Ciprofloxacin removal via sequential electro-oxidation and enzymatic oxidation

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Applied Microbiology

Background:

• Ciprofloxacin (CIP) is a persistent fluoroquinolone antibiotic found in water.
• Conventional water treatment methods are often insufficient for complete CIP removal.
• Developing effective methods for antibiotic removal is crucial for environmental and public health.

Purpose of the Study:

• To evaluate the combined efficacy of electro-oxidation and enzymatic oxidation for ciprofloxacin removal from water.
• To compare different electro-oxidation anodes and enzymatic oxidation mediators.
• To assess the degradation of CIP and the restoration of antimicrobial activity.

Main Methods:

• Electro-oxidation using boron-doped diamond (BDD) and mixed metal oxides anodes at various current densities.
• Enzymatic oxidation using laccase from Trametes versicolor, with and without redox mediators (syringaldehyde and ABTS).
• Sequential treatment strategies: enzymatic followed by electro-oxidation, and electro-oxidation followed by enzymatic oxidation.
• Analysis of CIP removal efficiency and residual antimicrobial activity in synthetic and real wastewater.

Main Results:

• The boron-doped diamond (BDD) anode at 35.4 A/cm² achieved >90% CIP removal in 6 minutes.
• Enzymatic oxidation with laccase required redox mediators (syringaldehyde or ABTS) for significant CIP transformation.
• The sequential combination of electro-oxidation followed by enzymatic oxidation resulted in 97-99% CIP removal.
• The treatment effectively eliminated the antimicrobial activity of ciprofloxacin.

Conclusions:

• The combined electro-oxidation and enzymatic oxidation system is highly effective for removing ciprofloxacin from water.
• The sequential application of electro-oxidation followed by enzymatic oxidation is superior for complete CIP degradation and detoxification.
• This integrated approach shows promise for treating complex matrices like wastewater contaminated with antibiotics.