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

Abstract

Triton X-114 based cloud point extraction has been demonstrated to be an advantageous approach for the recovery of nanosized copper oxide (NCO) from water. The removal of NCO was influenced by the concentrations of TX-114 and salt, incubation temperature and time, as well as solution pH. With the addition of 0.3% (w/v) Triton X-114, over 88% of the spiked NCO was removed from wastewater after incubation at 35°C for 2 h and centrifugation, whereas over 85% of NCO was recovered after incubation at 28°C for 20 h by gravity phase separation, which is economical and energy-saving. This study suggests that the cloud point extraction technique has great potential in removal of nanomaterials from wastewater. . With the development of nanotechnology and the wide application of nanomaterials, engineered nanomaterials are also inevitably released into the aqueous environment. Recently the safety of engineered nanomaterials is increasingly concerned, as studies suggested that the toxicity of nanomaterials is not only from their own intrinsic toxicity, but also from their effects on the generation, transport and exposure of toxic substances [4,5].Therefore, we have to address the problem of removal of nanowaste with potential toxicity. A few procedures have been proposed for the recovery of nanomaterials from aqueous phase. 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. Recently, our group has discovered that Triton X-114 based cloud point extraction (CPE) provides a general, simple, and cost-effective route for reversible concentration/separation and dispersion of various nanomaterials in aqueous phase [11].The objective of this study is to evaluate the applicability of CPE for the recovery of nanomaterials in wastewater by using nanosized copper oxide (NCO) as a model. NCO is reported to widely exist in semiconductor industrial waste water with a considerable concentration [1].

Intensification of the separation of CuO nanoparticles from their highly diluted suspension using a foam flotation column with S type internal

“…It is indicated that the cationic surfactant is the most suitable to serve as the collector of CuO nanoparticles at pH 6.5. Liu et al (2010) observed that the zeta potential of CuO nanoparticles was zero at pH 6.0 and decreased to a negative value as pH increased over this point. At pH 6.5, the surface of CuO nanoparticles was negatively charged, so CTAB was able to more effectively capture CuO nanoparticles onto the gasliquid interface than the other two surfactants according to the charge theory.…”

“…The removal or recovery of nanoparticles from water faces two major challenges: one is that they cannot freely precipitate due to their high dispersity in water and the other is that their concentrations in water are extremely low (Westerhoff et al 2011;Liu et al 2010). Thus, centrifugation and membrane separations are not suitable options due to their high separation costs.…”

“…However, it needs long processing time and it also results in the large loss of useful nanoparticles. For flocculation and cloud point extraction, the subsequent separation of low-concentration precipitates by centrifugation or membrane separation needs high costs, despite the high removal percentages (Liu et al 2010;Zhang et al 2008). Similar to cloud point extraction, foam flotation also uses surfactants to capture fine particles.…”

Can cloud point-based enrichment, preservation, and detection methods help to bridge gaps in aquatic nanometrology?

“…Comparably, CPE procedures were established for CuO NPs and ZnO with enrichment factors of 100 and 220 and extraction efficiencies of almost 90 and 64–123 %, respectively [ 11 , 12 ]. In the case of ZnO NPs, TEM and UV/Vis measurements revealed that particle size and shape were stable over 2 months of storage.…”

Aspirin in Food Samples for Separation and Micro Determination of Copper(II) Using Cloud Point Extraction/Solvation Method

“…Amoxicillin can be applied as a ligand to the determine copper(II) by CPE joined with spectrofluorometric in the presence of Triton X-114 as the surfactant [25]. Applied to extract Cu, Co and Ni in water testers using 2-(5-bromo-2-pyridylazo)-5-(diethyl amino) phenol (5-Br-PADAP) as ligand and Triton X-114 [26]. The study indicates that the CPE has excellent potential in Nano-materials removal from wastewater Triton X-114 suitable for the recovery of Nano sized Copper oxide (NCO) from the water.…”