Chlortetracycline hydrochloride removal by different biochar/Fe composites: A comparative study

In the last years, the synthesis and applications of biochar/Fe composites have been extensively studied, but only few papers have systematically evaluated their removal performances. Herein, we successfully synthesized and structurally characterized Fe-0, Fe3C, and Fe3O4-coated biochars (BCs) for the removal of chlortetracycline hydrochloride (CH). Evaluation of their removal rate and affinity revealed that Fe-0@BC could achieve better and faster CH removal and degradation than Fe3C@BC and Fe3O4@BC. The removal rate was controlled by the O-Fe content and solution pH after the reaction. The CH adsorption occurred on the O-C groups of Fe-0@BC and the O=C and O-Fe groups of Fe3C@BC and Fe3O4@BC. Electron paramagnetic resonance analysis and radical quenching experiments indicated that HO center dot and O-1(2)/O-2(center dot-) were mainly responsible for CH degradation by biochar/Fe composites. Additional parameters, such as effects of initial concentrations and coexisting anions, regeneration capacity, cost and actual wastewater treatment were also explored. Principal component analysis was applied for a comprehensive and quantitative assessment of the three materials, indicating Fe-0@BC is the most beneficial functional material for CH removal.

Automated summary

Synthesis and applications of biochar/Fe composites have been extensively studied, with Fe-0@BC showing better removal and degradation of chlortetracycline hydrochloride compared to Fe3C@BC and Fe3O4@BC. Removal rate is controlled by O-Fe content and solution pH, with CH adsorption occurring on different functional groups.