Detoxification of phorbol esters in crude Jatropha curcas seed oil using modified nanosilica from purified rice hull ash

Date

5-2013

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Milagros M. Peralta

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

Phorbol esters extracted from crude Jatropha curcas seed oil using methanol were found to comprise about 6 % of the oil. Although the phorbol esters were found to be a minor component, these compounds were mainly responsible for the toxicity of the oil based on the cytoxicity studies that were conducted. Decontamination of the seed oil was accomplished by adsorption on nanosilica that had been modified using the phorbol esters or their oxime derivatives in order to increase its ability to remove these toxic components. The phorbol ester oxime derivative (PEOD) was prepared from the phorbol ester?rich methanol extract by chemical derivatization using hydroxylamine hydrochloride.Nanosilica was prepared from purified rice hull ash under hydrothermal conditions that included alkali treatment and calcination at 600-650 °C. Preliminary imaging using low power (10000x) scanning electron microscopy (SEM) revealed an agglomeration of amorphous particles, with an estimated mean particle size of 156.00-220.00 nm. Modification of nanosilica was employed using the crude phorbol ester-rich fraction and the phorbol ester oxime derivative as organic templates. Different mass ratios of modified nanosilica mixtures were prepared using 1% and 10% stock template solutions consisting of 10 g silica per 8 g NaOH and 80 g distilled H2O. The resulting mixtures were aged for 2 hours with effective stirring at room temperature. Calcination was further employed to remove the organic template. Low power (10000x) SEM images of modified nanosilica products showed that the CPE-modified nanosilica was an agglomeration of amorphous, porous materials with a size range of 73.30-164.00 nm while PEOD-modified nanosilica consisted of agglomerated, amorphous porous solids with a mean particle size range of 51.80-146.00 nm. Detoxification of the seed oil by removal of the phorbol esters through adsorption on modified nanosilica was carried out using the following optimized parameters: 8 % (w/v) amount of adsorbent, 60 minutes adsorption time, ambient temperature and 300 rpm stirring rate. The optimum conditions resulted in a maximum removal up to 90.12 % of toxic phorbol ester from Jatropha oil. Brine Shrimp Cytotoxicity Assay results showed that the untreated crude Jatropha curcas seed oil exhibited the highest mortality rate on brine shrimp nauplii based on a LC50 value of 0.30 μg/mL. Treatment with 10:3.3 (w/w) modified nanosilica:CPE yielded the least toxic seed oil sample with the highest LC50 value of 124.40 μg/mL. Statistical results using Tukey?s Multiple Comparison Test showed that the differences in the adsorption treatments using unmodified nanosilica and modified nanosilica products were found to be highly significant. Although untreated seed oil and seed oil treated with unmodified nanosilica were not different from each other, they were significantly different from the other adsorption treatments. Therefore, 10:3.3 (w/w) modified nanosilica:CPE product was considered the most suitable adsorbent for phorbol esters removal from crude Jatropha curcas seed oil.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2013 C42 /L36

Document Type

Thesis

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