Effect of AC/DC electrical fields on ZnO nanoparticles kinetics

Abstract

Long-term electrokinetic processes affect the motion of different soil fractions mainly ionic-species in soil-type environments. Primarily, this governs direct (DC) and alternating (AC) electrical fields due to the different thermal, acid-base ion gradients generated close to electrodes resulted in electro-migration, electrophoresis, and other electrolysis-related-processes. The migration of metal ionic-species, including zinc, which occurs mainly under DC electrical field is generally acknowledged, but metal-corresponding nanoforms such as ZnO nanoparticles (ZnO-NP) under low-level DC and AC electrical fields absent in the literature. The aims of the research was the analysis of pressure-driven transport at two different electric potentials; the equipotential-voltage lines in sand-media with ZnO-NP under 1 V, and 3 V (for DC), and AC under 1 V, 3 V (1 kHz of sinusoidal waves), detection of the migration of Zn from ZnO-NP to anode-to-cathode area (DC), and to the electrodes areas for AC with pH changes within three-hours of treatment and X-ray diffraction investigation of structural changes of ZnO-NP. The results showed that the AC electric field had more uniform equipotential-voltage pattern of sand-media than the DC fields for both voltages applied. In addition, different zinc concentrations up to 11% and electro-active substances were detected between the DC anode-to-cathode and Electrode 1 area compared to the AC Electrode 2 area. The higher pH value also correlated only with DC. X-ray diffraction analysis detected no structure transformation of ZnO-NP, but deterioration of relatively stable graphite electrodes appeared. Our results at the low-level AC and DC electrical fields confirmed the potential of electro-accelerated nanoparticle kinetics.