Biochemistry and Microbiology

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Browsing Biochemistry and Microbiology by Author "Dlamini, Nkosinathi Goodman"

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    Biosynthesis of copper nanoparticles using a bioflocculant from Alcaligenis faecalis, characterization and its application
    (University of Zululand, 2017) Dlamini, Nkosinathi Goodman
    Nanotechnology offers a great deal of possibility for the efficient removal of pollutants in the area of water purification. Most common method used for nanoparticles formation such as physical (condensation evaporation) and chemical (oxidation and reduction) are very efficient traditional methods. However, both methods have been found to have some shortcomings. One may require a large amount of energy and the other may involve the use of toxic and expensive chemicals which may results in the binding of the nanoparticles on the surface of these chemicals. Naturally occurring secretion secreted by microorganisms (bioflocculants), have attracted considerable interest due to their harmlessness, biodegradability, and negligible secondary pollution. Therefore, in this present study, biosynthesis of copper nanoparticles was successfully achieved by using a bioflocculant from Alcalegenis feacalis and copper sulphate salt. Nanoparticles were characterized using a scanning electron microscope equipped with elementary detector (SEM), UV-visible absorption, Thermogravititional analysis (TGA), Fourier Transform Infrared Spectrophotometer (FT-IR) and transmission electron microscopy (TEM). This new synthesis method shows excellent stability and is eco-friendly. Scanning electron microscopy (SEM) images revealed that the huge significant increase of copper compared to the bioflocculant. The synthesized nanoparticles showed a 35.8% copper and 37% oxygen concentration. This was an indication that nanoparticles were successful synthesized. The synthesized copper nanoparticles were shown to have higher flocculating activity and removal efficiency of both BOD and COD when compared with the bioflocculant and commercial flocculant. Moreover, the potential of CuNPs was also observed when compared to the bioflocculant and iron chloride in kaolin clay, mine water, industrial waste water and domestic waste water. The highest flocculating activity was achieved with the lowest concentration of CuNPs (0.002g/L) with 96% and the least activity was 80% at 0.01g/L. The synthesized copper nanoparticles (CuNPs) are cation independent with 96% flocculating activity following 1% behind the most effecting cations (K+, Mn2+ and Li+) which had 97%. It functioned the best at pH with 7 with 96% FA. It was not as effective at pH 3 as it was least effective with 55% FA. Furthermore, the nanoparticles were found to be thermostable with a flocculating activity was above 90% in a temperature range of 50-100 ℃. A temperature of 100 ℃ was the least effective with 91% flocculating activity. The synthesized copper nanoparticles are also high in removal efficiency of staining dyes, such as safranin (92%), carbol fuchsine (94%), malachite green (97%) and methylene blue (85%). Furthermore, the synthesized CuNPs were shown to possess high removal efficiencies for elements such as sulphur, calcium, aluminium and phosphorus both in mine and waste water. Nutrients such as nitrate (NO3-) were also removed effectively by the CuNPs. Removal efficiency for both COD and BOD was also high compared to that of FeCl3 and the pure bioflocculant, with a RE of 76% and 80% respectively.
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    A comparative study between Fe@Cu core-shell nanoparticles with iron and copper nanoparticles synthesized using a bioflocculant: characterization, industrial application and biosafety
    (University of Zululand, 2020) Dlamini, Nkosinathi Goodman
    Nanotechnology addresses numerous environmental problems such as wastewater treatment. Ground water, surface water and wastewater that is contaminated by toxic organic, inorganic solutes and pathogenic microorganisms can now be treated through the application of nanotechnology. This thesis focuses mainly on the synthesis of single metallic and core-shell metallic nanoparticles using a greener approach and application of these materials in the wastewater treatment. Characterization of the as-synthesised materials (FeNPs, CuNPs and Fe@Cu core-shell) was achieved with the analytical techniques such as Fourier Transform-Infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and UV-Vis spectroscopy (UV-Vis). The as-synthesised iron nanoparticles (FeNPs) revealed a spherical morphology and elements such as oxygen and iron contributed 65.25 % Wt% with oxygen having 47.94 followed by iron with 17.31% through TEM and SEM-EDX analysis. The X-ray diffractograms reveals the broad peaks that are observed between 2θ ~ 24°, 29°, 30° and 35°. The presence of hydroxyl (–OH) and amine (–NH2) groups were shown by FT-IR spectroscopy studies. The highest flocculation activity (FA) was achieved at a dosage of 0.4 mg/mL. The iron nanoparticles were found as pH stable as their flocculation activity was 77 and 93 % at pH 3 and 11 respectively. These nanoparticles flocculate best in the presence of cations and are thermostable as the flocculation activity was above 88% at 100 °C. Moreover, the as-synthesized FeNPs showed to possess no antimicrobial activity and the removal efficiency of dyes was very poor in the absence of cation. With the addition of 2mL, 1% Mg2+, the removal of methylene orange improved from 45% to 58% in 5 minutes. The transmission electron microscopy analysis of as-synthesised copper nanoparticles (CuNPs) showed close to spherical shapes with an average particle size of ∼53 nm. Energy dispersive X-ray spectroscopy analysis confirmed the presence of the Cu nanoparticles and also the other elements such as O, C, P, Ca, Cl, Na, K, Mg, and S originated from the bioflocculant. FT-IR results showed the presence of the –OH and –NH2 functional groups. The highest flocculation activity (96%) was achieved with the lowest concentration (0.2 mg/mL) of copper nanoparticles and the least 80% was attained at 1 mg/mL. The CuNPs showed a maximum flocculation activity of 96% without the addition of the cation and worked best at all pH ranges of acidic, neutral, and alkaline regions with an optimal FA at pH 7 (96%). Furthermore, the as- xxiv | P a g e synthesised copper nanoparticles were found to be thermostable with 91% FA at 100 °C. The synthesized copper nanoparticles are also high in removal efficiency of staining dyes, such as safranin (92%), carbol fuchsine (94%), malachite green (97%), and methylene blue (85%). The high removal efficiency of nutrients such as phosphate and total nitrogen in both domestic wastewater and Mzingazi river water was observed. In comparison to ciprofloxacin, CuNPs revealed some remarkable properties, as they are able to kill both the Gram-positive and Gram-negative microorganisms. In the optimization of Fe@Cu core-shell nanoparticles; to enhance best concentration for core-shell formation, different ratios of iron to copper were prepared. Sample 1 (S1) contained 1:3 iron to copper (Fe 25% - Cu 75%), sample 2 (S2) contained 1:1 iron to copper (Fe 50% - Cu 50%) and third sample (S3) contained 3:1 iron to copper (Fe 75% - Cu 25%). The flocculation activity was above 98% at a dosage of 0.2 mg/mL for all the samples and flocculate well at acidic, alkaline and neutral pH conditions. Sample 3 showed to be thermostable with flocculation activity above 90% and both sample 2 and 1 were also thermostable, but the flocculation decreased to 87 at 100 ℃. All three samples revealed some remarkable properties for staining dye removal as the removal efficiency was above 89% for all dyes tested. The synthesized core-shell nanoparticles could remove nutrients such as total nitrogen and phosphate in both domestic wastewater and Mzingazi river water. Furthermore, high removal efficiency for COD and BOD was also observed. The Fe@Cu core-shell nanoparticles possess antimicrobial activity against both Gram-positive and Gram-negative microorganisms. The Minimal Inhibitory Concentration (MIC) and Bactericidal Minimal Concentration (MBC) was observed at a lower concentration of 1.563 mg/mL. Cell viability against HEK 293 and MCF7 was high at the lower concentration with the increase in concentration the decrease in cell viability was observed. The high removal efficiency (RE) of COD, BOD, total nitrogen and phosphate was observed in all wastewater samples examined. The removal efficiency of the dyes was found to be above 93% for all dye samples.
University of Zululand