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Undergraduate Theses

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

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Degree: search.filters.degree.Bachelor of Science in ChemistryKeyword: search.filters.keyword.Optimization

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    Optimization of pH, sorbent dose, and contact time in biosorption of Cu, Cd and Pb in sugarcane bagasse in a tri-metal aqueous system
    Abetria, Pauline Grace R. (Department of Chemistry, College of Arts and Sciences, Univsersity of the Philippines Visayas, 2013-04)
    Adsorption is one of the physicochemical treatment processes found to be effective in removing heavy metals from aqueous solutions. The biosorption of Cu, Cd, and Pb in sugarcane bagasse in a tri-metal aqueous system was optimized for pH, sorbent dose, and contact time using Doehlert design and it was found that the optimal values are pH 5, a sorbent dose of 1.33g sorbent/mg metal, a contact time of 4 hours, and the available sites on the sorbent for metal binding were influenced by pH. Furthermore, the effect of initial metal concentration on the metal uptake of the sorbent was also studied and it was found that at increasing metal concentrations the metal uptake also increased at a fixed (optimum) sorbent dose. The sorbent affinity was observed to be increasing in favor of increasing ionic radius, Cu < Cd < Pb, at relatively low metal concentrations and Cd < Cu < Pb at relatively high metal concentrations. Each metal behaved differently on the sorbent. Copper obeyed the Langmuir isotherm whereas cadmium and lead both obeyed the Freundlich isotherm. Finally, the IR spectrum of the sorbent was elucidated and -OH and -COOH groups were present but complexation was absent. Hence, in a tri-metal aqueous system containing Cu, Cd and Pb, the biosorption process in bagasse is proposed to be by physical adsorption.
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    Optimization of extraction Conditions of water-soluble phenolics from tawa-tawa (Euphorbia hirta L.) based on Densitometric TLC using gallic acid as marker compound
    Aborka, Ma. Ayanne B. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    The present study aimed to optimize the extraction conditions of water-soluble phenolics for tawa-tawa (Euphorbia hirta L.) with gallic acid as the compound of interest. Water was used as extraction solvent. The effect of the interactions of different extraction temperature (50°C, 60°C and 70°C) and extraction time (20 min, 40 min and 60 min) were investigated. To evaluate the importance of the parameters on the extraction efficiency of gallic acid, a factorial design was used. The normal probability plot and estimates of standard error showed that time and temperature were both significant parameters. It further showed that time was a more significant contributor than temperature to the extraction efficiency of gallic acid. The results revealed that interaction of time and temperature did not have significant effects. The ANOVA results showed that only extraction parameter with significant effect was time (p < 0.05). Temperature and its interaction with time did not have significant effects. Based on the desirability values generated by Design-Expert 9.0.4, the optimal conditions in extracting gallic acid were the following: extraction time of 60 minutes and extraction temperature of 70°C. Results of FTIR analysis confirmed the presence of the following functional groups: O-H, C=O, C-O, C-H (aromatic), C=C (benzene) and out-of-plane bending or oops. Gallic acid in tawa-tawa is present in esterified form and exists as part of hydrolysable tannins.