Nano-iron wrapped by graphitic carbon in the carbonaceous matrix for efficient removal of chlortetracycline

The stability, versatility, and reusability of an adsorbent are of great significance to its practicability to remove antibiotics from water due to their universal residual. Herein, a magnetic composite of nano-iron wrapped by graphitic carbon in the carbonaceous matrix with hierarchical pores (Fe-in/C-700) was constructed by one-step pyrolysis using Fe-in/Zn-MOF as a precursor. Fe-in/C-700 exhibited a core-shell structure and super-paramagnetism behavior, which showed excellent chlortetracycline (CTC) adsorption with the maximum adsorption capacity of 546.5 mg/g. The adsorption process matched well with the pseudo-second-order kinetics model and Langmuir model, indicating chemisorption was likely contributed to the CTC adsorption. Electrostatic interaction, surface complexation, hydrogen bond, and pi-pi EDA interaction were the dominant driving forces. Cl- and SO42- significantly enhanced the CTC adsorption due to the electrostatic attraction or hydrogen bond formed among Fe-in/C-700, anions, and CTC. Fe-in/C-700 maintained high adsorption capacities in the mixed antibiotic system (255.1, 143.3, and 169.6 mg/g for CTC, ciprofloxacin, and sulfamethoxazole), in actual water (372.9, 383.3, 390.6, and 366.7 mg/g for CTC in Pearl River water, lake water, tap water, and ultrapure water), and regeneration (366.7, 354.2, 360.4, 314.6, and 301.0 mg/g for CTC in five runs), indicating a promising reusable adsorbent for the remediation of antibiotics in water. These findings provide a feasible and straightforward strategy to synthesize high stable magnetic nanoparticles derived from MOFs.

Automated summary

Fe-in/C-700, a magnetic composite material with excellent adsorption capacity for chlortetracycline, demonstrates promising applications in various scenarios and shows potential as a regenerable adsorbent for antibiotic remediation in water. This study provides a feasible and straightforward strategy to synthesize high-stability magnetic nanoparticles derived from MOFs.