Tourmaline for heavy metals removal in wastewater treatment: A review

Tourmaline, a novel adsorption material, is increasingly used in heavy-metal polluted waters treatment. For a comprehensive and in-depth understanding, this work focuses on the distinguishing features and adaptability of tourmaline in heavy metal wastewater treatment, as well as the associated removal mechanism and its modification on new functional materials synthesis. Characteristics of tourmaline and its specific properties (spontaneous polarization, piezoelectricity, and thermoelectricity) favorable to heavy metals removal in aqueous solution are well demonstrated in this work. The feasible application of tourmaline in water purification and its high removal efficiency on typical heavy metals are summarized and analyzed. The existing research results have shown that the removal mechanism of heavy metal ions by tourmaline mainly includes electrostatic adsorption, ion exchange, water polarization by tourmaline and the formation of hydroxide precipitation. Moreover, the advantages and feasibility of tourmaline as a new modifier in preparation of various functional materials for heavy metals adsorption are introduced and discussed. This article will be much helpful for better understanding on tourmaline as a new adsorbent and modifier in water treatment, and provide important information on development of more environmental-friendly and highly efficient adsorption materials based on tourmaline in water treatment in the future.