Upcycling waste into repurposed value

As a Senior Lecturer and Director of the Research Centre for Synthesis and Catalysis at the University of Johannesburg’s Department of Chemical Sciences, Dr Banothile Makhubela chose her career path because she wanted to be part of defining chemistry in the age of concern about sustainability. She wished to push frontiers and unlock new opportunities for the sustainable production and use of chemicals. 

Her research applies nano- and organometallic-catalysts to convert waste materials such as lignocellulose and carbon dioxide into sustainable chemicals and fuels. Chemical computations are used to understand how carbon dioxide and cellulose feedstocks interact with catalysts while being transformed, providing insights that ultimately support precise, wasteless chemical processes that enhance product yields. 

This research —which touches on catalytic materials design, novel synthetic methodologies and reaction engineering — allows access to sustainable commodity chemicals and fuels prepared using inexpensive, widely accessible feedstocks that otherwise would cause environmental pollution. Thus, waste is chemically upcycled and repurposed to value.

“Through my research, and my students’ work, I hope to demonstrate to manufacturing industries that produce or use chemicals that it’s still possible to improve waste management, and contribute to profitability while doing so,” she says. “For decades, the world’s energy and chemical demand has been met by fossil-based feedstock that’s processed in unsustainable ways. We want to find more sustainable approaches through renewable alternatives, for meeting liquid fuel and chemical demands.” 

For example, one of the products emerging from her research is FuraLev, a sustainable chemical technology that produces levulinic acid, which is used in a variety of applications such as resins, medical imaging and textiles. 

Waste biomass feedstock, in the form of kraft pulp liquor from Sappi, sugarcane bagasse from Tongaat Hulett and Illovo, citrus peels from Onderberg and corn cobs from GrainSA, are used to produce furfural from which levulinic acid can be made. This waste biomass is widely available locally and signs are that it will be available at around R100 to R150 per tonne. At 60-65% yield of furfural from waste biomass, and 70-80% yield of levulinic acid from furfural, preliminary feasibility studies indicate a competitive production cost for levulinic acid. This can feed a market that’s expected to generate $34-million by 2024. 

Highlights of Makhubela’s career include seeing the postgraduate students she mentored go on to make meaningful contributions in their careers, as well as the significant discoveries they have made together. 

“Working in a highly demanding research environment makes it challenging to achieve work-life balance,” she says. “One of our other challenges is securing sustained funding so that we can make meaningful contributions through our research. With South Africa being the largest emitter of greenhouse gases in Africa, thanks to electricity generation and synthetic fuels, the country is certainly in need of practical solutions to its carbon dioxide problem, and there are significant opportunities for us to find ways to address these.” — Kerry Haggard

Read the special Mail & Guardian supplement about all the NSTF-South32 Award winners.