No abstract

The electrochemically synthesized polypyrrole (PPy) is investigated as a possible active material of the low-cost aqueous based secondary power sources in combination with zinc, lead oxide, and lead sulfate. The discharge capacity of the polypyrrole in the chloride-based electrolyte (for the Zn|PPy cell) is in the range 110 mAh g -1 of PPy, while in the sulfate-based electrolyte ~150 mAh g -1 of PPy (for the PbSO4|PPy and PPy|PbO2 cells), which is close to the theoretically calculated values. Electrochemical and electrical parameters, reactions in the cells, specific capacity, specific capacitance, energy, and power, for the Zn|PPy, PPy|PbO2 and PbSO4|PPy cells are determined. In addition, the energy efficiency, for the considered systems is estimated. Obtained values of the specific power and energy, could classified investigated systems as a battery type hybrid superacapacitors or "supercapattery".

Polypyrrole (PPY) electrode was obtained by electrochemical oxidative polymerization of pyrrole on graphite electrode from aqueous electrolyte containing 0.1 mol dm?3 pyrrole monomer and 1.0 mol dm?3 HCl. Polymerization was achieved at the constant current density of 2 mA cm?2 during 1 h. The estimated active mass of PPY (assuming that the maximal doping degree of 0.33 was achieved and the polymerization efficiency of 100%) was 14 mg. Electrochemical characterization of PPY electrode was performed by galvanostatic experiments of charge (doping) and discharge (dedoping) with different current densities in the range between 0.5 and 1.5 mA cm?2. The experiments were performed in aqueous electrolyte containing 2.0 mol dm?3 NH4Cl and 1.1 mol dm?3 ZnCl2. Based on galvanostatic charge/discharge curves, following parameters of PPY electrode were evaluated: discharge capacity, specific discharge capacity, charge capacity, specific charge capacity, and Columbic efficiency. Both charge and discharge capacities were dependent on charge/discharge currents. The values decreased by increasing charge/discharge current, except for the lowest current density where Columbic efficiency exceeded 100%, which was explained by involvement of cations, from the electrolyte, in the doping process. An electrochemical cell in which PPY electrode served as a cathode and zinc electrode as the anode with an aqueous electrolyte containing 2.0 mol dm?3 NH4Cl and 1.1 mol dm?3 ZnCl2, was formed and relevant electrochemical and electrical parameters of the cell were estimated and discussed. Charge of the Zn|PPY cell was dependent on the charge/discharge current. Charge of the cell started between 0.5 and 0.7 V and proceeded up to 1.5 V, while the open circuit voltage of the fully discharged cell was 1.3 V. Specific discharge capacity of Zn|PPY cell, calculated based on discharge times, ranged from 95 to 70 mA h g?1, decreasing linearly with increasing discharge current density. On the other hand, calculated values of the theoretical capacity of the Zn|PPY cell was 105 mA g?1, meaning that practically 90% of the theoretical capacity can be achieved by discharging the cell with low current densities, while 67% of the theoretical capacity was obtained with the highest used current density. Based on Ragon parameters, the estimated values of specific energy that ranged between 46 and 68 W h kg?1, and the specific power between 125 and 380 W kg?1, Zn|PPY cell might be classified as a ?supercapattery?. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172046]

This paper presents the use of a software application for protection of the environment through modelling and simulation of air and soil pollution at the industrial waste deposit of Korlaće, Serbia, asbestos mine pit. In cases of abandoned mines, with a proper surveillance not being possible, a modelling-based pollution assessment is of utmost importance in implementation of measures for reduction and mitigation of the impact of dangerous waste deposits. For that purpose, a simulation of various climatic conditions typical of this region has been conducted -humidity 20%, air speed 2-7 m/s, and temperature range of -10 to 36ºC. Because of the minor probability for greater air speed in this area they have not been examined. The calculation has been done by means of SCREENVIEW software, and the obtained results have been compared with the investigation results of the samples taken from the site. The calculated results have shown a nice agreement with the experimental values, which demonstrates the applicability of the software application.