Tailor-made biochar-based nanocomposite for enhancing aqueous phase antibiotic removal

In the present study, an innovative biochar-based metal(loid) oxide nano-matrix doped hybrid nanocomposite (nMOC) from kitchen waste-derived biochar (KWB) and ZnO/SiO₂ was used for aqueous phase tetracycline removal. It involved a three-stage process, entailing thermal conversion of biomass to KWB, synthesis of ZnO/SiO₂ nano-matrix, and nMOC fabrication via ball-milling. Advanced characterizations were employed to determine surface chemistry, surface morphology, surface area, and elemental composition, exhibited thermostable, mesoporous, heterogeneous, ZnO/SiO₂-doped matrix with rich active surface-functional groups. The nMOC showed excellent performance (95.27 ± 0.304 %) for TC removal through batch mode adsorption study for 7.0 mg L⁻¹ aqueous TC solution at ambient temperature. The sorption data were statistically evaluated through linear and non-linear isotherms, kinetics, and thermodynamics modelling incorporating error function analysis, suggested spontaneous, exothermic, and multilayer chemisorption with complex diffusional adsorption phenomenon. The adsorption mechanisms were governed by, electrostatic interaction, H-bonding, π-π stacking interactions, and pore-filling. Regeneration study demonstrated the maximum efficiency using EDTA (81.39 ± 1.234 %). Experiments on interference by co-existing ions suggested lesser impact by monovalent anions (NO₃⁻) than divalent anions (SO₄²⁻), and monovalent cations (NH₄⁺). The nMOC showed enhanced TC adsorption and excellent reusability along with dual benefits of minimization of solid kitchen waste and very effective antibiotic removal from (waste)water.