Wyniki wyszukiwania - BazTech

1

Evaluation of colloidal silica obtained via the co-precipitation method using octane as an organic phase

Jesionowski T., Tepper B., Krysztafkiewicz A.

Polish Journal of Chemical Technology

|

2007

|

Vol. 9, nr 4

1-4

EN

The studies were conducted on the production of silica from emulsion systems by co-precipitation from solutions of sodium metasilicate and hydrochloric acid and octane were used as an organic medium. The obtained products were subjected to a comprehensive physicochemical analysis in order to define their dispersive and morphological properties. Particle diameters and polydispersity were determined by the NIBS (non-invasive back scattering) method while the shape and morphology of the particles were established using scanning electron microscopy (SEM). In order to determine the adsorptive properties of the obtained monodisperse silicas, isotherms of nitrogen adsorption/desorption on their surfaces were determined. Using the isotherms, also the specific surface area, the diameter and the volume of the pores were established. In order to define the hydrophilic/hydrophobic character of the products, profiles of wettability and of sedimentation in water were examined. The obtained products were well wettable with water and an increase in their weight depended on the amount of the applied surfactants. The particles of the precipitated silicas manifested a defined, spherical shape and showed a relatively low polydispersity.

2

Colloidal silicas obtained via co-precipitation method using cyclohexane as an organic phase

Tepper B., Jesionowski T., Krysztafkiewicz A.

Physicochemical Problems of Mineral Processing

|

2007

|

Vol. 41

195-203

EN

The process of obtaining colloidal silicas from the emulsion systems with the use of cyclohexane as the organic phase has been studied and the products obtained have been also characterised. The emulsion systems made of water solutions of sodium metasilicate and hydrochloric acid or alternatively sulfuric acid have been used. Non-ionic surfactants have been used as emulsifiers, while a homogeniser has been a dispersing tool. The optimum compositions of the emulsion systems and the optimum parameters of silicas precipitation have been established. The dispersion character of the colloids obtained has been examined and the shapes, size and morphology of the SiO2 particles formed have been analysed (including a tendency to agglomerate formation and polydispersity).

PL

W pracy prowadzono badania ukierunkowane na otrzymywanie cząstek krzemionki z układów emulsyjnych z zastosowaniem cykloheksanu jako fazy organicznej. Badania prowadzono z wodnymi roztworami metakrzemianu sodu i kwasu solnego lub kwasu siarkowego. Stosowanymi emulgatorami były niejonowe związki powierzchniowo czynne. Jako ośrodek dyspergujący zastosowano homogenizator. Ustalono optymalne składy emulsji i parametry strącania krzemionek. Oceniono charakter dyspersyjny otrzymanych koloidów oraz zbadano kształty i morfologię formowanych cząstek SiO2 (m.in. tendencję do tworzenia aglomeratów, polidyspersyjność). Podstawowym celem badań było otrzymanie wysoko zdyspergowanych krzemionek o sferycznych cząstkach i monodyspersyjnej naturze w reakcji strącania z układów emulsyjnych zawierających wodne roztwory metakrzemianu sodu oraz kwasu odpowiednio solnego bądź siarkowego(VI).

3

Preparation of spherical silicas in aliphatic hydrocarbons systems

Tepper B., Jesionowski T., Krysztafkiewicz A.

Polish Journal of Chemical Technology

|

2006

|

Vol. 8, nr 3

48-50

EN

Studies were performed on a group of highly dispersed silicas, formed using precipitation technique. The silicas were precipitated in an emulsion system from sodium metasilicate solution, using hydrochloric acid supplemented with emulsifiers and an appropriate amount of organic phase (cyclohexane, hexane, heptane, octane). The dispersion was induced using a homogenizer. The studies permitted to obtain SiO2 particles of optimum particle diameter and a defined spherical shape. For the obtained products, also the profiles of wettability and sedimentation in water were determined.