Elucidating structure-activity relationships and mechanism on antibiotic degradation efficiency by...

Area of Science:

• Environmental Chemistry
• Photocatalysis
• Molecular Mechanisms

Background:

• Aquatic environments face composite antibiotic contamination from tetracyclines, fluoroquinolones, and sulfonamides.
• Limited research exists on the comparative degradation and molecular mechanisms of these coexisting pollutants.

Purpose of the Study:

• To compare the photocatalytic degradation performance of six representative antibiotics (tetracyclines, fluoroquinolones, sulfonamides).
• To elucidate the distinct molecular mechanisms governing their divergent degradation behaviors.

Main Methods:

• Experimental photocatalytic degradation tests.
• Density Functional Theory (DFT) simulations for molecular mechanism analysis.
• Investigation of factors like pH and functional groups.

Main Results:

• Degradation efficiency order: tetracyclines > fluoroquinolones > sulfonamides.
• High removal rates for tetracyclines (>91%) and fluoroquinolones (>85%), with lower rates for sulfonamides.
• Optimal degradation is pH-dependent for each antibiotic.
• Interfacial adsorption energy and functional groups influence degradation efficiency.
• Reactive oxygen species target specific molecular regions, governed by adsorption configuration and HOMO orbitals.

Conclusions:

• Photocatalytic degradation efficiency varies significantly among antibiotic classes due to molecular structure and adsorption properties.
• Solution pH critically modulates antibiotic adsorption and degradation.
• Understanding these micro-mechanisms provides references for managing composite antibiotic pollution.