Facile synthesis of multifunctional bone biochar composites decorated with Fe/Mn oxide micro-nanoparticles: Physicochemical properties, heavy metals sorption behavior and mechanism.

The value-added utilization of waste resources to synthesize functional materials is important to achieve the environmentally sustainable development. In this work, novel micro-nano FeOx- and MnOx-modified bone biochars derived from waste bone meal were obtained at 300 °C, 450 °C and 600 °C, and applied to remove Cd(II), Cu(II) and Pb(II) from aqueous solutions. The results showed that the pyrolysis temperature greatly influenced the specific surface area (SSA), micropore creation, functional groups and heavy metal sorption capacities of FO-BCs and MO-BCs. The effects of solution pH, ionic strength, humic acid (HA), kinetics and thermodynamics on heavy metals adsorption were investigated. Langmuir and pseudo-second order kinetics models fit the adsorption data well, and the FO-BC-450 and MO-BC-600 displayed the highest sorption capacity for Cd(II) (151.3 mg/g and 163.4 mg/g), Cu(II) (219.8 mg/g and 259.0 mg/g) and Pb(II) (271.9 mg/g and 407.2 mg/g), respectively. Due to the dissolved partial hydroxyapatite (HAP), carbonate-bearing hydroxyapatite (CHAP) and the catalysis of Fe(NO), the FO-BCs with higher SSA than the MO-BCs, whereas the sorption capacity displayed an opposite trend. The chemical complex, cation-π bonds, ion exchange and coprecipitation were the dominant mechanisms for metals adsorption. Overall, waste bone resource co-pyrolysis with Fe(NO)/KMnO impregnation is a promising and high-efficient adsorbents for the remediation of heavy metals-contaminated waters.