Biofuel production from non-edible and arid plants in the UAE

Abstract

This study has two main purposes. The first one is to explore various catalysts for transesterification process in neem biodiesel production. Two types of neem oil, with different water content, were used as the feedstock. Attention was mainly focused on the organic base TBAH and modified conventional homogenous catalysts (KOH, NaOH) with crown ethers, which are considered as page-like structures for entrapment of trace elements within the cage diameter. Trace element content of biodiesel samples was analyzed by ICP-MS; and the toxic species: As3+, As5+ and Cr3+, Cr6+ were characterized by HPLC-ICP-MS. Physical properties of the biodiesel samples were tested and experimental results were compared with those derived from the unmodified treatment. The accumulated data revealed that product yields and metal retention were strongly influenced by catalytic modification. The best result was produced by the combined KOH/18-crown-6 treatment in the less water contaminated feedstock. The yield of the by-product, glycerol, was determined by FT-IR and the glycerol was also characterized for trace elements and toxic species using hyphenated mass spectrometry. The second aim of this work is to produce bioethanol from Americana agave plant which grows in arid and semi-arid areas. Sugar content was detected for both leaf and stem of the agave plant. The agave leaf was finally adopted in this experiment because more sugar can be extracted from it. A new method was developed to identify and quantify the product, bioethanol, using gas chromatography (GC) with suitable operation conditions. Optimization of the fermentation process was studied in terms of hydrolysis, fermentation period and yeast (S. cerevisiae) content. Acid hydrolysis of agave leaves with 1% H2SO4 resulted in higher soluble sugar levels than heat hydrolysis. Seven days fermentation and 20% v/v yeast solution/juice was proven to be optimal. Products were separated through fractional distillation and distillates in the range between 70C to 85C were collected. Trace elements were characterized by ICP-MS.

Date of Award	2015
Original language	American English
Supervisor	Avinash Pillay (Supervisor)