Separation and Recycling for Rare Earth Elements by Homogeneous Liquid-Liquid Extraction (HoLLE) Using a pH-Responsive Fluorine-Based Surfactant
A selective separation and recycling system for metal ions was developed by homogeneous liquid-liquid extraction (HoLLE) using a fluorosurfactant. Sixty-two different elemental ions (e.g., Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, In, Ir, La, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Re, Rh, Ru, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, Tl, Tm, V, W, Y, Yb, Zn, and Zr) were examined. By changing pH from a neutral or alkaline solution (pH ≥ 6.5) to that of an acidic solution (pH 90% efficiency into a sedimented Zonyl FSA® (CF3(CF2)n(CH2)2S(CH2)2COOH, n = 6–8) liquid phase. Moreover, all rare earth elements were obtained with superior extraction and stripping percentages. In the recycling of rare earth elements, the sedimented phase was maintained using a filter along with a mixed solution of THF and 1 M sodium hydroxide aqueous solution. The Zonyl FSA® was filtrated and the rare earth elements were recovered on the filter as a hydroxide. Furthermore, the filtrated Zonyl FSA was reusable by conditioning the subject pH.
Separation Factor of Y/Dy Emulsion on Membrane Process Using Nitric Acid and D2EHPA Solvent
Liquid extraction of Y that containing Dy using bis-2-Ethylhexyl phosphoric acid (D2EHPA) extractant has been conducted. The purpose of this study is to determine the optimum parameter in a separation process that uses membrane emulsion. As the aqueous phase, a mixed solution of Y2O3 and Gd2O3 containing Y 10 g/L and Gd 250 mg/L was used. D2EHPA as extractant or organic phase with a variety of concentration was diluted with kerosene. Emulsifier Span-80 was used to make an emulsion of membrane liquid. The internal phase of the liquid membrane used 0.20–0.50 M nitric acid, and the external phase used 1–5 M nitric acid. The studied parameters were extractant concentration, stirring speed, stirring time, and the ratio of the internal and external phase. X-Ray Fluorescence (XRF) was used for the analysis of Y and Dy. The analysis of Y and Dy used the X-Ray Fluorescence (XRF). The optimization results of the extraction process of Y with emulsion membrane using D2EHPA extractants obtained the following conclusions: the optimum stirring rate was 8500 rpm, the D2EHPA concentration was 4.5% in kerosene, the internal concentration was 0.45 M nitric acid, the external concentration was 4 M nitric acid, the stirring time was 10 min that fixed stirring rate was 500 rpm, and the ratio of internal and external phase was 1:1. This conditions acquired a separation factor (SF) Y-Gd of 7.57.
Stability of planar PEMFC in Printed Circuit Board technology
Abstract The use of planar PEMFCs in printed circuit board (PCB) technology with a thickness of less than 3.5 mm are presented. This planar design consists of an open cathode side which allows a completely passive, self-breathing operation of the fuel cell. Power densities of 100 mW/cm 2 at 500 mV with hydrogen as a fuel were achieved. A steady operation with this type of fuel cell was demonstrated over a week without any cell flooding. Since the electrical conducting elements of PCBs usually are made of copper, corrosion in the wet environment of a PEMFC is expected. Thus, a significant degradation in performance of fuel cells made of plain copper PCBs was seen in long-term operation. In order to avoid corrosion, the copper layer has to be coated. Fuel cells in PCB design with diverse coatings were tested in long-term operations up to 1000 h under load. Moreover, corrosion currents have been determined by the use of potentiodynamic scans. Promising coatings are electroplated Cr and Ni and a combination of Ni/Au.