Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination. In this study, activated Douglas-fir biochar is used as a low-cost carbon-based alternative electrode with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion and p-phenylenediamine treatment, respectively, which introduced sulfonate and amine functional groups to the electrode. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. These modified biochar electrodes were characterized by SEM-EDX and XPS. Cyclic voltammetry and galvanostatic charge/discharge measurements were performed to analyze the electrochemical properties of both types of electrodes and the electrosorption capacity was evaluated in a 3D-printed capacitive deionization flow cell using a chloride ion-selective electrode. It was found that an asymmetrical cell with Nafion cathode and amine biochar anode increased removal capacity by 54% over the activated biochar symmetrical cell (identical anode and cathode), with 6.01 mg NaCl/g biochar at the symmetrical cell and 9.25 mg g⁻¹ for the asymmetrical cell. This work shows that biochar can be engineered and explored broadly as an inexpensive sustainable electrode material for asymmetrical capacitive deionization.

基于电吸附的电容去离子 (CDI) 已成为微咸水淡​​化的可行工艺。在这项研究中，活性花旗松生物炭用作低成本的碳基替代电极，其吸附能力与从生物质前体获得的活性炭相当。在活化的生物炭中添加官能团增强了除盐能力，提供了阳离子和阴离子选择性。功能化电极由 Nafion 和p-苯二胺处理，分别将磺酸盐和胺官能团引入电极。这些修饰方法用途广泛，无需复杂的实验室环境即可轻松执行。这些改性的生物炭电极通过 SEM-EDX 和 XPS 进行表征。进行循环伏安法和恒电流充电/放电测量以分析两种类型电极的电化学性质，并在使用氯离子选择性电极的 3D 打印电容去离子流通池中评估电吸附容量。发现具有 Nafion 阴极和胺生物炭阳极的不对称电池比活化的生物炭对称电池（相同的阳极和阴极）提高了 54% 的去除能力，对称电池处的 NaCl/g 为 6.01 mg NaCl/g，生物炭为 9.25 mg g^-1为非对称单元格。这项工作表明，生物炭可以作为一种用于不对称电容去离子的廉价可持续电极材料进行广泛设计和探索。