Recovery of Gallium from Simulated GaAs Waste Etching Solutions by Solvent Extraction

Gallium arsenide is used in semiconductor industries worldwide. Numerous waste etching solutions are produced during the processes of GaAs wafer production. Therefore, a complete and eco-friendly technology should be established to recover gallium as a gallium chloride solution and remove arsenic ion from waste GaAs etching solution. In this study, the gallium trichloride and arsenic trisulfide powders were dissolved in ammonia solutions to prepare the simulated solutions, and the pH value was adjusted to pH 2 by nitric acid. In the extraction step, the GaAs etching solutions were extracted using 0.5 M Cyanex 272 solutions in kerosene at pH 2 and 0.1 O/A ratio for 5 min. The extraction efficiency attained 77.4%, which had an optimal ratio of concentration, and the four steps extraction efficiency attained 99.5%. After extraction, iron sulfate heptahydrates were added into the raffinate, and the arsenic ions were precipitated. The removed rate attained 99.9% when the Fe/As ratio was 10. In the stripping step, the organic phase was stripped with 0.5 M hydrochloric acid at 1 O/A ratio for 3 min, and 97.5% gallium was stripped. Finally, the purity of gallium chloride solution was 99.95% and the gallium was seven times the concentration of the etching solutions.

Azo-substituted ethoxyacridine – reagents for the extraction-photometric determination of gallium

The associates of halide (chloride) complexes of gallim azo-substituted ethoxyacridine have been studied by spectrophotometric method. It has been found that the associates are well extracted with a mixture of dichloroethane-acetone (3:2). The optimum volume of aqueous and organic phase is equal to 5 ml. The molar ratio of the components in the extractable compounds was studied by the methods of isomolar series, equilibrium shift and a straight line. It was found that gallium chloride associated with azo-ethoxyacridines (AE) in a ratio of 1:1. It was studied formation and extraction of associates of gallium chloride with AEADPA (2-ethoxy-6-(4-N,N-dipropylphenylazo)-9-aminoacridine) and AEAN (2-ethoxy-6-(2-hydroxynaphthylazo)-9aminoacridine). The maxima of light absorption of gallium chloride with AEADPA is observed at 520 nm, and the AEAN at 510 nm. The light absorption of the extracts of associates coincides with the absorption maxima of azoethoxyacridines, which indicates the electrostatic character of the interaction and the formation of complexes. Study of the effect of foreign ions on the accuracy of the determination of gallium with azo-substituted ethoxyacridine showed that the number of ions does not interfere (in parentheses are multiple relationships to gallium ions); Zn2+ (2000), NiII (1500), CuII (2500), CoII (1400), Cr III(1100), PbI (2250), Al3+(1600), Cd2+(700), FeII (1050), ReVII (500), PdIII (1200), Tl (2500). Number of ions interfered the determination: TeIV(1), FeIII (1), AuIII (1), SbV(1), TlIII(1), SeIV(3). The physico-chemical and analytical characteristics of the azo-substituted ethoxyacridines and their ionic associates with chloride gallium acidic complexes (λmax ε, βkD, D, R%) were determined. It was shown that chloro-gallium compounds with azo-substituted ethoxyacridines are ionic associates, the molar ratios of the components in which are: [Ga3+] : [Cl-] : R+ = 1:4:1.

Gallium-catalyzed reductive lactonization of γ-keto acids with a hydrosilane

Gallium chloride efficiently catalyzes cyclization of γ-keto carboxylic acids in the presence of PhSiH3 to produce the corresponding γ-lactone derivatives.

Heteronuclear NMR Spectroscopic Investigations of Gallium Complexes of Substituted Thiosemicarbazones Including X-Ray Crystal Structure, a New Halogen Exchange Strategy, and 18F Radiolabelling

Five thiosemicarbazone ligands have been synthesized, and their coordination chemistry with gallium was investigated. The reaction of these thiosemicarbazones with gallium chloride in alcohol solutions in the presence of a base yielded the corresponding penta-coordinated Ga-Cl metal complexes. In contrast, the reaction of gallium nitrate with the ligands in the presence of alkoxides resulted in the formation of the corresponding Ga-alkoxides, rather than the anticipated Ga-nitrate complex. The crystal structures of gallium chloride and gallium methoxide complexes of diphenylthiosemicarbazone comprise a planar configuration of the tetradentate-coordinated thiosemicarbazone with Ga3+ ion, with the chloride or methoxide groups occupying the apical coordination site. The corresponding ethoxido complex was also prepared in an identical fashion, and NMR analysis confirmed structural similarity to the methoxido complex. Facile halogen exchange reactions of the gallium chloride complexes were achieved by treatment with silver nitrate, followed by addition of KF or KI to generate the gallium fluoride and iodide complexes, respectively. This method of exchange using halogenated inorganic salts aids the preparation of group 13 fluorides, which are notoriously insoluble in organic solvents, for complexation with organic ligands. All compounds have been fully characterized by NMR, and the X-ray crystal structures of two of the complexes are reported. Additionally, the positron-emitting isotope 18F was introduced in the structure of the diphenyl gallium thiosemicarbazone complex.