Investigation of processes of obtaining cerium dioxide sol with polyvinyl alcohol having bioactive properties

Cerium dioxide sols are widely used in photocatalysis, catalysis, medicine and cosmetics. It is believed that sols with a CeO2 size of up to 10 nm have the most active biological properties. The method of sols preparation affects their functional properties. They are usually obtained through the stage of separating the oxide in the solid phase from the solution, which can lead to particle agglomeration, and then transferring the oxide to a colloidal solution under the action of various stabilizers. In this study, we propose the method of CeO2 sol obtaining without step of solid phase oxide separation. The stabilizer (polyvinyl alcohol (PVA)) is present at the stage of formation of weakly aggregated CeO2 nanoparticles from cerium(III) salt with an ammonia and hydrogen peroxide solution. Using IR, UV spectroscopy, viscometry and titration it was found that H2O2 eventually oxidizes Ce(III) in solution to Ce(IV) and does not oxidize PVA. The intermediate formed after the addition of ammonia solution to cerium (IV) salt has the composition Ce(OOH)(3)OH center dot nH(2)O, which is confirmed by the data of proton magnetic resonance, weight and thermal analyses. The process of CeO2 sol formation stabilized by PVA goes through the stages of Ce(OOH)(3)OH dissolution accompanying with an endothermic effect, followed by decomposition. Peroxide compounds in the solid phase are stable in air up to 90-100 degrees C. The prepared sol has the composition CeO2-PVA-ammonium nitrate, exhibit antioxidant properties, is not a nutrient medium for E. Coli and S. Aureus and is capable to form a calcium-phosphate layer on its surface from a model solution of SBF.

Automated summary

Cerium dioxide sols, widely used in various fields, can be prepared without separating the oxide from the solution. The stabilizer, PVA, plays a key role in forming weakly aggregated CeO2 nanoparticles. The prepared sol exhibits antioxidant properties and can form a calcium-phosphate layer.