- Title
- Synthesis and evaluation of pyrene grafted onto zinc oxide nanoparticles for the removal of organic contaminants from wastewater
- Creator
- Samuel, Zipho
- Subject
- Land treatment of wastewater
- Subject
- Zinc oxide
- Subject
- Water pollution control industry
- Date
- 2022-03
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10353/27754
- Identifier
- vital:69407
- Description
- Drinking water scarcity is a global crisis even though water covers about three quarters of the earth. One of the major causes of this scarcity is water pollution, which is a result of human activities. This has been noticed and reported for a number of years but is still unsolved and intensifying. Hence, scientists are busy trying to find solutions to this global menace. In this study, zinc oxide nanoparticles were synthesised via co-precipitation, a cost reasonable method and functionalized by grafting a pyrene ligand on its surface in order to provide a scaffold to which many other functionalities can be adsorbed. By so doing, the efficiency and capacity of bare nanoparticles is improved. The synthesised pyrene ligand was successfully characterised with nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscope (FTIR). The adsorbent was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), FTIR, energy dispersive x-ray (EDX) and thermogravimetric analyzer (TGA). The choice of zinc oxide nanoparticles as preferred adsorbent was due to their exceptional properties including large surface area, thermal and chemical stabilities. These properties are the reason zinc oxide nanoparticles possess high adsorption efficiency and capacity. The results of characterization indicated a decreased particle size and improved thermal stabilities of the pyrene grafted zinc oxide nanoparticles compared to the zinc oxide nanoparticles, showing that this material can be employed even at higher temperatures. The average particle size of the bare nanoparticles decreased from 290 to 181 nm after functionalization. Thermal stability increased from 550oC in the bare nanoparticles to 650oC in the functionalized nanoparticles. Characteristic reflections of zinc oxide nanoparticles in the XRD analysis were maintained even after functionalization However, diffractogram roughness was noticed for the functionalized nanoparticles due to the introduction of the amorphous layer from the ligand. This novel material was employed for the removal of an herbicide, simazine as well as two dyes, methyl violet and brilliant green from aqueous solutions by batch adsorption experiments. The kinetics and isotherm studies of the different adsorption processes were carried out by using three of the commonly used kinetic and isotherm models (pseudo-first order, intraparticle diffusion and pseudo-second order) and (Langmuir, Temkin isotherms and Freundlich) respectively. From all batch adsorption experiments conducted for simazine removal, the adsorbent showed effectiveness and high adsorption capacity for the removal of simazine. The highest observed efficiency and capacity were 71.3 percent and 137 mg/g respectively at pH equals 2, time equals 60 minutes, adsorbent dose equals 20 mg and adsorbate conc equals 0. 281 mg/L. Kinetics study for the adsorption of simazine favoured pseudo-first order. However, Langmuir isotherm could also be applicable to understand the adsorption process. The material also showed reusability potential of up to three cycles for this contaminant indicating that this material can be re-used. In the case of the removal of methyl violet from aqueous solution, the adsorbent showed a reasonable adsorption maximum capacity (qmax) (31.5 mg/g) at contact time equals 360 min, adsorbent dose approximately equals 40 mg, temperature equals 20 plus 2oC and pH equals 6.5, when compared to other adsorbents previously reported for the removal of methyl violet (MV) in literature. Kinetics and isotherm studies indicated that the process for the removal of this pollutant with this pyrene grafted onto zinc oxide nanoparticles proceeded via pseudo-first order (R2 equals 0.931) and Langmuir isotherm models (R2 equals 0.980) respectively. These results indicated that this material could serve as alternate material to already established materials for the removal of recalcitrant organic pollutants from aqueous solutions. Moreover, the adsorbent also showed reusability potential for this contaminant. Similarly, the adsorbent showed high removal efficiency and capacity in all batch adsorption experiments for brilliant green (BG) adsorption. The highest adsorption efficiency of 88.8 percent was accomplished with 79.8 mg at pH 6.50 and temperature of 20 equals 2oC within 360 minutes. BG adsorption rate mechanism was best explained by the pseudo-first order kinetic model (R2 equals 0.903). Dye adsorption behaviour was best explained using Langmuir isotherm (R2 equals 0.980). Reusability of the adsorbent showed that the adsorbent is efficient after three runs. The overall results of adsorption by a way of comparison of the adsorption capacity of this novel material with respect to the contaminants is in this trend: brilliant green greater methyl violet greater simazine. This study indicates that this novel material can serve as new material for the removal of herbicides and dyes as well as vast variety of pollutants from wastewater considering its high adsorption efficiency and its recyclability. Thus, industries can explore the use of this material for the removal of varying pollutants from wastewater.
- Description
- Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (xxv, 183 leaves)
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
- Rights
- All Rights Reserved
- Rights
- Open Access
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UFH Department of Chemistry
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details | SOURCE1 | Zipho Samuel- MSc Dissertation.pdf | 4 MB | Adobe Acrobat PDF | View Details |