Department of Chemical Engineering
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Department Process Engineering now has a new name, and will be known from March 2023, as Department of Chemical Engineering.
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Browsing Department of Chemical Engineering by browse.metadata.advisor "Akdogan, Guven"
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- ItemComparing the environmental impact of different hydrometallurgical processes for the recycling of lithium-ion batteries using a life cycle assessment approach(Stellenbosch : Stellenbosch University, 2024-03) Maritz, Roelof Frederick; Dorfling, Christie; Akdogan, Guven; Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.ENGLISH ABSTRACT: Lithium-ion batteries (LIBs) have become commonplace for everyday use in consumer electronics. These batteries have also gained a lot of popularity recently for usage in larger scale application such as electric vehicles (EV). The LIB market is projected to grow from 700 GWh in 2022 to 4.7 TWh in 2030 (Fleischmann et al., 2023). The consequence of this rapidly increasing demand for LIBs is the formation of a fast-growing end-of-life (EOL) LIB waste stream. This waste stream includes valuable metals such as lithium, cobalt, nickel, and manganese to potentially be recycled, thus providing benefits in terms of waste management and income from the sale of these recovered metals. There is thus a clear need for EOL LIB recycling and a necessity to find out what is the best process technology available to recycle EOL LIBs. Traditionally LIBs have been recycled using pyrometallurgy, but the recent industry focus has shifted towards alternative process technologies such as hydrometallurgy. There is, however, no clear consensus on how these hydrometallurgical flowsheets should be arranged. As such, the purpose of this study was to compare the environmental impacts of implementing different hydrometallurgical process flowsheets designed for the recovery of metals from EOL LIBs. This comparative environmental study was performed using the life cycle assessment (LCA) framework and considered the use of three lixiviants (hydrochloric-, sulphuric-, and citric acid) alongside the use of three flowsheet options (sequential metal precipitation, mixed metal precipitation, and hybrid sequential precipitation - solvent extraction systems). Lastly, the process was modelled based on a mixed feed of LiCoO2, LiFePO4, and NMC111 batteries. The potential environmental impacts of mineral acid-based processes were found to generally be lower than that of organic acid-based processes by 18 to 61 percentage points. Furthermore, mixed metal precipitation provided the greatest environmental benefit of the flowsheet options considered by 46 to 117 percentage points when compared to the closest competitor. The LCA system was subsequently subjected to multivariate uncertainty analysis and a discernability analysis regarding process feed sensitivity which served to confirm the trends already observed. The LCA system was also subjected to a weak point analysis, where the consumption of NaOH and electricity were listed as the main concerns for process improvement. The process solutions recommended to address both weak points involve the integration of membrane technology and antisolvent crystallisation. Furthermore, the LCA system was compared for a South African and a European context, where it was determined that South Africa’s overreliance on hard coal for energy generation is the main difference between the two regions. Finally, the hydrometallurgical EOL LIB recycling processes were subjected to an additional LCA study regarding the use of recycled metals for resynthesizing NMC cathode materials. This additional study showed that integrating the sequential precipitation recycling process with solid-state synthesis of NMC622 cathode could save up to 70% on energy consumption during cathode synthesis. Meanwhile, integrating the mixed NMC precipitation recycling process with the solid-state synthesis of NMC622 cathode could reduce the environmental impact of NMC cathode production by up to 67%.
- ItemIntegrated development and optimisation of an organic acid-based hydrometallurgical process for treatment of spent lithium-ion batteries (LIBs)(Stellenbosch : Stellenbosch University, 2022-04) Jeza, Sabelo Acceptance; Akdogan, Guven; Dorfling, Christie; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH SUMMARY: Lithium-ion batteries (LIBs) are the heart of some of the latest technological devices but these batteries become harmful waste at the end of their life. At present, the use of organic acid-based hydrometallurgy processing of spent LIBs is the most promising alternative route to pyrometallurgical processing in terms of economic feasibility and environmental impact. This study aimed to develop an integrated and optimised organic acid-based hydrometallurgical process for the treatment of LIBs to recover metals at end-of-life. This was achieved by conducting leaching, precipitation and solvent extraction batch experiments in a specific order, followed by flowsheet modelling using experimentally obtained values and techno-economic analysis to assess potential feasibility. Citric acid was selected as the organic acid with which to leach LIBs at a constant temperature of 95 °C, while stirring at 750 rpm, with a S/L ratio of 20 g/L and 2 vol. % H2O2. The effect of lixiviant concentration (0.75 M, 1 M, 1.5 M, 2 M and 3 M) on metal equilibrium extraction was also investigated. The concentration of 0.75 M resulted in equilibrium metal extraction of 94.3% Li, 95.1% Co, 96.2% Mn and 95.7% Ni after 1 hour. Ni was the first metal to be recovered through precipitation from a leachate solution using 0.07 M dimethyl glyoxime (DMG) at a pH of 6, followed by the solvent extraction of Mn using 10% D2EHPA at an O/A ratio of 3 and a pH of 5. Mn was stripped from the organic phase using 0.5 M H2SO4 at an O/A ratio of 1.33 followed by hydroxide precipitation. The aqueous phase from Mn solvent extraction mainly consisted of Co which was precipitated using NaOH at a pH of 13.5. Four process products were recovered: Ni(OH)2 with more than 99.5% purity and 62.7% Ni recovery; Mn(OH)2 with 89% purity and 90.2% recovery; Li2SO4 with 97% purity and 57.3% Li recovery and cobalt hydroxide based product (Co(OH)2) with 68 % purity and 71.4% Co recovery. A feed rate of 868 tonnes per year was used for the flowsheet modelling, based on the South African context in terms of expected LIBs waste, and this resulted in an estimated annual revenue of R190 023 414. The estimated capital expenditure was R162 920 270 and the operating expenditure was R88 148 631. An NPV value of R241 272 740 over a 10-year investment period was discounted at 11.11%, equivalent to a 67.95% IRR, which implies that the process would be profitable upon implementation.
- ItemInvestigation of submerged trommel screen(Stellenbosch : Stellenbosch University, 2022-04) Laker, Chris James; Akdogan, Guven; Bradshaw, Steven Martin; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH SUMMARY: Trommels are investigated as an alternative to drain and rinse vibrating screens for the purpose of dense medium recovery. Iron ore and cyclone 40 atomized ferrosilicon were used to test screen performance on a submerged washing trommel. This trommel consists of two types of chambers, one for medium drainage and two submerged wash chambers to wash adhering medium. The performance of the drain chamber was evaluated with overflow properties such as moisture content, FeSi content and FeSi carryover, by varying medium relative density (RD) between 2.7 and 3.6. The results were compared to past studies on a vibrating drain and rinse screen by Kabondo (2018). The test work was performed on two separate trommel designs, Submerged DMS Trommel (Mk1) and Trommel Mk2. Due to design limitations in the design of Mk1, there was great uncertainty in the results from the first investigation. Mk1’s performance was however highly promising compared to vibrating drain screens. Percentage moisture in the overflow of Mk1 had a maximum of 3.60 % at a medium RD of 3.6, while vibrating screen results ranged between 10.29 % and 27.91 % at lower medium RDs below 2.3. % FeSi in the overflow of the drain chamber of Mk1 ranged between 11.05 % and 18.76 %, while the vibrating screen ranged between 9.71 % and 36.01 %. % FeSi carryover on Mk1 reached a maximum of 4.96 % while the vibrating screen ranged between 3.12 % and 10.46 %. In addition to competitive drainage of trommel Mk1, batch tests performed in the submerged wash chambers of Mk1, combined with bench tests for submerged washing and rinsing, concluded that the most effective washing method was motion of particles within a submerged bath. Efficiency for submerged washing ranged from 84.82 % to 99.7 %, compared to 74.24 % for rinsing of medium. It was justified to design a new test trommel, Mk2, from the learnings of the first campaign. The second trommel (Mk2) was designed with nine different underflow discharges. For the first time in open literature, trommel Mk2 provided insight into material distribution and utilised screen area of a trommel by evaluating these discharges. It was found that 98 % of drainage occurs through the middle and towards the direction of rotation of the trommel. The work on trommel Mk2 was performed at similar operating conditions as Mk1. The results of Mk2 had higher repeatability and statistical significance. Confidence was provided in the results and it was concluded that trommels is a competitive alternative to vibrating drain and rinse screens. Future work will include test work on all remaining operating parameters to develop a complete understanding how these parameters govern the operation of trommels.
- ItemMomentum transfer from Arc to slag bath in an ilmenite smelting DC Arc furnace - a computational analysis(Stellenbosch : Stellenbosch University, 2021-12) Makgoale, Tumelo; Akdogan, Guven; Bogaers, Alfred; Zietsman, Johan; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT: Direct current (DC) arc furnaces are used for a variety of applications, including steelmaking, chromite smelting, ilmenite smelting, and nickel laterite smelting. Understanding the behaviour of DC plasma arcs is essential, as they are central to the operation of DC arc furnaces. The intent of this research project was to study and understand the interaction between the arc jet and slag bath in terms of momentum transfer to assist in furnace design and operation, particularly for ilmenite smelting processes. In an electric smelting furnace, there are a number of driving forces resulting in flow of the molten slag and alloy baths, and which influence the melting rate and temperature distribution. These include carbon monoxide bubbling, electromagnetic forces, arc jetting, and natural convection. The purpose of this research project was to find a computationally efficient and representative modelling method to describe an arc, and use this method to understand momentum transfer from arc to slag bath in DC arc furnaces. The first objective was to identify and investigate modelling methods that have been developed to describe plasma arcs, and to also select the most appropriate method to incorporate the description of an arc into multiphysics models. The criteria for an appropriate model includes: equivalence to arc behaviour, ability to reliably describe the interaction between plasma arc jet and molten bath, computational efficiency, and numerical stability during simulations. A steady-state turbulent gas jet was selected as an appropriate representation of an arc as it is capable of accounting for the thrust generated by an arc, yet is computationally simple enough to be included within a full multiphysics model suitable for furnace design. The second objective was to develop an understanding of the turbulent gas jet modelling method so that it can be applied effectively in simulations to provide an accurate and reliable arc description. A sensitivity study of the various parameters that can be modified when formulating a turbulent jet was performed. The analysis included: jet inlet velocity, gas density and viscosity, inlet nozzle diameter, jet length, as well as arc thrust. The idea was to isolate and highlight which of these parameters have significant influences on the impingement forces, and thereby highlighting which of these parameters should be chosen with care. An important finding from this investigation was the influence of the ρ 1 2 /μ ratio in maintaining Reynolds number equivalence. This approximation allows us to work with lower arc jet velocities without changing momentum transfer rate to the slag bath, while improving numerical stability and reducing computational cost. This investigation also showed that the inlet nozzle diameter has an influence on both momentum transfer to the slag bath and indentation size on the bath surface. Since there is no real physical argument to base the choice of inlet nozzle diameter, this parameter should be chosen with care. The last objective was to perform steady-state pilot plant scale simulations for a DC arc furnace to investigate the impact of furnace design and operating parameters using the turbulent jet approxi- mation as an arc. From these simulations, a 10 kA arc, with a length of 0.2 m, resulted in an average slag bath velocity of 0.0311 m s−1, an average transferred momentum of 3.342 × 10−3 kg m s−1, and a total slag bath kinetic energy of 9.3727 × 10−7 kW h. The results obtained in this study confirm that arc jetting can potentially be a major momentum driver within open bath furnaces, but the exact magnitudes may differ significantly for industrial scale furnaces.
- ItemOptimizing a method for leaching PGMs from simulated spent autocatalyst material using ozone & hydrochloric acid(Stellenbosch : Stellenbosch University, 2024-03) Knight, Marcus Alexander; Bradshaw, Steven Martin; Akdogan, Guven; van Wyk, Andries Pieter; Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.ENGLISH ABSTRACT:Catalytic converters are present in all modern vehicles and contain the PGMs Pt, Pd, and Rh. These PGMs act as catalysts for the oxidation of C, H, and O to CO2 and H2O; and the reduction of NOx to N2, H2O, CO2, and NO. Mining is the primary source of these metals, but much research and development has been conducted into recovery from secondary sources such as e-waste and scrap. Pyrometallurgical methods are most popular for large scale recycling but produce toxic fumes such as sulphur oxides and have a significant electrical requirement. Hydrometallurgical methods show good extraction efficiencies, especially on a smaller scale, but trade the high energy requirements and toxic emissions of pyrometallurgical processes for increased reagent requirements. A need is present for continued investigation into optimizing processes for recovering these PGMs from spent auto-catalysts using more environmentally benign hydrometallurgical methods. The use of ozone as an oxidant in chloride leaching is one option. The gas has a high oxidising potential and is safer and less aggressive when compared to other popular oxidants such as chlorine gas. Therefore, the aim of this investigation was to develop a process for leaching Pt, Pd, and Rh from simulated spent autocatalyst material using ozone and hydrochloric acid. Development of the chosen process was carried out through kinetic and statistical analyses. Experimentation was divided into two stages: Leach 1 and Leach 2. Both leaches were carried out using a Box-Behnken experimental design. The O3 mass flow, initial HCl concentration, and temperature were varied at factor levels of 3.34, 5.01, and 6.68 g/h; 1.0, 3.0, and 5.0 M; and 30, 60, and 90oC respectively. Fifteen runs were conducted with a centrepoint triplicate for each leach. From the results and a statistical analysis, it was concluded that when maximizing the overall PGM extraction the leach was optimized at 5.01 g/h O3, 5.0 M HCl, and 90oC with Pt, Pd, and Rh extractions of approximately 80%, 85%, and 42%. However, at these conditions a significant degree of impurity extraction was observed at 67% and 68% for Al and Mg. Due to the high dependency of Rh and these two impurities on temperature, a desirability analysis determined that adjusting the factor setpoints could potentially facilitate the selective extraction of Pt and Pd (at values >80%) while minimizing the extraction of Rh and impurities. This was the basis for Leach 2. The second leach was conducted at the same O3 mass flows, HCl initial concentrations of 4.0, 5.0, and 6.0 M, and temperatures of 25, 30, and 35oC. The analysis from this leach indicated optimum conditions of 3.34 g/h, 5.0 M, and 25oC. The extractions at these conditions were 64% for Pt and Pd, and Rh, Si, Al, and Mg extractions were 1.3%, 2.6%, 2.8%, and 4.1%. Therefore, the minimization of the Rh and impurity extraction was successful. However, throughout experimentation a decrease in the extractability of the PGMs was observed over time. This is highlighted by the difference in the optimum results for Pt and Pd between Leach 1 and 2, and the similar conditions used to facilitate these extractions. A possible cause of this decrease is the gradual hydroxylation of the PGM oxides as a result of their exposure to humid air. However, further investigation is required to establish exactly what decreased the PGM extractability over time.
- ItemPrediction of burden distribution and electrical resistance in submerged arc furnaces using DEM modelling(Stellenbosch : Stellenbosch University, 2024-03) Baumgartner, Shana Joy; Akdogan, Guven; Reynolds, Quinn; Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.ENGLISH ABSTRACT: This thesis investigates material segregation and its effect on electrical properties in the burden layer of a submerged arc furnace (SAF) used to produce ferrochrome. The study shows some correlation between material segregation and electrical resistance, which affects the efficiency of chemical reactions and energy efficiencies. Efficient control of raw material distribution ensures consistent heating and chemical conversion, maximising the quality and quantity of ferrochrome produced. Controlling electrical resistance is therefore important for optimising power utilisation. Variations in burden layer segregation can result in electrical inefficiencies, affecting energy consumption and manufacturing costs. A discrete element method (DEM) model developed using the LIGGGHTS-PUBLIC® software was applied to study material flow and distribution in the furnace burden, focussing on mechanical interactions influenced by intrinsic properties, interaction parameters, and morphological parameters. A resistance calculation algorithm is used to post-process the DEM results and assess electrical conduction conditions, including electrode-bath and electrode-electrode interactions using the DC circuit approximation method. The study uses cold-flow experimental testing and DEM simulations to characterise and calibrate material properties. Pellets are treated as approximately spherical, while anthracite and quartz particles are more irregular. Photogrammetric studies were conducted on the reductant and flux particles, and a multisphere approach was used to represent their shape characteristics in the DEM models. A base case furnace model was developed using material parameters from literature and experiments, and flow behaviour in the furnace burden was simulated using LIGGGHTS-PUBLIC® to calibrate specific properties such as the coefficient of friction between materials and the rolling friction of pellets. The base case model was then used for sensitivity studies in three key domains: morphological parameters (particle size and shape), intrinsic material properties (density, Poisson's ratio and Young's modulus), and parameters of interaction (restitution and friction coefficients). The model and related sensitivity cases were run using a high-performance computing cluster at the Centre for High Performance Computing in Cape Town, South Africa. The study demonstrates the potential value of DEM in studying material flow dynamics and resistance phenomena in SAFs used for the smelting of ferrochrome ore. The models show distinct particle segregation patterns, especially among anthracite and quartz, alongside walls and in the central delta region. The study suggests that morphological parameters such as particle shape, reductant fractions, reductant density, and particle size had an effect on both the particle segregation and resistance of the burden. The mechanical interaction parameters, such as the coefficient of friction and the coefficient of restitution, did not appear to show any significant correlations. In the current study the furnace geometry did not appear to show any significant effect on the resistance. Electrode length changes were examined and had a strong influence on resistance, although the segregation behaviour remained largely unchanged. Understanding the relationship between material segregation and electrical resistance is potentially an important factor for reliable and economical ferrochrome production methods. The introduction of DEM modelling provides an opportunity to gain a deeper understanding of material movement and electrical interactions within the furnace burden layer, and this insight may help with adapting to changes in the available raw materials and enhancing furnace productivity and efficiency.
- ItemSelective recovery of metals from citric acid leach solutions during the recycling of lithium-ion batteries(Stellenbosch : Stellenbosch University, 2022-04) Punt, Tiaan; Akdogan, Guven; Bradshaw, Steven Martin; van Wyk, Andries Pieter; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH SUMMARY: Recycling has become an imperative part of the lithium-ion battery (LIB) life cycle due to growing demand for energy storage in applications like electric vehicles and renewable energy technologies, as well as government legislations requiring the recycling of LIBs to reduce environmentally harmful waste. LIB recycling processes must therefore aim to provide a secondary source for strategically scarce metals, like lithium and cobalt, while seeking to reduce the environmental impact of LIB waste. This project aimed to develop a hydrometallurgical process based on environmentally-friendly reagents to recover manganese, lithium, cobalt, and nickel in separate product streams from end-of-life lithium-ion batteries. Organic acids are effective lixiviants in hydrometallurgical recovery of metals from scrap LIBs, having the added benefit of being more environmentally benign than mineral acids. Among these organic acids, citric acid exhibits similar extraction performance when compared to mineral acids. Leaching LiCoO2 (LCO) and LiNixMnyCozO2 (NMC) cathode powder following dismantling and aluminium removal with 1.5M citric acid, 2 vol.% H2O2 at 95°C and 20 g/L for 20 minutes, achieved 93% Al, 90% Co, 96% Li, 94% Mn, and 94% Ni dissolution, confirming citric acid’s performance as lixiviant. A combination of solvent extraction and precipitation technologies was then used to sequentially separate cobalt, lithium, manganese, and nickel from the citric acid leach solution. A diverse range organic extractants, namely: Versatic 10, Cyanex 272, PC-88A, D2EHPA, LIX 84-IC, LIX 984N-C, TBP, Alamine 308, Alamine 336, and Aliquat 336TG was screened to determine which metals can be selectively separated from the citrate leach solution. It was concluded that manganese and residual aluminium are best separated from the PLS under strong acidic conditions with D2EHPA, after which lithium can be separated under weak acidic conditions with D2EHPA in a second subsequent extraction. The cobalt and nickel were separated poorly by the organic extractants and would thus be separated by precipitation from the lithium extraction raffinate. The first separation of manganese and trace aluminium was optimized with 12 vol.% D2EHPA in kerosene at a pH of 2.5 and O/A ratio of 2 when using 3 counter current stages, which separated 99.9% Mn and 80% Al from the PLS. The co-extraction of other metals under optimum conditions was determined to be 7.7% Co, 12.1% Li, and 4.9% Ni. Comparable stripping performance was achieved with sulphuric acid and citric acid from the loaded organic and thus citric acid was chosen as stripping agent. Optimal stripping of the aluminium and manganese loaded organic was achieved with 1.5M citric acid at an A/O ratio of 2, where 78% Mn and 20% Al was stripped in a single stage. The novel second, sequential extraction separated 93.6% Li to a reversible 3rd phase under weak acidic conditions where the optimal lithium separation was achieved with 23 vol.% D2EHPA in kerosene at a pH 5.5 and O/A ratio of 4 with 3 counter-current stages. The co-extraction during the optimum lithium separation included 6.6% Co and Ni. The lithium loaded 3rd phase and diluent emulsion was selectively stripped with 1.5M citric acid and an A/O ratio of 1 to recover 71% Li with 24% Co and Ni in one stage. Optimal nickel precipitation from the lithium extraction raffinate using DMG was achieved with a Ni/DMG ratio of 0.2 at a pH of 8, which enabled 98.5% Ni precipitation with 20% Co co-precipitation. The final effluent from the process had a 96.1 wt.% cobalt purity (metal basis) in the aqueous phase. This hydrometallurgical process was therefore capable of effectively separating the LIB metals from an organic acid PLS to individual metal product streams.
- ItemUse of alkaline pre-treatment with cyanide and glycine to extract gold from tailings(Stellenbosch : Stellenbosch University, 2022-04) Nwagboso, Oluchi Esther; Tadie, Margreth; Akdogan, Guven; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH SUMMARY: In South Africa, particularly in the Witwatersrand area where mining has occurred since 1886, there has been a decrease in high–grade, free milling ores. Additionally, due to the long and lucrative history of mining there is an abundance of tailing dams. Several of these have caused environmental and social issues such as acid mine drainage and the occupation of land that has commercial potential. Therefore, the prospect of processing tailings has become of both environmental and economic interest as it may be less expensive to process the tailings that are already above ground. The possibility of recovering gold from a tailings heap was considered in this study. A mineralogical characterisation of the tailings was performed to comprehend the size, associations, and occurrence of the gold. Fire assay gave a gold grade of 0.208 g/t and 0.804 g/t for the low–grade and high–grade tailings, respectively. Whilst the X-ray diffraction and scanning electron microscopy displayed silicates were the most abundant mineral phase in the tailings. The outcome of the characterisation informed the selection of the methods of extraction of the gold from the tailings. Firstly, direct cyanidation as the most common method for the extraction of gold from most ores, was conducted on the two tailings groups. A 24-hour leach using 2 kg/t NaCN, 60% pulp density at pH of 11 resulted in an average of 40% and 67% gold dissolution for the low–grade and high–grade tailings respectively. Alkaline pre-treatment experiments were carried out using sodium hydroxide to break down the silicate matrices that encapsulating the microscopic gold. Leaching tests were performed to determine the rate and extent to which gold could be leached at different conditions. Following a six-hour leach period using 2 M sodium hydroxide at 80 °C, a 20% increase in gold recovery was observed. Further increase in sodium hydroxide concentration led to decrease in the gold dissolution. Secondly, tests were conducted to assess the use of glycine as a lixiviant for gold from tailings. Potassium permanganate was found to be effective as an oxidant in the gold-glycine leaching system. Gold was leached at ambient conditions, however, increased temperature proved to be essential for the process. Glycine concentration was found to be statistically significant to gold dissolution. At high glycine concentrations and elevated temperatures there was possible formation of polypeptides. Up to 52.3% gold dissolution was achieved using 0.05 M glycine solution at 60°C and 30% pulp density with 1 g/L KMnO4 as an oxidant. Preliminary techno-economic modelling and a sensitivity analysis showed that, in a brown stone field operation, using both an alkaline pre-treatment before cyanidation as well as glycine as an alternative lixiviant could be economically feasible and profitable endeavours.
- ItemUV degradation of bioplastics and conventional plastics in the marine environment(Stellenbosch : Stellenbosch University, 2023-03) Mzabane, Ondela; Akdogan, Guven; Chimphango, Annie Fabian Abel; Dorfling, Christie; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH ABSTRACT:In the modern era, there has been a significant increase in the production of and demand for conventional plastics. Increased plastic use is a serious concern for the world. This is because of the accumulation of plastic in the marine environment, which leads to negative impacts on the marine ecosystem. In the marine environment, plastics are exposed to ultraviolet (UV) radiation, temperature changes, physical stress, salinity, and oxidation. Therefore, a key strategy to address this issue is to actively promote and develop biodegradable plastics in efforts to address and alleviate plastic pollution in the marine environment. The study aimed to investigate and compare physical and chemical degradation between bioplastics and conventional plastics to micro-plastics in the marine environment, with little or no microorganism effects. Three different plastics were investigated: polypropylene (PP), polyethylene terephthalate (PET), and polylactic acid (PLA). All plastics were 4 cm × 10 cm in size. Plastics were exposed to two treatments in different environments: (i) a dry UV pretreatment (in air) of neat plastics at two UV irradiances (65 and 130 W/m2 ), and (ii) artificial seawater tests under the same UV conditions. Each run commenced for four weeks, during which UV radiation was cycled for a total of 24 hours: 12 hours on, and 12 hours off. Sampling took place every seven days for further analysis. For signs of degradation, changes in mass loss, carbonyl index, percentage crystallinity, hardness, and morphology were tracked. Results from UV pre-treatment tests showed that in air, high UV irradiation (130 W/m2 ) resulted in more degradation compared to low UV irradiation (65 W/m2 ). Polypropylene was more susceptible to degradation than polyesters (PET and PLA). Degradation in seawater was slow for all plastics. There was a decrease in most properties of seawater compared to the pretreatment tests. This is because, in seawater, the degraded surfaces from the pre-treatment may have been washed away, exposing new surfaces. This investigation showed that the degradation rate is temperature-dependent, and processes in the ocean are slowed down because seawater is a good heat sink. Polylactic acid was the least responsive plastic to UV degradation in both environments.