Preparation of biochar-supported nanoscale zero-valent iron (nZVI@BC) and its adsorption and degradation of chlortetracycline in water and soil

ABSTRACT

This study investigates the preparation and application of biochar-supported nanoscale zero-valent iron (nZVI@BC) for the removal of chlortetracycline (CTC) from water and soil. The nZVI@BC composite was synthesized via a modified co-precipitation method and characterized using XRD, SEM, N² adsorption-desorption, and XPS techniques. The material exhibited enhanced surface area and porosity compared to unmodified biochar. Batch experiments were conducted to evaluate the adsorption and degradation kinetics of CTC in aqueous solutions, revealing rapid initial uptake and equilibrium within 4 hours. The effects of pH, temperature, and adsorbent dosage on CTC removal were examined. In soil matrices, nZVI@BC significantly improved CTC adsorption capacity, with adsorption behavior best described by the Langmuir isotherm model. Thermodynamic analysis indicated an endothermic and spontaneous adsorption process. The impact of nZVI@BC on CTC degradation in soil was assessed through a 14-day experiment, monitoring CTC and its metabolites epichlortetracycline (ECTC) and isochlortetracycline (ICTC). Results demonstrated enhanced degradation of CTC and its metabolites in nZVI@BC-modified soils. This study provides valuable insights into the potential of nZVI@BC as an effective material for remediation of antibiotic-contaminated water and soil environments, showcasing its dual functionality in adsorption and catalytic degradation.

Keywords:
Antibiotic remediation; Composite material; Environmental contamination; Adsorption kinetics; Soil amendment