High-efficiency decontamination of Pb(II) and tetracycline in contaminated water using ball-milled magnetic bone derived biochar

Herein, bone-derived biochar loaded with Fe3O4 (MBBCBM) was synthesized by ball-milling process and was employed for the elimination of Pb(II) and tetracycline (TC) from water. Characterizations revealed that ball milling effectively ground the bone-derived biochar to nanometer size and achieved the loading of Fe3O4 with excellent magnetism. The adsorption of Pb(II) and TC onto MBBCBM reached equilibrium within 20/100 min and was appropriately described by Avrami fractional-order model. Moreover, the isotherm data was well fitted by Sips and Langmuir models with outstanding adsorption capacities of Pb(II) (339.39 mg/g) and TC (237.51 mg/g). The thermodynamic studies showed negative ΔG0 values, and positive ΔH0 values for Pb(II) (18.54 kJ/mol) and TC (32.92 kJ/mol), indicating the endothermic and spontaneous properties of the adsorption. Moreover, the adsorption performance of MBBCBM was basically steady during extensive pH range with high tolerance to co-existing ions, and the removal rate and desorption efficiency decreased slightly after three cycles. In addition, the MBBCBM achieved high Pb(II) capture through electrostatic attraction, precipitation, complexation, cation exchange, and coprecipitation, whereas the TC elimination was achieved through π-π stacking interaction, H-bonding, complexation, and pore-filling. All these findings suggested the ball milling-tailored MBBCBM to be an ideal adsorbent for decontamination of TC and Pb(II) contaminated water.