Sustainable Hydrocarbon Oligomer Solvent Systems for Sequestration of Trace Organics from Water

Abstract

Low‐viscosity poly(α‐olefin)s (PAOs) either alone or with functional hydrocarbon oligomer cosolvents are nontoxic, nonvolatile, recyclable solvent systems that effectively and efficiently sequester trace amounts of nonpolar organic compounds such as benzene and halogenated organics from water. More polar compounds including perfluorooctanoic acid and nitrobenzene or water‐miscible compounds such as THF and triethylamine can also be sequestered if the PAO phase contains an H‐bonding PAO‐anchored cosolvent.

Capsules of the Poly(α-olefin) PAO432 for Removal of BTEX Contaminants from Water

“…1 These attributes make them useful in simple recycling schemes that involve liquid−liquid extractions with polar solvents. 2 Their low flammability makes them safer as a solvent for pyrophoric chemicals. 3,5,6 They also have applications in cosmetics since they are as nontoxic as mineral oil.…”

“…3,5 These favorable properties, coupled with their separability, have led us to examine the use of PAOs as solvents in various chemical transformations. 2 Prior work by the Bergbreiter group demonstrated that PAO solutions can be used to recycle hydrocarbon-soluble catalysts or to sequester organic small molecules from polar solutions. For example, in a PAO medium, polyisobutylene (PIB) bound sulfonic acids were useful as esterification catalysts, 7 and the ester products could be isolated by vacuum distillation, quantitatively recycling the catalyst and the PAO solvent.…”

“…The Bergbreiter group also reported the use of PAO to remove benzene, hexane, dichloromethane, 1,2-dichloroethane, and 1,4-dichlorobenzene from water using a batchwise liquid−liquid extraction. 2 In these separations, PAO 432 was added to contaminated water, and then the biphasic mixture was agitated via vortex mixing or shaking to increase the interfacial area between the two phases. Using this method, 99% of benzene, hexane, and 1,4dichlorobenzene and >94% of dichloromethane and 1,2dichloroethane could be removed.…”

“…The Bergbreiter group also showed that PAO-anchored cosolvents capable of hydrogen bonding could facilitate sequestration of more polar contaminants from water, including nitrobenzene (99%) and triethylamine (96%). 2 have many desired attributes and demonstrated application in sequestration of contaminants from water, liquid/liquid biphasic extractions can, in some cases, lead to emulsion formation, especially when PAO-based cosolvents or additives serve as surfactants. 8 Centrifugation can minimize this problem but adds a significant process step, and formation of emulsions is not always predictable or completely avoidable.…”

“…Stock contaminant solutions of benzene, toluene, ethylbenzene, and p-xylene were made in a manner similar to that previously reported. 2 p-Xylene was chosen as a surrogate for xylenes to simplify quantitative analysis, as it has two singlets that facilitate 1 H NMR spectroscopic analysis of the separations. Briefly, 4 mL of the selected contaminant and 20 mL of distilled water were added to a 50 mL centrifuge tube.…”