Deivis Plausinaitis

Quartz Crystal Microbalance-Based Evaluation of the Electrochemical Formation of an Aggregated Polypyrrole Particle-Based Layer

Electrochemical quartz crystal microbalance (EQCM) was used for the evaluation of conducting polymer polypyrrole (Ppy), which was formed by a sequence of potential pulses on a Au-plated EQCM disc. The Ppy layer was obtained from freshly prepared polymerization solution consisting of pyrrole that was dissolved in phosphate buffer. The main aim of the study was to determine some aspects of the Ppy layer formation process. The polymerization process was estimated by EQCM and chronoamperometry. The Cottrell equation was used for the integration of total charge that was passing through the electrochemical cell during the formation of the Ppy-based layer. It was found that the charge of the electrical double layer, which was estimated while applying an Anson plot, is negative. From this observation, it could be assumed that the pyrrole oxidation process could be well described by principles of heterogeneous kinetics. The negative value of the electrical double layer was the result of a charge-transfer restriction. This restriction of charge transfer could occur due to partial blocking of the electrode surface by an aggregated Ppy particle-based layer. Quartz crystal motional resistance (R) was taken into account during this research. Ppy layer formation is represented schematically on the basis of the obtained experimental results and analytical data.

Reduction in pressure drop for pipe flow due to applied electric potentials to the pipe

For all forms of transport of fluids in pipes, there is loss of pressure due to the friction. It has been shown that an electrical potential applied to the pipe wall can reduce water flow friction. Piezometric pressure loss over the 13.1 m slanting epoxy coated pipe made of steel, through which water was flowing, decreased when pipe was exposed to positive DC-potentials in the range 0.6–1.6 V. Maximum reduction was 2% with an applied potential of 1.0 V. Results from full scale experiments in a hydroelectric power plant (12.5 MW, 85 GWh) show that head loss decreased from 45.9 m to 39.8 m at maximum flow rate after 2.5 years of exposure to 1.1 V. Similar results for the head loss in another power plant (28 MW, 116 GWh) were 17.5 and 17.2 m, respectively, after 9 months of exposure to this DC-potential. The positive polarization of the pipes was noticeable throughout the whole length of the pipe.

Erbium concentration anomaly as an indicator of nuclear activity: Focus on Natural waters in the Chernobyl exclusion zone

This study focused on measurement of lanthanides in surface water (SW) and ground water (GW) samples from the Chernobyl Exclusion Zone. Results showed that the total lanthanide concentration in SW ranges from 500 to 1100ngL-1 and is about 10 times lower than the GW concentration. The normalized patterns of lanthanide concentrations increase from lighter elements to heavier lanthanides. Concurrently, concentration anomalies of Ce, Eu, and Er are visible. The Er anomaly is the most noticeable and exceeds the theoretical calculation by about 13 times. The Ce and Eu anomalies are likely related to the variety of oxidation states of these elements. Meanwhile, the cause of the Er anomaly is not completely clear, but is likely related to the Chernobyl Nuclear Power Plant accident, since increased concentrations correlate with the distribution of contamination in the zone. 137Cs activity measurements partially confirm this hypothesis. Simultaneously, there is a relationship between the positive Er anomaly and increase in 235U concentrations. However, there is no reliable information in the literature that indicates that Er was used in the Chernobyl Nuclear Power Plant before the reactor accident.