Metal Phosphates/Phosphonates for Membranes

Abstract

Metal phosphates and phosphonates have been extensively studied for applications in membranes due to their desired features including coordination capacity, ion exchange ability, controllable morphology, and good thermal/chemical stability. The membrane performances are influenced by several factors including the types of metal ions, the structure of phosphoric or phosphonic acids, the ratios between them, and the synthetic methods. In this chapter, metal phosphates are discussed in the first section, which is further divided into four sub-sections including metal salts of phosphoric acid, metal salts of pyrophosphoric acid, metal salts of hydrocarbyloxy phosphoric acids, and other inorganic metal phosphates. The second section focused on metal phosphonates for membranes, contains three sub-sections including metal salts of alkyl phosphonic acids, metal salts of aryl phosphonic acids, and other metal salts of phosphonic acids. The synthesis and structure of metal phosphates and phosphonates were introduced while the membrane fabrication and performances were discussed. Next-generation high-performance membranes applied in ion exchange, gas separation, liquid–liquid separation and catalysis can be developed under the guidance of the valuable studies established in this field.