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Thermochemical conversion of lignocellulosic biomass into biofuels and petrochemicals
No full textSubmitted in fulfilment of the requirements of the degree of Doctor of Philosophy in Engineering, Durban University of Technology, Durban, South Africa, 2024.The depletion of conventional fossil fuel reserves, including oil, gas, and coal, has intensified
concerns over environmental sustainability and energy security. Consequently, there has been
a substantial shift towards exploring alternative energy technologies and developing
sustainable products and processes. Biomass has gained significant traction as a renewable
feedstock of interest in recent decades. Bio-oil derived from biomass holds promise for diverse
energy production, chemical synthesis, and potential energy carrier applications. However,
crude bio-oil exhibits inherent challenges stemming from its physical and chemical properties
that preclude its direct integration into existing fuel infrastructures. Notably, the high acidity,
low viscosity, high density, elevated oxygen content, substantial moisture levels, low heating
value, complex molecular composition, and instability. These drawbacks can lead to issues
such as corrosion, coking during upgrading, and difficulties in storage and transport.
Addressing these challenges require advanced refining and treatment techniques to enhance the
bio-oil's compatibility and usability within established industrial frameworks. Hence, studies
that aimed to improve the properties of the bio-oil organic phase were conducted. Initially, the
research embarked on catalytic and non-catalytic fast pyrolysis of Giant Reed using a zeolite
as a catalyst. The results indicated that the presence of the HZSM-5 catalyst significantly
improved the quality of the pyrolysis oil. Catalytic pyrolysis consistently yielded bio-oil with
lower moisture content and higher carbon content than non-catalytic pyrolysis. At 550°C and
10 °C/min, the HHV of the catalytic pyrolysis product was 23.0 MJ/kg compared to 21.3 MJ/kg
for non-catalytic pyrolysis. Applying the HZSM-5 catalyst at 650°C and 50 °C/min
significantly enhanced the production of aromatic hydrocarbons and phenolic compounds
while reducing the presence of undesirable oxygenates in the bio-oil organic phase. However,
this observation was a trade-off to lower bio-oil yields and high energy consumption due to a
high operating temperature. As a result, 550°C and 10 °C/min was considered as the operating
condition for bio-oil organic phase production.
Another sub-study focused on investigating the effect of periodic variations on the fuel
properties of Giant Reed and assessing its influence on pyrolysis product yield, quality, and
distribution. This study was carried out after the incineration of giant reed along the river banks
in Ladysmith, RSA, with the aim of minimizing artificial flooding occurrence as a result of
stormwater drainage blockages. Four periodic variations, late spring (HS-4), late summer (HS1), late autumn (HS-2), and late winter (HS-3), were considered to investigate the effect of characterization, and bio-oil organic phase (BOP) fuel properties. The considered biomasses
herein had average calorific values of 18.86 ± 0.05, 19.73 ± 0.05, 19.23 ± 0.04, and 18.44 ±
0.04 MJ/kg during HS-1, HS-2, HS-3, and HS-4, respectively. The biomass, bio-oil organic
phase, biochar, and pyrolysis gas were characterized using thermogravimetric analysis (TGA),
gas chromatography-mass spectroscopy (GCMS), Fourier transform infrared spectroscopy
(FTIR), micro-GC, and scanning electron microscopy (SEM/EDS). The organic phase of biooil was isolated using a 125 ml separating funnel, allowing natural stratification of the
immiscible phases. BOP yield increased from 5 to 11 wt% during HS-4 and HS-3, respectively.
The increase in the BOP yield correlated with the lignification effect significantly, as shown
by the R2
value of 0.97. Higher heating values (HHV) of the BOP ranged from 19.4 ± 0.03 to
22.6 ± 0.02 MJ/kg in relation to the active growth stage and senescence-dormant phase.
Physical and chemical properties (TAN, density, viscosity, water content, and CHNS) and
chemical compound groups of organic phase bio-oil were analyzed. The produced BOP was
rich in phenolics for all considered periods. The effect of harvest time showed that biomass
and bio-oil organic phase fuel properties are improved during the senescence-dormant period.
As a result, giant reed biomass should be harvested during autumn to avoid incineration that
releases carbon dioxide into the atmosphere and will also reduce the occurrence of artificial
flooding.
Fast pyrolysis of biomass is crucial for sustainable biofuel production, necessitating thorough
characterization of feedstocks to optimize thermal conversion technologies. The third study
investigated the isothermal pyrolysis of bamboo and pinewood biomass in a sand-fluidized bed
reactor to assess biomass suitability for commercial bio-oil production. The pyrolysis products
and biomass species were characterized through proximate and ultimate analyses, GCMS,
FTIR, SEM/EDX, and structural analysis, to assess their chemical and physical properties.
Results indicated that pine bio-oil possesses superior energy density, with a higher calorific
value (20.38 MJ/kg) than bamboo (18.70 MJ/kg). Pine biomass yielded greater organic phase
bio-oil (BOP) at 13 wt%, while bamboo produced 9 wt%. Energy yields were also notable,
with pine exhibiting an energy yield of 15% for bio-oil organic phase (EBOP), compared to
11% for bamboo. The fibrous nature of bamboo biomass resulted in less reacted biomass at
constant reaction time due to flow resistance during pyrolysis. Pine bio-oil organic phase (PBOP) demonstrated a higher heating value (23.90 MJ/kg) than bamboo (B-BOP). The findings
suggest that while both biomass types are viable renewable energy sources, pine biomass is
more favourable for commercialization due to its superior energy properties and efficiency in
pyrolysis. Conventional mild hydrotreatment processes of bio-oil present significant challenges of high
degree of polymerization, low oil yield, high coke formation, and poor catalyst recovery. To
address these challenges, the fourth study looked into investigating and enhancing the
properties of raw bio-oil organic phase samples via a solvent-assisted stabilization approach
using methanol (METH), ethanol (ETHA), isopropyl alcohol (IPA), and ethyl ether (ETH).
Solvents like methanol (METH) and ethanol (ETH), which are highly polar, yielded higher oil
fractions (64% and 62% respectively) compared to less polar solvents like ethyl ether (DME)
at 59%. Isopropyl alcohol (IPA), with intermediate polarity, achieved a balanced oil yield of
63%, indicating its ability to dissolve both polar and non-polar components. The moisture
reduction in stabilized bio-oils followed the order: IPA > ETH > METH > DME, with IPA
showing the highest reduction due to its structural characteristics facilitating dehydration.
Viscosity reduction varied with IPA > ETH > DME > METH. Carbon recovery in stabilized
bio-oils ranged from 65% to 75% for DME, ETH, and METH and was 71% for IPA. The
heating values of stabilized bio-oils ranged from 28 to 29 MJ/kg, with IPA-stabilized bio-oil
showing the highest value (29.05 ± 0.06 MJ/kg). METH demonstrated high efficiency (74.8%)
in stabilizing bio-oil, attributed to its strong hydrogen-donating capability. ETH followed
closely at 69.5%, indicating its comparable performance in bio-oil stabilization. With moderate
efficiency (69.3%), IPA presented a balanced alternative considering its molecular structure
and hydrogen solubility. In contrast, DME exhibited lower efficiency (63.6%) due to its weaker
hydrogenation capability and propensity for undesired side reactions. The study suggested that
subcritical conditions up to 200°C are adequate for METH, ETH, and IPA in bio-oil
stabilization, comparable to results obtained under supercritical conditions.
harvest time on biomass fuel properties, pyrolysis product distribution, non-condensable gas
Effects of concrete quality and natural Johannesburg environment on concrete carbonation rate
No full textThis study presents the results of a project undertaken to study the combined effects of concrete quality (binder type, w/b, and duration of initial moist curing) and natural Johannesburg environment on carbonation rate of concretes containing 100% PC, 35% fly ash (FA), 50% ground granulated blast-furnace slag (BS), 10% silica fume (SF) and (30% BS + 10% SF). The results show that apart from the SF blended concretes, the carbonation rate of the SCM blended concretes are higher than the PC concretes. Reducing the w/b and increasing the duration of initial moist curing reduced the carbonation rate in the concretes. The indoor exposed concretes have the highest carbonation rates and reducing the w/b ratio is more efficient and sustainable in lowering the carbonation rate rather than extending the duration of the initial moist curing
Rhizophora mangle L. leaf biochemical characterization : natural-green total-corrosion inhibition prospect on concrete steel-reinforcement in 3.5% NaCl
No full textEffective corrosion-protection by plant-extract on metals, in aggressive service-environment, is dependent on the biochemical constituents of which the natural plant is made-up. This paper investigates biochemical characterization of inorganic and organic constituents of Rhizophora mangle L. leaf for gaining insight on its steel-reinforcement corrosion mitigating prospect in NaCl-immersed concretes. For the study, atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FT-IR) and phytochemical screening analyses were employed. Total-corrosion effect was also studied from steel-reinforced concrete samples, having different concentrations of the leaf-extract as admixture, and which were immersed in 3.5% NaCl (simulating saline/marine environment). Results, by AAS, showed that Rhizophora mangle L. leaf inorganic constituents were highest in iron, Fe = 10,316.17 μg/g and lowest in cadmium, Cd = 6.2019 μg/g but has neither lead (Pb) nor chromium (Cr). Also, organic constituents, by FT-IR, indicated extract from the leaf constitutes aromatic chained compounds rich in π-electrons as well as sulphur, nitrogen and oxygen-bearing ligands to which iron (steel-rebar) exhibits coordinate affinity. Phytochemical characterization showed that the leaf-extract contains alkaloids, tannins, phlobatannins, saponins, steroids and glycosides. Corrosion-inhibiting prospect testing, using the leaf-extract, indicated reduced steel-reinforcement total-corrosion effects that correlated with the extract admixture concentrations employed in the 3.5% NaCl-immersed steel-reinforced concretes
Primary headaches among students in a South African university
No full textHeadaches are recognised as a common health-related complaint, impacting student attendance and overall productivity. This study determined the prevalence of headaches within a selected group of students and its effects on their health. A questionnaire was administered to undergraduate allied health science students in three selected departments at a university in South Africa. A total of 420 students were invited to participate in the study, of which 314 participated (75% response rate) – 311 students completed the questionnaire. Of these, 27.0% (n=84) did not experience headaches over the previous three months; the remaining 73.0% (n=227) were classified as having had migraine-type headaches (31.2%; n=97), tension-type headache (30.2%; n=94) or cluster-type headache (1.3%; n=04). Students suffering with migraine-type headaches indicated a decrease in capacity and missed classes more frequently compared to students who experienced tension-type headaches and cluster-type headaches respectively. Some of the respondents with migraine-type headaches (53.4%; n=31) did not continue with classes in order to rest. Migraine-type headache sufferers were more likely to take medication than those with other types of headaches (p=0.014). The findings of the study highlight the influence of headaches on students. Health knowledge and access to treatment is highlighted as a simple contributor to reducing headache prevalence and attaining overall health and well-being.</jats:p
Influence of demographics on drivers of, and preference for, digital personal banking in South Africa
No full textThis paper evaluates how the perceptions of consumers from different demographic backgrounds influence their adoption and use of digital personal banking, and suggests marketing activities required to increase digital banking by these different demographic target groups. The method involved an online survey of a sample of 400 respondents with bank accounts in the iLembe district of KwaZulu-Natal, South Africa, focusing on the demographic dimensions of age, gender, education and income. The study found that high digital banking users were older (24+), with higher education and a higher income, while low digital banking users were younger (18-23), with a lower level of education and a lower income. No differences according to gender were found. The convenience of digital banking and a good online banking experience were the factors that most encouraged digital banking use by high users, while perceptions of high cost and having low control over their online banking activities were factors that discouraged low users from more digital banking use. These findings confirmed the previous research about the influence of age and education on digital banking use, but contributed new knowledge about the influence of income, and the lack of influence of gender, on digital banking adoption and use. Comprehensive recommendations for banks, policy makers and other stakeholders are provided
Cause-related marketing and consumer behaviour in the greater eThekweni area
No full textCause-related marketing (CRM) is a marketing strategy in which a company’s name, brand or service is
partnered with a cause or a charity. This type of link has become increasingly popular throughout the
world, presenting economic and social opportunities for businesses. Various research studies in such
first world countries as the United States and the United Kingdom reveal that a large proportion of
consumers are responsive to CRM. One of the objectives of this study was to establish whether
selected socio-demographic factors affect the evaluation of a CRM offer in the eThekweni region of
South Africa. It is anticipated that, its findings will be of assistance to marketers enabling them to make
a more accurate identification as to the responsiveness of various groups to a CRM strategy. A
quantitative study was conducted in shopping malls, using a structured questionnaire administered via
interviews. Results established that there is a relationship between socio-demographic characteristics
and the evaluation of a CRM offer
Improving household satisfaction with government-provided houses in the city of Durban
Get PDFSubmitted in fulfilment of the requirements of the degree of Master of Management Sciences Specialising in Public Administration, Durban University of Technology, Durban, South Africa, 2025.The South African government provides low-cost houses to households whose
combined average monthly income is below R3 500. This is done to promote an
integrated society by developing sustainable human settlements and quality housing
within a subsidy system for different income groups. Nevertheless, occupants
frequently express dissatisfaction with their homes, often citing common complaints
about the subpar quality of these houses. The government spends a lot of money on
constructing these houses, and occupants ought to derive maximum satisfaction. This
study sought to establish possible ways to improve household satisfaction with the
low-cost houses provided by the government. The study adopted a descriptive crosssectional design, collecting quantitative data from 375 occupants of governmentprovided low-cost houses across the city of Durban. The principal component analysis
and probit regression models were then used to estimate the key determinants of
household satisfaction with government-provided houses. The results from the study
are essential for informing public policy on the planning and construction of low-cost
houses. More precisely, the results inform public policy on human settlements.
Evaluation of anti-ageing potential of lemongrass tea and its mechanisms of action
Get PDFSubmitted in fulfilment of the academic requirement for the degree of Doctor of Philosophy in Food Science and Technology, Durban University of Technology, Durban, South Africa, 2025.Ageing is a complex process that involves the loss of physiological integrity and negatively
impacts the well-being of an organism. It is associated with various diseases such as hypertension,
cardiovascular and neurodegenerative diseases. However, the proportion of geriatrics is increasing
globally, and they are susceptible to these diseases. Regrettably, there is no known medication for
managing ageing and its associated complications. One of the plants that is widely consumed as
tea is lemongrass (Cymbopogon citratus) due to its aroma and refreshing taste. Several studies
have reported the pharmacological properties of lemongrass, but there is no information on its
effect on ageing. Therefore, this study investigated the anti-ageing properties of Cymbopogon
citratus (lemongrass) tea using in vitro, in silico and in vivo techniques. Fresh and dry lemongrass
infusions were subjected to proximate, mineral, amino acid, and phytochemical analysis using
Inductively Coupled Plasma Mass Spectrometry (ICP-MS), high-performance liquid
chromatography (HPLC), and Liquid Chromatography – Mass Spectrometer (LC-MS). This was
followed by the determination of the antioxidant, anti-ageing and neuroprotective potentials of the
lemongrass infusion using in vitro methods. Computational techniques, including molecular
docking, molecular dynamics simulation and pharmacokinetic profiling, were employed to probe
the possible mechanism of anti-ageing effects of the lemongrass teas. The in vivo anti-ageing
property of the lemongrass teas was evaluated by including different concentrations of the teas in
the diet of D-galactose-induced ageing in Drosophila melanogaster for 14 days, followed by
determination of both biochemical and molecular parameters. The results showed that both fresh
and dry lemongrass teas are rich in nutrients and phytochemicals. While both lemongrass infusions
have similar neuroprotective effects in vitro, the dry lemongrass infusion exhibited better
antioxidant activities (with lower EC50 values for DPPH, hydroxyl and superoxide radicals), and
these are comparable to the reference standard, gallic acid. It also displayed better anti-ageing
properties (with lower IC50 values for inhibition of collagenase, elastase, hyaluronidase and
tyrosinase) similar to the standard, oleanolic acid. In the in-silico studies, kaempferitrin had the
lowest binding energy for collagenase (-41.57 kcal/mol) and hyaluronidase (-52.09 kcal/mol),
while lonicerin and isovitexin-2”-O-arabinoside possessed the lowest binding energies for elastase
(-35.55 kcal/mol) and tyrosinase (-53.09 kcal/mol), respectively. Kaempferitrin displayed the
highest number of stable interactions with collagenase and hyaluronidase, while limocitrin-7-(6”-
acetylglucoside) and isovitexin-2”-O-arabinoside interacted more with elastase and tyrosinase, respectively. The resulting complexes formed with chamaemeloside (-66.59 kcal/mol),
isocarlinoside (-65.79 kcal/mol), neocuscutoside C (-41.09 kcal/mol), and aspulvinone H (-72.28
kcal/mol) against acetylcholinesterase, butyrylcholinesterase, β-secretase and monoamine
oxidase, respectively, had the lowest binding free energy values compared to the respective
standards. However, benzyl alcohol β-D-rutinoside, kaempferitrin, neocuscutoside C and
aspulvinone H possessed the most stable interactions with acetylcholinesterase,
butyrylcholinesterase, β-secretase and monoamine oxidase, respectively. The D-galactose-treated
flies experienced significant distortion (p ˂ 0.05) in their antioxidant status and enzymes (catalase,
superoxide dismutase and glutathione peroxidase). However, the inclusion of dry lemongrass
infusion in the diet restored all the alterations witnessed in the D-galactose flies. The dry
lemongrass infusion also upregulated the SOD1, CAT and dFOXO genes while downregulating
the DILP2 gene. It can be concluded that both fresh and dry lemongrass infusions are rich in
nutrients and phytochemicals, with the dry infusion displaying better antioxidant and anti-ageing
properties in vitro. This is confirmed by the in vivo studies where the dry lemongrass infusion was
more effective in ameliorating ageing-related complications in Drosophila melanogaster. Though
the phytochemicals present in both teas are similar, they are more abundant in the dry tea, which
may account for its more potent activities. These phytochemicals include lonicerin,
chamaemeloside, kaempferitrin and neocuscutoside C. Consequent upon the outcome of this study,
a ready-to-drink beverage may be developed from the dry lemongrass while its bioactive
compounds are isolated for future drug development.
Towards a multimodal framework for work integrated learning assessments
Get PDFA thesis submitted in fulfilment of the requirement for the Doctor of Philosophy in Library and Information Science, Durban University of Technology, Durban, South Africa, 2025.Work-integrated learning (WIL) is an educational paradigm that allows for the
integration of theory with practice to improve student success. WIL provides university
undergraduate students with the opportunity of going to industry to apply what they
have learnt in the classroom. Successful WIL programmes are heavily depended on
three main stakeholders: the academic institution, the student, and industry. However,
WIL is important because it provides real-work experience; development of mutual
relationships with industry partners and enhances students’ employability. However,
WIL is confronted with multiple challenges among is assessments. The aim of the
study was to develop a multimodal framework for work-integrated learning using
grounded theory (GT). The study had three research questions, namely, how can
multimodal platforms be used to assess work-integrated learning? What is the nature
of the technology used in multimodal work-integrated learning assessments? and what
multimodal framework should be developed for effective work-integrated learning
assessments?
This study applies Grounded Theory to understand the challenges associated with
WIL with particular emphasis on assessment. This study adopted the constructivist
grounded theory developed by (Charmaz 2004; 2014). The constructivist grounded
theory was chosen because of its simplicity in application, though the theory does have
the classical GT themes. Thereafter, the P3 multimodal WIL assessment framework
was developed. The developed framework was validated using user-feedback from
three expert evaluators who had participated in the study using Charmaz (2004)’s
evaluation criteria. Two of the four expert evaluators felt that the P3 multimodal
framework will allow academics to understand and implement efficient WIL
assessments.
The study solicited academics’ views, perceptions, and experiences on multimodal
WIL assessments during the COVID-19 lockdown and after. Participants of the study
were chosen because of being involved with WIL assessments in DUT. Data collection
was mainly face-to-face with two participants opting for online using Ms TEAMS
