Sorption of Cr(III) from aqueous media via naturally functionalized microporous biochar: Mechanistic study.

Abstract Biochar is a highly efficient and attractive candidate for remediation of heavy metals in aqueous media, due to its immense porosity and surface functionalities. In this study farmyard and poultry manure were converted to biochars. The biochars' pre- and post-characterization was performed through various analytical techniques such as thermogravimetry, X-ray photon spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive spectroscopy. The contemporary batch adsorption work articulates the effect of biochars concentration, H+ ion concentration, contact time and temperature on sorption efficiency of Cr(III) ions from aqueous media. The sorption kinetics of Cr(III) was sound tailored to the pseudo-second-order equation which confirmed the chemisorption. The sorption isotherms suggested the well-fitting of Freundlich model due to the unfolding of multilayer adsorption. The Cr(III) sorption was assessed as 37.75 and 33.94 mg/g for farmyard manure and poultry manure-derived biochars, respectively. The thermodynamic values designated the spontaneous and exothermic nature of the reaction. Graphical abstract Unlabelled Image Highlights • Biochar showed the potential of Cr(III) removal from aqueous media. • Chemisorption and multi-layer sorption were the prevailing sorption mechanisms. • Cr(OH) 3 and Cr 2 O 3 stable complexes were confirmed by FTIR and XPS. • Manure could be a valuable feedstock for biochar production and metal sorption. [ABSTRACT FROM AUTHOR]