This thesis evaluates the performance of marine algal-based biosorbents in treating trace metal bearing aqueous solutions. Native seaweed varieties (Ascophyllum nodosum, Lessonia flavicans, Durvillea potatorum and Laminaria hyperborea) were selected on the basis of their varying algin composition as well as their characteristic mannuronic/guluronic acid content. Dealginated seaweed residues, i.e. waste materials arising during algin extraction from brown marine algae were also evaluated as potential metal biosorbent materials. The biosorbents showed significant metal sorption capacity for copper, cadmium, nickel and zinc from synthetic single metal and multi-metal bearing aqueous solutions. The equilibrium biosorption process may be described using a surface complex formation model. Copper biosorption involved chelation-type surface reactions as well as ion exchange whereas nickel and zinc biosorption may be described by simple ion exchange and electrostatic interactions between metal ions and the negatively charged algal surface. Evidence of stoichiometric release of protons upon metal biosorption has been found. Metal biosorption was found to be dependent upon transport limitations due to intraparticle diffusion. Surface functional groups within algal biosorbents that are responsible for metal-ion binding were identified in an attempt to understand the mechanisms of metal biosorption. Physical and chemical characterization techniques such as potentiometric titrations and esterification were used for surface acidity measurements, nitrogen sorption porosimetry for surface area and pore size distribution analysis and FT-IR spectroscopy to identify carboxyl groups attached to structural polysaccharides in algae. Performance of native and dealginate algal fixed-bed mini-columns provided optimum operating conditions for dynamic exchange between metal ions in solution and the algal biomass. Selected biosorbents were successfully employed to treat real industrial metal-plating rinse waters. The most efficient eluants for regeneration of metal-laden biosorbent columns were also identified.

Wrack beds are accumulations of seaweeds of various kinds that have become detached from the rocks on which they have grown and have been cast up on to the sea-shore. If such accumulations are formed beyond the high tide level, they may remain but little disturbed for several days or even for months. Here, as they gradually decompose, these wrack beds become the home and breeding place for many invertebrate animals* It is with these animals that this thesis is concerned. The most prominent of them are various species of flies, beetles and amphipods, and with them there occurs, less obviously, various mites, oligochaetes and nematodes. over and above these regularly occurring animals there are numerous incidental visitors to the wrack beds.

No description available.

This thesis reports the use of capillary electrophoresis (CE) for the analysis of carrageenans, anionic polysaccharides extracted from red seaweeds and widely used in the food industry for their gelling and thickening properties. The three main types, kappa, iota and lambda, differ in the number of sulfate groups and the presence or absence of a 3,6-anhydro bridge in the disaccharide residue repeat unit. CE separates analytes according to their charge to frictional coefficient ratios, therefore it is suitable to separate these biopolymers. In order to detect polysaccharides in CE, our approach consisted in derivatising the reducing ends of the saccharides by reductive arnination with a fluorophore, l-arninopyrene-3,6,8- trisulfonate (APTS). This allowed sensitive detection by laser induced fluorescence. Method development gave optimal conditions for separation using a polyvinyl alcohol coated capillary and a 25 mM ammonium acetate, pH 8.0 background electrolyte. The effects of changes of both instrumental parameters (temperature, injection mode, field strength) and, the composition of the BGE (concentration and pH) are reported, and explained in terms of the physical chemistry of the BGE and the biopolymers. The conditions of the derivatisation reaction were studied in order to minimise degradation due in particular to acid catalysis and to reduction of the reacting sites occurring in competition with derivatisation. Characterisation of the derivatised carrageenans by SEC-MALLS- RI was performed and showed that the extent of degradation occurring during the labelling reaction was a maximum of 40 % for kappa and 20 % for iota and lambda. The presence of the label APTS in excess and its reaction with the reagents during the labelling reaction produces peaks interfering with those from the carrageenan. A sample clean-up was therefore required before injection onto CEo A comparison was made of a range of clean-up procedures (centrifugation, dialysis, preparative SEC) to remove side products of the reaction and salts and to concentrate the carrageenans. Various seaweed extracts were analysed, including standards of carrageenans not available commercially. This study revealed that carrageenans are complex structures, and often occurring as hybrids between sUb-types. CE has the ability to characterise these hybrids, unlike spectroscopic methods which detect individual residues. When using actual food products, preliminary steps such as defatting and dialysis were found to be necessary to allow satisfactory detection of carrageenans. Finally the strategy for sample purification, derivatisation, clean-up and separation was successfully applied to additive mixtures used as raw materials in the food industry and to finished products (jelly, dairy products). CE has proved to be a fast and sensitive method to identify and provide semi-quantitative information on carrageenans present in such mixtures.

<p>The aims of this study were therefore: 1) to test the suitability of various seaweed-based diets against that of the formulated feed Abfeed&reg / -S34 on the growth of the abalone H. midae / and 2) to compare the growth of H. midae fed protein-enriched U. lactuca as opposed to those fed wild, naturally low protein U. lactuca in both single-species and mixed feeds.</p>

Tasco® made of sun dried brown seaweed (Ascophyllum nodosum) by Acadian Seaplants Ltd., has displayed prebiotic like properties with ruminants and may be an alternative to antibiotic growth promoters. Tasco® was fed to male broiler chickens for 35 days in a series of three trials which compared Tasco® to the prebiotic inulin and an antibiotic and determined Tasco®’s optimal inclusion level for broilers. Trials investigated Tasco® fed at 2.0% for 14 days only and examined its effects in a 45 day trial and when subjected to microbial challenge. Tasco® enhanced growth comparatively to inulin and the antibiotic virginiamycin. Alteration of physiological variables in all three trials supported the possibility of microflora changes in the gut as a mode of action. Low levels of Tasco® (0.25% and 0.5%) were consistently effective at improving growth. Microbiological profiles, currently under way, will aid in final determination of Tasco®’s qualifications as a prebiotic.

<p>The aims of this study were therefore: 1) to test the suitability of various seaweed-based diets against that of the formulated feed Abfeed&reg / -S34 on the growth of the abalone H. midae / and 2) to compare the growth of H. midae fed protein-enriched U. lactuca as opposed to those fed wild, naturally low protein U. lactuca in both single-species and mixed feeds.</p>

No description available.

Magister Scientiae - MSc / The direct methanol fuel cell or DMFC is emerging as a promising alternative energy source for many applications. Developed and developing countries, through research, are fast seeking a cheap and stable supply of energy for an ever-increasing number of energyconsuming portable devices. The research focus is to have DMFCs meet this need at an affordable cost is problematic. There are means and ways of making this a reality as the DMFC is found to be complementary to secondary batteries when used as a trickle charger, full charger, or in some other hybrid fuel cell combination. The core functioning component is a catalyst containing MEA, where when pure platinum is used, carbon monoxide is the thermodynamic sink and poisons by preventing further reactions at catalytic sites decreasing the life span of the catalyst if the CO is not removed. Research has shown that the bi-functional mechanism of a platinum-ruthenium catalyst is best because methanol dehydrogenates best on platinum and water dehydrogenation is best facilitated on ruthenium. It is also evident that the addition of other metals to that of PtRu/C can make the catalyst more effective and increase the life span even further. In addition to this, my research has attempted to reduce catalyst cost for DMFCs by developing a low-cost manufacturing technique for catalysts, identify potential non-noble metal catalytic systems and develop a basic process to combine various non-noblel, less expensive metallic systems to form binary, ternary and quaternary catalysts. The initial research focused on the identification of a suitable Pt/C preparation method, and characterization of the resulting catalysts by electrochemical methods (including voltammetry), elemental analysis (by EDS), and morphological characterization (by TEM). Once the preparation method for Pt/C had been established, binary (Pt–M/C), ternary (Pt–M1M2 /C) and quaternary (Pt–M1M2M3 /C) catalysts were prepared by modifying the initial Pt/C preparation method. These multi-metallic catalysts primarily function in preventing CO poisoning and allowing MeOH oxidation at the anode. To determine the effectiveness of the in-house multi-metallic catalysts the catalysts were then compared to the commercially available bench mark JM commercially available catalyst. Cyclic voltammetric and chronoamperommetric analysis revealed that the in-house catalysts electrochemical catalytic activity were similair to that of the commercially available catalysts. The Fuel application testing revealed similair trends to that of the EC activity at 0,5V (Ag/AgCl) test results, with the quaternary catalyst proving to be the most active anode catalyst producing the highest power density. The quaternary catalysts proved to be superior with its increased mass activity and high surface area (80% of the catalytic particles < 3nm). / South Africa

No description available.