An Analysis of the Formation Mechanism of Geopolymer Made from Obsidian Mineral and Its Potential Application as a Slow Release Fertilizer

Abstract

Geopolymer is the inorganic polymer commonly made from kaolin, clay, fly ash, or slag. Obsidian mineral is the new candidate material for geopolymer formation. Obsidian is a material that used in ancient eras, but nowadays, this function has been replaced by various metals. Obsidian consists of cristobalite and sodium aluminum silicate. Obsidian was reacted with disodium metasilicate (Na2SiO3) to form a mineral-based geopolymer. An analysis of the formation mechanism through X-ray diffraction and Fourier transform infrared spectroscopy showed that the geopolymer formation from obsidian takes place in two stages. The first stage is the formation of a geopolymer from a reaction among cristobalite, disodium metasilicate, and amorphous aluminum silicates, whereas the second stage is the incorporation of crystalline sodium aluminum silicate into the former geopolymer structure. Geopolymer is usually utilized to form brick or concrete for an infrastructure purpose, but in this research, the geopolymer is proposed to control the release rate of elements from fertilizer. The result of potassium release test shows that the geopolymer has a slow-release property.

Novel binder material in geopolymer mortar production: Obsidian stone powder

“…Obsidian is a rock mineral that can be used as cutting and driller tools such as knives and spears in activities like hunting, war, and protection from predators since ancient times when people lived in caves. [37][38][39] Also, obsidian, a natural stone, known as volcanic glass, is formed by the rapid melting of molten magma. At this point, obsidian, together with its high Si source, shows an amorphous glassy structure, suggesting that it may have high mechanical properties.…”

“…Obsidian is a rock mineral that can be used as cutting and driller tools such as knives and spears in activities like hunting, war, and protection from predators since ancient times when people lived in caves 37–39 . Also, obsidian, a natural stone, known as volcanic glass, is formed by the rapid melting of molten magma.…”

Diatomite Geopolymer Carrying Potassium Poly(dihydroxymethyl)urea Phosphate for Efficient Nutrient Management

“…According to reported work, although Dia is widely used in agricultural materials, ignores its surface-rich Si−OH, 26 as Dia can be modified into geopolymers. As we know, the geopolymer, an inorganic polymer from minerals or silicates, 27 could be used as an emerging porous material, and its advantages are ecologically friendly and excellent performance. 28,29 Herein, we selected Dia as a natural carrier to prepare diatomite geopolymer (DG) by alkaline excitation.…”