title: Separation and recycling of nanoparticles using cloud point extraction with non-ionic surfactant mixtures.
abstract: A viable cost-effective approach employing mixtures of non-ionic surfactants Triton X-114/Triton X-100 (TX-114/TX-100), and subsequent cloud point extraction (CPE), has been utilized to concentrate and recycle inorganic nanoparticles (NPs) in aqueous media. Gold Au- and palladium Pd-NPs have been pre-synthesized in aqueous phases and stabilized by sodium 2-mercaptoethanesulfonate (MES) ligands, then dispersed in aqueous non-ionic surfactant mixtures. Heating the NP-micellar systems induced cloud point phase separations, resulting in concentration of the NPs in lower phases after the transition. For the Au-NPs UV/vis absorption has been used to quantify the recovery and recycle efficiency after five repeated CPE cycles. Transmission electron microscopy (TEM) was used to investigate NP size, shape, and stability. The results showed that NPs are preserved after the recovery processes, but highlight a potential limitation, in that further particle growth can occur in the condensed phases.
authors.affiliation: Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan. faizan_qau@yahoo.com
authors.forename: Muhammad Faizan
authors.initials: MF
authors.lastname: Nazar
authors.forename: Syed Sakhawat
authors.initials: SS
authors.lastname: Shah
authors.forename: Julian
authors.initials: J
authors.lastname: Eastoe
authors.forename: Asad Muhammad
authors.initials: AM
authors.lastname: Khan
authors.forename: Afzal
authors.initials: A
authors.lastname: Shah
mesh_terms: D005591:Chemical Fractionation; D017743:Equipment Reuse; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D015080:Mesna / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D017830:Octoxynol / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D059027:Recycling; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D008024:Ligands; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D010165:Palladium; D006046:Gold; D017830:Octoxynol; C010615:Nonidet P-40; D015080:Mesna