Browsing by Author "Kamgang Djioko, Fredy Harcel"

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    Development of zeolite/bio-magnetite Nanocomposites for elimination of pharmaceutical pollutants in aqueous solution: Experimental and computational studies (Unpublished Doctoral Thesis). Federal University of Technology, Owerri, Nigeria
    (Federal University of Technology, Owerri, 2024-11) Kamgang Djioko, Fredy Harcel
    Discharges of pharmaceutical micropollutants (antibiotics) are steadily increasing. These toxic, persistent pollutants are generally responsible for a number of adverse health effects. The main objective of this work was to synthesize biomagnetite/zeolite nanocomposites for the effective removal of ciprofloxacin in aqueous solution. Biomagnetite nanoparticles were synthesized by the co-precipitation method, zeolite 4A and nanocomposites by the hydrothermal method and characterized by FT-IR, XRD, XRF, MAS-NMR, TGA/DTG, SEM/EDS, BET and pHpzc analysis. Batch adsorption experiments were conducted to evaluate the adsorption capacity of zeolite 4A and nanocomposites, and then study the effect of loading of magnetite nanoparticles in nanocomposites for the removal of ciprofloxacin as pollutant model in aqueous solution. Thus, the zeolites 4A were synthesized from raw kaolin by the hydrothermal method, While, the bio magnetite nanoparticles were synthesized by co-precipitation method using Tabernaemontana penduliflora as stabilizing and reducing agents and the nanocomposites by coating method. It was noted that the synthesized nanocomposites had a paramagnetic mesoporous crystalline structure with a cubic morphology coated with magnetite nanoparticles and a high specific surface area (53.258 m2/g) compared to that of zeolites 4A (34.232m2/g 𝑎𝑛𝑑 38.443 m2/g). The adsorption of ciprofloxacin on different materials, revealed the maximum adsorption for zeolites 4A was also obtained at pH 8, a contact time 80 minutes, an initial concentration of the CIP 60 ppm and a dose of zeolite 4A of 20 mg at 25°C. The removal efficiency was 91.75% and 90.74% with a maximum adsorption capacity (𝑞max) 87.72 mg/g and 95.24 mg/g obtained from the Langmuir model for zeolite 4A derived fromKaolin picked up in the locality of Bong and Famgamg, respectively. For the MZ-6 nanocomposite, the maximum adsorption for zeolite 4A was obtained at pH 8, a contact time 60 minutes, an initial CIP concentration 90 ppm and an MZ-6 dose of 10 mg at 25°C. The removal efficiency was 98.78% with a maximum adsorption capacity (qmax) 175.44 mg/g. Isotherm studies suggested that the Langmuir isotherm was the most suitable. Which indicates that the adsorption process of CIP was monolayer adsorption on a homogeneous surface. The DFT results revealed that in the aqueous phase, the CIP molecule is stable, reactive in the form of zweitterion (CIP±) and that the oxygen, nitrogen atoms and the aromatic ring were responsible for this reactivity. The Monte Carlo simulation results showed that the adsorption of CIP molecules on the surface of zeolite 4A and MZ composite were favorable and spontaneous and the predominant interaction was chemisorption. In addition, CIP molecules showed high affinities with the surface of the MZ composite. The regeneration study showed that the synthesized adsorbents were chemically stable and recyclable. We can therefore affirm that abundant natural resources such as kaolin and certain plants can contribute to the preparation of low-cost but highly effective materials for combating water pollution.