A novel electrode was constructed and tested in a bio-battery. This configuration consisted of a composite electrode with immobilized bacteria (Escherichia coli K-12) in the anode and a composite electrode with immobilized Carbon Nanoparticles (CNP) and algae (Chlorella vulgaris/Scenedesmus sp.) suspended in the cathode. The composite electrode consisted of three parts: a 304L stainless steel mesh base, an electro-polymerized layer of pyrrole, and an electro-polymerized layer of methylene blue. The bacteria were immobilized on the anode electrode using a technique incorporating CNP and a Teflontm emulsion. The anode and cathode electrodes were tested separately in conjunction with chemical cathodes and anodes respectively. The composite electrode with immobilized bacteria was tested in a bioanode setup. The cathode chamber of the cell contained a potassium ferricyanide and buffer solution with a graphite electrode. Factors affecting electrode performance, such as Teflontm and carbon nanoparticle concentration, were investigated to find optimum values. The maximum power density generated by the composite electrode with immobilized bacteria and a chemical cathode was 378 mW/m2. This electrode configuration produced approximately 69% more power density and 53% more current density than composite electrodes with bacteria suspended in solution. Electrochemical Impedance Spectroscopy analysis determined that a significant portion of the bio-battery’s resistance to charge transfer occurred at the surface of the anode and this resistance was significantly lowered when using immobilized bacteria (51% lower than bio-batteries with suspended bacteria). Similarly, biocathodes containing composite electrodes coated with CNP were tested using two algae species, Chlorella vulgaris and Scenedesmus sp., suspended in solution. This electrode configuration was compared with composite electrode without CNP coating. The anode chamber contained potassium ferrocyanide solution with a graphite counter electrode. The composite electrode with CNP produced approximately 23% more current density than composite electrode without CNP. A complete bio-battery was designed using a composite electrode with immobilized bacteria anode and a CNP coated composite electrode with algae suspended in the cathode. EIS analysis showed that the resistance was higher in the biocathode than in the bioanode and a significant portion of the ohmic resistance was contributed by the membrane.

>Magister Scientiae - MSc / In recent times, the occurrence and presence of complex recalcitrant toxic contaminants in water and wastewater is increasing and consequently contributes to the non-availability of clean and safe drinking water. Water treatment is complex, time demanding and energy intensive due to the physico-chemical structural complexity and diversity of the pollutants. Non-availability of good drinking water has negatively affected human health and the ecosystem. Over the years, numerous conventional treatment techniques were used to degrade and remove these pollutants, but investigations indicated that some of the pollutants are not susceptible to conventional treatment. Advanced oxidation technology, among which heterogeneous photocatalysis (involving the use of a semiconductor) has emerged as one of the more promising techniques to remediate contaminated water. Titanium dioxide (TiO2) semiconductor photocatalysis is considered to be a good option due to its cost effectiveness, chemical and thermal stability, and inertness in the area of wastewater reclamation and re-use. However the post separation of the titania particles poses a threat to the wastewater remediation. Hence there is a need to develop a supported high surface area photocatalyst that will resolve the post separation challenge. This present study aimed to prepare high surface area TiO2 anatase nanocrystals supported on a stainless steel mesh. These new composite materials were used to remove methylene blue (MB) from aqueous solutions. The supporting procedure involved the thermal decomposition of a sol gel solution coated upon stainless steel mesh. The nanocrystalline anatase phase was formed by thermal decomposition on a stainless steel mesh coated with 8 % PAN/DMF/TiO2 sol gel formation calcined at varying temperatures of 300 °C, 400 °C, 500 °C and 600 °C. The heating rate of 50 °C/min and independent holding time of 1 h, 2 h, 3 h and 4 h were applied to find the optimum supporting conditions. The synthesised TiO2 nanocomposites materials were characterised using the following analytical techniques: XRD, HRSEM, EDS, HRTEM, SAED, FTIR and UV-Vis absorption spectroscopy materials were characterised, and the results indicate that synthesised TiO2 nanocrystals were in the anatase form, polycrystalline in nature, and contained additional carbon-carbon bonds from the polymer used during preparation with TiO2 particle sizes range from 13.6 nm to 2285 nm.

Tato Diplomová práce se zabývá vlivem vyztužení na mechanické vlastnosti materiálu pro přípravu snímatelných náhrad. Pro testování byly použity tři sady vzorků: PMMA pryskyřice, PMMA pryskyřice s Dentapreg Mesh výztuží a PMMA pryskyřice vyztužena zesilující síťkou z nerezové oceli.Pro měření chování vzorků při statickém a dynamickém namáhání byl použit třibodový ohybový test a Charpy rázové kladivo. Viskoelastické vlastnostzi byly měřeny dynamicko-mechanickou analýzou (DMA). Skenovací elektronová mikroskopie (SEM) byla použita k charakterizaci lomových ploch. Během statického namáhání vzorků výztuž nehraje důležitou roli v porovnání s nevyztuženou pryskyřicí. Nicméně byl pozorován opačný trend při dymanickém namáhání, kde efekt výzruže rostl v řadě PMMA pryskyřice – síťka z nerezové oceli – Dentapreg Mesh.