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Undergraduate Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14583/13

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    Spontaneous formation of silver nanoparticles in humid acid-rich water of Santa Barbara, Iloilo
    Cadelina, Mary Dored Ann D. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
    Humic acid (HA) - rich water of Sta. Barbara, Iloilo is successful in acting as a reducing and capping agent in the synthesis of silver nanoparticles (AgNPs). UV-Visible spectroscopy was used to determine the effect of irradiation time, varying HA and AgNO3 concentration, and electrolyte addition. Furthermore, the bactericidal efficacy of AgNPs was evaluated using broth microdilution method. Measurement of AgNPs was done using transmission electron microscopy (TEM). Lower irradiation time (10- 40 min) shows an increasing absorbance trend. However, absorbance decreased and showed bathochromic shifts when irradiated at longer times (50-60 min). AgNP formulations of 40 ppm HA with 4 mM AgNO3 and 50 ppm HA with 4 mM AgNO3 showed the highest peak intensity for varying AgNO3 and HA concentration, respectively. These results were found in both irradiated and un-irradiated samples. Aggregation occurred upon the addition of 50 mM, 100 mM, and 500 mM NaCl but was more prominent at 500 mM NaCl. Dialyzed and un-dialyzed AgNPs have bactericidal activity. However, un-dialyzed AgNP was a more effective treatment because it showed a bactericidal activity up to 1:16 dilution for both Staphylococcus aureus and Escherichia coli as compared to the dialyzed AgNPs which showed a bactericidal activity up to 1:4 for S. aureus and 1:8 for E. coli. The dialyzed AgNPs are polydispersed but were mostly small with sizes less than 10 nm based on the TEM image.
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    Mud crab (Scylla serrata) shells for the removal of humic acids from Santa Barbara well water
    Asdillo, Reina Jean A. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2010-04)
    The chemical contamination of drinking water from a wide range of contaminants such as humic acids can potentially lead to health-related in living organisms, especially humans. In rural areas of the Philippines, the use of low cost methods to remove water pollutants is, therefore, of great interest. In this study, osterized mud crab (Scylla serrata) shells or exoskeletons from cooked crab wastes were used to remove humic acids from the Santa Barbara well water. Adsorption experiments were done to evaluate its capacity to remove humic acids from the well water. Adsorption Isotherms and Fourier Transform Infrared Spectroscopy were employed to study the characteristics of the adsorption of humic acids onto the OSSE (osterized Scylla serrata exoskeletons). Adsorption experiments showed that at an average 1.0010 g of OSSE and after six hours of agitation, an average 74.95% of humic substances were removed from 50 mL of Montinola, Santa Barbara well water sample. Isotherm experiments showed that the experimental data can be fitted in both Langmuir and Freundlich models with low K values of 0.0235 L/mg and 0.4450 (mg/g)(L/mg), respectively. Based on the results of the above experiments, OSSE is a good adsorbent for humic acids in well waters (although more research need to be done on the removal of the substances remaining in the water after OSSE treatment) and the U-OSSE (used osterized Scylla serrata exoskeletons) can possibly be recycled.