Preparation, characterization and adsorption potentiality of magnetic activated carbon from Eucalyptus sawdust for removal of amoxicillin: Adsorption behavior and mechanism

Abstract

The magnetic activated carbon (MAC) from eucalyptus sawdust was prepared by one-step method and utilized to remove amoxicillin (AMX) from wastewater. MAC was characterized by N2 adsorption-desorption, XRD, FT-IRS, Raman, XPS, FESEM, SEM-EDS, vibrating sample magnetometer (VSM) and the point of zero charges (pHpzc). The magnetic parameters of MAC were found Hc of 55.92 Oe, Ms of 21.68 emu g1 and Mr of 0.63 emu g1, which resulted from existence of α-Fe and γ-Fe2O3. MAC existed micropores and mesopores, the specific surface area (SBET) and average pore width were 1263.7 m2 g1 and 2.07 nm, respectively. Batch adsorption experiments was designed to investigate AMX adsorption behavior on MAC, the adsorption mechanism was also investigated. The AMX removal efficiency was more than 94.3% when 50 mL 400 mg L1 AMX aqueous solution (3 of pH) was adsorbed by 0.055 g MAC for 6 h at 25 °C. The AMX adsorption process was consistent with Langmuir isotherm model and the pseudo-second order kinetic model, with maximum adsorption capacities of 485.4 mg g1 for AMX, the process was affected by the intraparticle diffusion, membrane diffusion and surface adsorption. The AMX adsorption on MAC was spontaneous nd endothermic. The adsorption of AMX on MAC was based on electrosttic interactions, π–π conjugation interactions, and hydrogen bond interactions. MAC had satisfactory adsorption capacity for AMX and recyclability. This work provides a green and environment-friendly method on antibiotic contamination wastewater treatment and a low-carbon green chemical technology for the high-value utilization of eucalyptus residues.