Several salts of pyrophosphoric heteropoly acid: characterization and ion-exchange behavior for calcium removal from manganiferous water

Abstract

In this study, five salts of pyrophosphoric heteropoly acid were synthesized as ion exchanger to remove Ca²⁺ in manganiferous water and characterized by Fourier Transform Infrared spectroscopy and scanning electron microscope. Their performances like ion-exchange capacities, selectivities were tested and the results were compared with zirconium phosphate and molecular sieves (13X and 5A). It can be found that Ca exchange reaction is easy to occur on these ion exchangers. The outcomes for zirconium tungstophosphate (ZWPP) were the best among the mentioned salts, its dynamic exchange capacity has been verified through static and column experiments. The specific surface areas, pore structure, and particle size of ZWPP were also calculated, therein ZWPP being classified into materials with nanoparticles and mesoporosity. Therefore, the salts of pyrophosphoric heteropoly acids, especially ZWPP, can be used as a potential ion exchanger for Ca removal in processed water and effluents from metallurgical industries.

Keywords:

• Salts of pyrophosphoric heteropoly acid
• Ca ion exchange
• Manganiferous water