Surface Engineering and Applied Electrochemistry

The fabrication of an electrochemical sensor based on a screen-printed electrode modified by ZnO/Al2O3 nanocomposite for sensing hydrochlorothiazide is described and discussed here. The electrochemical behavior of this sensor was evaluated through the differential pulse voltammetry, cyclic voltammetry, and chronoamperometry. The electrochemical studies revealed that modification with ZnO/Al2O3 nanocomposite leads to an increment of current response through the synergistic augmentation. The used modified electrode showed a detection limit of 8.0 × 10–8 M in the concentration range of 0.1 to 100.0 μM, which is promising in sub-micromolar detection of hydrochlorothiazide.

This work studied the electrochemical degradation of $${\text{NH}}_{4}^{ + }$$ -N in mariculture wastewater using an activated carbon fiber composite anode. The effects of the operating parameters and by-products were investigated. Based on the analysis of the removal rate of $${\text{NH}}_{4}^{ + }$$ -N, energy consumption, and current efficiency under various operating conditions, the optimal conditions were ascertained as follows: an initial $${\text{NH}}_{4}^{ + }$$ -N concentration of 40 mg/L, a current density of 1.4 mA/cm2, a pH value of 8, no extra electrolyte, an electrode gap of 17 mm and the degradation rate of $${\text{NH}}_{4}^{ + }$$ -N could reach 94% after 90 min of electrolysis. At the same time, the energy consumption needed in the whole reaction process was extremely low and by-product mass generated from the reaction was negligible. In addition, dynamic fitting indicates the degradation procedure was in accordance with the first-order kinetic model.

The regimes of electrodischarge treatment of components of coal-water fuel that allow producing stable suspensions were found experimentally. A method of calculation of the productivity of powdering brown coal using electrodischarge treatment was proposed. The parameters are represented that influence the productivity of the powdering.

The effect of electromagnetic radiation of an extremely high frequency on the productivity and biosynthetic activity of Saccharomyces cerevisiae CNMN-Y-18 and Saccharomyces cerevisiae CNMN-Y-20 yeast strains, depending on the duration of irradiation, has been revealed. It was established that at the irradiation with millimeter waves with a frequency of 53.33 GHz during 10 and 20 minutes the amount of biomass, carbohydrates, mannoproteins, β-glucans, proteins gets the maximum and the catalase activity is the highest. For the first time, procedures to increase the content of mannoproteins and β-glucans using the electromagnetic radiation of an extremely high frequency as stimulating factor, are proposed.

The relaxation time of a near-electrode space charge in magnetic colloids based on dielectric liquids is experimentally established via electrooptical methods as being in the range of 0.05–0.3 s depending on the conductivity of the sample. The results agree with the data of the electrosurface effect in magnetic colloids.

It was demonstrated that the application of ultrasonic, hydroacoustic, and bifrequency cavitation for bentonite dispergation allows one to obtain finely dispersed suspensions, including those of submicron particles. It was found out how the particle dimensions depend on the amplitude of the oscillations, the duration of the treatment, and the static pressure. The results of electron microscopic examination of the suspensions were analyzed.

The phenomenon of electrochemical nucleation in micro-and nanoparticles was investigated. The theory of metastable nucleation was developed on the basis of the first principles of statistical physics.