Advances and challenges in metal ion separation from water

Abstract

Major technologies for metal ion recovery from water and wastewater include chemical precipitation, membrane filtration, adsorption, and electrochemical separation. Recent studies have focused on membrane, adsorption, and electrochemical methods, sophisticating them to obtain high selectivity and recovery. Membrane filtration plays an important role in separating monovalent and divalent metal ions. Metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and porous-organic polymers (POPs) have recently been studied to separate a specific metal ion selectively. Electrochemical methods are critical and useful options to make best use of adsorption because electrochemical power can strengthen the recyclability and stability of adsorbents. Technologies for selective metal ion separation from water and wastewater are currently attracting strong research interest as a pathway to greater sustainability. The chemistry of metal ion separation processes is critical for understanding the mechanisms of selectivity and making the technologies viable. This paper discusses current advances and challenges in metal ion separation technologies from chemical points of view and proposes how they should be approached in the future. Technologies for selective metal ion separation from water and wastewater are currently attracting strong research interest as a pathway to greater sustainability. The chemistry of metal ion separation processes is critical for understanding the mechanisms of selectivity and making the technologies viable. This paper discusses current advances and challenges in metal ion separation technologies from chemical points of view and proposes how they should be approached in the future. porous materials adsorb contaminants. Kinetics and uptake are determined by its internal structure and composition. chemicals (e.g., sulfide and hydroxide reagents) react with metal ions to form insoluble precipitates, which are then separated from the water by sedimentation or filtration. target contaminants and resources include water, gases, salts, metals, and organic compounds, which are separated from the aqueous phase to reduce environmental impacts or to be recycled and used as valuable resources. a class of materials that only involve light organic elements (C, N, O, B, and Si) through strong covalent bonds (B−O, C−N, B−N, and B−O−Si). COFs have emerged as an important class of porous materials, with the advantages of designed structures, tunable pore size, and functionality. charge controlled electrodes can capture and release contaminants. Design of chemical specificity between electrodes and contaminants is the key to performance. a thermally driven process in which a hydrophobic porous membrane separates vapor from a warm liquid solution stream. The hydrophobicity of the membrane prevents liquid passage through the pores while allowing the passage of solvent vapor. pressure drives water through pores in a membrane, separating particles larger than the pores. This approach is most effective when the particles are sufficiently large. a class of compounds made by assembling inorganic units and organic linkers that form one-, two-, or three-dimensional structures. MOFs are often porous polymers. noncrystalline, but still highly porous and stable materials. More diverse synthetic coupling reactions, including Sonogashira−Hagihara, Suzuki−Miyaura, Yamamoto, or Eglinton couplings are used to make high-performance POPs with additional thiol chelating groups. involve the transfer of electrons and the subsequent oxidation or reduction of a compound.