Patel Sohum K, Pan Weiyi, Shin Yong-Uk, Kamcev Jovan, Elimelech Menachem
Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States.
Department of Chemical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
Environ Sci Technol. 2023 Mar 21;57(11):4578-4590. doi: 10.1021/acs.est.3c00058. Epub 2023 Mar 9.
Boron removal from aqueous solutions has long persisted as a technological challenge, accounting for a disproportionately large fraction of the chemical and energy usage in seawater desalination and other industrial processes like lithium recovery. Here, we introduce a novel electrosorption-based boron removal technology with the capability to overcome the limitations of current state-of-the-art methods. Specifically, we incorporate a bipolar membrane (BPM) between a pair of porous carbon electrodes, demonstrating a synergized BPM-electrosorption process for the first time. The ion transport and charge transfer mechanisms of the BPM-electrosorption system are thoroughly investigated, confirming that water dissociation in the BPM is highly coupled with electrosorption of anions at the anode. We then demonstrate effective boron removal by the BPM-electrosorption system and verify that the mechanism for boron removal is electrosorption, as opposed to adsorption on the carbon electrodes or in the BPM. The effect of applied voltage on the boron removal performance is then evaluated, revealing that applied potentials above ∼1.0 V result in a decline in process efficiency due to the increased prevalence of detrimental Faradaic reactions at the anode. The BPM-electrosorption system is then directly compared with flow-through electrosorption, highlighting key advantages of the process with regard to boron sorption capacity and energy consumption. Overall, the BPM-electrosorption shows promising boron removal capability, with a sorption capacity >4.5 μmol g-C and a corresponding specific energy consumption of <2.5 kWh g-B.
从水溶液中去除硼长期以来一直是一项技术挑战，在海水淡化以及锂回收等其他工业过程中，硼去除在化学品和能源使用中占比极大。在此，我们引入了一种基于电吸附的新型硼去除技术，该技术有能力克服当前最先进方法的局限性。具体而言，我们在一对多孔碳电极之间加入了双极膜（BPM），首次展示了一种协同的BPM - 电吸附过程。对BPM - 电吸附系统的离子传输和电荷转移机制进行了深入研究，证实了BPM中的水电离与阳极处阴离子的电吸附高度耦合。然后我们展示了BPM - 电吸附系统对硼的有效去除，并验证了硼去除机制是电吸附，而非碳电极或BPM上的吸附。接着评估了施加电压对硼去除性能的影响，结果表明，由于阳极处有害法拉第反应的发生率增加，施加电位高于约1.0 V会导致工艺效率下降。然后将BPM - 电吸附系统与流通式电吸附直接进行比较，突出了该工艺在硼吸附容量和能耗方面的关键优势。总体而言，BPM - 电吸附显示出有前景的硼去除能力，吸附容量>4.5 μmol g-C，相应的比能耗<2.5 kWh g-B。
