Effect of Humic Acids on the Generation of Potential Differences in a Bioelectrochemical System

Abstract

The possibility of increasing the electrogenic properties of the root environment through the use of potential electron carriers, humic acids (HA), was studied. For this purpose, a bioelectrochemical cell has been created, including electrode systems introduced into the planters to remove the potential difference formed during the development of plants. Using the example of Typhoon lettuce, it was determined that an increase in the concentration of HA in the root environment by 2 times allowed to increase the voltage by 7–16% of the control variant, depending on the place of their introduction. The best result – a more stable generation of a high potential difference from the early periods of vegetation was typical for the variant with addition of HA to the upper electrode area – the average voltage value for it was 418 ± 29 mV and a specific power of 0.2 MW/m2. A number of physicochemical parameters of near-electrode regions in plant bioelectrochemical systems have been studied: electrical conductivity, pH, concentration of humic acids at the end of the growing season. The potential electroactivity of microorganisms in the root environment of lettuce has been revealed. It is shown that the ability of humic acids to play the role of a redox mediator in a bioelectrochemical system largely depends on the place of their concentration.