Fish scale-based biochar with defined pore size and ultrahigh specific surface area for highly efficient adsorption of ciprofloxacin

A fish scale-based porous activated biochar with defined pore size (DPBC) was fabricated by a one-step calcination and activation method. The DPBC possessed an ultrahigh specific surface area of 3370 m2 g−1 and its pore diameter centered at 1.49 nm which fits into the ciprofloxacin (CIP) molecular dimension, making it an ideal adsorbent for CIP adsorption due to the molecular pore-filling effect. The maximum Langmuir monolayer adsorption capacity of DPBC for CIP was higher than 1000 mg g−1 and the equilibrium time was less than 4 h, superior to most adsorbents reported in literature. Thermodynamic analysis indicated the adsorption process was spontaneous and endothermic. Notably, fixed-bed experiments showed an encouraging adsorption performance towards CIP, with a high saturated dynamic adsorption capacity of 880.3 mg g−1. Both Thomas and Yoon-Nelson models predict the fixed-bed column adsorption performance well. Hydrophobic effect, π-π interaction, π-π EDA, cation exchange, hydrogen bonding formation, pore filling effect, electrostatic and cation-π interaction involved in the CIP adsorption on the DPBC. [Display omitted] •Fish scale based biochar with defined pore size (DPBC) was prepared.•DPBC has high specific surface area (3370 m2 g−1) & total pore volume (1.91 cm3 g−1).•DPBC shows high CIP static adsorption capacity (>1000 mg g−1) & fast adsorption rate.•DPBC also shows excellent CIP dynamic adsorption capacity (880.5 mg g−1).•Hydrophobic & π-π interactions, cation exchange, etc. involved in CIP adsorption.