Capacitive deionization toward fluoride elimination: Selective advantage, state of the art, and future perspectives

Capacitive deionization (CDI) technology, renowned for its operational simplicity, energetic efficiency, and cost-effectiveness, has gained prominence as a powerful solution for water desalination and decontamination. With time, the predominance of CDI has evolved from mere saline reduction in brackish water to targeted removal of hazardous impurities. In particular, fluoride, an ion with substantial health repercussions, has been identified as a key eradication target. In this context, the advent of potent and cost-friendly methods for eradicating fluoride from water becomes crucial-a requisite that CDI technology is promisingly equipped to fulfill. Herein, this article presents a comprehensive review of recent advancements in the design and synthesis of nuanced materials characterized by tailored morphology, structural complexity, and enhanced fluoride elimination performance. As a departure from previous reviews, this piece commences by delineating the merits and limitations of conventional fluoride purging methods. Thereafter, the discussion is steered toward the burgeoning field of advanced pseudocapacitive electrode materials for fluoride expulsion, crafted using a variety of organic and inorganic active substances. These range from carbon material, hydroxyapatite, layered metal oxide, and to metal-organic frameworks (and their derivatives) as well as conducting polymers. The inherent morphological and structural attributes of these materials significantly dictate their ultimate efficacy in fluoride removal. The review also delves into some of the prevailing scientific challenges and opportunities linked to fluoride purging applications. With the intent of grabbing the attention of scholars worldwide for the design and synthesis of high-utility materials for fluoride extraction, this article aims to pave the way for future explorations in this critical research area.