Previous Article in Journal
Acetonitrile-Induced Destabilization in Liposomes
Article Menu

Export Article

Open AccessReview
Colloids Interfaces 2018, 2(1), 7; doi:10.3390/colloids2010007

Two-Liquid Flotation for Separating Mixtures of Ultra-Fine Rare Earth Fluorescent Powders for Material Recycling—A Review

1
Ecole Nationale Supérieure de Géologie, GeoRessources UMR 7359 CNRS, University of Lorraine, 2 Rue du Doyen Marcel Roubault, BP 10162, 54505 Vandoeuvre-lès-Nancy, France
2
Department of Systems Innovation, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
*
Author to whom correspondence should be addressed.
Received: 10 January 2018 / Revised: 2 February 2018 / Accepted: 7 February 2018 / Published: 13 February 2018
View Full-Text   |   Download PDF [5101 KB, uploaded 14 February 2018]   |  

Abstract

This paper reviews two separation methods applying two-step two-liquid flotation for recovering ultra-fine rare earth fluorescent powders (i.e., red, green, and blue). The paper aims to extract the science behind separation by two-liquid flotation, and to provide resulting engineering tips for material recycling. Two-liquid flotation, also called liquid-liquid extraction, involves two solvents (i.e., non-polar and polar solvents) to capture hydrophobic/hydrophobized particles at their interface, and a surfactant to selectively modify the surface property of the target powder(s). For separating a three powder mixture, two different developed flowsheets, composed of two-step separation are discussed. The major difference found was the polar solvents used. The first flowsheet (called the aqueous-organic system) employed water as a polar solvent while the second flowsheet (called the organic-organic system) utilized N,N-dimethylformamide, DMF as a polar solvent. The organic-organic system at the optimized conditions achieved both the grade and recovery of all the separated fluorescent powders at greater than 90% while the aqueous-organic system did not satisfy these criteria. This paper also reviews the mechanism behind the separation, as well as performing a cost comparison between the two methods. The cost comparison indicates that the organic-organic system is a more cost effective method for recovering rare earth fluorescent powders than the aqueous-organic system. Since the size of powders (i.e., several µm) is too small for the application of conventional separation technologies (e.g., froth flotation), two-liquid flotation is a unique pathway for the material recycling of ultra-fine rare earth fluorescent powders. View Full-Text
Keywords: polar solvent; surfactant; zeta potential; Derjaguin-Landau-Vervey-Overbeek (DLVO) theory; coagulation polar solvent; surfactant; zeta potential; Derjaguin-Landau-Vervey-Overbeek (DLVO) theory; coagulation
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Otsuki, A.; Dodbiba, G.; Fujita, T. Two-Liquid Flotation for Separating Mixtures of Ultra-Fine Rare Earth Fluorescent Powders for Material Recycling—A Review. Colloids Interfaces 2018, 2, 7.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Colloids Interfaces EISSN 2504-5377 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top