Department of Chemical Sciences

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Browsing Department of Chemical Sciences by Author "Alfred, Moses Oladele"

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    Cu/Fe@ ZnWO4-kaolinite Composites for Degradation of Acetaminophen, Ampicillin and Sulfamethoxazole in Water
    (Ceramics International, Elsevier, 2021) Alfred, Moses Oladele
    This study reports the development of biomass-assisted sunlight-active semiconductor-tungstate-clay photocatalytic composite for the removal of pharmaceutical contaminants (PCs): Acetaminophen (ACT), Ampicillin (AMP) and Sulfamethoxazole (SMX), from water. Materials prepared (Cu@ZnWO4–K, Fe@ZnWO4–K and Cu/Fe@ZnWO4–K) composites, were characterized using Scanning Electron Microscopy (SEM), Fourier Transformed Infrared spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy, High Resolution TEM and X-ray Diffraction (XRD). XRD analysis showed the presence of Scheelite (CuWO4), Ferberite (FeWO4) and Sanmartinite (ZnWO4) crystal phases in the composites. Moreover, results showed that Cu@ZnWO4–K composite gave the best efficiency for the photodegradation of AMP (100%), ACT (83%), and SMX (68%) molecules. This composite showed more preference for the photodegradation of AMP molecules (>98%) even in the presence of ACT and SMX molecules. After five reuse cycles, the composite still had ca. 90% efficiency for AMP molecules but far less for the other two molecules. The presence of anions reduced the photocatalytic efficiency of this composite but increased the photodegradation of SMX molecules. The rate of photodegradation of the PCs was comparably fast, leading to high removal capacity. The concentrations of inorganic ions released as by-products of photodegradation, were far below WHO standard limits for their presence in drinking water.
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    Development of Solar-Active Photocatalytic Composites for the Degradation of Phrarmaceuticals in Water
    (2021) Alfred, Moses Oladele
    Pharmaceutical chemicals belong to a group of water contaminants of emerging concerns known as emerging contaminants and their presence in water leads to aquatic toxicity, antibiotic resistance development in pathogenic bacteria to mention but few. Although there are some techniques available for their removal in water, yet they are either too expensive to maintain, quite slow and ineffective at some elevated concentration or produce toxic by-products into treated water. Photocatalysis is a promising technique for water treatment due to its low mass transfer limitation, chemical stability, rapid dynamics of mineralization of organic pollutants and efficient operation at ambient temperature. This study reports the synthesis of solar-active composites from combination of waste biomass namely Carica papaya seeds and Musa paradisiaca peels and abundant clay for the purpose of removing Acetaminophen (ACT), Ampicillin (AMP), Arthemether (ART) and Sulfamethoxazole (SMX) in water. The composites were prepared in two forms: TiO2-modified and metal-doped photoactive composites with tungstate and kaolinite being common to them. The X-ray diffraction (XRD) patterns of these composites indicate the presence of semiconductors: ZnWO4, CuWO4, FeWO4 and TiO2, which are responsible for their photocatalytic activity. Photoluminescence and Electron Paramagnetic Resonance (EPR) spectroscopic techniques suggest the presence of defect states in these composites induced by the presence of carbon and kaolinite. Evaluating the photocatalytic activity of TiO2-modifed composites on the pharmaceutical chemicals under sunlight, suggests that TiO2@ZnWO4 composite possesses the best efficiency that allows photodegradation to be complete in 30 min with mineralization of 80% and ~50% for AMP and SMX respectively. However, the metal-doped composites gave better photodegradation efficiency with Cu@ZnWO4 being the best with an efficiency of 100% and 68% for AMP and SMX molecules respectively. Photo-mineralization was however ≤ 45% for both pharmaceutical molecules. The photocatalytic reaction releases inorganic by-products (〖SO〗_4^(2-), 〖NO〗_3^- and 〖NH〗_4^+) at levels below WHO permissible limits for drinking water. Generally, changing the concentrations of electrolyte did not influence the efficiency of both types of composites except for Cu@ZnWO4 with an increment in efficiency of SMX molecules. This suggests that adsorption may not precede photocatalysis, contrary to common models. A small loss in efficiency (~6%) was observed with both type of composites when they were reused for the removal of AMP molecules over 5 cycles while there was consistent loss of efficiency of Cu@ZnWO4 when it is reused for the removal of SMX molecules from water for same number of reuse cycles. From EPR studies, it was concluded that surface oxygen vacancies and defects in the crystal lattices of these composites are the main driving forces characterizing their improved photocatalytic activity. These composites were found efficient for the removal of AMP and SMX molecules from more complex water matrices like raw wastewater from an abattoir, a river, and a hand-dug well for drinking water. This highlights the potential of the composites to effectively treat drinking water, which could find applications in the development of point-of-use water treatment devices.
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    Facile Synthesis of New amino-functionalized agrogenic Hybrid Composite Clay Adsorbents for phosphate Capture and Recovery from Water
    (Journal of Cleaner Productions, Elsevier, 2017-06-21) Alfred, Moses Oladele
    New hybrid clay materials with good affinity for phosphate ions were developed from a combination of biomass-Carica papaya seeds (PS) and Musa paradisiaca (Plantain peels-PP), ZnCl2 and Kaolinite clay to produce iPS-HYCA and iPP-HYCA composite adsorbents respectively and functionalized with an organosilane to obtain NPS-HYCA and NPP-HYCA composite adsorbents. The pHpzc for the adsorbents were 7.83, 6.91, 7.66 and 6.55 for iPS-HYCA, NPS-HYCA, iPP-HYCA and NPP-HYCA respectively. Using the Brouer-Sotolongo isotherm model which best predict the adsorption capacity of composites for phosphate qmax values of 61.5, 59.2, 63.3 and 67.4 mg/g were obtained for iPP-HYCA, iPS-HYCA, NPP-HYCA, and NPS-HYCA composite adsorbents respectively. When compared with some commercial resins, the amino-functionalized adsorbents had better adsorption capacities. Furthermore, amino-functionalized adsorbents showed improved adsorption capacity and rate of phosphate uptake (as much as 40-fold), as well as retain 94% (for NPS-HYCA) and 84.1% (for NPP-HYCA) efficiency for phosphate adsorption after 5 adsorption-desorption cycles (96 h of adsorption time with 100 mg/L of phosphate ions) as against 37.5% (for iPS-HYCA) and 35% (for iPP-HYCA) under similar conditions. In 25 min desorption of phosphate ion attained equilibrium. These new amino-functionalized hybrid clay composite adsorbents, which were prepared by a simple means that is sustainable, have potentials for the efficient capture of phosphate ions from aqueous solution. They are quickly recovered from aqueous solution, non-biodegradable (unlike many biosorbent) with potentials to replace expensive adsorbents in the future. They have the further advantage of being useful in the recovery of phosphate for use in agriculture which could positively impact the global food security programme.
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    Investigation of the Binding Interaction of α-amylase with Chrysophyllum albidum Seed Extract and its Silver Nanoparticles: A Multi-Spectroscopic Approach
    (Chemical Data Collections, Elsevier, 2020) Alfred, Moses Oladele
    The interactions between α-amylase, one of the key enzymes linked with postprandial glucose regulation, and Chrysophyllum albidum seed methanolic extract(CSME) and its greensynthesized silver anoparticles(CSAgNP) were investigated using multiple spectroscopy including Fourier Transform-Infrared(FT-IR), ultraviolet(UV)-visible absorption, fluorescence spectroscopy, and biochemical analysis. FT-IR spectroscopy revealed presence of some functional groups in the samples. CSME and CSAgNP inhibited α-amylase. The intrinsic fluorescence intensity of α-amylase was quenched by CSME and CSAgNP via static mechanisms, indicating formation of complex between the enzyme and inhibitors. α-AmylaseCSAgNP complex had higher binding constants. The binding processes were exothermic, entropy driven, spontaneous, and involved hydrogen bonds and van der Waals force. Synchronous fluorescence quenching indicated alteration in microenvironment of α-amylase catalytic site tyrosine residues.FT-IR spectroscopy revealed shifts in amide I peak position of α-amylase due to interaction with CSME/CSAgNP. Absorption spectroscopy also affirmed changes in enzyme conformation. This study may provide theoretical basis for designing novel α-amylase inhibitors.
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    Occurrence and Human Exposure Assessment of Parabens in Water Sources in Osun State, Nigeria
    (Science of the Total Environment, Elsevier, 2022) Alfred, Moses Oladele
    Parabens are chemicals extensively used in pharmaceuticals, cosmetics, personal hygiene and food products as preservatives. They are classified as emerging contaminants with endocrine-disrupting capability. In this study, the concentrations of Methylparaben (MeP), Ethylparaben (EtP), Propylparaben (PrP) and Butylparaben (BuP) were obtained from groundwater, surface-water and packaged water samples collected from urban and rural areas of Osun State, Nigeria using HPLC-UV equipment. Data obtained were subjected to descriptive (Mean ± SD), inferential (KruskalWallis test) and multivariate analyses. MeP had the highest average concentration of 163 and 68 μg L−1 in surface water and groundwater respectively while concentrations of MeP, EtP, PrP and BuP were higher than previously reported in other countries. Methylparaben had the highest detection frequencies (88.0 and 50.0%) followed by BuP (69.0 and 50.0%) in surface water and groundwater respectively. No significant difference was observed for concentrations of parabens in groundwater samples in urban and rural sampling sites, suggesting that people living around these sites are equally exposed to any health implications from the use of paraben-polluted potable water. Principal Component Analysis (PCA) data suggest that the pairs MeP & EtP, PrP & BuP (in surface water samples) and MeP, EtP, & PrP (in groundwater samples) are from similar pollution sources. Ecological risk assessment using Algae, Fish, and Daphnia suggests Daphnia as the most sensitive organism while BuP and PrP show the highest health risk. Human exposure assessment showed that higher overall median estimated daily intake (EDI) values for groundwater were observed in infants (1.71 μg kg−1 bw day−1, ∑PBs) compared to toddlers (1.03 μg kg−1 bw day−1, ∑PBs), children (0.64 μg kg−1 bw day−1, ∑PBs), teenagers (0.51 μg kg−1 bw day−1, ∑PBs) and adults (0.62 μg kg−1 bw day−1, ∑PBs). Although these values are below limits set in a few countries, potential bioaccumulation could lead to severe health consequences.
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    The Sequestral Capture of fluoride, nitrate and phosphate by metal-doped and surfactant-modified Hybrid Clay Materials
    (Chemical Papers, Springer, 2017) Alfred, Moses Oladele
    Toxic anions removal for increased access to potable water remains a problem that has not been adequately addressed. This study, reports the successful preparation and modification of kaolinite-papaya seed based adsorbents under vacuum (VHYCA) for the removal of Nitrate (NO3-), Fluoride (F-) and Phosphate (PO43-). Modified adsorbents via metal-doping using Zinc were more efficient in removing these anions from aqueous solution compared with surfactant-modified adsorbents. However, both type of adsorbents showed a higher preference for NO3- removal with Zn-VHYCA and FeVHYCA adsorbents having 98 and 85% removal of the anion from aqueous solution, respectively. The removal of F- and PO43- was best achieved by Ortho-phenylenediamine (OP) and N,N,N0,N0-Tetramethyl-1,4-phenyldiaminedihydrochloride (TPD) modified VHYCA, respectively. However, Zn-VHYCA adsorbent showed comparable results with TPD-VHYCA in the removal of PO43- from aqueous solution. Overall, the metal-doped hybrid clay adsorbents showed better efficiency for the removal of anions than the surfactant-modified hybrid clay adsorbents.
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    Solar-active clay-TiO2 Nanocomposites Prepared via Biomass Assisted Synthesis: Efficient Removal of Ampicillin, Sulfamethoxazole and Artemether from Water
    (Chemical Engineering Journal, Elsevier, 2020-07) Alfred, Moses Oladele
    New solar-active nanocomposites free from toxic reagents or precious metals were developed. They were prepared from natural kaolinite clay, Na2WO4, titania, and biomass. The photocatalytic activity of the nanocomposites against two antibiotics [Ampicillin (AMP) and Sulfamethoxazole (SMX)] and an antimalarial drug [Artemether (ART)] under sunlight suggests an unusually fast photodegradation that is > 90% complete in 30 min especially with the photocatalytic nanocomposite prepared from Musa paradisiaca peels (plantain peels) @ 500 °C (TZPP5). The presence of both biomass and TiO2 is essential for the effective function of the photocatalytic nanocomposites. With TZPP5, ca. 80% and ca. 50% mineralisation of AMP and SMX, respectively, was observed after 60 min. The photocatalytic reaction releases inorganic by-products (SO42−, NO3− and NH4+) at levels below WHO permissible limits for drinking water. The presence of anions reduces the efficiency of TZPP5, indicating that it releases electrons and reactive oxygen species that are also responsible for photodegradation of the drugs. However, changing concentrations of electrolyte (NaCl) do not influence its efficiency, suggesting that adsorption may not precede photocatalysis, contrary to common models. Reuse studies suggest a slight loss in photodegradation efficiency (≈6%) of the nanocomposite for AMP in the first two cycles followed by subsequent stability at 70% for subsequent cycles. This is different for SMX, which maintained ≈58% removal for all cycles after the 1st cycle. With efficient treatment of raw wastewater from an abattoir, a river, and a hand-dug well for drinking water, the photocatalytic nanocomposite shows potential for treating drinking water, especially in point-of-use water treatment devices.
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    Synthesis of nano-sized hydrocalumite from a Gastropod Shell for aqua System phosphate Removal
    (Separation and Purification Technology, Elsevier, 2014-01-22) Alfred, Moses Oladele
    Material with high affinity for oxyanions, Hydrocalumite (HC), was synthesized using a waste biogenic resource as a precursor and its ability to remove phosphate from aqua system was studied. The synthesis of HC samples with particle sizes that ranged between 116 and 135 nm was confirmed by XRD analysis. High correlation coefficient values (r2 = 1.000) were obtained when the time–concentration profile data were fitted to the pseudo second order kinetic model. The formation of supersaturated Ca and Al phosphate salts were confirmed by the positive saturation index values and the feasibility of precipitate formation by the supersaturated salts were confirmed by the thermodynamic parameters (i.e. DG < 0). Process variables optimization (pH, ionic strength and organic load) had nominal influence on the magnitude of phosphate removal. The fractionation of the phosphate laden HC (PHC2) showed that the greater percentage (>99%) of the phosphate was distributed within the calcium matrix. Comparison of the EDAX spectra of the virgin HC with the PHC2 showed that anion exchange could also be a player in phosphate removal by the HC.
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    Toxicity and Removal of Parabens from Water: A Critical Review
    (Science of the Total Environment, Elsevier, 2021) Alfred, Moses Oladele
    Parabens are biocides used as preservatives in food, cosmetics and pharmaceuticals. They possess antibacterial and antifungal activity due to their ability to disrupt cell membrane and intracellular proteins, and cause changesin enzymatic activity of microbial cells. Water, one of our most valuable natural resource, has become a huge reservoir for parabens. Halogenated parabens from chlorination/ozonation of water contaminated with parabens have shown to be even more persistent in water than other types of parabens. Unfortunately, there is dearth of data on their (halogenated parabens) presence and fate in groundwater which serves as a major source of drinking water for a huge population in developing countries. An attempt to neglect the presence of parabens in water will expose man to it through ingestion of contaminated food and water. Although there are reviews on the occurrence, fate and behaviour of parabens in the environment, they largely omit toxicity and removal aspects. This review therefore, presents recent reports on the acute and chronic toxicity of parabens, their estrogenic agonistic and antagonistic activity and also their relationship with antimicrobial resistance. This article further X-rays several techniques that have been employed for the removal of parabens in water and their drawbacks including adsorption, biodegradation, membrane technology and advanced oxidation processes (AOPs). The heterogeneous photocatalytic process (one of the AOPs) appears to be more favoured for removal of parabens due to its ability to mineralize parabens in water. However, more work is needed to improve this ability of heterogeneous photocatalysts. Perspectives that will be relevant for future scientific studies and which willdrive policy shift towards the presence of parabens in our drinking waters are also offered. It is hoped that this review will elicit some spontaneous actions from water professionals, scientists and policy makers alike that will provide more data, effective technologies, and adaptive policies that will address the growing threat of the presence of parabens in our environment with respect to human health