Theses & Dissertations

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https://hdl.handle.net/20.500.14170/194

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Browsing Theses & Dissertations by Subject "Adsorption"
  • Publication
    Development of N-Ce-AC-TiO₂ composite via sol-gel assisted microwave irradiation for the adsorption-photodegradation of antibiotics
    (Universiti Malaysia Perlis (UniMAP), 2024)
    Nur Athirah Awatif Abdul Rahman
    The widespread antibiotic pollution in the environment has emerge as a global challenge due to its adverse impacts on ecology, human health, and well-being. Hence, photodegradation is the promising method to remove this pollutant in polluted water treatment. Therefore, this study aims to synthesize N-Ce-AC-TiO₂ photocatalyst via the sol-gel approach with microwave irradiation assistance in the adsorptionphotodegradation of amoxicillin (AMX) and tetracycline (TC). Response surface methodology (RSM) was used to determine the optimum conditions in preparing the photocatalyst. N-Ce-AC-TiO₂ showed a stable anatase phase with a crystallite size of 5.48 nm, a good Brunauer-Emmett-Teller (BET) surface area of 278.87 m2 g-1 and a low band gap energy, which was reduced significantly from 3.20 eV of pristine TiO₂ to 2.16 eV. From the optimization studies, N-Ce-AC-TiO₂ synthesized with 0.02 g nitrogen, 0.20 g cerium, 0.50 g activated carbon, and activated with irradiation power of 600 W in 15 mins achieved maximum degradation for TC and AMX at 93% ± 0.23 and 96% ± 0.16 within 100 min under UV light irradiation for an initial concentration of 10 mg L-1, at 30 ℃, with solution pH 7 for TC and pH 6 for AMX. Active species that contribute to the photodegradation process the most are holes (h+) and superoxide radicals (∙O2-). The TC degradation was appropriately obeyed by Langmuir isotherms, pseudo-first order (R2:0.999), and Langmuir-Hinshelwood (R2: 0.988) kinetic models. The AMX degradation obeyed Langmuir isotherms, pseudo-first order (R2: 0.999), and Langmuir-Hinshelwood (R2: 0.976) kinetic models. The change in enthalpy (Δ𝐻) (TC: 27.65 kJ mol-1, AMX: 15.50 kJ mol-1), entropy (Δ𝑆) (TC: 0.09 kJ mol-1, AMX: 0.05 kJ mol-1), and Gibbs free energy (Δ𝐺) (TC: -1.05 to -3.88 kJ mol-1, AMX: -1.16 to -2.80 kJ mol-1) suggested that the adsorption process was endothermic, favourable, and spontaneous for both antibiotics. Possible interactions involved between TC and AMX with N-Ce-AC-TiO₂ include 𝑐𝑎𝑡𝑖𝑜𝑛𝑖𝑐 − 𝜋, electrostatic interaction, hydrogen bonding, 𝑛 − 𝜋, and 𝜋 − 𝜋 interactions. Additionally, N-Ce-AC-TiO₂ stability was confirmed through 80% removal efficiency after the fourth (AMX) and fifth (TC) cycles. In essence, this work offers new perspectives on creating effective, reusable, and improved photocatalysts using a convenient microwave-assisted synthesis approach for antibiotic decontamination.