Adsorption performance and kinetics of Cr(VI) onto activated carbons derived from the waste leaves of invasive plants Rhus typhina and Amorpha fruticosa

Environ Sci Pollut Res Int. 2023 Sep 20. doi: 10.1007/s11356-023-29833-7. Online ahead of print.ABSTRACTTo maximize the potential of biomass from invasive plants, waste leaves from Rhus typhina (RT) and Amorpha fruticosa (AF) were used to prepare activated carbons (ACs) for the efficient removal of chromium from wastewater. Six ACs were prepared by CO2 activation at 850 °C with varying flow rates (500, 1000, and 1500 mL/min) and characterized by yield, pH, N2 adsorption isotherm, FTIR, SEM, TG, and XPS. The adsorption isotherm and kinetics for chromium removal were analyzed. The outcomes showed that the ACs had mesoporous structures with specific surface areas of 408.05-701.01 m2/g and pore volumes of 0.360-0.653 cm3/g. The pores are distributed among the agglomerated nanoparticles on the surface of the granules. The existence of two kinds of chromium compounds and two valance states, Cr(III) and Cr(VI), in spent ACs was identified by the FTIR and XPS spectra. The Cr (VI) equilibrium data and adsorption kinetics were well-fit with the Langmuir isotherm (R2 = 0.936-0.967) and pseudo-second-order kinetic models (R2 = 0.795-0.937). The maximum Langmuir Cr adsorption capacities of ACRT1.0 and ACAF0.5 were estimated to be 266.54 and 255.21 mg/g at pH = 2.0, respectively. Concentrations of Cr(III) and Cr(VI) in filtrates after equilibrium, combined with XPS and TGA analysis of spent ACs, illustrated that Cr(VI) was converted to the less harmful trivalent chromate Cr(III) during th...
Source: Environmental Science and Pollution Research International - Category: Environmental Health Authors: Source Type: research