Regulating pH distribution of soda saline-alkali soil during electrochemical treatment by conditioning catholyte pH coupled with approaching anodes.

Abstract

Soda saline-alkali soils pose significant challenges to agricultural productivity due to high pH and excessive sodium content. This study investigated the removal of excess salts in soda saline-alkali soil through electrochemical treatment (ECT). Traditional ECT often led to uneven soil pH distribution, with acidic conditions near the anode and alkaline conditions near the cathode, which limited its effectiveness for soil improvement. We explored the impact of conditioning the catholyte pH coupled with approaching anode electrochemical treatment (AA-ECT) on soil pH distribution and the removal of soluble sodium ions in soda saline-alkali soil. The results demonstrated that AA-ECT was less effective than fixed anode electrochemical treatment (FA-ECT) in regulating soil pH, achieving a relatively uniform pH range of 7.31-8.44. Adding acetic acid further improved pH uniformity, narrowing the range to 7.32-8.02. Moreover, all experimental groups exhibited high removal of soluble sodium ions efficiency, and the acetic acid coupled with AA-ECT achieved an average removal efficiency of 91.90%. Notably, the soil was successfully transformed from severely alkali soil (exchangeable sodium percentage (ESP) > 61%) to non-alkali soil (ESP < 14%). Additionally, the AA-ECT groups showed lower energy consumption than the FA-ECT groups. These findings highlighted that conditioning the catholyte pH coupled with AA-ECT was a highly effective strategy for improving soda saline-alkali soils, offering a sustainable solution for soil remediation and agricultural productivity enhancement.