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Undergraduate Theses

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

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Committee Member: search.filters.committeemember.Escayo, Sherwin L.

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    Extraction of humic substances from vermicompost and application as component matrix for slow-release fertilizers
    Boloron, Nina Loren R. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
    Humic acid was extracted from vermicomposts (hereafter referred as VCHAs) by alkali/acid fractionation and their concentration were determined to be 54.79 (± 0.25) g HS/kg vermicompost in average. The extracted humic substances from vermicomposts were also determined to contain an average K+ of 0.0671 (± 0.0053) g K/kg vermicompost. The Fourier transform infrared spectra of crude VCHSs show similar spectral features with humic acids extracted from vermicomposted materials. The VCHSs were complex with K nutrient and encapsulated in cross-linked Ca-alginate to form vermicompost humic substance — potassium slow-release fertilizer bead (VCHS-K SRF). The synthesized VCHS-K SRF were subjected to total nutrient analysis, swelling kinetics, and slow release test to evaluate the role of nutrient compositions on its capability and capacity as slow- release fertilizer. Results for total nutrient analysis show that with an increase in nutrient loading, encapsulation efficiency is low and nutrient concentration is low. These findings imply that at neutral pH of HS solution, binding sites are saturated with Na+, therefore with having the same affinity as K+ , minimal ion exchange took place and it became difficult for K+ to bind to the HS complex. It also suggests that the amount of polymer coating and the degree of crosslinking were not sufficient to hold all nutrients. Discrepancies on the amount of released K+ was also observed on the release profile as a product of errors on acid digestion and matrix effect, this lead to elevated amounts of release by the VCHS-K SRF. The result of the release behavior profile of VCHS-K SRF shows that with an increase in enriched nutrient load, the release rate is faster. The results on the release profile of the VCHS-K SRF exhibited a parabolic and burst release. This finding in relation to the observed fluctuations on the absorbency pattern suggests that internal pressure build-up on the polymer matrix caused abrasions on the surface of the polymer coating resulting to the instantaneous release of nutrient and absorbed water. Overall, the VCHS-K SRF cannot be classified as a slow-release fertilizer. The present findings suggest the need for further improvement on the study of VCHS-K SRF from vermicompost.
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    A novel water-in-oil-in-water emulsion to encapsulate antibacterial agents
    Balcarcel, Angelica V. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
    Encapsulating bioactive compounds can protect them from adverse conditions. This study aimed to encapsulate bioactive agents in a stable multiple emulsion system using a material that can be recovered easily from a product abundant here in the country. Results of the study revealed that the method of encapsulation used is effective in encapsulating and releasing the bioactive compound encapsulated. The antibacterial activity determination showed that encapsulated chlorhexidine is effective against both S. aureus and E. coli bacteria. Further investigation was made by encapsulating aqueous guava (Psidium guajava) extract in the same emulsion system (water-in-oil- in-water) using recovered coconut milk protein (CMP) as a gelling agent. The evaluation of the stability of the emulsions revealed that the treatment with 40% guava extract in the aqueous phase of its primary emulsion (Emulsion 3) is the most stable among the other treatments. This treatment showed the smallest droplet size range and most uniformed droplet sizes. The creaming index of this treatment also showed the lowest values after three (3) weeks of storage. On the other hand, the treatment with 60% guava extract in the aqueous phase of its primary emulsion (Emulsion 4) appeared to be the most stable against heating. However, no antibacterial activity was observed for any of the emulsion systems both S. aureus and E. coli bacteria. Additional test revealed that the bioactive compound present in the plant extract was disrupted by the sonication process