Mudzielwana, R.Ayinde, W. B.Nemakanga, Selby2024-10-192024-10-192024-09-06Nemakanga, S. 2024. Synthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from water. . .https://univendspace.univen.ac.za/handle/11602/2752MENVSCDepartment of Geography and Environmental SciencesPeople living in developing nations are challenged by acute water scarcity, hence they often rely on groundwater as their primary drinking water sources. Unfortunately, in most cases, groundwater is often contaminated with high levels of fluoride and pathogens, posing a significant health risk. This dissertation aims to synthesize Zr4+/Ag+ metal oxides modified zeolite adsorbent for use in fluoride and pathogens removal from water. The first section of this research aimed at optimizing the synthesis of zeolite from bentonite clay using the response surface methodology (RSM). The process involved alkali dissolution of calcined bentonite clay through ultrasonication, followed by hydrothermal treatment to obtain zeolite. The ultrasonication conditions were optimized by varying NaOH concentration (0.5 to 2.5 M) and aging time (10 to 120 minutes). Temperature (70 °C to 140 °C) and time (1.5 to 6 hours) were evaluated for hydrothermal treatment. The X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX) and Fourier transform infrared (FTIR) analysis were used to characterize the obtained materials, revealing that crystallinity of the obtained synthesized materials increased at higher hydrothermal temperatures and times. Furthermore, the XRD analysis indicated there was the formation of zeolite NaP phases at lower temperatures and times, while higher temperatures and times led to hydroxy sodalite mineral phases. Preliminary defluoridation experiments were conducted on all hydrothermally treated samples, with the sample prepared at 2 hours sonication, 105°C hydrothermal treatment, and 1 hour 30 minutes exhibiting a capacity for adsorbing fluoride of 0.19 mg/g hence, this zeolite was used subsequent experiments. The second chapter of results presented the evaluated effectiveness of the synthesized zeolite NaP on fluoride and pathogen removal. Batch experiments were conducted to assess zeolite NaP's effectiveness in removing fluoride from water under various operating conditions while the well-assay diffusion method was used to study the antimicrobial potency of the zeolite. The optimum conditions for achieving maximum fluoride adsorption were identified as a contact time of 60 minutes, an initial concentration of 6.2 mg/L using a synthetic fluoride solution, an initial pH of 2, and an adsorbent dosage of 0.5 g/100 mL. Under these conditions, the maximum adsorption capacity reached 0.16 mg/g. Additionally, it was determined that the fluoride adsorption process followed a chemisorption mechanism, as evidenced by the fitting of experimental data to a pseudo-second-order kinetic model. Moreover, the adsorption isotherm data fitted well with the Langmuir model. This indicates that fluoride adsorption occurred on a surface in a single layer, with a limit on the number of active sites at any given time. Antimicrobial assessments revealed that zeolite NaP lacked v potency against gram-negative E. coli and gram-positive S. aureus strains. In conclusion, zeolite NaP demonstrated minimal defluoridation efficiency and no antimicrobial efficacy. The chapter suggests enhancing fluoride adsorption, antimicrobial potency, and material reusability through the introduction of cations into the zeolite frameworks. The third chapter of results focused on the modification of zeolite NaP by incorporating zirconium/silver metal oxides to enhance its efficacy in removing fluoride and pathogens from water. The Zr4+/Ag+ modified zeolite NaP was prepared using 0.5 M and 0.3 M ZrCl4 and AgNO3 respectively. The mixture of 10 g of calcined bentonite, 2 M of NaOH, and Zr and Ag solutions was subjected to ultrasonication for 2 hours followed by hydrothermal treatment at 105 °C for 90 minutes. The obtained material was therefore characterized using XRD, XRF, FTIR, Particle Distribution Analysis, and SEM-EDS. Defluoridation and antimicrobial potency were evaluated through batch adsorption experiments and well-assay diffusion method, respectively. Under optimal conditions, including a pH of 6 ± 0.5, a contact time of 270 minutes, an initial fluoride concentration of 6.2 mg/L, and an adsorbent dosage of 0.5 g/100 mL at an agitation speed of 250 rpm, the modified zeolite demonstrated a peak fluoride removal percentage of approximately 50%. The data fitted better to the pseudo-second-order kinetic model suggesting the dominance of chemisorption as the fluoride removal mechanism while adsorption isotherm data followed the Langmuir isotherm model suggesting that adsorption occurred on a monolayered surface for the Zr4+/Ag+ modified zeolite. Antimicrobial studies revealed a 15 mm and 12 mm zone of inhibition against the gram-negative E. coli and gram-positive S. aureus strains, respectively. In conclusion, the synthesized zeolite functionalized with zirconium and silver metal oxides exhibited improved fluoride removal efficiency and antimicrobial potency. Further research is recommended to improve the properties of synthesized zeolite for better removal of fluoride and pathogens from water.I online resource (xiv, 142 leaves) : color illustrationsenUniversity of VendaGroundwaterUCTDFluoridePathogensWater treatmentAdsorptionZeoliteSynthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from waterDissertationNemakanga S. Synthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from water. []. , 2024 [cited yyyy month dd]. Available from:Nemakanga, S. (2024). <i>Synthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from water</i>. (). . Retrieved fromNemakanga, Selby. <i>"Synthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from water."</i> ., , 2024.TY - Dissertation AU - Nemakanga, Selby AB - People living in developing nations are challenged by acute water scarcity, hence they often rely on groundwater as their primary drinking water sources. Unfortunately, in most cases, groundwater is often contaminated with high levels of fluoride and pathogens, posing a significant health risk. This dissertation aims to synthesize Zr4+/Ag+ metal oxides modified zeolite adsorbent for use in fluoride and pathogens removal from water. The first section of this research aimed at optimizing the synthesis of zeolite from bentonite clay using the response surface methodology (RSM). The process involved alkali dissolution of calcined bentonite clay through ultrasonication, followed by hydrothermal treatment to obtain zeolite. The ultrasonication conditions were optimized by varying NaOH concentration (0.5 to 2.5 M) and aging time (10 to 120 minutes). Temperature (70 °C to 140 °C) and time (1.5 to 6 hours) were evaluated for hydrothermal treatment. The X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX) and Fourier transform infrared (FTIR) analysis were used to characterize the obtained materials, revealing that crystallinity of the obtained synthesized materials increased at higher hydrothermal temperatures and times. Furthermore, the XRD analysis indicated there was the formation of zeolite NaP phases at lower temperatures and times, while higher temperatures and times led to hydroxy sodalite mineral phases. Preliminary defluoridation experiments were conducted on all hydrothermally treated samples, with the sample prepared at 2 hours sonication, 105°C hydrothermal treatment, and 1 hour 30 minutes exhibiting a capacity for adsorbing fluoride of 0.19 mg/g hence, this zeolite was used subsequent experiments. The second chapter of results presented the evaluated effectiveness of the synthesized zeolite NaP on fluoride and pathogen removal. Batch experiments were conducted to assess zeolite NaP's effectiveness in removing fluoride from water under various operating conditions while the well-assay diffusion method was used to study the antimicrobial potency of the zeolite. The optimum conditions for achieving maximum fluoride adsorption were identified as a contact time of 60 minutes, an initial concentration of 6.2 mg/L using a synthetic fluoride solution, an initial pH of 2, and an adsorbent dosage of 0.5 g/100 mL. Under these conditions, the maximum adsorption capacity reached 0.16 mg/g. Additionally, it was determined that the fluoride adsorption process followed a chemisorption mechanism, as evidenced by the fitting of experimental data to a pseudo-second-order kinetic model. Moreover, the adsorption isotherm data fitted well with the Langmuir model. This indicates that fluoride adsorption occurred on a surface in a single layer, with a limit on the number of active sites at any given time. Antimicrobial assessments revealed that zeolite NaP lacked v potency against gram-negative E. coli and gram-positive S. aureus strains. In conclusion, zeolite NaP demonstrated minimal defluoridation efficiency and no antimicrobial efficacy. The chapter suggests enhancing fluoride adsorption, antimicrobial potency, and material reusability through the introduction of cations into the zeolite frameworks. The third chapter of results focused on the modification of zeolite NaP by incorporating zirconium/silver metal oxides to enhance its efficacy in removing fluoride and pathogens from water. The Zr4+/Ag+ modified zeolite NaP was prepared using 0.5 M and 0.3 M ZrCl4 and AgNO3 respectively. The mixture of 10 g of calcined bentonite, 2 M of NaOH, and Zr and Ag solutions was subjected to ultrasonication for 2 hours followed by hydrothermal treatment at 105 °C for 90 minutes. The obtained material was therefore characterized using XRD, XRF, FTIR, Particle Distribution Analysis, and SEM-EDS. Defluoridation and antimicrobial potency were evaluated through batch adsorption experiments and well-assay diffusion method, respectively. Under optimal conditions, including a pH of 6 ± 0.5, a contact time of 270 minutes, an initial fluoride concentration of 6.2 mg/L, and an adsorbent dosage of 0.5 g/100 mL at an agitation speed of 250 rpm, the modified zeolite demonstrated a peak fluoride removal percentage of approximately 50%. The data fitted better to the pseudo-second-order kinetic model suggesting the dominance of chemisorption as the fluoride removal mechanism while adsorption isotherm data followed the Langmuir isotherm model suggesting that adsorption occurred on a monolayered surface for the Zr4+/Ag+ modified zeolite. Antimicrobial studies revealed a 15 mm and 12 mm zone of inhibition against the gram-negative E. coli and gram-positive S. aureus strains, respectively. In conclusion, the synthesized zeolite functionalized with zirconium and silver metal oxides exhibited improved fluoride removal efficiency and antimicrobial potency. Further research is recommended to improve the properties of synthesized zeolite for better removal of fluoride and pathogens from water. DA - 2024-09-06 DB - ResearchSpace DP - Univen KW - Groundwater KW - Fluoride KW - Pathogens KW - Water treatment KW - Adsorption KW - Zeolite LK - https://univendspace.univen.ac.za PY - 2024 T1 - Synthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from water TI - Synthesis of Zr4+/Ag+ metal oxides modified zeolite for application in fluoride and pathogens removal from water UR - ER -