pH-dependent phase transitions in ferrofluids: A Monte Carlo simulation study using an extended DLVO model

被引：4

作者：

Paula, F. L. O. ^{[1
]}

Castro, L. L. ^{[1
]}

Cassiano, T. S. A. ^{[1
]}

dos Santos, S. G. ^{[1
]}

Gomide, G. ^{[1
]}

Depeyrot, J. ^{[1
]}

Campos, A. F. C. ^{[2
]}

机构：

[1] Univ Brasilia, Inst Phys, Complex Fluids Grp, BR-70919970 Brasilia, Brazil

[2] Univ Brasilia, Lab Environm & Appl Nanosci, Planaltina Campus, BR-73345010 Planaltina, Brazil

来源：

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS | 2023年 / 658卷

关键词：

Ferrofluids; X-DLVO theory; Surface charge density; 2-pK model; Phase transition; Monte Carlo simulation; AQUEOUS MAGNETIC LIQUIDS; NANOPARTICLES; PARTICLES; STABILIZATION; ADSORPTION; SEPARATION; DIAGRAM; FLUID; STATE;

D O I：

10.1016/j.colsurfa.2022.130578

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The present survey focuses on the pH-dependent phase behavior of acidic ferrofluids using Monte Carlo simulations. Samples based on CoFe2O4@gamma-Fe2O3 core@shell nanoparticles with five different mean sizes were investigated. The interparticle interactions were modeled employing an extended DLVO theory, which includes the anisotropic magnetic dipolar interaction. The electrostatic repulsive component considers the dependence of the surface charge density with pH and nanoparticle mean size. The simulations highlight the effect of pH on the phase behavior of the samples, where the pH increase towards neutral induces an increase in the number of agglomerates, while also reducing first-neighbor distances, especially for samples based on larger nanoparticles. The results obtained in these simulations agree with experimental observations carried out on acidic ferrofluid samples and allow a reliable characterization of the stability domains of these systems. Ultimately, the general pH-dependent phase behavior is confirmed through a detailed analysis of the results of the simulated samples.

引用

页数：8

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