title: Solid phase extraction and enrichment of essential fatty acid methyl esters from soy-derived biodiesel by novel pi-complexing sorbents.
abstract: 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.
authors.affiliation: Department of Chemistry, Box 9573, Mississippi State University, Mississippi State, MS 39762, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Patrisha J
authors.initials: PJ
authors.lastname: Pham
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Charles U
authors.initials: CU
authors.lastname: Pittman
authors.forename: Tingyu
authors.initials: T
authors.lastname: Li
mesh_terms: D000327:Adsorption; D001674:Bioelectric Energy Sources; D003247:Conservation of Natural Resources; D004952:Esters / Q000302:isolation & purification*; D005228:Fatty Acids, Essential / Q000302:isolation & purification*; D052578:Ionic Liquids; D012822:Silicon Dioxide; D052616:Solid Phase Extraction / Q000379:methods*; D012997:Solvents; D013025:Glycine max / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D017962:alpha-Linolenic Acid / Q000302:isolation & purification
chemical_list: D004952:Esters; D005228:Fatty Acids, Essential; D052578:Ionic Liquids; D012997:Solvents; D017962:alpha-Linolenic Acid; D012822:Silicon Dioxide