Patrisha J. Pham

Lipid storage compounds in raw activated sludge microorganisms for biofuels and oleochemicals production

Activated sludge contains a microbial population responsible for the biological treatment of wastewater. This microbial population mostly consists of heterothrophic bacteria which utilize the organic content of the wastewater for growth, either as part of their cellular structures or as energy and carbon storage compounds. These compounds are mostly lipidic in nature and are or could be important raw materials for a multitude of applications in biofuel and oleochemical industries. In this study, a municipal activated sludge was analyzed for lipid storage compounds and other compound classes present in significant concentrations. Three extraction techniques, namely; Bligh & Dyer (applied on dried and partially dewatered samples) and accelerated solvent extractions, were initially investigated to identify the one resulting in the highest gravimetric and biodiesel yields. The highest yields were obtained using the Bligh & Dyer of partially dewatered sludge samples and thus, the extracts from this extraction technique were subjected to a series of analytical procedures such as precipitation, solid phase extraction, thin layer chromatography (TLC), gas chromatography with flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) to characterize the major compound classes present. Results indicated that the major compounds in the samples were polyhydroxyalkanoates, wax esters, steryl esters, triacylglycerides, free fatty acids, free sterols and phospholipids. Hydrocarbons, diacylglycerides and monoacylglycerides were also detected. These compounds are either synthesized by microorganisms or from exogenous contributions. Regardless of the source of these compounds, their persistent presence in activated sludge offers another feedstock for a wide range of applications.

Solid phase extraction and enrichment of essential fatty acid methyl esters from soy-derived biodiesel by novel π-complexing sorbents

The essential fatty acid (EFA) methyl esters, methyl linolenate (18:3) and methyl linoleate (18:2), were extracted and enriched from soy-derived biodiesel using novel pi-complexing sorbents. These pi-complexing sorbents were prepared by covalently immobilizing ionic liquids (ILs) onto silica and then coating these silica-supported ILs with silver salts. The silica-supported hydrophobic ILs enhanced the retention of silver salts on the solid sorbents. After the extraction of the polyunsaturated fatty acid methyl esters (PUFAMEs) 18:3 and 18:2 from biodiesel using the sorbents, a decrease in NO(x) emissions and an enhancement of the oxidation stability of biodiesel can be obtained. Solid phase extraction was investigated using a simple three-step procedure consisting of (1) sorbent pre-treatment, (2) sample extraction onto the sorbent and (3) stripping the sorbent by desorption solvent. The factors influencing extraction capacity and selectivity were also studied. 10.5 Mg of sorbent AgBF(4)/SiO(2) x Im(+) x PF(6)(-) could completely adsorb the 18:3 (0.66 mg) from standard biodiesel hexane solution in 5 min. After a consecutive two-step stripping by diethyl ether and 1-hexene, the 18:3 concentration (wt.%) was increased from around 8.5% in the original biodiesel hexane solution to approximately 90% in the 1-hexene stripping solvent.

Selective extraction of polyunsaturated triacylglycerols using a novel ionic liquid precursor immobilized on a mesoporous complexing adsorbent.

Mesoporous silica (SBA‐15) synthesized by using Pluronic123 as the structure‐directing template was functionalized by imidazolium‐based ionic liquid precursors. Silver salts were then immobilized onto the supported ionic liquids using the incipient wetness impregnation technique. The separation of unsaturated species was achieved through the reversible and specific interaction between silver ions and carbon–carbon double bonds. This adsorbent was examined for the selective separation of polyunsaturated triacylglycerols (PUTAG) using High Pressure Liquid Chromatography (HPLC) with Evaporative Light Scattering Detection (ELSD) as the quantification methodology. AgBF4/SBA15·HPSiOEtIM·PF6 showed an adsorption capacity for linolenin of about 217 mg adsorbed/gram of sorbent. This adsorbent had good selectivity and a high capacity for the most highly unsaturated triacylglycerol when applied to a mixture of triacylglycerols with varying degrees of unsaturation. Consequently, a stepwise methodology was also developed to increase the recovery of the adsorbed components. This adsorbent retained its selectivity and capacity when recycled up to five times.

Liquid Phase Extraction and Separation of Noble Organometallic Catalysts by Functionalized Ionic Liquids

Abstract The separation of two noble organometallic catalysts from a homogeneous organic phase was investigated using liquid phase extraction with functionalized ionic liquids. Thirteen functionalized ionic liquids containing amino, hydroxy, thioether, carboxylic, or olefin functional groups were prepared by a standard neutralization method. The extractions of Jacobsens catalyst and Wilkinsons catalyst were conducted using the functionalized ionic liquids as the extraction phase without adding any other metal complexing extractant. The distribution factors between the ionic liquid (IL) phase and toluene (organic solution phase) demonstrated that the functional groups in ILs exhibited moderate to high affinity with the metal complexes. The influence of the ionic liquid structure on the distribution factors was also investigated.

Biocatalyzed Production of Structured Olive Oil Triacylglycerols

Functional properties of fats and oils do not depend only on their fatty acid composition but also on the distribution of these fatty acids in the three positions of the glycerol backbone. This gives the fat or oil its commercial value. (Zhao,2005) There is a growing demand for lipids with desired characteristics ,thus researches have given way to these demands by the development of structured lipids with triacylglycerols that have predetermined composition and distribution of fatty acids. Structured lipids are now considered as alternatives to conventional fats not on the basis of saturate/polyunsaturate ratios but rather on their impact on cholesterol deposition. With the advances in the biotechnology and chemistry of fats and oils it is now possible to design fats and oils with properties that are desired. Recent years have seen great interest in the biotechnological modification and synthesis of structured triacylglycerols. Modification of fats and oil triacylglycerols to improve functionality have been carried out with various oils including olive oil. Olive oil enjoys a privileged position amongst edible oils and is still a buoyant commerce because of the large consumption of Mediterranean inhabitants (Oh et al,2009). It is one of the most expensive vegetable oils and of all the vegetable oils, olive oil is the best source of the monounsaturated fatty acid, oleic acid (72-83%)Risk factors for cardiovascular disease such as the level of homocysteine and total and low density lipoprotein (LDL) cholesterol in plasma have been reported to be reduced by oleic acid (Baro et al,2003). Olive oil is more than just oleic acid and because of its properties and qualities, it is used almost entirely in dietary consumption and even new markets have been created for this oil.