Synthesis, Structural, and Adsorption Characteristics of γ-Fe2O3/SiO2 Composite

The γ-Fe2O3/SiO2 composite is synthesized by coprecipitation of the magnetic carrier γ-Fe2O3 (specific surface area S = 17 m2/g, pore volume V = 0.51 cm3/g) and silicon dioxide from a solution of sodium-liquid glass. The influence of the synthesis conditions (SiO2 content, temperature, introduction of electrolyte into reaction mixture) on the structural and adsorption characteristics of the resulting composites is studied. Coprecipitation in the presence of electrolyte (5% NaCl) makes it possible to obtain the most highly porous composites. At SiO2 content from 20 to 50%, S is from 70 to 150 m2/g, V is from 0.74 to 0.89 cm3/g. These composites have a large adsorption capacity for test substances: a main dye, methylene blue, and an enzyme, cytochrome C. The capacity of these composites on dye (15–40 mg/g) is approximately 10–30 times larger that of the initial iron oxide (1.2 mg/g), and on enzyme (130–280 mg/g) 3–6 times greater than the capacity of iron oxide (45 mg/g). Such composites can be used as magnetic sorbents to for purification, concentration or immobilization of water-soluble organic substances and biopolymers.