Synthesis and characterization of mesoporous silica-coated magnetite containing cetyltrimethylammonium bromide and evaluation on the adsorption of sodium dodecylbenzenesulfonate

• Published in: Applied surface science Vol. 420; pp. 954 - 962
• Main Authors: Dorigon, Larissa, Ruiz de Almeida da Frota, Juan Pablo, Kreutz, Juliana Cristina, Mello Giona, Renata, Pereira Moisés, Murilo, Bail, Alesandro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.10.2017
• Subjects: Brönsted acidity; Magnetite; Mesoporous-silica; Physisorption; Sodium dodecylbenzenesulfonate; Brönsted acidity; Magnetite; Physisorption; Mesoporous-silica; Sodium dodecylbenzenesulfonate
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2017.05.249

•An unusual core-shell structure formed by silica-coated magnetite was obtained.•Brönsted acidity was notably changed and discussed in terms of Tanabe’s postulates.•CTAB incomplete monolayer allowed hydrophobic interaction with the SDBS molecule.•High accessibility to the adsorption sites made a fast process possible. Silica-coated magnetite (Mag-Sil) was prepared by the co-precipitation method using sodium metasilicate under an inert atmosphere and a fine pH control. Cetyltrimethylammonium bromide (CTAB) was adsorbed onto Mag-Sil aiming at decreasing the natural hydrophilicity of the silica surface, allowing the study of the hydrophobic interaction with sodium dodecylbenzenesulfonate (SDBS) to be carried out. Mag-Sil presented low surface Brönsted acidity once the pH at the point of zero charge was 7.5. The synthesized materials were characterized by X-ray diffraction (XRD), nitrogen physisorption analysis, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) and transmission electron microscopy (TEM). Moreover, results were discussed in terms of CTAB concentration and arrangement onto the Mag-Sil surface based on two-step and four-region models for surfactant adsorption.