Browsing by Author "Oyetade, Joshua"

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Application of Magnetic Surfactants in Nanoparticle Fabrication
(ACS Publication, 2023-08-28) Ademola, Ebenezer; Oyetade, Joshua; Adeeyo, Adeyemi
Magnetic nanoparticles (MNPs) are a group of nanoparticles made from a magnetic material such as iron, chromium, manganese, cobalt or nickel and a chemical component that exhibit superparamagnetic properties. They have a wide range of applications in medicine, wastewater treatment and bioremediation, food industries, and molecular biology, among others, due to their size effects, surface-to-volume ratio, interaction, magnetic separation, specificity, and surface chemistry. However, the incorporation of amphiphilic surface active agents called surfactants into MNPs to serve as capping, structure-directing, ion-exchange, oxidation, and reduction agents is known to affect MNPs physicochemical properties including size, shape, dispersability, stability, surface charge, biocompatibility, optical properties, thermal properties, selectivity, cellular uptake, magnetic energy, functionality, and applicability. Thereby increasing their applications in drug delivery, cancer therapy, biosensors, diagnostic testing, bioimaging, water treatment, enhanced oil recovery, catalysis, energy storage, and information storage. This chapter addresses the mechanisms of synthesis of Magnetic Surfactant Nanoparticles (MSNPs), the roles of surfactants in MNPs fabrication, the influence of surfactants on the properties of MNPs, comparative performances and applications of MSNPs, cost analysis and future prospects, and likely challenges.
Development of photocatalytic semiconductors and nanocomposites with excellent optoelectronic and electrochemical properties for dye effluent remediation -A review
(Elsevier, 2024-12) Oyetade, Joshua; Van Hulle, Stijn; Machunda, Revocatus; Hilonga, Askwar
Myriads of photocatalytic semiconductors and their corresponding nanocomposites have been investigated for the remediation of toxic dye molecules in textile effluent however, notable challenges are reported of their performance. These challenges are based on the optoelectronic and electrochemical features that precede their photocatalytic performance in dye effluent remediation. Thus, the need arises to investigate the development of state-of-the-art photocatalytic semiconductors and their composites fabricated with excellent optoelectronic and electrochemical features having proficient activities under visible photon irradiation. The study focused on vital optoelectronic and electrochemical features needful for the development of high-performance photocatalysts under a green photon source. It also provides concise synthetic and composite fabrication approaches aimed at developing photocatalytic semiconductors with these properties. The report presents various doping processes and introduction of elements into the structural lattices of the semiconductors while equally offering a recent approach to developing nanocomposites with heterostructures. The review evaluated bandgap modification, separation of charge carries, structural defects and mobility concerning the investigated process. The study was able to present an inorganic doping technique with intercalated nitrogen, codoping and nanocomposite fabrication as the versatile and industrially scalable approach for the development of high-performance photocatalytic semiconductors.
Development of ternary PANI/GO-Fe3O4@AgNps nanocomposites for photocatalytic remediation of toxic dye effluent under energy-efficient system
(Elsevier, 2025-03) Oyetade, Joshua; Van Hulle, Stijn; Machunda, Revocatus; Hilonga, Askwar; Buysser, Klaartje
The environmental toxicity of effluents contaminated with synthetic industrial dyes and their resistance to conventional treatments drive the need for developing innovative treatment technologies such as visible photoactive catalysts in a photocatalytic system. In this study, novel nanocomposite photocatalysts were synthesized for photocatalytic remediation of toxic dye effluent under energy-efficient Light Emitting Diode (LED) irradiation. Concise instrumental analysis was used to investigate the morphological, functional, particle size, thermal and optoelectronic features of the developed photocatalytic nanocomposites. Their performance was tested with cationic (methylene blue) and anionic (methyl orange) model dyes. The instrumental elucidation reveals the coating of amorphous polyaniline with other composites, giving the blend rapid reactivity, which promotes photocatalyst-dye interaction. The composites exhibit lowered bandgap (2.66 eV, 2.85 eV and 2.27 eV) when compared to polyaniline (3.34 eV) used as macromolecular support via in situ coupling. This accounts for the efficiency of 95 % and 98 % reported for methylene blue and methylene orange, respectively, at optimal experimental conditions of 90 min irradiation time, pH of 5 and dosage of 20 mg/100 mL dye effluent. The study also proposed a Z-scheme mechanism with the vital role of •O2 –, •OH and h+ reactive species in the photodegradation of the dye molecules.
Fenton-mediated solar-driven photocatalysis of industrial dye effluent with polyaniline impregnated with activated TiO2-Nps
(Elsevier, 2024) Oyetade, Joshua; Machunda, Revocatus; Hilonga, Askwar
Various integrated technologies have been investigated for the remediation of heavily polluted industrial dye effluent. Also, more than 70 % of these dyes are known to be solely azo dyes used in the textile industry with 5–30 % presence in the effluent as loose dye molecules which are recalcitrant to treatment. These challenges led to the investigation of energy-efficient processes (solar) and the fabrication of high-performance nano-photo- catalysts for proficient photocatalysis of dye effluent while mediating the process with Fenton reagents. The study fabricated nanopolymeric catalyst composites (P-AKT) via novel in situ coupling and impregnation of the polyaniline (PANI) with surface-activated TiO2 NPs. This fabrication is aimed at developing a high-performance catalyst with rapid and proficient photocatalytic activities to photons from sunlight irradiation. The photo- catalytic process was mediated using a novel Fenton reagent to enhance the generation of radical species for dye degradation. Various instrumental characterization methods were used to study the structural, molecular, elemental, functional and optoelectronic properties of the fabricated nanocomposite photocatalysts. The result reveals functional groups aiding dye-catalyst bonding and morphological interaction reveal a surface-activated tetragonal crystalline mixture of anatase and rutile from TiO2 Nps embedded in the macromolecular chain of PANI. It also reveals the optimal conditions of 20 mg dosage, 10 mg/L initial concentration with substantial effectiveness at pH of 5 and 7. However, the most efficient photocatalyst recorded was P-AKT-2 % and P-AKT-3 % having 95 % and 94 % efficiencies at 90 min of solar irradiation. The photocatalyst equally demonstrated its capacity for effluent treatability up to 4 cycles of use
Functional impacts of polyaniline in composite matrix of photocatalysts: an instrumental overview
(Royal Society of Chemistry, 2023-05-22) Oyetade, Joshua; Machunda, Revocatus; Hilonga, Askwar
The challenges associated with photocatalysts including their agglomeration, electron–hole recombination and limited optoelectronic reactivity to visible light during the photocatalysis of dye-laden effluent make it necessary to fabricate versatile polymeric composite photocatalysts, and in this case the incredibly reactive conducting polyaniline can be employed. The selection of polyaniline among the conducting polymers is based on its proficient functional impacts in composite blends and proficient synergism with other nanomaterials, especially semiconductor catalysts, resulting in a high photocatalytic performance for the degradation of dyes. However, the impacts of PANI in the composite matrix, which result in the desired photocatalytic activities, can only be assessed using multiple characterization techniques, involving both microscopic and spectroscopic assessment. The characterization results play a significant role in the detection of possible points of agglomeration, surface tunability and improved reactivity during the fabrication of composites, which are necessary to improve their performance in the photocatalysis of dyes. Accordingly, studies revealed the functional impacts of polyaniline in composites including morphological transformation, improved surface functionality, reduction in agglomeration and lowered bandgap potential employing different characterization techniques. In this review, we present the most proficient fabrication techniques based on the in situ approach to achieve improved functional and reactive features and efficiencies of 93, 95, 96, 98.6 and 99% for composites in dye photocatalysis.
Green synthesis of silver silver chloride (Ag/AgCl) nanoparticles using macadamia nutshell xylan extract, characterization and evaluation of its antibacterial activity
(Discover Nano, 2025-07-26) Yegon, Andrew; Oyetade, Joshua; Mtavangu, Stanslaus; Rwiza, Mwemezi; Machunda, Revocatus
Currently, there is unprecedented emergence of antimicrobial resistant (AMR) bacteria which demand urgent development of novel strategies to combat bacterial infections in humans. In this study, we report on a facile and eco-friendly green synthesis of silver-silver chloride nanoparticles (Ag/AgCl-NPs) using macadamia (Macadamia integrifolia) nut-shell (MNS) agro-waste. The effects of physicochemical parameters including pH, Ag ion precursor concentration, time, and temperature were investigated. The biosynthesized Ag/AgCl-NPs sample was characterized using ultraviolet visible spectroscopy (UV–Vis), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, field emission scanning spectroscopy (FE-SEM), Transmission electron microscopy (TEM), and energy dispersive X-ray (EDX). UV–Vis spectroscopy exhibited surface plasmon resonance (SPR) between 420 and 446 nm typical for silver nanoparticles (AgNPs). FT-IR spectroscopy provided an insight of the phytochemicals responsible for the reduction of Ag+ into Ago and capping/stabilizing the formed Ag/AgCl-NPs. XRD spectroscopy revealed the formation of crystalline Ag/AgCl-NPs with characteristic peaks at around 38.3°, 44.1°, 64.6°, and 77.5° for AgNPs, and 28.9°, 31.9°, 45.4°, 56.3°, and 66.1° for AgCl NPs. FE-SEM spectroscopy exhibited spherical and block like morphologies of agglomerated Ag/AgCl-NPs. TEM illustrated polydisperse spherical shapes of Ag/AgCl-NPs with average particle sizes of 31.11 nm. EDX confirmed the presence of Ag and Cl elements confirming the formation of Ag/AgCl-NPs. The antibacterial activity of the green synthesized Ag/AgCl-NPs was performed using disc diffusion method and the zone inhibition (ZOI) evaluation showed their effectiveness against Gram negative (E. coli) and Gram positive (S. aureus).
Investigation of functional performance of treatment systems for textile wastewater in selected textile industries in Tanzania
(IWA Publishing, 2023-02-01) Oyetade, Joshua; Machunda, Revocatus; Hilonga, Askwar
Textile industrialization is an integral part of the economic growth in Tanzania. However, the corresponding wastewater from textile treat ment processes consists of dyes and auxiliaries associated with acute toxicological impacts. This necessitates an investigation of the functional performance of the industrial treatment systems used before effluent discharge. The study primarily accesses the catalog of indus trial dyes and the functionality of the treatment system at Arusha, Morogoro and Dar es Salaam vis-à-vis the effluent physicochemical properties. The analytical study reveals disperse (42%), vat (34%) and reactive (26%) as the most used industrial dyes. The physicochemical properties of the quantified wastewater reveal a significant amount of and phosphorus which was consequent to the high turbidity, bio chemical oxygen demand (BOD) and chemical oxygen demand (COD) apart from the color at the different sampling points. Although the treatability of the wastewater was 90% efficient using an activated carbon system (237.33 + 0.67 mg/L). Similarly, the use of aerated con structed wetlands shows efficiency in the remediation of the recalcitrant having a value of 12.13 + 0.89b mg/L (90%) and 13.22 + 0.15a mg/L (94%). Thereafter, needful recommendations were suggested based on the physicochemical properties of the textile wastewater and to improve the functionality of the treatment systems in the respective industries.
Mitigation of Fluoride Contamination in Drinking Water Supply Sources by Adsorption Using Bone Char: Effects of Mineral and Organic Matrix
(MDPI, 2024-10-20) Ibrahim, Mohamed; Oyetade, Joshua; Dalhatou, Sadou; Nikiforov, Anton; Leys, Christophe; Hilonga, Askwar
This study focused on fluoride (F−) contamination of water sources in Bahimi village, Cameroon. After the first investigation, results revealed that all water samples collected had elevated concentrations of fluoride ions (2.3 ± 0.1) mg/L to (4.5 ± 0.2) mg/L above the WHO guidelines (less than 1.5 mg/L). To mitigate the F− levels, the use of bone char (BC) as an adsorbent material was proposed and its performance was tested. BC was prepared from bovine bones at different calcination temperatures (350 °C, 450 °C, 550 °C and 650 °C) and residence times (1 h and 2 h). The prepared materials were characterized in detail by SEM/EDS, BET, FTIR, and XRD. The BET findings indicated that the surface area of BC samples decreased with increasing calcination temperature and residence time. At a lower heating temperature and holding time (350 °C, 1 h), the prepared BC exhibited a higher specific surface area (112.3 ± 0.3) m2/g and adsorption capacity for F− in the sampled water. Also, the batch adsorption experiments showed that the optimized adsorbent dose of 8 g/L facilitates the reduction in the F− level of the sampled water below the acceptable limit level (1.5 mg/L) within 5 min of treatment. The presence of Ca2+ and Mg2+ in natural water has a positive effect on the removal of F− in BC resulting in a high adsorption performance range of (72.5 ± 1.4)% to (80.3 ± 0.6)%. It was found that the adsorption of Ca2+ on the BC surface occurs via cation exchange with Na+. However, an increase in dissolved organic carbon (DOC) in the treated water limited the application of BC. Overall, the study presented a cost-effective adsorbent for the removal of this recalcitrant ion in the water source.
Performance evaluation of in situ Fenton-mediated photocatalysis of industrial dye effluent with enhanced TiO2 nanoparticle
(IWA Publishing, 2023-05-17) Oyetade, Joshua; Hilonga, Askwar; Machunda, Revocatus
Effluents resulting from the frequent use of industrial azo dyes in textile operations have posed great toxicological impacts on man and the environment. The limitations of conventional treatment infrastructure necessitate the use of rapid Fenton-mediated catalytic systematic pro cess to tackle the attendant treatment limitations. The study applied in situ Fenton-mediation process with constructed low power UV-LED reactor for rapid catalytic treatment of dye-laden effluent using enhanced acid and alkali TiO2-nanoparticles (Nps) (1–5%, i.e. 1–5 M) at definite experimental conditions, respectively. A comprehensive instrumental study was done to access the morphological, functional and elemental constituents of these nanocatalysts. The performance of the respective catalyst was evaluated using methylene blue (MB) dye at definite experimental conditions of pH, dosage, concentration and irradiation time. The results revealed a mesoporous structural nanocatalyst with increasing surface area after enhanced modification. The optimal experimental conditions of pH and concentration were recorded as 5 and 10 mg/L, respectively; while the most efficient nanocatalyst was 3 wt% alkali-modified TiO2 (3% Ak-TiO2) having a degradation efficiency of 89.15% at 90 min of irradiation using 50 mg dosage in contrast to higher irradiation time and catalyst dosage for other catalysts.
Photocatalytic degradation of azo dyes in textile wastewater by Polyaniline composite catalyst-a review
(Elsevier B.V., 2022-09) Oyetade, Joshua; Machunda, Revocatus; Hilonga, Askwar
Azo dyes in industrial textile and dye effluent (5–30%) have become irresistibly recalcitrant and toxic to both treatments and the environment respectively. Global concerns about the persistent nature of these dyes and the limitation of the conventional treatment currently in place have led to this critical analysis and evaluation of the photocatalytic approach using nano-technology. The review of literature has indicated that although this approach is effective, however, the limitation of frequent electron-hole recombination during the process coupled with challenges of agglomeration of nano particle powder, photo-corrosion and photosensitivity of the various nano-materials are still challenges associated with the development of polymeric based nano composite catalyst of polyaniline (PANI). The unique features of incredible charge transport properties, surface morphology and enhanced functional properties gave PANI the choice of use among other conductive polymers for composite fabrication with materials such. Photoactive properties, conductivity mechanical, thermal and chemical stability equally offers the polymer the propensity of bandgap tunability when in composites with other materials. Consequently, effective recovery and reuse of the composite catalyst for more than four runs with efficiency > 90% becomes obtainable. These appreciable advantages offer fabricated nano composite polymeric-based catalysts an effective outlook of use in the remediation of toxic azo dyes industrially as compared to the bio-catalyst and pure nano adsorbent materials. Therefore, the review discusses the treatment process for azo dyes, fabrication and performance evaluation of improved composite catalyst of PANI as an alternative to the conventional catalyst in wastewater and recommends for further investigation in PANI to enhance treatability of azo dyes.
Photocatalytic remediation of selected emerging organic pollutants in industrial effluent using conducting polymeric-based nanocomposites photocatalysts -A review
(Elsevier, 2025-11-15) Oyetade, Joshua; Oluwafemi, Kolajo; Hammond, Vanessa; Boateng, Angela; Machunda, Revocatus; Hilonga, Askwar
Emerging organic pollutants in industrial effluents pose huge environmental and health challenges, with conventional effluent treatment methods often insufficient for effective abatement of these toxic pollutants. This is the rationale behind the need for the development of a novel class of photocatalysts known as conducting polymeric-based nanocomposites for proficient photocatalytic remediation of these pollutants. The pollutants of interest in this review are the pharmaceutically active compounds (PhACs), pesticides and per- and poly-fluoroalkyl substances (PFAS) with appreciable presence in industrial wastewater. The review comparatively reported various state-of-the-art engineering approaches for the fabrication of this class of nanocomposite photocatalysts with well-tailored properties for high-performance especially under visible photon irradiation. The findings identified in-situ polymerization, hydrothermal methods and facile decoration as proficient approaches for the development of this class of novel photocatalysts with over 90 % photocatalytic performance. The study also underscored the concise impacts of the conducting polymers especially their ability to serve as structural support thereby preventing possible leaching of other photocatalytic materials, especially metals. The review also presents the appreciable benefits of lowered agglomeration and efficient separation of electron-hole pairs and unique heterostructures formed due to the synergistic effect of the macromolecules with other materials in the nanocomposite. These attributes point to the stability and recyclable potentials of these fabricated photocatalysts and their versatile applicability for the remediation of targeted EOPs in wastewater.
Process modeling and optimization of photocatalytic treatment of dye-polluted effluent using novel polyaniline/graphene oxide-Fe3O4-Ag nanocomposites
(Elsevier, 2024-12-01) Oyetade, Joshua; Hulle, Stijn; Hammond, Vanessa; Boateng, Angela; Machunda, Revocatus; Hilonga, Askwar
This study developed a novel photocatalytic nanocomposite via in situ polymerization with 3 % blend of graphene oxide (GO), magnetite (Fe3O4) and silver nanoparticle (Ag-Nps) from AgNO3. Also, the process applied a new Fenton mediative approach for efficient abatement of toxic dye molecules in textile effluent under an energy-efficient source. The research focused on modeling and optimizing photocatalytic degradation of methylene blue dye (10 mg/L), using the most influencing variables such as pH (3–7), photocatalyst dosage (10–30 mg/100 mL) and irradiation time (20–90 min). The study demonstrated high photocatalytic efficiency for a 2.27 eV bandgap photocatalyst under 18 W visible LED light irradiation. The selected statistical model at optimized conditions allowed effective treatment of heavily polluted dye effluent from the flax textile industry, assessing efficiency via physicochemical property changes. The result suggested the selected quadratic model whose value of R2Adjusted was close to R2predicted with good correlation and reliability. All experimental variables via the analysis of variance were statistically significant (p-values <0.0001), with irradiation time and photocatalyst dosage having the greatest interactive influence on dye-effluent photocatalysis. Also, the optimization of the response gave an efficiency of 96.10 % which was validated by 5 repetitive experimental runs having an efficiency of 95.8 % ± 0.05 at selected optimized conditions of 79.24 min, 5.25 pH and dose of 21.76 mg/ 100 mL effluent. Thereafter, at the optimized conditions and 360 min of irradiation, 95.99 % dye effluent treatment were achieved. Thus, the study presents versatile industrial photocatalysts for treating heavily polluted dye effluent.
Recovery of precious metals from processed wastewater: conventional techniques nexus advanced and pragmatic alternatives
(IWA Publishing, 2023-06-01) Adeeyo, Adeyemi; Bello, Olugbenga; Agboola, Oluwatobi; Adeeyo, Rebecca; Oyetade, Joshua; Alabi, Mercy; Edokpayi, Joshua; Makungo, Rachel
The loss of highly sought-after metals such as gold, silver, and platinum during extraction processes not only constitutes a significant waste of valuable resources but also contributes to alarming environmental pollution. The ever-growing adverse impacts of these highly valued metals significantly increase the contamination of water bodies on discharge, while reducing the reusability potential of their corresponding processed wastewater. It is, therefore, of great interest to identify pragmatic solutions for the recovery of precious materials from processed water. In this review, pollution from targeted precious metals such as gold, silver, platinum, palladium, iridium, ruthenium, and rhodium was reviewed and analyzed. Also, the hazardous effects are elicited, and detection techniques are enumerated. An insightful approach to more recent treatment techniques was also discussed. The study reveals nano- and bio-sorption techniques as adoptable pragmatic alternatives, among other techniques, especially for industrial applications with merits of cost, time, waste management, and eco-friendliness. The results indicate that gold (46.2%), palladium (23.1%), platinum (19.2%), and silver (11.5%) are of utmost interest when considering recent recovery techniques. High yield and cost analysis reduction are reasons for the observed preference of this recovery process when considering groups of precious metals. The challenges and prospects of nanomaterials are highlighted.
Tuning water chemistry for the recovery of greener products: pragmatic and sustainable approaches
(Royal Sociaty of Chemistry, 2023-02-17) Adeeyo, Adeyemi; Oyetade, Joshua; Adeeyo, Rebecca; Samie, A; Makungo, R.
The early techniques for recovery of bioactive metabolites involve conventional cold or hot solvent extraction.1 The choice is a function of the nature of the bioactive compound of interest.2 The adverse effect of organic solvents (Table 1) which are mostly preferred extraction techniques has warranted the search for greener alternatives. One of the ways green extrac tions is described involves the isolation of medicinally active portions from a bio-material,3 with the simultaneous use of eco friendly solvents and optimal use of energy.4–9 Prospecting for green solvents has brought water to the fore of extraction technology.10 Water is affirmatively described as the “greenest solvent” imaginable, with its availability at the required purity, it is cost-effective, readily recycled, non-toxic, non-ammable, and eco-friendly.10–13 Based on the green chemistry precept, water is considered a green chemical per excellence.14–16 Water is useful in the recovery of various phytochemicals including alcohols, sugars, proteins, and organic acids with natural water soluble properties.12,16–21 However, water as a solvent has some physical and chemical property disadvantages when compared to organic solvent.21–23 The polar nature of water in its natural form reduces its efficacy and acceptability when compared with organic solvents for some kinds of extractions. Organic solvents are extensively desirable since they exhibit better recovery than water at ambient conditions.3 Further setbacks experienced when using conventional hydro-extraction include time and energy consumption, thermal decomposition of thermo sensitive metabolites and low recovery of hydro-solvent in its natural form. There exists the need to investigate water properties that can be improved to complement its natural advantage and eradicate its attendant limitations as a solvent for extraction.5,8,10,28,29 have indicated that improving traditional extraction must entail decreased energy input, sustainability and a non-toxic nal product. Improving water to own variable chemistry will aid the extraction of a broad range of polar and non-polar biomolecules from sustainable natural products with non-toxic quality and eco-friendliness.10,21,29 This approach will prevent the use of organic solvents, fossil energy, chemical waste and risks of extraction. It is known that water existing in its tunable form satises the conditions of green solvents.11–13 Recently, the