Adsorption-Luminescent Determination of Y(III) Using 8-oxyquinoline Derivatives Fixed on the Silica Surface

Silicas, sequentially modified with polyhexamethylene guanidine and 8-hydroxyquinoline‑5-sulfonic acid (SiO2-PHMG‑oxine) or 7-iodine‑8-hydroxyquinoline‑5-sulfonic acid (SiO2-PHMG‑ferron), have been proposed for the adsorption-luminescent determination of Y(III) in natural waters. Complex compounds of Y(III) are formed on the surface of adsorbents during adsorption from solutions at pH 6–7, which luminesce in a yellow-green color (λlum = 485 nm (SiO2-PHMG‑oxine) and λlum = 490 nm (SiO2-PHMG‑ferron)). This is the basis for the method of its sorption-luminescent determination. The detection limit of Y(III), calculated according to the 3s criterion, is 1 μg/L (SiO2-PHMG‑oxine) and 2 μg/L (SiO2-PHMG‑ferron), the analytical range is 4–400 μg/L (SiO2-PHMG‑oxine) and 6–500 μg/L (SiO2-PHMG‑ferron). The developed methods were tested in the determination of yttrium in the Yenisei and Kacha rivers of the Krasnoyarsk Krai

Adsorption of selected pharmaceuticals on activated carbons from water

The possibility of using activated carbon for the removal of salicylic acid andiibuprofen sodium has been explored. These compounds are observed in crude and treated sewage and in surface water. The effect of pH on the adsorption efficiency was assessed. Tests were carried out from solutions with pH ranging from 2 to 10 (salicylic acid) and from 6 to 10 (iibuprofen sodium). It was found that the higher pH, the lower the adsorption of the compounds tested. Salicylic acid was most efficiently adsorbed from a solution with pH = 2, in which it occurred mainly in an undissociated form. The achieved efficiency of salicylic acid adsorption from solutions with pH=2 was 91%, while from those with pH=10, it was 55% (Co=4 mmol/L). The efficiency of removing ibuprofen sodium from the pH=6 solution was 64%, while from the pH = 10 solution, 60%.The adsorption of both salicylic acid and ibuprofen sodium follows the kinetics equation of the pseudo-2nd order. For the description of the adsorption isotherms, the Freundlich, Langmuir, Temkin and Dubibin-Radushkevich models were employed. The both compounds are described with the highest correlation coefficient in the case of the Freundlich equation.

Influence of the “wetting–drying” compaction on the adsorptive characteristics of nanosilica A-300

The methods of low-temperature 1H NMR and IR spectroscopy, densitometry, and adsorption from solutions are applied to study the influence of “wetting–drying” compaction on the adsorptive characteristics of the nanosilica A-300 in relation to water and gelatin. It was shown that if the bulk density changes from 0.05 to 0.25 g/ml, the protein adsorptive capacity of the nanosilica decreases no more than by 30%, which, apparently, is connected with the decrease of the part of the surface, available for the protein molecules. Interfacial energy in relation to water increases from 37 to 52 mJ/m2 if the bulk density increases and this is connected with the increase of the contribution from minor clusters (nanodrops) adsorbed on the surface water.