Adsorption affinity of Zn (II) ions for nanostructured zirconium phosphate/silica or titania composites

Study on electrical double layer nanostructure on zeolitic materials’ surface in the presence of impurities of different nature

The aim of the research was to compare the adsorption mechanisms of heavy metal ions (Pb(II) and Zn(II)), as well as organic substances [diclofenac molecules and pol(acrylic acid) macromolecules on the surfaces of Na-X and Na-P1 synthetic zeolites as well their Na-X© and Na-P1© carbon composites]. The single and mixed adsorbate systems were considered. The more probable structures of the formed adsorption layers were proposed based on the results of the solid surface charge density and zeta potential experiments. The great applicability of the analysis of the parameters characterizing the electrical double layer in determination of the binding mechanism of simple inorganic ions and more complex organic molecules on the surface of the examined solids from the one- and two-component solutions was proved. Moreover, the changes of the surface and electrokinetic factors after the addition of the organic molecules enable specification of drug molecule orientation as well as the polymeric chain conformation at the solid/liquid interface.

Highly efficient removal of strontium from contaminated wastewater by a porous zirconium phosphate material

Effective and efficient disposal of radioactive pollution has been crucial for responding to unexpected nuclear accidents and guaranteeing the sustainable development of nuclear energy. In this study, a kind of porous zirconium phosphate was synthesized with a sol-gel process followed by a post-synthesis modification to remove the radioactive Sr²⁺ from wastewater. The prepared materials were characterized by different technologies including FT-IR, SEM-EDS, XRD and XPS, and then the adsorption performance was evaluated in batch and column modes. Experimental results suggested that the porous zirconium phosphate adsorbent was successfully prepared with Na⁺ dispersed in the channels for exchange. It inherited the excellent properties of zirconium dioxide aerogel and exhibited mesoporous structure and large specific surface area. Compared with traditional zirconium phosphate, the adsorption kinetics and the adsorption capacity were improved simultaneously. Especially, it showed excellent selectivity towards Sr²⁺ among different cations, and even could remove the low-level Sr²⁺ from natural seawater efficiently, which powerfully demonstrated that the prepared material could be applied in the treatment of practical wastewater. Spectra studies uncovered that the adsorption activities were dominated by the ion exchange mechanism between external Sr²⁺ and interlaminar Na⁺ or H⁺. In conclusion, this paper not only reports a novel synthesis strategy for the acquisition of porous zirconium phosphate, but also presents a promising adsorbent for the Sr²⁺ removal.

Adsorption of Ag (I) Ions at the Zirconium Phosphate/KNO3 Aqueous Solution Interface

The paper presented the mechanical (MChT), microwave (MWT), and hydrothermal (HTT) methods of zirconium phosphate samples modification in order to improve its adsorption affinity for the Ag (I) ions. The FTIR studies proved that the modification of both gel and xerogel samples with the ultrasonic microwaves causes an increase in the concentration of phosphate groups on the surface of MWT-modified zirconium phosphate: the isoelectric point pHiep = 2.2–2.9 for these samples against 3.9 for the initial sample and pKa2 values were 4.7–5.6 and 6.3, respectively. As resulting from the Ag⁺ ion adsorption studies, the MWT treatment of zirconium phosphate samples caused the greatest affinity of Ag⁺ ions for the surface of MWT zirconium phosphate. Compared with the initial ZrP sample, the shift of the Ag (I) ion adsorption edge towards lower pH values was observed, e.g., with adsorption of Ag (I) ions from the solution with the initial concentration of 1 µmol/dm³ for the initial ZrP sample pH50% = 3.2, while for the sample MWT ZrPxero pH50% = 2.6.