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Wpływ surfaktantów na właściwości adsorpcyjne substancji organicznych i jonów metali ciężkich w układach koloidalnych

Chibowski Stanisław, Wiśniewska Małgorzata

Wiadomości Chemiczne

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2021

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[Z] 75, 9-10

1181--1202

EN

The main purpose of this paper is description of the mechanisms governing the adsorption process of organic substances (such as polymers and dyes soluble in water) and inorganic substances (i.e. heavy metal ions) on the solid surface in the presence of synthetic surfactants of various ionic nature (anionic SDS, cationic CTAB and nonionic Triton X-100). The following polymers were applied: polyacrylamide, poly(ethylene glycol), poly(vinyl alcohol) and poly(acrylic acid). Moreover, the mono-, di- and triazo dyes with acidic, reactive and direct characters were used. Metal oxides – both simple (alumina, zirconia, titania) and mixed (double: silica-alumina, silica-titania and triple: alumina-silica-titania), as well as activated carbons obtained from biomass and peat were applied in the role of adsorbents. The effects of solution pH, ionic character of adsorbate, its molecular weight, elemental composition of the solid, its acid-base properties and textural structure, were determined. The understanding of the phenomena occuring at this type of interface is extremaly important for the effective control of colloidal suspensions stability, which is essential for practical applications. The formation of mixed adsorption layers composed of polymer-surfactant, dye-surfactant or polymer-surfactant-metal ion complexes results in many cases in a significant modification of the surface properties of solids, which is manifested not only by the changes in amount of bound adsorbate, but also by the changes in the structure of electrical double layer. The analysis of the obtained results indicated two main mechanisms of the surfactants influence on the adsorption process of organic and inorganic substances in colloidal systems containing a highly dispersed solid. The first one is the formation of polymer-surfactant, dye-surfactant or polymer-surfactant-metal complexes through both hydrophobic and electrostatic interactions, which show different affinity to the adsorbent surface. In most of the examined systems, these complexes were effectively bound at the solid-liquidinterface, which resulted in the adsorption increase of polymer, dye and heavy metal ions. The second important mechanism is the competition of surfactant molecules and other adsorbates for the active sites of the solid surface (the components of mixed adsorbates had the same ionic character). As a result of these two processes, mixed adsorption layers with a specific structure were formed, which determined the stability of the colloidal suspension.

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Electrokinetic properties of silica-titania mixed oxide particles dispersed in aqueous solution of C.I. Direct Yellow 142 dye – effects of surfactant and electrolyte presence

Chibowski Stanisław, Wiśniewska Małgorzata, Wawrzkiewicz Monika, Hubicki Zbigniew, Goncharuk Olena

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 6

6--13

EN

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.

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Alumina-silica-titania adsorbent for hazardous azo and phtalocyanine dyes removal from textile baths and wastewaters – the impact of ionic surfactants

Wiśniewska Małgorzata, Wrzesińska Katarzyna, Wawrzkiewicz Monika, Chibowski Stanisław, Urban Teresa, Goncharuk Olena, Gun’ko Vladimir M.

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 6

178--193

EN

Two aspects of interfacial phenomena were discussed in the manuscript. The first one concerns the adsorptive removal of two azo dyes such as C.I. Acid Yellow 219 (AY219) and C.I. Direct Yellow 142 (DY142) as well as the phtalocyanine C.I. Reactive Blue 21 (RB21) on the alumina silicatitania oxide (4% wt. Al2O3 – 8% wt. SiO2 – 88% wt. TiO2; AST88) in the ionic surfactants presence. The second one deals with the determination of interaction mechanism in the dyes-AST88, dyes-surfactant-AST88 systems using the data obtained from the surface charge density and zeta potential studies. The sodium dodecyl sulphate (SDS) with anionic character and hexadecyltrimethylammonium bromide (CTAB) with cationic ones were used. The adsorption capacities of 205.2 mg/g for AY219, 36.5 mg/g for RB21 and 18 mg/g for DY142. The potentiometric titration and Doppler laser electrophoresis methods enable determination of sign and magnitude of charge located in both the surface and the slipping plane layers around the solid particles. The structure of electrical double layer was determined in the AST88 systems without as well as with dyes and with mixed dye + surfactant adsorbates.