Tan Guangcai, Wan Shun, Mei Shu-Chuan, Gong Bo, Qian Chen, Chen Jie-Jie
CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
Water Res X. 2023 May 10;19:100182. doi: 10.1016/j.wroa.2023.100182. eCollection 2023 May 1.
Capacitive deionization (CDI) is a promising technique for brackish water desalination. However, its salt electrosorption capacity is insufficient for practical application yet, and little information is available on hardness ion (Mg, Ca) removal in CDI. Herein, hierarchical porous carbon (HPC) was prepared from low-cost and renewable microalgae via a simple one-pot approach, and both MnO/HPC and polyaniline/HPC (PANI/HPC) composites were then synthesized using a facile, one-step hydrothermal method. Compared with the MnO electrode, the MnO/HPC electrode presented an improved hydrophilicity, higher specific capacitance, and lower electrode resistance. The electrodes exhibited pseudocapacitive behaviors, and the maximum salt electrosorption capacities of MnO/HPC-PANI/HPC CDI cell was up to 0.65 mmol g NaCl, 0.71 mmol g MgCl, and 0.76 mmol g CaCl, respectively, which were comparable and even higher than those of the previously reported CDI cells. Additionally, the MnO/HPC electrode presented a selectivity order of Ca ≥ Mg > Na, and the divalent cation selectivity was found to be attributed to their stronger binding strength in the cavity of MnO Multiscale simulations further reveal that the MnO/HPC electrodes with the unique luminal configuration of MnO and HPC as supportive framework could offer a great intercalation selectivity of the divalent cations and exhibit a great promise in hardness ion removal.
电容去离子化（CDI）是一种用于微咸水脱盐的很有前景的技术。然而，其盐电吸附容量在实际应用中仍不足，且关于CDI中硬度离子（Mg、Ca）去除的信息很少。在此，通过一种简单的一锅法由低成本且可再生的微藻制备了分级多孔碳（HPC），然后使用简便的一步水热法合成了MnO/HPC和聚苯胺/HPC（PANI/HPC）复合材料。与MnO电极相比，MnO/HPC电极表现出改善的亲水性、更高的比电容和更低的电极电阻。这些电极表现出赝电容行为，MnO/HPC - PANI/HPC CDI电池的最大盐电吸附容量分别高达0.65 mmol g NaCl、0.71 mmol g MgCl和0.76 mmol g CaCl，与先前报道的CDI电池相当甚至更高。此外，MnO/HPC电极呈现出Ca≥Mg>Na的选择性顺序，并且发现二价阳离子选择性归因于它们在MnO空腔中更强的结合强度。多尺度模拟进一步表明，具有独特的MnO内腔结构和HPC作为支撑框架的MnO/HPC电极可以提供对二价阳离子的良好插层选择性，并在去除硬度离子方面展现出巨大潜力。
