Department of Chemical Sciences

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Browsing Department of Chemical Sciences by Author "Koko, Daniel Terlanga"

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    Agrogenic Modified Clay For The Removal Of Gram-Negative Bacteria From Water
    (run.edu.ng, 2016-08) Koko, Daniel Terlanga
    The presence of pathogens in the few available water resources which have been reported to cause diseases and subsequent deaths especially in children of ages less than five years have given rise to the development of cost-effective, environmentally friendly, efficient and convenience means of water treatment. This project reports on the preparation of Zn-modified kaolinite clay biomass Carica papaya seeds and Musa paradisiaca peels) composite adsorbents for the removal of some enteric bacteria (E. coli, S. typhi and V. cholerae ) from the water. Three composite adsorbents were prepared: Zn-modified kaolinite clay adsorbent and Carica papaya seeds (ZKPS); Zn-modified kaolinite clay and plantain peels (ZKPP) and Zn-modified kaolinite clay-papaya seeds and plantain peels (ZKPPPS). The mixtures were treated to microwave at 500 W for 10 min and washed to neutral pH. The characterization with SEM shows they are homogeneous composites, while electron mapping results showed the presence of elements obtainable from the composites. The EDX analysis confirmed the presence of the all the elements contained in the composites and their varying concentration in which Zn was observed to be highest in all the composite adsorbents. Fourier Transformed Infrared spectroscopy and X-ray Diffraction (XRD) indicates chemical functionalities involved in the interaction between Carica papaya seeds and/or plantain peels with kaolinite in the presence of an activating agent. The FTIR spectra did confirm the presence of Zn in the composite adsorbents at ca. 462 cm-1. Surface area analysis via N2 sorption shows that ZKPP composite adsorbent has the highest surface area (342 m2 /g), followed by ZKPPPS composite adsorbent with 150 m2/g while ZKPS composite adsorbent had 117 m2/g. Surface area results suggest that the particles sizes of the composite adsorbents were in the nanoscale. The pH point of zero charges (pHpzc) of the composites adsorbents were obtained to be 7.0 for ZKPP and ZKPS composites adsorbents, while that of ZKPPPS composite adsorbent was obtained to 6.47 in contrast to that of kaolinite clay obtained to 4.98. This implies that at a temperature below pHpzc the adsorption of negatively charged particles are favored. Bacterial removal activities of the three composite adsorbent showed that ZKPS composite adsorbent had better activity on S. typhi and V. cholerae because the breakthrough time was observed at 700 min (5.6 L) and 400 min (3.2 L) respectively followed by ZKPP composite adsorbent with 400 min (3.2 L) respectively for S. typhi and V. cholerae, while ZKPPPS composite adsorbent was less efficient on the two bacteria with 275 min and 200 min for S. typhi and V. cholerae respectively. The three composite adsorbents showed no good efficiency for the removal of Escherichia coli from water.
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    The Halogen-Oxyanion Derivatives as Contaminants of Concern in Water
    (Springer, Cham, 2021-07-02) Koko, Daniel Terlanga
    Due to the adverse health and environmental effects of halogen, based on oxyanions in water, the occurrence and distribution have been of great concern, worldwide. Therefore, in this chapter, the occurrence, chemical structure, the natural and anthropogenic sources of these oxyanions were appraised. The impacts on human health and the environment and their fate in water are carefully enunciated. Different techniques that have been developed for the determination of halogen-oxyanions in aqueous solutions are discussed. Finally, a perspective for future research on halogen-based oxyanions is provided, and the possible research gaps, which are begging for answers, are also highlighted.
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    Novel Metal-doped Bacteriostatic Hybrid Clay Composites for Point-of-Use Disinfection of Water
    (ELSEVIER Journal of Environmental Chemical Engineering, 2017-06) Koko, Daniel Terlanga
    This study reports the facile microwave-assisted thermal preparation of novel metal-doped hybrid clay composite adsorbents consisting of Kaolinite clay, Carica papaya seeds and/or plantain peels (Musa paradisiaca) and ZnCl2. Fourier Transformed IR spectroscopy, X-ray diffraction, Scanning Electron Microscopy and Brunauer–Emmett–Teller (BET) analysis are employed to characterize these composite adsorbents. The physicochemical analysis of these composites suggests that they act as bacteriostatic rather than bacteriacidal agents. This bacterostactic action is induced by the ZnO phase in the composites whose amount correlates with the efficacy of the composite. The composite prepared with papaya seeds (PS-HYCA) provides the best disinfection efficacy (when compared with composite prepared with Musa paradisiaca peels-PP-HYCA) against gram-negative enteric bacteria with a breakthrough time of 400 and 700 min for the removal of 1.5 × 106 cfu/mL S. typhi and V. cholerae from water respectively. At 103 cfu/mL of each bacterium in solution, 2 g of both composite adsorbents kept the levels the bacteria in effluent solutions at zero for up to 24 h. Steam regeneration of 2 g of bacteria-loaded Carica papaya prepared composite adsorbent shows a loss of ca. 31% of its capacity even after the 3rd regeneration cycle of 25 h of service time. The composite adsorbent prepared with Carica papaya seeds will be useful for developing simple point-of-use water treatment systems for water disinfection application. This composite adsorbent is comparatively of good performance and shows relatively long hydraulic contact times and is expected to minimize energy intensive traditional treatment processes.