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This work describes the use of low-voltage (0.5 - 5 V) pulsed electric fields to prevent Pseudomonas aeruginosa biofilm development. Interdigitated electrodes (IDEs) with 29-mum spacing between 22-mum-wide electrodes, were used as a platform where the effect of localised, high-strength electric fields could be tested. Alternating current, square-wave pulses were applied to the IDEs in 1 sec intervals. A two-level, three-variable factorial design experiment was used to detect the effects of applied voltage, frequency, and pulse duty ratio (i.e. percentage of pulsing time over one cycle) on the inhibition of biofilm formation. The observations indicated that a pulse configuration of 1% duty ratio, 5 V, and 200 Hz frequency reduced the area of the electrodes covered by biofilm by 50%. In general, the application of low-duty ratio pulses had a positive effect on preventing biofouling. Comparatively, frequency and applied voltage were observed to have less influence on biofouling.

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In this manuscript, carbon materials having different microstructural and electrochemical properties were coated with metal oxide thin-films of SiO2 or γ-Al2O3/γ-AlOOH. The metal oxide deposition was influenced by four factors: number of times dipped into the sol, sol concentration, proximity of the sol to its isoelectric pH and drying temperature. Upon coating, microstructural and electrochemical properties of the resulting composite electrode (metal oxide + carbon) were largely dependent upon the carbon material. For instance, an increase in specific surface area (by over a factor of 5) was observed when a low surface area carbon was coated; however, coating a high surface area carbon resulted in a decrease in the specific surface area of the composite. Likewise, surface groups associated with the coatings also appeared to increase the wettability of select carbons. When comparing the capacitance of the different carbon materials, it was shown that properties other than surface area (i.e. - wettability) played a role in performance. In several cases, the coated electrodes had increased capacities over that of the uncoated carbon supports; however, this was carbon specific as some materials experienced little change in capacity with the metal oxide coatings.

Contamination of groundwater with nitrates is a major concern, especially for areas relying on this as a drinking water source. In this work, a capacitive deionization (CDI) system equipped with carbon electrodes coated with different metal oxides was studied to determine its ability to reduce nitrate concentrations. Results performed in a three-electrode cell were used as a proof of concept and demonstrated that coated electrodes had higher nitrate removal than that of uncoated electrodes, likely because of a reduction in hydrophobicity and an increase in surface area provided by the metal oxides. Moreover, tests using different electrolytes (NaNO 3 and Ca(NO 3) 2) revealed similar nitrate removal values, although different electrosorption patterns were observed for Na + and Ca 2+. Furthermore, an operational mode based on a multistep approach showed that nitrates could be removed below regulatory limits while reducing the volume of waste brine. A larger, eight-cell flow CDI reactor was also tested. The results from this reactor showed that the cell potential, as well as the ion being removed from a multicomponent solution (Ca 2+ , Na + , Cl-, NO 3-) influence electrosorption kinetics. Different adsorption mechanisms based on ion charge/size/electrode affinity are discussed, possibly leading to a methodology for preferentially removing certain ions by CDI technology.

The increasing needs for environmental friendly antifouling coatings have led to investigation of new alternatives for replacing copper and TBT-based paints. In this study, results are presented from larval settlement assays of the barnacle Amphibalanus (¼ Balanus) amphitrite on planar, interdigitated electrodes (IDE), having 8 or 25 mm of inter-electrode spacing, upon the application of pulsed electric fields (PEF). Using pulses of 100 ms in duration, 200 Hz in frequency and 10 V in pulse amplitude, barnacle settlement below 5% was observed, while similar IDE surfaces without pulse application had an average of 40% settlement. The spacing between the electrodes did not affect cyprid settlement. Assays with lower PEF amplitudes did not show significant settlement inhibition. On the basis of the settlement assays, the calculated minimum energy requirement to inhibit barnacle settlement is 2.8 W h m 72.

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