Insight into the co-removal of Cu(II) and ciprofloxacin by calcite-biochar composite: Enhancement and competition

The discharge of metals and antibiotics pose a serious risk to public health and environment. Gaining insight into the removal process is an imperative implication for comprehending environmental transformation of contaminants. In this study, a low-cost calcite-biochar (CAB) composite was prepared through a facial pyrolyzed process from shell waste for the removal of Cu(II) and ciprofloxacin (CIP) in single and mixed systems. CAB exhibited superior removal performance toward these two pollutants. In single system, CIP removal was adsorption coupled with flocculation and Cu(II) removal was adsorption combined with precipitation. The CIP removal followed the PSO kinetic and Freundlich isotherm model, while Cu(II) removal were better described by PSO kinetic and Langmuir isotherm model. In binary system, Cu(II) had an promotional and inhibitory effect on the removal of CIP, which depended on the concentration of Cu(II). But the adsorption capacity of Cu(II) removal was reduced with the existence of CIP. The microstructure analysis indicated that the cation bridging, hydrogen bonding, surface complexation and 7C-7C interaction were attributed to the CIP removal and Cu(II) could act as a bridge or competitor. While the Cu(II) removal was inhibited by competing with the active sites or suppressing the formation of posnjakite in the coexistence of CIP. These results provided valuable information for the co removal of CIP and heavy metal.

Automated summary

The discharge of metals and antibiotics poses a serious risk to public health and the environment. This study explored the use of a low-cost calcite-biochar composite for the removal of Cu(II) and ciprofloxacin (CIP). The composite exhibited superior removal performance for both pollutants, with CIP removal being adsorption coupled with flocculation and Cu(II) removal being adsorption combined with precipitation. In a binary system, Cu(II) had both promotional and inhibitory effects on CIP removal, depending on its concentration. The microstructure analysis revealed the mechanisms of CIP and Cu(II) removal, with cation bridging, hydrogen bonding, surface complexation, and 7C-7C interaction playing important roles.