The liquid-liquid extraction of Germaniun with the 7-alkylated 8- hydroxyquinoline derivative - KELEX 100.

Thesis (M.Sc.)-University of Natal, Durban, 1990.Germanium can be extracted from aqueous solutions by KELEX 100 dissolved in an appropriate diluent. KELEX 100 is a commercially available chelating extractant containing the active constituent 7-(4ethyl-l-methyloctyl)-8-hydroxyquinoline. Previous work in the solvent extraction of germanium with this reagent has shown that germanium is extracted most efficiently at low pH. When the germanium is present in sulphuric acid solutions at pH less than 2, the extracted complex is GeL3+HS04-,however at pH 3 to 8, the metal is extracted as GeL2(OH)2 (where HL = KELEX 100). In this work, the extraction kinetics and equilibrium extraction of germanium in the GeKELEX 100 solvent extraction system is examined by AKUFVE and shaking assemblies, which both employ rapid mixing of the organic and aqueous phases, and by a quiescent interface Lewis Cell. The AKUFVE is a Swedish designed apparatus for solvent extraction, its performance and suitability for solvent extraction studies is evaluated using the extraction experiments carried out on the GeKELEX 100 solvent extraction system. Experiments conducted using an experimental set-up with a large interfacial area to phase volume ratio reveal that the extraction of germanium occurs in two distinct kinetic regimes. The first regime occurs in the first few minutes of an extraction experiment and is fast relative to the second kinetic regime which follows this fast initial extraction period and occurs until the extraction of germanium attains the equilibrium value. In this work an extraction mechanism involving interfacial reaction of germanium and extractant is proposed to explain this kinetic behaviour. An increase in ionic strength is shown to reduce the rate of germanium extraction in the Ge-KELEX 100 solvent extraction system. Modifiers, such as organic alcohols, are shown to greatly improve extraction kinetics

Quantitative analysis of powder mixtures by raman spectrometry : the influence of particle size and its correction

Particle size distribution and compactness have significant confounding effects on Raman signals of powder mixtures, which cannot be effectively modeled or corrected by traditional multivariate linear calibration methods such as partial least-squares (PLS), and therefore greatly deteriorate the predictive abilities of Raman calibration models for powder mixtures. The ability to obtain directly quantitative information from Raman signals of powder mixtures with varying particle size distribution and compactness is, therefore, of considerable interest In this study, an advanced quantitative Raman calibration model was developed to explicitly account for the confounding effects of particle size distribution and compactness on Raman signals of powder mixtures. Under the theoretical guidance of the proposed Raman calibration model, an advanced dual calibration strategy was adopted to separate the Raman contributions caused by the changes in mass fractions of the constituents in powder mixtures from those induced by the variations in the physical properties of samples, and hence achieve accurate quantitative determination for powder mixture samples. The proposed Raman calibration model was applied to the quantitative analysis of backscatter Raman measurements of a proof-of-concept model system of powder mixtures consisting of barium nitrate and potassium chromate. The average relative prediction error of prediction obtained by the proposed Raman calibration model was less than one-third of the corresponding value of the best performing PLS model for mass fractions of barium nitrate in powder mixtures with variations in particle size distribution, as well as compactness

Fragment molecular orbital-based variational quantum eigensolver for quantum chemistry in the age of quantum computing

Abstract Quantum computers offer significant potential for complex system analysis, yet their application in large systems is hindered by limitations such as qubit availability and quantum hardware noise. While the variational quantum eigensolver (VQE) was proposed to address these issues, its scalability remains limited. Many efforts, including new ansätze and Hamiltonian modifications, have been made to overcome these challenges. In this work, we introduced the novel Fragment Molecular Orbital/Variational Quantum Eigensolver (FMO/VQE) algorithm. This method combines the fragment molecular orbital (FMO) approach with VQE and efficiently utilizes qubits for quantum chemistry simulations. Employing the UCCSD ansatz, the FMO/VQE achieved an absolute error of just 0.053 mHa with 8 qubits in a $${{\text{H}}}_{24}$$ H 24 system using the STO-3G basis set, and an error of 1.376 mHa with 16 qubits in a $${{\text{H}}}_{20}$$ H 20 system with the 6-31G basis set. These results indicated a significant advancement in scalability over conventional VQE, maintaining accuracy with fewer qubits. Therefore, our FMO/VQE method exemplifies how integrating fragment-based quantum chemistry with quantum algorithms can enhance scalability, facilitating more complex molecular simulations and aligning with quantum computing advancements