Sustainability and application of corncob-derived biochar for removal of fluoroquinolones

Biochar-inspired tertiary removal system is beneficial in preventing antibiotic residue discharged from hospital wastewater treatment. Taking advantage of a simple kiln controlled at around 600 degrees C, we succeeded in carbonizing corncobs to biochar with a surface area of 306 m(2)/g. Using ciprofloxacin (CFX), ofloxacin (OFX), and delafloxacin (DLX), we demonstrated the performance of the corncob biochar for the sorption removal. The pseudo-second-order rate of DLX was lower than CFX and OFX. The maximum sorption capacity Q(max) of 93.9 mu g/g for DLX, 399.6 mu g/g for CFX, and 306.0 mu g/g for OFX were estimated using the Langmuir model. The parameter K-L relating to binding strength for DLX is 8 times larger than CFX and OFX. The Q(max) could be mainly determined by the pore size distribution of the biochar and the dimensions of FQs considering hydration. Furthermore, we discussed that these results might relate to the number of halogen atoms and functional groups in the fluoroquinolones.