Extraction of Nanosize Copper Pollutants with an Ionic Liquid

Abstract

Speciation and possible reaction paths of nanosize copper pollutants extracted with a RTIL (room-temperature ionic liquid ([C4mim][PF6], 1-butyl-3-methylimidazolium hexafluorophosphate)) have been studied in the present work. Experimentally, in a very short contact time (2 min), 80-95% of nanosize CuO as well as other forms of copper (such as nanosize Cu, Cu2+, or Cu(II)(ads) (in the channels of MCM-41)) in the samples could be extracted into the RTIL. The main copper species extracted in the RTIL as observed by XANES (X-ray absorption near edge structure) were Cu(II). Existence of Cu-N bondings with coordination numbers (CNs) of 3-4 for copper extracted in the RTIL was found by EXAFS (extended X-ray absorption fine structural) spectroscopy. Interestingly, chelation of Cu(II) with 1-methylimidazole (MIm) in the RTIL during extraction was also observed by 1H NMR (nuclear magnetic resonance). At least two possible reaction paths for the rapid extraction of nanosize copper pollutants with the RTIL might occur: (1) an enhanced dissolution of nanosize CuO (to form Cu2+) and (2) formation of [Cu(MIm)4(H2O)2]2+ that acted as a carrier of copper into the RTIL matrix.

Instrumental approach toward understanding nano-pollutants

“…Huang et al extracted copper nano-pollutants in environmental contamination sources by room-temperature ionic liquid (RTIL) and analyzed them by XANES and EXAFS. Existence of Cu-N bonding with coordination numbers of 3-4 for Cu was found by EXAFS [53]. They also extracted ZnO and ZnS nanoparticles from phosphor ash waste into RTIL.…”

“…using a room-temperature ionic liquid (RTIL). Their NMR analysis showed that chelation of Cu(II) with 1-methylimidazole group in RTIL is responsible for rapid extraction of Cu species in RTIL [53]. Ryu et al fabricated different mesoporous TiO 2 particles by changing the calcination temperature (300-700°C).…”

Use of cloud point extraction for removal of nanosized copper oxide from wastewater

“…NCO is reported to widely exist in semiconductor industrial waste water with a considerable concentration [1].…”

“…They are transferred or enriched in the wastewater from conventional air pollution control devices such as scrubbers [1], and some traditional industrial sludges are actually nanowastes with adsorbed heavy metals or organic pollutants [2]. For example, nanoparticles (68-120 nm) have been found in CMP (chemical mechanical planarization) wastewater in the semiconductor manufacturing industries [3], and Chinese chlor-alkali and chlorate plants generate over 800 kilotons of Mg(OH) 2 -containing nanowastes per year [2].…”

“…C 60 fullerene was extracted by liquid-liquid extraction with toluene or by solid-phase extraction with octadecylsilyl [6,7]. Ag nanoparticles were recovered with anion exchange resin beads [8], whereas Au nanoparticles [9], CdTe quantum dots [10], and nanosized copper [1] were extracted with ionic liquids separately. These procedures were conducted on the basis of various mechanisms, thus a general, effective, economic, and mature method that is applicable to various nanomaterials is urgently needed.…”