In Situ Encapsulation of Hydrogen Peroxide in a Silica Matrix in the Presence of Divalent Metal Ions (Mg super(2+) and Ca super(2+))

• Published in: Industrial & engineering chemistry research Vol. 56; no. 9; pp. 2607 - 2614
• Main Authors: Zalluhoglu, Fulya Sudur, Dogan, Ezgi Melis, Namusuubo, Naigambi Patience, Orbey, Nese, Jahngen, Edwin
• Format: Journal Article
• Language: English
• Published: 08-03-2017
• Subjects: Hydrogels; Hydrogen peroxide; Metal ions; Precursors; Silicates; Silicon dioxide; Sodium silicates
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.7b00278

Encapsulating hydrogen peroxide (H sub(2)O sub(2)) in silica hydrogels is a simple, environmentally friendly, and cost-effective method that is easy to scale up. Sodium silicate is the most commonly used aqueous silicate in sol-gel chemistry. Previously, we studied the effects of Na super(+) and K super(+) ions in the starting silicate precursor on the structure of hydrogels and the stability of entrapped H sub(2)O sub(2). In the present study, we present the results obtained when divalent ions, Mg super(2+) and Ca super(2+), were introduced in the sol. The use of divalent metal ions resulted in hydrogel structures that are different from those previously obtained. H sub(2)O sub(2) stability increased with the addition of Mg super(2+) and Ca super(2+) ions and with decreasing pH. At low pH values, 93% of the peroxide was retained at the end of 10 days with Mg super(2+)-containing hydrogels, compared to 91% retention with Ca super(2+)-containing hydrogels, 87% retention with K super(+)-containing hydrogels, and 68% retention with a unmodified sodium silicate precursor. The results show that the structure of the hydrogels can be changed using different types and amounts of metal ions to tailor the release of H sub(2)O sub(2) for an intended application.