The effect of microwave and muffle furnace-assisted heating on the surface characteristics of teff husk activated carbons: Thermodynamic, isotherm, and kinetics study of Pb removal

Abstract

This study explored the fabrication of activated carbon from teff husk biomass using microwave and muffle-furnace-assisted heating and observed its effect on surface characteristics and the thermodynamics, isotherm, and kinetics of Pb2+ ions removal. Chemical activation of the teff husk was carried out using ZnCl2 as an activating agent. The microwave-assisted activated carbons (MW-THAC) and muffle furnace-assisted activated carbon (MF-THAC) were characterized for surface area, pHzpc, functional groups, thermal stability, phase composition, surface morphology, and surface-elemental compositions. The surface area of MW-THAC and MF-THAC was found to be 9.81 m2/g and 327.54 m2/g, respectively. Thermodynamic parameters indicated that the interaction with MW-THAC and MF-THAC was spontaneous and endothermic. The maximum Pb adsorption capacities of MW-THAC and MF-THAC calculated using the Langmuir model at 45 °C were found to be 20.45 mg/g and 26.04 mg/g, respectively. Pb2+ removal through MW-THAC followed the Langmuir isotherm and the pseudo-first order kinetic model. However, the Freundlich isotherm and pseudo-second order kinetic models best describe Pb2+ adsorption onto the MF-THAC surface. The desorption study shows that 80.6 % and 78.7 % of Pb2+ ions can be recovered from the surfaces of the MW-THAC and MF-THAC adsorbents. This study confirms that activated carbon derived from teff husk could be a potential candidate for the adsorption and recovery of Pb2+ ions.