1. Sustainable Energy and Environment Research Group, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa
2. Clean Coal and Sustainable Energy Research Group, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
3. Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam
4. Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam