Controlling the pH of Soil, Catholyte, and Anolyte for Sustainable Soil Electrokinetics Remediation: A Descriptive Review

Abstract The use of soil electrokinetics as a physicochemical technique has been shown to be useful in many different fields, including polluted soil restoration, biostimulation, fertilizer synthesis, consolidation, dewatering, building materials restoration, and reclaiming salt-affected soils. An analysis of six search engines published between 1993 and 2024 (32 years) is used for this review. To guarantee the high effectiveness of electrokinetics application, the pH of soil, catholyte, and anolyte were adjusted in accordance with the primary research endeavor. A number of strategies are involved in regulating pH, including 1) circulating electrolyte mixture, 2) separate circulation of catholyte and anolyte, 3) approaching/moving electrodes, 4) pulsed electric fields, 5) reversing polarity, 6) choosing the best electrokinetics design, and 7) mixing chemicals into the soil. Although circulating electrolytes (anolyte and catholyte) can regulate electrolyte pH, a suitable treatment is needed to prevent pollutants from reentering/returning to treated soils. In addition to pH regulation, catholyte and anolyte separate circulation can also serve as a chemical injection system. The anode approach can increase the soil's acidity in the direction of the cathode, but the cathode approach can have a reverse effect. Pulsed electric fields allow contaminants to move from the solid to the liquid phase (interstitial fluid) and may improve the migration and/or desorption of charged species. By reversing polarity, the soil's pH, temperature, and moisture content may be controlled. Effective selection or modification of the vertical, horizontal, and mixed electrokinetic designs might regulate the pH of the soil. Lastly, adding chemicals (acids and bases) to the soil is believed to be the fastest way to control the pH of soil, catholyte, and anolyte. A thorough understanding of soil electrokinetics will be beneficial to researchers so that their work can be applied more effectively in various fields. Graphical Abstract