Communities, municipalities and industries could soon have access to faster and cheaper tools to detect harmful dye pollution in water. Environmentally friendly nanomaterials can outperform conventionally produced alternatives in monitoring water quality, according to the doctoral research of Dr Mokole Seleke, who recently graduated from the North-West University (NWU) with a PhD in chemistry.
For his study, he developed electrochemical sensors using plant-based nanomaterials capable of detecting dye pollutants at very low concentrations. The findings suggest that this can improve the performance of water-quality sensors while reducing the environmental impact associated with traditional chemically based methods.
The research addresses a growing challenge in South Africa, where limited freshwater resources face pressure from industrial, agricultural and urban pollution. Dyes released from the textile, printing, leather-processing and cosmetics industries can persist in water systems, affecting ecosystems and posing risks to human health if left undetected.
"South Africa's water resources are already under pressure, and contamination from industrial activities makes continuous monitoring essential," said Dr Seleke, whose PhD research has already generated four papers and a presentation at a conference in Germany.
Detecting pollutants before they pose a danger
"My research developed highly sensitive electrochemical sensors that can detect dye pollutants before they accumulate to harmful levels. Early detection provides regulators, municipalities and industries with scientific tools to better protect public health and freshwater resources."
Electrochemical sensors measure changes in electrical signals to identify pollutants in water. Unlike conventional laboratory testing, these sensors could allow water quality to be monitored directly at rivers, dams and industrial sites. “This opens the possibility of developing affordable, portable sensors that environmental agencies and industries can use for rapid on-site screening instead of depending only on laboratory-based analysis," explained Dr Seleke.
A key finding of the study was that nanomaterials produced from natural plant extracts consistently performed as well as, and often better than, chemically synthesised materials during tests on river water samples.
"In simple terms, we found that materials produced using plant extracts created sensors that were more sensitive and reliable under real environmental conditions," Dr Seleke said.
This opens the possibility of developing affordable, portable sensors that environmental agencies and industries can use for rapid on-site screening instead of depending only on laboratory-based analysis."
According to the research, plant-derived compounds help control the growth and surface properties of nanoparticles, improving the movement of electrons within the sensors and increasing their ability to detect pollutants in complex water samples.
From the lab into practice
Dr Seleke, who is currently a research assistant at the NWU, said the long-term goal is to translate the laboratory findings into practical technologies that support routine environmental monitoring.
"I hope this research becomes the foundation for sensor devices that provide rapid and accurate water quality assessment in the field."
"For communities, this means earlier detection of pollution before it reaches harmful levels. For industry, it offers a practical way to monitor wastewater and comply with environmental regulations. For researchers, it demonstrates that sustainable nanotechnology can produce materials that perform at the highest level while supporting greener scientific innovation."
The research also supports the United Nations Sustainable Development Goal 6, which promotes access to clean water and sanitation through improved water quality monitoring and protection of freshwater resources.
Dr Mokole Seleke
