National Nanotechnology Center, National Science and Technology Development Agency, Thailand Science Park, Pathum Thani, Thailand.
Water Environ Res. 2024 Nov;96(11):e11152. doi: 10.1002/wer.11152.
A single-pass mode of membrane capacitive deionization (MCDI) stack unit was fabricated for alternative desalination in local brackish groundwater. Nakhon Ratchasima (Korat), Thailand, is in the northeastern region and mostly faced the salinity groundwater problem. A commercial coconut shell-based activated carbon (PAC) was used for electrode material due to an available and cost-effective choice. Comparing two different specific surface areas of PAC (1153 and 2145 m g) for the electrode material was studied regarding a basic electrosorption capacity. It revealed that the more hydrophilic surface of PAC and lower internal resistance, the higher electrosorption performance was observed, regardless of the specific surface area in the case of a similar pore structure. The MCDI stack unit with a large active area (16 × 16 cm) of 80 pairs of electrodes (a large lab-scale unit) demonstrated a sufficient removal efficiency in single-pass mode to reduce salinity and hardness in Korat groundwater, composed of multi-coexisting ions (TDS ~ 2000 mg L). A relative selectivity coefficient (RSC) demonstrated that highly charged cations with smaller hydrated ionic radii predominantly played a crucial role in removal efficiency. While the initial concentration was strongly affected by the same charged ions. Total removal efficiency (RE) and ion removal efficiency (RE) revealed performance stability during 20 days of operation and produced purified water with acceptable standards for consumption. Finally, this finding demonstrated the possibility of applying the PAC1-MCDI stack unit for natural groundwater desalination with a satisfactory desalination performance. We hope that the data in this study can be beneficial guidance for further practical MCDI system improvement and setup in a local area of Thailand, dealing with the salinity groundwater problem. PRACTITIONER POINTS: Desalination of brackish groundwater by membrane capacitive deionization (MCDI). Hydrophilic surface of activated carbon materials predominantly influenced a higher electrosorption performance. Relative selectivity coefficient mainly relied on ionic charges and hydrated ionic radii. Using MCDI for local brackish groundwater desalination applications produced water safe for consumption.
一种用于替代当地微咸地下水脱盐的单通道膜电容去离子（MCDI）堆叠单元被制造出来。泰国呵叻府（Korat）位于东北部，主要面临着地下水含盐量过高的问题。由于具有可用性和成本效益的选择，商业椰壳基活性炭（PAC）被用作电极材料。研究了两种不同比表面积的 PAC（1153 和 2145 m²/g）作为电极材料的基本电吸附容量。结果表明，PAC 的亲水性表面和更低的内阻，表现出更高的电吸附性能，而在相似的孔结构下，比表面积则不那么重要。具有 80 对电极（大型实验室规模单元）的大有效面积（16×16 cm）的 MCDI 堆叠单元在单通道模式下表现出足够的去除效率，可以降低呵叻府地下水的盐分和硬度，该地下水由多种共存离子组成（TDS~2000 mg/L）。相对选择性系数（RSC）表明，带高价电荷且水合离子半径较小的阳离子在去除效率中起着至关重要的作用。而初始浓度则受到同电荷离子的强烈影响。总去除效率（RE）和离子去除效率（RE）在 20 天的运行过程中表现出稳定性，并产生了可接受的饮用水标准的净化水。最后，这一发现表明，PAC1-MCDI 堆叠单元有可能用于天然地下水脱盐，具有令人满意的脱盐性能。我们希望本研究中的数据能够为进一步改进和在泰国当地实际 MCDI 系统提供有益的指导，以解决地下水含盐量过高的问题。
