Washing water clean with waste ash from coal
South Africa’s economy and the employment of its citizens rely heavily on the mining sector and the country’s abundance of mineral resources. However, this sector is equally reliant on a resource that remains scarce on the continent – water. The waste generated by industry, and its contamination of water and the environment, are significant ongoing challenges that need to be overcome to ensure the stability and sustainability of the economy and of employment. It is a challenge that has been taken up by Professor Leslie Petrik.
A professor of chemistry at the University of the Western Cape (UWC), she has dedicated the past 10 years to researching water chemistry and effluent remediation in search of a way to change waste into something useful.
“I am a material scientist, so my primary occupation is developing new materials,” says Petrik. “I was working in the chemical engineering department at the University of Cape Town, creating heterogeneous catalysts, specifically zeolites, for different applications. I brought this thread of work with me when I started working at UWC and we discovered that we could convert fly ash into zeolites.”
The discovery was significant. It meant that instead of using expensive commercial chemicals to create catalysis, she and her team could use the waste left over from burning coal to achieve the same goal.
Waste fly ash is the largest solid waste stream in South Africa, and Petrik has developed several patents that reuse this waste to reduce environmental damage. Her patents provide industry with new, low-cost and efficient processes for the reuse of waste fly ash for mine water treatment and building materials, or its conversion into high-value, porous catalytic materials that have impressive applications across various industries.
“We have been applying these catalysts in a variety of ways and have recently moved into other areas, such as electro catalysis and photo catalysis,” says Petrik. “I did my Master’s and PhD studies in electro catalysis, and since then, have developed materials activated by sunlight – through photo catalysis – not heat. This is the greenest route for doing catalysis and it is now forming a significant part of our work. Our goal is to find ways to take the pollutants out of water and find routes to cleaning it effectively.”
Petrik and her team have developed a suite of different nanomaterials that can be applied in water purification, including a nano-iron that works as an agent for advanced oxidation. She is also responsible for the creation of the Environmental and Nano Sciences research group in the department of chemistry at UWC. The group has led the way in the development of technologies and processes that are essential to South African industry.
Through her career, Petrik has been granted three patents, has written 10 book chapters, and has had more than 132 journal papers published. She has delivered 264 conference presentations and has graduated more than 80 postgraduate students. Her research has been supported by notable institutions including, among others, the National Research Foundation, the Water Research Commission and industry partners such as Coaltech Sasol and BiofuelsON.
Petrik is also on several advisory boards, including Eskom’s ash applications steering committee. She is also a member of the steering committee on chemicals and waste management in the department of environmental affairs, and is a member of several steering committees for the Water Research Commission.
“I am motivated by curiosity and the need to explore, to see if I can improve systems or change old ones,” concludes Petrik. “I am also inspired by our students, by helping them to achieve their educational goals and gain t