Conference Publications

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Biowaste biorefineries in South Africa: Current status, opportunities, and research and development needs
(2023-12) Sekoa, Patrick T; Chunilall, Viren; Msele, K; Buthelezi, L; Johakimu, Jonas K; Andrew, Jerome E; Zungu, M; Moloantoa, K; Maningi, N; Habimana, O; Swartbooi, Ashton M
As one of the highest carbon-emitting nations, South Africa is working tirelessly to swiftly transition to sustainable technologies in order to strengthen its green economy initiatives. Amongst the technologies that are explored in the scientific and industrial community, biorefineries are seen as the most efficient technologies that can be used to create economic opportunities and will contribute to the advancement of a bio-based economy as they can synthesize diverse industrially-competitive products. Despite their numerous socio-economic advantages, the establishment of large-scale biorefineries in developing nations like South Africa is very scarce. Therefore, it is imperative to address the technological gaps that hinder the growth of large-scale biorefineries and provide practical solutions that could be used to solve these bottlenecks. This work provides a comprehensive review of the development of biowaste biorefinery-based technologies in South Africa. Different biowaste valorization technologies applicable to locally available organic waste streams, and the resulting market-based compounds that can be obtained from these sustainable feedstocks, are reviewed. Finally, the work provides insights into research and development needs (knowledge gaps) that should be explored by scientists and industries, as these technological solutions might propel biorefineries toward industrialization in South Africa.
Cellulose nanocrystals and snail shell-reinforced polyvinyl alcohol bioplastic films: Additive concentration optimization and mechanical properties assessment
(2022-07) Gbadeyan, Oluwatoyin J; Fagbemi, Olajumoke D; Jerome, Andrew E; Adali, S; Glen, B; Sithole, Bishop B
This study focused on modeling and optimization of the concentration of poly (vinyl alcohol) (PVA), cellulose nanocrystals (CNC), snail shell nanoparticles (SSN), and glycerol for the development of bioplastic films. The response surface methodology using Box–Behnken experimental design was used to investigate the effect of the independent parameters (additives concentrations) on the ultimate tensile strength and Young's modulus of fabricated bioplastic films. A varied ultimate tensile strength and Young's modulus with different component loadings was observed, proving the effect of nanoparticles loading effect on the mechanical properties of bioplastic films. The quadratic polynomial model experiment data provided a coefficient of determination (R2) of 0.795 for ultimate tensile strength and 0.732 for Young's modulus, evidencing the fitness of the models to pilot the optimization space. The optimum parameters were PVA (7.820%), CNC (1079%), SSN (1241%), and glycerol (2.657%). The ultimate tensile strength and Young's modulus of 27.2 MPa and 31.2 MPa were obtained for the developed bioplastic film with optimized concentrations of each component. The bioplastic films showed improved thermal stability and degradation. The scanning electron microscopy (SEM) imaging revealed a homogeneous dispersion of SSN and CNC in the matrix, which explained the improved properties observed.
Nanofluids and their application in carbon fibre reinforced plastics: A review of properties, preparation, and usage
(2023-08) Lawal, SA; Medupin, RO; Yoro, KO; Okoro, UG; Adedipe, O; Abutu, J; Tijani, JO; Abdulkareem, AS; Ukoba, K; Sekoai, Patrick T
Renewed call for the replacement of conventional materials with carbon fibre reinforced plastics (CFRPs) in many high-performance applications is responsible for the current wave of research on minimum quantity lubrication (MQL) strategy in machining. Due to their competitive advantages over conventional materials, polymer matrix composites (PMCs) are now attracting the attention, of researchers, especially in the field of machining. Although most manufacturing methods require less machining, precision machining like milling and drilling call for more research inputs. For this purpose, this review article assesses various aspects of nanofluid preparation and its application in CFRPs. Recent scientific reports on nanofluids with a focus on properties, preparation, and application (including respective methodologies) were analyzed, to contribute to the growing database for future research in this field. This review article shows that cutting temperature and cutting force remain the key determinants of surface finish, while tool wear constitutes a major parameter that machining scientists would like to keep under full control by the use of appropriate cutting fluids. Uncertainties around the quality of nanofluids which is scarcely discussed in the literature is raised in this review, while advocating for more research to unravel it. Furthermore, this review article sheds more light on the machining operations of carbon fiber-reinforced plastics using nanoparticle-laden fluids for a safe and sustainable machining experience. Finally, this review assesses the possibility of achieving excellent CFRP processing using a sustainable approach to fill existing gaps identified in literature like wasted cutting liquids, environmental pollution, and exposure of operators to health hazards.
A review of technologies used in handling the acid mine drainage challenge: Perspectives on using green liquor dregs as a sustainable option for treatment of acid mine drainage
(2021-02) Sebogodi, Keolebogile R; Johakimu, Jonas K; Sithole, Bishop B
Acid mine drainage (AMD) is one of the repercussions that result from earth-moving activities around the sulfide-bearing mineral hosts. The detrimental effects associated with this AMD are driven by its characteristics, which include low pH and high concentrations of sulfate and toxic dissolved metals. Traditionally, the prevention and treatment of AMD are achieved by using technologies that use, amongst other, naturally occurring soils and carbonates. However, the continual use of these materials may eventually lead to their depletion. On the other hand, industrial by-products have been proven to occupying land that could have otherwise been used for profitable businesses. Additionally, the handling and maintenance of landfills are costly. In this current trend of a circular economy that is driven by industrial symbiosis, scientists are concerned with valorizing industrial by-products. One such by-product is the green liquor dregs (GLD) from Kraft mills. The neutralizing and geotechnical properties of these wastes have prompted the research pioneers to seek their potential use in handling the challenges associated with AMD. In this review, the formation AMD, trends in technologies for treatment and prevention of AMD are critically analyzed. This includes the feasibility of using GLD as an alternative, promising sustainable material.
Role of cellulose nanofibrils in improving the strength properties of paper: A review
(2021-11) Jele, TB; Lekha, Prabashni; Sithole, Bishop B
The pursuit for sustainability in the papermaking industry calls for the elimination or reduction of synthetic additives and the exploration of renewable and biodegradable alternatives. Cellulose nanofibrils (CNFs), due to their inherent morphological and biochemical properties, are an excellent alternative to synthetic additives. These properties enable CNFs to improve the mechanical, functional, and barrier properties of different types of paper. The nanosize diameter, micrometre length, semicrystalline structure, high strength, and modulus of CNFs have a direct influence on the mechanical properties of paper, such as tensile index, burst index, Scott index, breaking length, tear index, Z-strength, E-modulus, strain at break, and tensile stiffness. This review details the role played by CNFs as an additive to improve strength properties of paper and the factors affecting the improvement in paper quality when CNFs are added as additives. The paper also includes techno-economic aspects of the process and identifies areas that need further research.
Systematic review of WAVE water treatment design software and related technologies
(2023-01) Roopchund, R; Andrew, Jerome E; Sithole, Bruce B
The water treatment industry needs customized solutions. Despite the advancement of water treatment technologies, proposed designs must pass pilot trials before industrial implementation. Technology piloting is costly and time-consuming. Water treatment software tools can optimize processes through simulation to meet the industry's need for rapid process solutions, thus saving time and money. However, not many studies demonstrate the requirements and capabilities of water treatment design software. Hence, this study aims to demonstrate the ability of the Water Application Value Engine (WAVE) software to design a demineralized water production plant for a Biorefinery process. The feedwater data was input in WAVE. The ultrafiltration (UF) and reverse osmosis (RO) process operations were specified, and the required water output was specified. WAVE simulated the process and provided the water quality exiting each process operation. The UF reduced the total suspended solids in the feedwater, while the RO lowered the total dissolved solids, thus reducing the ions by 98.56%. This ion removal ensures that the process equipment is protected from corrosion while yielding a high-quality product in the biorefinery process. Several design warnings were issued, analyzed, and mitigated. The study concluded that WAVE could effectively design and simulate new water treatment processes. Additionally, WAVE can serve as a diagnostic tool to optimize existing water treatment plants. The findings implied that Engineers and Academics could use WAVE to meet the industry’s demand for rapid and accurate process solutions. The reported methodology can serve as an empirical guideline for WAVE and similar software tools.

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