Stanislaw Chibowski

Pracownię Radioizotopową w Instytucie Chemii Wydziału Matematyki, Fizyki i Chemii UMCS utworzono w 1969 roku, a w 1974 roku w miejsce Pracowni powołano Zakład Radiochemii i Zastosowań Radioizotopów. Od 1983 roku jednostka przyjęła nazwę Zakład Radiochemii i Chemii Koloidów, który w 2019 roku połączono z Zakładem Chemii Środowiskowej w Katedrę Radiochemii i Chemii Środowiskowej. Pomiary prowadzone od wielu lat koncentrują się na wielokierunkowym monitoringu skażeń promieniotwórczych środowiska naturalnego (oznaczanie aktywności promieniotwórczej izotopów naturalnych i pochodzenia antropogenicznego w powietrzu, wodzie i glebie, a także ich transferu do organizmów roślinnych). Dodatkowo ważny obszar badawczy stanowi adsorpcja związków wielkocząsteczkowych na granicy faz ciało stałe – roztwór, synteza biomateriałów, biokompozytów i radiofarmaceutyków, otrzymywanie biowęgli i ich wykorzystanie w procesach remediacji gleb oraz zastosowanie izotopów promieniotwórczych w badaniach mechanizmów adsorpcji i stabilności w układach koloidalnych

Feroxyhyte (δ‐FeOOH) was synthesized and characterized using X‐ray diffractometry (XRD), simultaneous thermal analysis (STA), scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy (SEM‐EDS), and low‐temperature nitrogen adsorption‐desorption measurements. Its potential application as adsorbent of an anionic and cationic dyes such as C.I. Acid Violet 1 (AV1) and C.I. Basic Blue 3 (BB3) was investigated by determining the adsorption capacities based on the Langmuir (36.6 mg/g for AV1 and 187 mg/g for BB3), Freundlich and Dubinin‐Radushkevich isotherm models. Adsorption of AV1 and BB3 by δ‐FeOOH drops with the presence of additives such as cationic and anionic surfactants (CTAB, SDS) and ionic polymers (PAA, PEI). The surface and electrokinetic properties of examined suspensions were also described. They include determination of the solid surface charge density and the zeta potential, as well as values of point of zero charge and isoelectric point of feroxyhyte particles without and with adsorbed layers of organic substances. Their analysis made possible to propose the most probable structure of electrical double layer formed at the iron mineral/aqueous solution interface.

The worldwide production of colored products and intermediates is increasing year on year. The consequence of this is an increase in the number of liquid effluents containing toxic dyes entering the aquatic environment. Therefore, it is extremely important to dispose of them. One of the techniques for the elimination of environmentally harmful dyes is adsorption. The main purpose of this study was to explore the possibility of using a carbon and silica (C/SiO₂)-based composite for the removal of the azo dye C.I. Basic Red 46 (BR46). The adsorption capacity of C/SiO₂ was found to be temperature dependent and increased from 41.90 mg/g to 176.10 mg/g with a temperature rise from 293 K to 333 K in accordance with the endothermic process. The Langmuir isotherm model seems to be the better one for the description of experimental data rather than Freundlich or Dubinin–Radushkevich. The free energy (ΔG^o) confirmed the spontaneous nature of BR46 adsorption by C/SiO₂. Kinetic parameters revealed that BR46 uptake followed the pseudo-second-order equation; however, the external diffusion plays a significant role. Surfactants of cationic, anionic and non-ionic type influenced BR46 retention by C/SiO₂. The electrokinetic results (solid surface charge density and zeta potential) indicated that the adsorption of cationic dye and surfactant influences the structure of the electrical double layer formed at the solid–liquid interface.

The adsorption and electrokinetic properties of hybrid silica materials composed of nickel and silicon oxides (Ni_xO_y-SiO₂), characterized by different contents of nickel oxide (from 0.5 to 3 mmol/g SiO₂), were examined. These solids were also modified by poly(vinyl alcohol) to change their surface characteristics. The polymer is non-toxic and very well soluble in water. Due to incomplete hydrolysis of the polymer acetate groups, its macromolecules become negatively charged. The limited range of studied pH (6–10) resulted from high solubility of nickel oxide at more acidic pH values. The spectrophotometric, surface charge and electrophoretic measurements indicated that PVA exhibits higher adsorption affinity for the surfaces of mixed oxide with a larger content of nickel in its structure. Moreover, the presence of polymeric layers on the solid surface influences considerably the structure of electrical double layer formed at the mixed oxide-aqueous solution interface.

The mixed SiO2-TiO2 oxide obtained by the pyrogenic method with the silica: titanium percentage ratio equal to 20:80 (ST80) was used in the experiments. The influence of azo dye C.I. Direct Yellow 142 (DY) adsorption at the mixed oxide-solution interface on the electrokinetic properties of solid particles was studied. To determine solid surface charge density and zeta potential of examined suspensions the potentiometric titration and Doppler laser electrophoresis techniques were applied. The changes in structure of electrical double layer formed on the mixed oxide surface in the dye presence were specified as a function of DY concentration, inorganic salt addition and surfactant introduction. The effects of surfactant type and its concentration were determined. Three surfactants of different ionic character (anionic SDS, cationic CTAB and nonionic Triton X-100) were used in measurements. The obtained electrokinetic characteristics of ST80 mixed oxide dispersed in aqueous solutions with various adsorbate compositions is essential for such suspensions stability.

The influence of metal oxide type on the adsorption affinity of anionic polyacrylamide for the solid surface was studied. There were selected three metal oxides: chromium(III) oxide, zirconium(IV) oxide and aluminium(III) oxide. The adsorption behaviour of high-molecular weight polymer containing 30% of carboxyl groups was determined based on the results of spectrophotometric, electrokinetic and turbidimetric measurements. The anionic polymer exhibits the greatest adsorption on the surface of chromium(III) oxide whereas PAM affinity for the aluminium(III) oxide is the lowest. The polymer presence has a pronounced impact on the electrokinetic properties of examined suspensions manifesting in changes in pH_pzc and pH_iep values of PAM-containing systems compared to those without polyacrylamide. The anionic PAM addition at pH 6 has the greatest effect on the stability of metal oxide aqueous suspensions.