Scientists Develop Efficient Photocatalyst to Break Down Sulfamethoxazole, Mitigating Antibiotic Contamination Risks

A team led by Prof. Devasish Chowdhury synthesized copper zinc tin sulfide (Cu2ZnSnS4 or CZTS) nanoparticles and a composite of copper zinc tin sulfide with tungsten disulfide (CZTS-WS2).

Researchers from the Institute of Advanced Study in Science and Technology (IASST), Guwahati, have developed an innovative photocatalyst that effectively degrades sulfamethoxazole, a widely used broad-spectrum antibiotic, into less harmful chemicals. This breakthrough promises to address the growing environmental and health concerns related to antibiotic contamination, which contributes to antibiotic resistance, ecological damage, and human health risks.

A team led by Prof. Devasish Chowdhury synthesized copper zinc tin sulfide (Cu2ZnSnS4 or CZTS) nanoparticles and a composite of copper zinc tin sulfide with tungsten disulfide (CZTS-WS2). This composite, created through a hydrothermal reaction using zinc chloride, copper chloride, tin chloride, and tungsten disulfide, serves as a highly efficient photocatalyst that can degrade sulfamethoxazole (SMX), a drug frequently used to treat urinary and respiratory infections.

Sulfamethoxazole poses a significant environmental threat as more than 54% of the antibiotic is excreted into the environment through human waste, causing widespread contamination. This raises concerns about its potential to promote antibiotic resistance and negatively impact ecosystems.

"CZTS and its nanocomposites are multifunctional quaternary semiconductor nanomaterials composed of earth-abundant, inexpensive, and non-toxic elements. Their remarkable photostability makes them highly valuable for applications in light-harvesting and photocatalysis," explained Prof. Chowdhury.

The research team, which includes Nur Jalal Mondal, Rahul Sonkar, Mridusmita Barman, and Dr. Mritunjoy Prasad Ghosh, found that the CZTS-WS2 composite exhibited excellent photocatalytic activity, effectively breaking down sulfamethoxazole into less harmful intermediates. These findings were confirmed through liquid chromatography-mass spectrometry (LC-MS), an analytical technique used to identify the degraded products and intermediates, which were mostly found to be less hazardous than the original antibiotic.

Additionally, the CZTS-WS2 composite demonstrated more than 80% radical scavenging efficiency, which further underscores its potential in environmental cleanup. The catalyst can be recovered and reused multiple times without losing its effectiveness, making it both economically and environmentally viable.

This study, published in the Journal of Photochemistry & Photobiology A, offers promising solutions for mitigating the environmental impact of antibiotic contamination. The antibacterial properties of the composite also suggest future applications in broader wastewater treatment and environmental remediation efforts.