TY - JOUR

T1 - Charged colloidal SiO2 dispersions in water and chloroform: Synthesis, properties and perspectives in dyes adsorption

AU - Shaparenko, Nikita O.

AU - Demidova, Marina G.

AU - Erlygina, Lyubov A.

AU - Bulavchenko, Alexander I.

N1 - This work was financially supported by the Russian Foundation for Basic Research , Project № 20-03-00017 and by the Ministry of Science and Higher Education of the Russian Federation , Project № 121031700315-2 .

PY - 2023/7/20

Y1 - 2023/7/20

N2 - The paper proposes a new method for the synthesis of ultradispersed amorphous SiO2 powders in the reverse emulsions stabilized by sodium bis-(2-ethylhexyl) sulfosuccinate (AOT). Colloidal dispersions of the powders were obtained by ultrasonication in water and chloroform. The number average effective hydrodynamic diameter of particles in the sols was 90 and 200 nm, and ζ-potential was − 68 ± 3 and 52 ± 7 mV for water and chloroform, respectively. Accountable for charge formation and transformation are the AOT molecules that were adsorbed on the SiO2 surface during the synthesis in АОТ emulsions. In water, АОТ– ions serve as the potential-determining ones, while Na+ ions act as the counterions that form the diffusion part of the electrical double layer. With a decrease in the solvent polarity, Na+ ions become the potential-determining ones, and АОТ– ions – the counterions. Thus, the АОТ molecules embedded into the hybrid SiO2 @ АОТ particle during the synthesis are a certain switch key of the particle surface potential. The transformation of the surface charge in dependence on polarity of the organic solvent makes it possible to apply the synthesized powders both as the cation- and anion-exchange sorbents for the recovery of dyes from aqueous and non-aqueous media. In terms of fundamental advances, the novelty of our work consists in extending the ion-exchange sorption mechanism of ionic dyes to the media with a low dielectric constant.

AB - The paper proposes a new method for the synthesis of ultradispersed amorphous SiO2 powders in the reverse emulsions stabilized by sodium bis-(2-ethylhexyl) sulfosuccinate (AOT). Colloidal dispersions of the powders were obtained by ultrasonication in water and chloroform. The number average effective hydrodynamic diameter of particles in the sols was 90 and 200 nm, and ζ-potential was − 68 ± 3 and 52 ± 7 mV for water and chloroform, respectively. Accountable for charge formation and transformation are the AOT molecules that were adsorbed on the SiO2 surface during the synthesis in АОТ emulsions. In water, АОТ– ions serve as the potential-determining ones, while Na+ ions act as the counterions that form the diffusion part of the electrical double layer. With a decrease in the solvent polarity, Na+ ions become the potential-determining ones, and АОТ– ions – the counterions. Thus, the АОТ molecules embedded into the hybrid SiO2 @ АОТ particle during the synthesis are a certain switch key of the particle surface potential. The transformation of the surface charge in dependence on polarity of the organic solvent makes it possible to apply the synthesized powders both as the cation- and anion-exchange sorbents for the recovery of dyes from aqueous and non-aqueous media. In terms of fundamental advances, the novelty of our work consists in extending the ion-exchange sorption mechanism of ionic dyes to the media with a low dielectric constant.

KW - Adsorption

KW - Dyes

KW - Electrokinetic potential

KW - Silica nanoparticles

KW - Sols

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85153318105&origin=inward&txGid=93288ecfc57e4b6dd4b4136d2c253e49

UR - https://www.mendeley.com/catalogue/1b79345b-bc2e-37e1-a1a4-3b446f4cdc71/

U2 - 10.1016/j.colsurfa.2023.131505

DO - 10.1016/j.colsurfa.2023.131505

M3 - Article

VL - 669

JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects

JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects

SN - 0927-7757

M1 - 131505

ER -