Yang Jing, Gong Hui, Chai Shuqian, Zhu Danyang, Chen Kejin, Liu Qinpei, Liu Xiaoguang, Dai Xiaohu
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
Water Res. 2025 May 1;275:123228. doi: 10.1016/j.watres.2025.123228. Epub 2025 Jan 31.
Fluorine (F), critical for various industries, faces resource scarcity due to limited reserves of its primary source, fluorite (CaF₂). While fluorine-containing wastewater from industrial processes represents a valuable potential resource, recovering fluorine from low-concentration wastewater remains challenging. This study introduces a cyclic "preconcentration + recovery" system combining flow-electrode capacitive deionization (FCDI) and fluidized bed crystallization (FBC) to address this gap. FCDI preconcentrates fluorine ions into high-concentration brine, and FBC facilitates the formation of high-purity fluorite crystals. Experimental parameters influencing FCDI efficiency - such as influent fluoride concentration, electrode solution composition, and flow rate - were systematically evaluated. Additionally, the cyclic operation was modeled to enhance the whole recovery rate across multiple cycles. The experimental results demonstrated that FCDI achieves an 83.90% fluoride removal rate under optimal conditions with energy-efficient operation. FBC produces fluorite crystals of up to 97.20% purity, classified as acid-grade. The integrated FCDI-FBC system achieves a fluoride recovery rate of 64.40% in single operation mode, with further improvements in cyclic mode. The proposed system offers a sustainable and economically feasible solution to fluorine recovery from low-concentration wastewater, representing a significant step toward the sustainable utilization of non-renewable fluorite resources.
氟（F）对各种行业至关重要，但由于其主要来源萤石（CaF₂）的储量有限，面临资源短缺问题。虽然工业过程中产生的含氟废水是一种宝贵的潜在资源，但从低浓度废水中回收氟仍然具有挑战性。本研究引入了一种循环的“预浓缩+回收”系统，该系统结合了流动电极电容去离子化（FCDI）和流化床结晶（FBC）来弥补这一差距。FCDI将氟离子预浓缩至高浓度盐水，FBC则促进高纯度萤石晶体的形成。系统评估了影响FCDI效率的实验参数，如进水氟化物浓度、电极溶液组成和流速。此外，对循环操作进行了建模，以提高多个循环中的整体回收率。实验结果表明，FCDI在最佳条件下实现了83.90%的氟去除率，且运行节能。FBC生产的萤石晶体纯度高达97.20%，属于酸级。集成的FCDI-FBC系统在单操作模式下实现了64.40%的氟回收率，在循环模式下有进一步提高。所提出的系统为从低浓度废水中回收氟提供了一种可持续且经济可行的解决方案，代表了朝着不可再生萤石资源的可持续利用迈出的重要一步。
