Hokonya, Nichodimus (2014) Green Synthesis of Trimetallic Nanoparticles using Flacourtia Indica (Burm.F.) Merr. Characterization and Applications. Doctoral thesis, Bindura University of Science Education.
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Text (GREEN SYNTHESIS OF TRIMETALLIC NANOPARTICLES USING FLACOURTIA INDICA (BURM.F.) MERR.: CHARACTERIZATION AND APPLICATIONS)
HOKONYANICHODIMUSB1336991DOCTOROFPHILOSOPHYTHESIS2024._111057.pdf - Submitted Version Restricted to Repository staff only Download (4MB) | Request a copy |
Abstract
Anthropogenic activities have led to environmental pollution by toxic heavy metals and dyes such as Congo red. Trimetallic nanoparticles can be used for enrichment heavy metals and photocatalytic degradation of Congo red from the environment. However, the processes used to synthesize nanoparticles can be hazardous to the environment. In the study, green synthesis of Phosphorous doped ZrO2CeO2ZnO nanoparticles were carried out using Flacourtia indica leaf aqueous extracts with phytochemicals as reducing agents. The nanoparticles were used as photocatalysts for degradation of Congo red dye and as sorbents for enrichment of selected toxic metals: lead, cadmium, arsenic and chromium. The influence of various parameters during the synthesis and solid phase extraction stages were investigated using Half, Full and Taguchi experimental designs. Interactions between factors were determined using ANOVA and response surface methodologies. The enrichment methods were validated by using spiked borehole, well, tap and effluent water samples. The P−ZrO2CeO2ZnO nanoparticles and P−ZrO2CeO2ZnO nanoparticles/alginate beads were characterized using Ultra Violet Visible spectrometry, Scanning Electron Microscope(SEM), Fourier Transform- Infra Red Spectroscopy, Transmitting Electron Microscopy (TEM), Brunauer Emmet Teller (BET) analysis, X- ray Photoelectron Spectroscopy (XPS) and X ray Diffraction (XRD). The most significant factors for P−ZrO2CeO2ZnO nanoparticle synthesis were pH, metal ion concentration and leaf extract concentration. The surface areas obtained under optimum synthesis conditions were 0.459 m2 g −1 and 7.33 m2 g −1 for P−ZrO2CeO2ZnO nanoparticles and P−ZrO2CeO2ZnO nanoparticles/alginate beads respectively. The synthesized nanoparticles were crystalline and irregularly shaped The nanoparticles average size was 0.255 nm and the range of the size was from 0.1-4.51nm. Zn−O, Zr−O, C−O, O−H, functional groups were present in the nanoparticles from FTIR data. The optimum conditions for photocatalytic degradation of Congo red using P−ZrO2CeO2ZnO nanoparticles were 0.05 g/L catalyst dosage concentration, 10 mg/L Congo red concentration, 250 min irradiation time. The reaction followed pseudo first order kinetics with a rate constant of 0.069 min-1 and degradation efficiency of 85.85%.The reaction mechanism was explained by light, superoxide radicals and h+ holes. The most significant variable for cadmium recovery using P−ZrO2CeO2ZnO nanoparticles / alginate beads was the sample volume and for chromium recoveries these were sample volume, eluent flow rate and sorbent dosage. Interactions between factors during enrichment occurred between sorbent dosage and pH, sample volume and sorbent dosage, sample volume and pH. The method recoveries were 33.12-116.5, 57.0 -147.70, 46.56-130.65 and 20.96-82.51% and, limits of detection were 0.1022, 0.0297 g/L 0.084 and 0.439 ng/L for lead, cadmium, chromium and arsenic respectively. The SEM, TEM and XRD results showed that P−ZrO2CeO2ZnO nanoparticles can be synthesized using F. indica leaves extracts and they can efficiently degrade Congo red dye. It was also demonstrated that P−ZrO2CeO2ZnO nanoparticles encapsulated in alginate beads enhanced the detection limit of selected heavy metals, which may find applications in toxic metal analysis.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Subjects: | Q Science > QD Chemistry |
| Divisions: | Africana |
| Depositing User: | Dr Nichodimus Hokonya |
| Date Deposited: | 24 Sep 2025 13:20 |
| Last Modified: | 24 Sep 2025 13:20 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/10006 |
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