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 , Fe 3 C, and Fe 3 O 4 -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 Fe 3 C@BC and Fe 3 O 4 @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 Fe 3 C@BC and Fe 3 O 4 @BC. Electron paramagnetic resonance analysis and radical quenching experiments indicated that HO and 1 O 2 / O 2 − 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.