
keywords: Adsorption; Isotherm; Kinetics; Nanofibers; Polyaniline; Reactive black 5