Exploring the mechanism of removing Cd from polluted soil using electrochemical leaching with straw carbon film electrode

The study presents a novel approach to remediating heavy metal-contaminated soil using electrochemical technology and chemical leaching. The researchers developed a new electrode material from waste straw and an environmentally friendly leaching agent using straw fermentation liquid. Combining electrochemical technology with chemical leaching provides a powerful remediation solution for heavy metal-contaminated soil, demonstrating efficiency and thoroughness. However, challenges include developing recyclable electrode materials and environmentally friendly leaching agents. This study addresses these challenges by pioneering a biochar-based electrode material and an eco-friendly leaching agent. Waste straw undergoes pyrolysis at 1000 °C to produce a conductive biochar, which is then combined with ethyl cellulose to form a film, creating biochar electrode materials. The developed straw fermentation solution, an environmentally friendly leaching agent, is used for Cd-contaminated soil remediation through combined electrochemical-chemical leaching. Results show soil Cd removal efficiency peaking at 59.5% with a singular chemical leaching agent. The combined method increases the Cd removal rate to a maximum of 91%. Furthermore, the study elucidate the potential mechanism of cadmium removal through techniques such as XRD, SEM, and infrared spectroscopy. To evaluate the efficacy of our approach, the study conducted Chinese cabbage pot-cultivation experiments. Remarkably, the physicochemical properties of soil remained largely unchanged after the reaction, while Chinese cabbage growth in treated soil surpassed that of the control group. This study not only removes Cd from the soil, reducing secondary pollution, but also establishes electrode recyclability, offering a prospective solution for large-scale soil heavy metal pollution remediation. •Transforming waste rice straw into conductive biochar through a single-step process.•Developed a novel method for making biochar electrodes.•Employed straw fermentation broth innovatively as an eco-friendly leaching solution.•Pot-cultivation experiments with Chinese cabbage validated the effectiveness of soil remediation.•Attained a remarkable Cd removal rate of up to 91.0% while maintaining soil properties unchanged.