Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The ability of dealginated seaweed, a waste material derived from the commercial processing of seaweed for alginate production, to remove cadmium, lead, nickel, copper, chromium, silver, aluminium and gold from solution was determined. Metal sorption was found to be rapid (90% removal within 5 minutes), achieving a residual concentration of 0.9 mg L[-1] after 1 h contact time from an initial solution concentration of 10 mg L[-1]. The binding of metal by dealginate was found to be pH dependent, optimal sorption occurring at around pH 6-8 for cadmium, lead, nickel, copper and chromium and pH 3-4 for aluminium and gold respectively, suggesting an ion exchange mechanism. Determination of a molar ratio in the displacement of calcium by cadmium on dealginate supported the presence of an ion-exchange relationship, since the displacement of approximately 1 mol of calcium by 1 mol of cadmium was observed. The sorption data was best fitted in the ion exchange approximation as opposed to the Langmuir model. The binding capacities were found to be 1.2, 0.5, 1.6, 0.8, 1.2, 0.4, 0.9 and 0.4 mmol g-1 for cadmium, lead, nickel, copper, chromium, silver, aluminium and gold respectively. The ion exchange constants were calculated to be 3.3 x 10[-6], 4.1 x 10[-6], 6.2 x 10[-6], 1.8 x 10[-6], 2.3 x 10[-6], 2.4 x 10[-7],8 x 10[-10] for cadmium, lead, nickel, copper, chromium, silver and aluminium. The values of the capacities and ion exchange constants showed affinity of the biosorbent to specific metals. The identification of the binding sites on the surface of dealginated seaweed was investigated by a number of techniques. Potentiometric titration revealed three distinct pKa values, the first having a similar value to carboxyl groups, the second being comparable with that of saturated thiols and amines and the third similar to sulphonate groups. Esterification of the dealginate resulted in the subsequent reduction in metal sorption, indicating that carboxyl groups are largely responsible for sorption except in the case of aluminium and gold, where 40-60% of the metal remained in solution after modification of the surface. Evidence of the FT-IR spectra confirmed the presence of carboxyl groups in untreated dealginate, while the number of carboxyl groups was markedly reduced in the esterified sample. The occurrence of other mechanisms apart from ion exchange was suggested by the FT-IR spectrum for aluminium and gold. ESEM images of the surface of dealginated seaweed showed the algae cell structure still present in large areas. X-ray maps revealed the presence of silver, aluminium and gold associated with sulphur atoms on the dealginate surface. EXAFS results showed that cadmium, lead, copper and silver were bound to the dealginate through oxygen atoms, possibly from carboxylate groups. Evidence of gold reduction from Au (III) to Au(l) and Au(O) was also confirmed by the bond distance calculated for this metal. Methods for the on-line preconcentration of cadmium, chromium, copper and lead and chemical speciation of Cr[3+] and CrO[4][2-] using a microcolumn packed with dealginated seaweed were developed. Effective column capacities were 4.0, 8.7, 9.4 and 8.5 mumol L[-1] for cadmium, chromium, copper and lead, respectively. The application of the method was extended to the determination of zinc, cobalt, mercury, scandium, strontium, vanadium, arsenic, selenium, manganese and antimony. The analytical procedures developed for metal preconcentration and chromium speciation were validated by analyses of two Lake Ontario reference materials, TMDA 51.2 and TMDA 54.2 and a synthetic seawater sample. The findings of this study demonstrated that the sorption of metal by dealginate is mainly due to an ion-exchange mechanism. The binding capacities of the biosorbent for the elements studied were adequate for trace analysis and the use of dealginate was shown to be a cheaper alternative to synthetic resins.

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Biodiesel purification processes generate wastewater streams that require a large amount of energy when distillation is used as a treatment technology. Process simulation software was used to show that an alternative water treatment process involving ion exchange would require only 31% of the energy used by distillation. Experiments showed that multiple washing stages were required to meet the standard specification for sodium, an impurity present in crude biodiesel, when washing biodiesel made from used frying oil. A comparison was made between washing biodiesel in a cross-current washing configuration and a counter-current configuration. Both configurations met the specification for sodium within three washing stages; however, the counter-current configuration required less water, making it the more efficient process. Lastly, the removal of sodium from wastewater samples using an ion exchange resin was experimentally investigated. The results validated the use of ion exchange to reduce energy consumption in biodiesel purification.

This thesis describes a simple method for the separation of strontium from an excess of barium using ion exchange techniques. This process has been applied to the separation of strontium and rubidium in barites. The resin used is Dowex-50 (200-400 mesh, hydrogen form) and the column dimensions are 1.1 by 8 cm. The column is eluted at room temperature with 1.5 M hydrochloric acid at a flow rate of approximately 1 ml/ min. Strontium and rubidium from two samples of barites were analysed using a solid-source mass spectrometer to determine strontium-87/strontium-86 ratios. The above chemical techniques have also been employed in the separation of strontium and rubidium from galenas. The concentration of strontium in one sample of galena (U.B.C. No. 1) has been determined using isotope dilution techniques. The results show an absence of strontium in the galena sample studied. Finally the common strontium ratios of two barite samples are compared with common lead ratios of associated galenas (Slawson and Austin, 1962) and a possible correlation between these ratios has been observed. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate