Nitrate removal from aqueous solution using polyaniline modified activated carbon: Optimization and characterization

Based on high surface area and porosity of activated carbon and special doping mechanism of polyaniline, the polyaniline modified activated carbon (PAN/AC) composite was prepared to effectively remove nitrate form groundwater using the chemical oxidative polymerization. The surface physicochemical properties were analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), specific surface analyzer (BET), X-ray diffraction analyzer (XRD), Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS).The effects of adsorbent dosage, initial concentration, pH and coexisting oxyanions on nitrate adsorption were investigated. The response surface methodology was employed to optimize nitrate adsorption according to the single-factor experimental results. Both error statistics and residual plot were used to determine the optimal kinetic and isotherm models. The maximum adsorption capacity predicted by the Sips model was 11.04 mg g(-1) (as NO3--N) or 48.9 mg g(-1) (as NO3-) at 25 degrees C. The nitrate adsorption mechanisms were mainly electrostatic attraction and anion exchange. The good acidalkaline resistance, short equilibrium time and easy regeneration prompted the PAN/AC composite to become a promising adsorbent for nitrate removal. (C) 2020 Elsevier B.V. All rights reserved.