Synthesis and Characterization of Novel Materials, Tin Potassium Vanadate and Zirconium Potassium Vanadate Inorganic Multi-Component Ion Exchangers
Nano polyoxometallate-cation exchangers, tin potassium vanadate (TPV), and zirconium potassium vanadate (ZPV), with stereoregular particulate structures have been chemically synthesized using a homogeneous precipitation technique under a variety of conditions. The experimental parameters such as mixing, volume ratio, order of mixing and pH were established for the synthesis of the materials and fairly compromised to optimize the ion exchange properties of the produced ion exchangers. Structural characterizations of the materials were performed using XRF, XRD, thermal analysis, surface area and porosity measurements, and infra-red spectroscopy. The results were correlated to the lattice parameters, unit cell parameters, and space group of the exchangers. Scanning electron microscopy and atomic force microscopy revealed their sereoregularity in space. Compositions and molecular formulae of both the amorphous and crystalline materials have been investigated. Ion exchange properties and distribution coefficients, Kd, for some heavy metals namely, Co2+, Cu2+, Ni2+, and Cr6+ were measured at different pH values. TPV and ZPV selectivities have been examined by achieving some important and analytically difficult binary and multi-component separations. The results indicated that TPV is practically utilized for best separation of Co2+/Cu2+, Ni2+/Co2+, Cr6+/Co2+, Ni2+/Cu2+, Cr6+/Cu2+, Ni2+/Cr6+, Ni2+/(Co2+, Cu2+), and Ni2+/(Co2+, Cu2+, Cr6+), while ZPV could be efficiently used for separation of Cu2+/Co2+, Ni2+/Co2+, Cr6+/Co2+, Cu2+/Ni2+, Cr6+/Cu2+, Cr6+/Ni2+, and Cr6+/(Co2+, Cu2+, Ni2+).