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Optimisation of the operational conditions of trichloroethylene degradation using Trametes versicolor under quinone redox cycling conditions using central composite design methodology

Marcel Vilaplana, Ana Belén García, Gloria Caminal, Francisco Guillén, Montserrat Sarrà

Biodegradation, 23 (2), 333–341, 2012

Extracellular radicals produced by Trametes versicolor under quinone redox cycling conditions can degrade a large variety of pollutant compounds, including trichloroethylene (TCE). This study investigated the effect of the agitation speed and the gas–liquid phase volume ratio on TCE degradation using central composite design (CCD) methodology for a future scale-up to a reactor system. The agitation speed ranged from 90 to 200 rpm, and the volume ratio ranged from 0.5 to 4.4. The results demonstrated the important and positive effect of the agitation speed and an interaction between the two factors on TCE degradation. Although the volume ratio did not have a significant effect if the agitation speed value was between 160 and 200 rpm, at lower speed values, the specific pollutant degradation was clearly more extensive at low volume ratios than at high volume ratios. The fitted response surface was validated by performing an experiment using the parameter combination in the model that maximised TCE degradation. The results of the experiments carried out using different biomass concentrations demonstrated that the biomass concentration had a positive effect on pollutant degradation if the amount of biomass present was lower than 1.6 g dry weight l-1. The results show that the maximum TCE degradation was obtained at the highest speed (200 rpm), gas–liquid phase volume ratio (4.4), and a biomass concentration of 1.6 g dry weight l-1.

 

Three-Dimensional Interdigitated Electrode Array as a Tool for Surface Reactions Registration

Andrey Bratov, Natalia Abramova, M. Pilar Marco, Francisco Sanchez-Baeza

Electroanalysis 24 (1), 69 – 75, 2012

Possible applications of a new transducer based on a three dimensional interdigitated electrode array (3D-IDEA) with electrode digits separated by an insulating barrier are discussed. Due to the presence of insulating barriers that separate the adjacent digits of the electrodes the main portion of the probing electrical current goes close to the surface of the barrier. Chemical modification of the barrier surface with the probe molecules permits to realise direct detection of subsequent target analytes in solution. The functional mechanism of the device is based on registration of changes in conductivity at the surface of the barrier provoked by electrical charge redistribution caused by surface chemical reactions. Three-dimensional sensor shows considerable improvement in sensitivity compared with a standard planar IDEA design sensors. The potential of the developed device as a sensor transducer to detect various chemical and bio chemical reactions is demonstrated. Examples include enzyme immobilisation, polyelectrolytes layer-by-layer deposition, covalent chemical modification with molecules containing reactive thiol groups.

 


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