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Master of Science - Chemistry / Complexation of CrIII was studied using the ligand 2, 2’ Bipyridyl (Bpy). Potentiometric titration was used in the modelling of CrIII-Bpy complexes and establishment of complex stability constants by use of ESTA software package. Investigation of the mechanism involved in the voltammetric determination of chromium by adsorptive cathodic stripping voltammetry (AdCSV) showed different behavior of chromium in 0.1 M ammonium buffer when compared to a neutral electrolyte (0.1 M sodium nitrate). Alternating current voltammetry (ACV) showed evidence of Bpy adsorption on the electrode surface (HMDE) whereas CrIII did not show any adsorption evidence but complexes of CrIII-Bpy were also adsorbed onto the electrode. Cyclic voltammogram (CV) of Bpy exhibits a reversible process and CrIII was characterized by a quasireversible process. CrIII-Bpy is investigated here as a model metal-ligand system used in analytical procedure. A set of generalized requirements for the determination of CrIII by AdCSV is proposed and discussed. It is anticipated that the generalized requirements will be applicable to any metal-ligand system used by that analytical technique. It is assumed that it should lead to an “educated” choice of a suitable ligand in order to increase selectivity and improve the detection limit in ultra trace analysis (ppb-ppt levels) by AdCSV.

A new preparative route to the only neutral chromium (V) oxide fluoride, chromium oxide trifluoride, has been accomplished by the reaction of xenon difluoride with chromyl fluoride at high temperature. The chromium oxide trifluoride is produced as crystals which are suitable for single crystal studies. In reactions of chromium oxide trifluoride with alkali and alkaline metal fluorides in anhydrous hydrogen fluoride, new chromium(V) oxide fluoride salts were obtained; these salts were not of high purity due to unknown problems. An attempt to prepare chromium oxide tetrafluoride by the reaction of xenon difluoride with chromyl fluoride in anhydrous hydrogen fluoride failed to produce the desired product.

Radioactive chromium-51, a waste byproduct from operation of nuclear reactors at Hanford, Washington, has been followed down the Columbia River and into the Pacific Ocean. Chemical factors influencing the partitioning of ⁵¹Cr between solution and sediment have been considered. Chromium-5l, in a hexavalent oxyanion when introduced into the Columbia River, largely remains in solution in a hexavalent anion during its passage through the lower river and after its entrance into the Pacific Ocean. A minor fraction of Hanford-induced ⁵¹Cr becomes attached to suspended particles and bottom sediments. Reduction of Cr(VI) to Cr(III) apparently precedes or accompanies sorption. Iron oxides appear to be the most important sorption substrate. Sediment organic matter acts both as a reducing agent, making ⁵¹Cr less soluble, and as a sorption substrate. Ion exchange on sediment particles is not important in retention of ⁵¹Cr by Columbia River sediment. Chromium-51 is a sensitive and unique tracer for Columbia River water at sea and has been used to trace the Columbia River plume up to 525 km away from the mouth of the river. Dispersion of ⁵¹Cr by the Columbia River system would be adversely affected by: 1) lowered pH; 2) presence of particulate organic wastes; 3) increased temperature; 4) increased biological oxygen demand. These factors would increase the rate of uptake of ⁵¹Cr by sediments and thus increase the steady-state inventory of ⁵¹Cr on the bottom of the river. / Graduation date: 1967

Graduation date: 1971

Thesis (Ph. D.)--University of Delaware, 2006. / Principal faculty advisor: Klaus H. Theopold, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

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Thesis (Ph. D.)--Florida State University, 2002. / Advisor: Dr. David Lind, Florida State University, College of Arts and Sciences, Dept. of Physics. Title and description from dissertation home page (viewed Sept. 29, 2003). Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xix, 219 p.: ill. (some col.). Includes abstract and vita. Advisor: Samuel J. Traina, Environmental Science Graduate Program. Includes bibliographical references (p. 201-219).