MUSCAT, Oman — An international research team involving scientists in Oman has found that the starting material used to produce graphitic carbon nitride can substantially affect its properties and its ability to break down pharmaceutical pollutants in water.
The researchers compared graphitic carbon nitride (g-C₃N₄) synthesized from three nitrogen-rich precursors: melamine, urea and thiourea. They then tested the resulting materials against acetaminophen, cephalexin and levofloxacin—pharmaceutical compounds that may enter aquatic environments after use and disposal.
The study, published in the Sultan Qaboos University Journal for Science , involved researchers from the University of Technology and Applied Sciences and Sultan Qaboos University in Oman, working with collaborators from Hokkaido University in Japan and the University of South Africa.
The team produced the three carbon nitride materials under the same thermal conditions and examined their crystal structure, surface morphology, and optical and electronic properties. Their photocatalytic performance was tested in model water solutions containing five milligrams per liter of each pharmaceutical under a controlled artificial light source.
Carbon nitride produced from melamine achieved the highest manufacturing yield, at 31.14%, compared with 8.62% for the urea-derived material. The melamine-derived material also demonstrated the strongest overall photocatalytic performance against the three pharmaceutical compounds, while the material produced from thiourea showed the lowest performance.
The researchers attributed the stronger performance of the melamine-derived material to a combination of structural and electronic properties, including greater structural uniformity, crystallinity, charge separation and a moderate band gap. All three catalysts accelerated pharmaceutical degradation compared with the light-only control experiment.
Total organic carbon levels also decreased during treatment, indicating that the process did more than simply transform the original pharmaceuticals into other organic compounds. It contributed to the breakdown of the pharmaceuticals and some of their degradation products into simpler substances.
To examine residual biological activity after treatment, the researchers tested the treated solutions against Escherichia coli. The growth-inhibition zones associated with cephalexin and levofloxacin became smaller during treatment and were no longer detectable under the test conditions after several hours.
This finding should not be interpreted as proof that the treated water was completely non-toxic or environmentally safe. The bacterial assay measured residual antibacterial activity against E. coli only; it did not constitute a comprehensive assessment of all degradation products or their possible ecological effects.
The results demonstrate that precursor selection is not merely a manufacturing consideration. It can determine the production yield, physical properties and most suitable applications of graphitic carbon nitride. The findings could support the development of relatively inexpensive, metal-free photocatalysts for treating pharmaceutical contaminants in water.
The experiments were conducted using model solutions under controlled laboratory conditions. Further research will be necessary to evaluate the material in real wastewater, identify all degradation products, conduct broader ecotoxicity testing, determine catalyst stability and reusability, and assess performance under natural sunlight before the approach can be considered for large-scale treatment.
Sultan Qaboos University Journal for Science [SQUJS]
Experimental study
Not applicable
Pharmaceuticals Acetaminophen, Cephalexin and Levofloxacin: Elimination and Toxicity Study via Carbon Nitride-Based Photocatalyst
25-Jul-2026