Adsorption of Copper (II) by Using Farmyard and Poultry Manure BiocharâÂÂs:Efficiency and Mechanism

Biochar has recently become an attractive adsorbent for the removal of toxic metals from aqueous media. In this study, the adsorption efficiency of biochars derived from farmyard and poultry manure for the removal of Cu2+ from water was evaluated. The porosity, surface structure, internal morphology, thermal stability, and functional groups of the biochars were analysed using different analytical techniques such as scanning electron microscopy, X-ray photon spectroscopy (XPS), thermogravimetry, and Fourier transmission infrared spectroscopy. Kinetics and isotherm data were acquired in batch adsorption mode. The isotherm sorption data correlated well (R2 >0.98) with the Freundlich model describing multilayer orption of Cu2+ on heterogeneous biochars. The maximum Cu2+ sorption was estimated as 44.50 mg/g for farmyard manure-derived biochar and 43.68 mg/g for poultry manure-derived biochar. The sorption data fit the pseudo-second order kinetics equation best, indicating chemical interaction between Cu2+ and the negatively charged surface of biochar. The thermodynamic parameters indicated that the reaction was exothermic and spontaneous. Post-adsorption analysis of the biochars by XPS suggested the formation of CuO and carbonate dihydroxide. The outcomes of the present study indicated that manure-derived biochars could be valuable green sorbents for removing Cu2+ from contaminated aqueous media.