Parametric Study on Free Fatty Acid (FFA) Reduction of Used Cooking Oil using Silica Gel Produced from Sugarcane (Saccharum officinarum (L.)) Bagasse Bottom Ash

Author : Mallen, John Vincent Damayo
Major Adviser : Movillon, Jovita A. 
Committee Members : Arocena, Rhebner E.; Valencia, Jeanne Michelle T.
Year : 2017
Month : June
Type : Thesis
Degree: BS
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The study aimed to produce silica gel from sugarcane bagasse bottom ash (SCBBA) and use it as adsorbent to reduce the FFA content in used cooking oil as feedstock pretreatment for biodiesel production. First, silica gel was extracted and precipitated from SCBBA. The percent crude yields of silica gel precipitated at pH 5 and pH 9 were 84.60% and 77.16%, respectively. The silica gel was then characterized to determine its adsorption properties. SEM images showed the porous surface of the silica gel. FT-IR spectrums identified silanol and siloxane groups to be the major functional groups present in the silica gel. Also, XRF and flame photometry showed that the major impurities present in the gel were Na and K. The parametric experiment involved testing the effect of temperature (50, 150 °C), adsorbent loading (1, 5% w/w), contact time (6, 20 minutes) and precipitation pH (pH 5, pH 9) on percent FFA reduction. The highest percent FFA reduction (66.26%) was observed at 150°C temperature, 5% w/w adsorbent loading, 20 minutes contact time, and precipitation pH of pH 9. From the ANOVA, it was found that temperature, adsorbent loading, contact time, precipitation pH, temperature-adsorbent loading interaction, and adsorbent loading-precipitation pH interaction have significant effect on percent FFA reduction. Results of the isotherm experiment showed that the Freundlich isotherm (R² = 0.8550 for pH 9, R² = 0.9494 for pH 5) best describes the adsorption system. The high reduction of FFA on used cooking oil implies that silica gel produced from SCBBA is a suitable adsorbent for the reduction of FFA in used cooking oil.

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