V. N. Belyakov

Influence of water hardness on removal of copper ions by ion-exchange-assisted electrodialysis

Abstract The organic ion exchangers (Dowex HCR-S, Dowex 50WX-2) and inorganic ion exchangers with phosphate functional groups (zirconium phosphates ZrP-1, ZrP-2) were studied as transport media for ion-exchange-assisted electrodialysis of diluted solutions containing Cu (II) ions. The ion-exchange and electric conductive properties of ion exchangers containing Cu(II) ions were studied. The most conductive exchangers were chosen. The adsorption data showed a high selectivity of the zirconium phosphate towards copper ions in a concentration range from 0 to 0.5 mmol. Both exchangers were tested in ion-exchange-assisted electrodialysis of a 10 −2 M solution, containing copper and hardness ions in a ratio of 1:9. It was found that efficiency of removal of the Cu(II) ions was better for the inorganic ion exchanger.

Interaction of sorbed Ni(II) ions with amorphous zirconium hydrogen phosphate

Samples of amorphous zirconium hydrogen phosphate with different zirconium and phosphorus concentrations in hydrogen and nickel-substituted forms are studied by means of electronic, 31P NMR, and impedance spectroscopy. It is shown that Ni(II) → H+ ion exchange is accompanied by the hydrolysis of sorbed cations and the formation of complexes with the dihydro- and hydrophosphate groups of the inorganic ionite. It is found that the coordination environment of Ni(II) in the sorbent phase includes 2–4 fragments of phosphate groups, along with OH groups and water molecules.

Anion-exchange properties of composite ceramic membranes containing hydrated zirconium dioxide

Composite membranes consisting of an inert ceramic matrix based on aluminum and zirconium oxides and of an ion-exchange component, hydrated zirconium dioxide, were prepared. The selectivity of these membranes to Cl− ions was studied.

The effect of introduction of manganese hydroxide and hydrated aluminum oxide on the pore structure and surface charge of Zr(IV), Ti(IV), and Sn(IV) oxyhydrates

The specific surface area, micropore volume, and pore size distribution for the Zr(IV), Sn(IV), and Ti(IV) oxyhydrates and double hydrates of the composition MxMn1−xOy·nH2O and MxAl1−xOy·nH2O [M = Zr(IV), Sn(IV), Ti(IV), x = 0.5–0.9 were calculated. The specific surface charge and zero-charge point in 0.12 M KNO3 were determined.

Desalination of glycerol-water solutions by electrodyalysis using the organo-inorganic membranes

The organo–inorganic ion exchange membranes based on heterogeneous membrane materials and inorganic ion exchangers (zirconium hydrophosphate and hydrated zirconium dioxide) have been developed for electrodialysis desalination of glycerol–water solutions. It was shown that the electrodialysis efficiency with pristine polymer membranes decreases with time due to formation of deposit directly in the membrane pores. In contrast, the organo–inorganic membranes exhibit resistance to poisoning by organic substances, and the current yield during the electromembrane treatment can reach 95–98%.

Selectivity of new inorganic ion–exchangers based on oxides of titanum and manganese at sorpion of lithium from aqueous media

We have obtained new composite materials of TiO2–MnO2 saturated with lithium ions and treated at 500 and 600°C. Using methods of low-temperature adsorption of nitrogen, infrared and X-ray spectroscopy their structural properties were investigated. It has been shown that given ion–exchangers display substantial selectivity at sorption of lithium ions with respect to other cations.

Sorption of Cr(VI) ions by oxyhydrates of MxAl1−xOy · nH2O composition, where M is Zr(IV), Ti(IV), or Sn(IV)

The equilibrium and kinetics of Cr(VI) ion sorption from acidic (pH 2.5) and alkaline (pH 10.5) aqueous solutions by oxyhydrates of the MxAl1 − xOy · nH2O composition, where M is Zr(IV), Ti(IV), or Sn(IV) and x = 0.0−0.7, are studied. It is shown that the sorption equilibrium can be described using the Langmuir model. The effective diffusion coefficients of Cr(VI) ions calculated from the exchange half-time and specific conductivity of oxyhydrates measured after the sorption of the target component are (0.11–0.28) × 10−11 m2 s−1.