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The economic impacts of marine plastic debris in South Africa: A preliminary estimate

(2024-12) Nahman, Anton; Oelofse, Suzanna H; Haywood, Lorren K

Marine plastic debris can affect the delivery of ecosystem services and cause direct damage to affected industries; with resulting impacts on the economy. This paper applies a version of the benefits transfer method to provide a preliminary estimate of the economic impacts of marine plastic in South Africa, in terms of impacts on ecosystem services, direct damage to industry, and clean-up costs. The total economic impact associated with the plastic reaching South Africa's marine environment each year ranges between R3.5 billion and R34.9 billion per year (0.05 to 0.5 % of annual GDP), with a mid-range estimate of R14.1 billion per year (0.2 % of GDP). The cost per tonne of plastic (per year) ranges between R70 635 and R698 186 (mid-range estimate of R282 028 per tonne). The lifetime cost per tonne of marine plastic, in terms of its impacts on ecosystem services over its lifetime, ranges between R3.4 million and R33.8 million per tonne (mid-range estimate = R13.5 million per tonne). The plastic entering South Africa's marine environment each year imposes a total cost of between R169 billion and R1.69 trillion (mid-range estimate = R677 billion) in terms of impacts on ecosystem services over its lifetime. However, there is a need for further research to assess the full set of environmental, social and economic costs and benefits of plastics, of alternatives to plastic, and of various types of intervention strategies; to inform the most suitable strategies for reducing the leakage of plastic waste to the environment.

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Comparative investigation and optimization of cutting tools performance during milling machining of titanium alloy (Ti6Al4V) using response surface methodology

(2024-02) Phokobye, SN; Desai, DA; Tlhabadira, I; Sadiku, ER; Mutombo, Kalenda

The purpose of this paper is to study the optimization of the cutting performance of three different cutting inserts, during the machining operation of titanium alloy (Ti6Al4V) by making use of the response surface methodology (RSM) on a computer numerical control (CNC) milling. The cutting tools employed for the optimisation of the cutting performance during machining operation are silicon, aluminium, oxygen, nitrogen (SiAlON), cubic-boron nitride and carbide cutting inserts. Scanning electron microscope (SEM) was used for the determination of the tool wear for the cutting inserts being compared during machining of Ti6Al4V, and the cutting parameters, which are cutting speed (Vc), feed per tooth (fz) and depth-of-cut that were evaluated from the cutting tools as per the manufacturer’s design specifications. The determination of the tool wear on the cutting inserts was achieved by using the SEM, while the machining operation for the experimental trails was performed from the CNC milling machine, where face milling operation was executed. The optimization process showed that carbide cutting inserts yielded the best performing results and were considered the most significant choice of cutting insert in machining Ti6Al4V when compared to SiAlON and CBN cutting inserts. This choice was from the cutting tool life obtained where a cutting tool life of 29 min was obtained from a use of carbide cutting inserts; 28 min resulted from a use SiAlON cutting inserts and 26 min from a use of CBN cutting inserts. This work finds appropriate value in assisting the machinists in the selection of the best most performing and cost-effective cutting tool.

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Infrastructure in human settlements in South Africa

(2024-07) Gibberd, Jeremy

The purpose of this paper is to present research that develops and tests human settlement infrastructure policy statements as input for a new White Paper on Human Settlements in South Africa. The study develops infrastructure policy statements for human settlements. These are tested through an online survey of human settlement stakeholders. Data gathered through the survey are analysed to provide findings for the study and recommendations for human settlement policy development. The findings indicate that addressing infrastructure in human settlements in South Africa is a high priority. It shows that there is strong support for alternative delivery and operational models, increased involvement of the private sector and communities, innovative financing and the use of sustainable technologies and systems, in the development and operation of infrastructure in human settlements. The study is original as it explores new approaches to addressing infrastructure backlogs in human settlements in South Africa. It contributes new thinking on how the private sector and communities can be involved, alternative delivery models developed, and how sustainable technologies may be applied in addressing these backlogs.

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Development of advanced Pd-Based electrocatalysts for high performing fuel cell system

(Springer Cham, 2024-05) Fuku, Xolile G; Mkhohlakali, Andile C; Maumau, Thandiwe R; Modibedi, Remegia M; Raju, K, K; Makgopa, K; Modibane, KD; Lichfouse, E

The globe is in increased need of non-fossil energy sources due to existing energy limits and global pollution issues. This chapter will discuss fuel cell energy systems as a cleaner and more environmentally friendly alternative energy source. Fuel cells have gotten a lot of press in the twenty-first century because of their potential as an alternate component of energy production. The present barrier of the fuel cell is the high cost of production materials and the manufacturing process itself. The chapter will focus on core practices that can help fuel cells compete with other energy production technologies by reducing costs and improving operational performance. This will entail providing insights into recent breakthroughs in energy materials, with a focus on new approaches or methods of synthesising materials such as platinum group metal and non-platinum group metal electrocatalysts. The electrochemical kinetic processes and catalytic activity of created catalysts, as well as the power outputs of the manufactured membrane electrode assembly in the desired Fuel cell systems, such as proton exchange membrane fuel cell (PEMFC) and Anion exchange membrane fuel cells (AEMFC), will be discussed in further detail in this chapter. Between the two systems, AEMFC is more advantageous over PEMFC because of the tolerance of non-platinum group metal catalysts thus becoming a preferred future system over PEMFC. Hence, AEMFC will be used as a preferred fuel cell system for our application.

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Microstructure and mechanical properties study of Ti-12Mo alloy for biomedical applications

(2024-07) Raganya, Mampai L; Moshokoa, N; Obadele, B; Machaka, Ronald; Makhatha, E

The aim of the work was to study the microstructural characteristics and mechanical properties of Ti-10Mo and Ti-12Mo alloys. The stability of the β phase was predicted using the molybdenum equivalence, average electron concentration ratio, and d-electron approaches. Microstructural examination was conducted using scanning electron microscopy and electron backscatter diffraction, while phase analysis was performed by x-ray diffraction. Uniaxial tensile test machine was employed to conduct tensile tests. The microstructure of Ti-12Mo alloy revealed primary BCC beta (β) phase and some nanoparticles of martensitic α" phase and hexagonal omega (ω) phase precipitated in the β matrix. The precipitation hardening of the ω phase resulted in superior microhardness, tensile and yield strengths. Contrarily, the existence of the ω phase contributed to the brittle fracture that occurred during tensile tests, a higher elastic modulus and lower elastic admissible strain than those of the human bone. Nonetheless, the characteristics and mechanical properties observed of the studied β-type alloy qualify it as a promising candidate for biomedical applications.