Low molecular weight hyperbranched (HB) polyesters were synthesized via melt polymerization from tri-methylolpropane and three aliphatic dicarboxylic acids, namely, succinic acid (SA), adipic acid (AA) and dodecanedioic acid (DA). The degrees of branching (DBs) ranged between 30% and 75% depending on the monomer ratio. Their DB, cyclic index and terminal index were all determined, indicating that the shorter chain HB polyesters PE-SA and PE-AA showed a greater degree of intramolecular cyclization, compared to the longer aliphatic chains within PE-DA. The HB polyesters form stable colloidal suspensions in buffered aqueous media and were found to be pH responsive. The stability of the colloidal suspensions is enhanced by two factors: (1) increasing the aliphatic chain length and (2) increasing the pH of the solution for the same HB polyester.

4-Dodecylbenzenesulfonic acid (DBSA) was employed in the esterification of oleic acid (OA) and the trans-esterification of oleic oil (OO) with 1-butanol as alcohol in the presence of various degrees of excess water. Under these conditions DBSA was found to be a highly active esterification catalyst regardless of excess water content, but was found to be a less effective for trans-esterification reactions. Lipophilic alcohols of differing straight and branched C3-6 chains were also tested on mixtures of OA/water (1:1) in DBSA-catalyzed esterifications; OO/water (1:1) in trans-esterifications; and OA/OO/water (1:1:1) in simultaneous esterifications and trans-esterifications. While longer straight chain alcohols generally gave a two-fold increase in yield of their corresponding alkyl oleates to 80%+, we observed a doubling from 30-50% to 60-95% of alkyl oleate yield for the OO/OA/water mixture. DBSA-catalyzed amidations of OO and methyl oleate emulsions in water were conducted with 1-butyl and 1-heptyl amine where it was found that the more lipophilic the ester moiety the higher the yield of alkyl amide. Practical applications: The practical advantages of DBSA as catalyst are high conversions to the desired product along with its tolerance to high quantities of water, emulsified within the lipid material. A capacity to transform a range of substrates with varying lipophilic character in a range of condensation reactions. In addition, we demonstrate that esterification and trans-esterification reactions could be performed simultaneous and in the presence of high quantities of water. This is of direct interest to the transformation of waste sources of lipids that often contain a mixture of triglycerides and free fatty acids in various concentrations, emulsified with waste water. Furthermore, we demonstrate that all of the value-added products/co-products can be separated by an effective and industrially relevant methodology, including recovery of the DBSA catalyst as well as the water and water soluble co-products, such as glycerol. A 4-Dodecylbenzenesulfonic acid (DBSA) is demonstrated to be an effective polyvalent catalyst for the recovery of aqueous emulsified lipids by conversion into value-added products. DBSA proved to be a polyvalent catalyst showing high activity using a range of substrates, performing esterification, trans-esterification, and amidations reactions efficiently despite the potential detrimental presence of high water loadings. The commercial incentive of our system is the phase separation of the product mixture into the converted lipids for use as biofuels and glycerol for resale as a fine chemical.

Two types of Animal Fatty Wastewater Sludges (AFWS 1 and 2) were analyzed and fully characterized to determine their suitability for conversion into biofuel. AFWS 1 was determined to be unsuitable as it contains 68.8wt.% water and only 32.3wt.% dry material, of which only around 80% is lipids to be converted. AFWS 2 has only 15.7wt.% water and 84.3wt.% dry material of which is assumed to 100% lipids as the protein and ash contents were determined to be negligible. The 4-dodecylbenzenesulfonic acid (DBSA) catalyzed esterification of AFWS with 1-butanol was performed in a novel batch reactor fitted with a drying chimney for the "in situ" removal of water and optimized using a non-conventional Doehlert surface response methodology. The optimized condition was found to be 1.66mol equivalent of 1-butanol (with respect to total fatty acid chains), 10wt.% of DBSA catalyst (with respect to AFWS) at 105°C for 3h. Fatty Acid Butyl Esters (FABEs) were isolated in good yields (95%+) as well as a blend of FABEs with 1-butanol (16%). The two potential biofuels were analyzed in comparison with current and analogous biofuels (FAME based biodiesel, and FABE products made from vegetable oils) and were found to exhibit high cetane numbers and flash point values.