Sunlight-Assisted Photodegradation of Tetracycline Using ZnS-Melamine-Formaldehyde Nanocomposites.

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Tetracycline hydrochloride (TCH) is a persistent antibiotic pollutant in aquatic systems, posing environmental risks.
• Effective and sustainable methods are needed for the removal of TCH from contaminated water sources.

Purpose of the Study:

• To synthesize and evaluate a novel zinc sulfide (ZnS) nanoparticle-based melamine-formaldehyde polymer (MFP) nanocomposite (ZnS-MFP) for TCH degradation.
• To investigate the photocatalytic efficiency and mechanism of ZnS-MFP under natural sunlight.

Main Methods:

• Fabrication of ZnS-MFP nanocomposite via hydrothermal polymerization and precipitation.
• Photocatalytic degradation experiments using TCH solutions under natural sunlight and artificial light.
• Spectroscopic analysis (¹H NMR, UV-vis, HR-MS) to confirm TCH degradation and identify intermediates.
• Radical scavenging experiments to elucidate the degradation mechanism.

Main Results:

• ZnS-MFP achieved 90% degradation of 100 mg L^-1 TCH within 120 minutes under natural sunlight.
• Photocatalytic degradation followed pseudo-first-order kinetics, with significantly higher efficiency under sunlight compared to artificial light.
• Spectroscopic analysis confirmed TCH degradation, and HR-MS identified degradation intermediates.
• Radical scavenging studies indicated the primary role of holes (h⁺) and hydroxyl radicals (•OH) in the photodegradation process.

Conclusions:

• ZnS-MFP is a highly efficient and recyclable photocatalyst for the sunlight-driven degradation of TCH in aquatic environments.
• The study demonstrates the potential of ZnS-MFP for treating antibiotic-contaminated wastewater.
• The developed nanocomposite offers a promising solution for environmental remediation of pharmaceutical pollutants.