Thesis (M.S.)--University of Wisconsin--Madison, 1946. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Senior Honors thesis--Regis University, Denver, Colo., 2007. / Title from PDF title page (viewed on June 26, 2007). Includes bibliographical references.

A constant temperature room employing the comparatively new method of temperature control by means of a thyratron relay has been constructed. A high precision conductance bridge has been built in a very convenient form. Improvements include the incorporation of a cathode ray oscilloscope as null detector and the inclusion of a very stable oscillator of the phase shift type which is capable of giving a very pure wave form. Tests carried out on a system of degenerative tuning showed the the system is not easily applicable to high gain amplifiers. A new form of conductometric titration cell, employing the dipping type electrodes has been designed with special precautions against possible Parker Effect. A series of tests has been carried out on three types of cell to ascertain the effects of absorption, polarisation and Parker Effect on the accuracy of an ordinary conductometric titration. Conductometric titrations of NaOH solutions of violet and green chromic sulphate has been carried out, and the effect of aging these solutions closely studied. In addition, conductometric titrations of BaCL₂ into the chromic solutions have been made, and the NaOH titrations have been studied potentiometrically as well.

From Summary: The complexes present in chromium(III) carboxylate solutions (acetate or formate) were separated using ion exchange chromatography, electrophoresis and gel filtration. Eight cationic species and one non-ionic species with charges from 0 to +3 and nuclearities ranging from mononuclear to quadranuclear were isolated from chromium(III) acetate solutions. Six cationic species with charges from +1 to +3 and nuclearities ranging from mononuclear to trinuclear were isolated from chromium(III) formate solutions. The empirical formulae for these complexes were determined by analytical methods. Infra- red spectroscopy was used to distinguish between monodentate and bidentate bridged carboxylate ligands. An immediate change in the visible spectrum of a complex on its acidification was used as evidence that a terminal hydroxo group was present.

Although chromium coordination compounds are of considerable technological importance, they have been subjected to few thorough investigations since Werner's original experlments, in spite of the fact that we now possess a number of accurate physical methods, not available in Werner's time for the study of coordination complexes, The object of the work described in this thesis was to obtain further information on the chemistry of complex chromium(III) ions with special reference to the dioxalato-diaquochromiate system, [Cr(C₂0₄)₂(H₂0)₂]. For this purpose; spectrophotometric and potentlometrlc measurements were combined to yield information on a number of topics, The spectrophotometric investigations consisted in measuring the absorption spectra of the potassium salts of the complexes under consideration and in observing the changes in light absorption which occur during their formatlon and decomposition. The instrument used was a Beckmann Quartz Spectrophotometer model du. More than than twelve new absorption spectra were measured in this work and in conjunction with the spectra of other chromium and cobalt complexes reported by earlier workers, these are used to review the position of spectrophotometry as a method of investigating chromium complexes. The reasons for the shapes of the absorption spectra are discussed and it is concluded that spectrophotometry is useful for observing the progress of reactions involving complex ions and for analysing solutions, but that more fundamental data cannot be expected from the absorption curves.

by Yeung Chung Kin. / Bibliography: leaves 105-106 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

Thesis (Ph.D.) in Biochemistry and Molecular Biology--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 186-219).

No description available.

M.Tech. / A study was undertaken to develop and test the process for the recovery of high purity chromium oxide green from chromium waste. The process developed has a combination of leaching, ion exchange, coagulation, chelation and calcination. Based on the research findings, strong acid cation resin (Purolite 106) and weak acid cation exchange (Lewatit NCP 80) resins were selected for extraction of aluminium Ill ions and chromium Ill ions respectively. The optimal conditions for extraction of chromium (Ill) with ion exchange resins from chromium leachate solution were established taking into account the composition and the parameters of the chromium solution, the resin manufacturer's defined operating conditions and the empirical dependencies established in previous studies on model solutions of chromium (Ill). The effects of pH, compositions and the temperature on the extraction of chromium (Ill) were also examined. The yield of chromium (Ill) from tannery chromium hydroxide solid was about 96-98% after 35 min of phase contact with the sulphuric acid solution. Chromium hydroxide with Cr20 3 content of 88% was achieved by extracting chromium (Ill) with weak acid cation resin. The ferric and calcium ions present in the treated chromium hydroxide product were then removed by soaking the hydroxide cake in 0.1 to 0.2M ethyldiaminetretraacetic (EDTA) acid solution. The final product, chromium oxide green, with a Cr20 3 content of at least 95.14% achieved with the described process.

No description available.