A biochar electrode based on conductive straw for Cd removal and recovery from wastewater by DC electrochemical deposition

Biomass-derived charcoal, possessing high surface area, temperature resistance, and stability, has diverse applications. Traditional methods overlook its conductivity. In this work, a new approach was devised. By controlling the pyrolysis temperature and preparation atmosphere, rice straw was converted into biochar electrodes at 1000 °C in a N₂-containing environment. The temperature effect on the conductivity of biochar made from rice straw was elucidated through methods such as resistivity measurement, XRD, and Raman spectroscopy. Furthermore, the biochar electrode material was employed as the cathode and the electro-deposition method was employed to treat wastewater containing Cd. The results indicated that the treatment efficiency of simulated Cd wastewater can reach a maximum of 88.96 % in 7 h at relatively low power consumption. After the reaction, a simple acid washing step effectively separated the electrode and Cd, which allowed the Cd to be recovered and the electrode to be used again. This method offers a innovative low-cost, high-efficiency technique for preparing biochar electrodes from rice straw, achieving sustainable waste conversion while providing new techniques and novel solutions for electro-deposition in heavy metal wastewater treatment. Therefore, the research hold significant practical a significance and scientific value. •Converted rice straw into conductive biochar at 1000 °C under a N2 atmosphere.•Developed and refined a novel process for fabricating straw biochar electrodes.•Investigated the electrochemical removal of cadmium from wastewater.•Reported significant influence of applied current and treatment duration on cadmium removal.