Mudau Fulufhelo, Motsa Machawe, Hassard Francis, de Kock Lueta-Ann
Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709, South Africa.
Cranfield Water Science Institute, Cranfield University, College Way, Bedford MK43 0AL, UK.
Membranes (Basel). 2022 Jul 27;12(8):736. doi: 10.3390/membranes12080736.
Arid areas often contain brackish groundwater that has a salinity exceeding 500 mg/L. This poses several challenges to the users of the water such as a salty taste and damage to household appliances. Desalination can be one of the key solutions to significantly lower the salinity and solute content of the water. However, the technology requires high energy inputs as well as managing waste products. This paper presents the fabrication of ultrafiltration heterogeneous ion exchange membranes for brackish groundwater treatment. Scanning electron microscopy (SEM) images showed a relatively uniform resin particle distribution within the polymer matrix. The mean roughness of the cation exchange membrane (CEM) and anion exchange membrane (AEM) surfaces increased from 42.12 to 317.25 and 68.56 to 295.95 nm, respectively, when resin loading was increased from 1 to 3.5 wt %. Contact angle measures suggested a more hydrophilic surface (86.13 to 76.26° and 88.10 to 74.47° for CEM and AEM, respectively) was achieved with greater resin loading rates. The ion exchange capacity (IEC) of the prepared membranes was assessed using synthetic groundwater in a dead-end filtration system and removal efficiency of K, Mg, and Ca were 56.0, 93.5, and 85.4%, respectively, for CEM with the highest resin loading. Additionally, the anion, NO and SO removal efficiency was 84.2% and 52.4%, respectively, for the AEM with the highest resin loading. This work demonstrates that the prepared ultrafiltration heterogeneous ion exchange membranes have potential for selective removal for of ions by ion exchange, under filtration conditions at low pressure of 0.05 MPa.
干旱地区通常含有盐度超过500毫克/升的微咸地下水。这给用水者带来了诸多挑战，比如水有咸味以及对家用电器造成损害。脱盐可能是大幅降低水的盐度和溶质含量的关键解决方案之一。然而，该技术需要高能量输入以及管理废弃物。本文介绍了用于微咸地下水处理的超滤非均相离子交换膜的制备。扫描电子显微镜（SEM）图像显示聚合物基质内树脂颗粒分布相对均匀。当树脂负载量从1 wt%增加到3.5 wt%时，阳离子交换膜（CEM）和阴离子交换膜（AEM）表面的平均粗糙度分别从42.12纳米增加到317.25纳米以及从68.56纳米增加到295.95纳米。接触角测量表明，随着树脂负载率的提高，表面亲水性增强（CEM和AEM分别从86.13°变为76.26°以及从88.10°变为74.47°）。在死端过滤系统中使用合成地下水评估了所制备膜的离子交换容量（IEC），对于树脂负载量最高的CEM，K、Mg和Ca的去除效率分别为56.0%、93.5%和85.4%。此外，对于树脂负载量最高的AEM，阴离子NO和SO的去除效率分别为84.2%和52.4%。这项工作表明，所制备的超滤非均相离子交换膜在0.05 MPa的低压过滤条件下，具有通过离子交换选择性去除离子的潜力。
