Rapid and efficient adsorption of tetracycline from aqueous solution in a wide pH range by using iron and aminoacetic acid sequentially modified hierarchical porous biochar

The object of this work was to synthesize an iron and aminoacetic acid sequentially modified hierarchical porous biochar (AC-Fe@HPBC) for tetracycline (TC) removal from aqueous solution. Results showed that AC-Fe@HPBC had a larger surface area (362.5370 m(2)/g), developed microporous structure (0.1802 cm(3)/g), and numerous functional groups, which provided more adsorption sites. The maximum adsorption capacity towards TC by ACFe@HPBC was 457.85 mg/g, 1.43, 1.29 and 1.20-fold than that of HPBC, AC@PHBC and Fe@HPBC, respectively, and the super-fast adsorptive equilibrium was achieved within 10 min. Additionally, introducing amino and carboxyl functional groups on the AC-Fe@HPBC surface significantly broadened the operation pH range (3-11). Site energy analysis indicated TC and AC-Fe@HPBC had stronger adsorption affinity at a higher temperature. The adsorption mechanism involved pore filling, surface complexation, H-bond and p-p interaction. Moreover, the reusability experiments proved AC-Fe@HPBC as an effective adsorbent for TC removal from aqueous solution.