Zeolite is the general term of Zeolite minerals families, an aqueous alkali-metal or alkaline-earth metal aluminum silicate mineral, which was first discovered in 1756 in Europe。 Swedish mineralogist Cronstedt found one natural aluminosilicate mineral boiling during burning, and hence name it zeolite which in Greek means boiling (Zeo) stone (lithos)。
Zeolite is the silicon, aluminum, oxygen composed tetrahedra, wherein the silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron consists the unlimited expanded three-dimensional structure.
In the tetrahedral structure of the zeolite, the negative charge caused by the replacement from silicon ions to aluminum ions will be balanced by sodium ions, potassium ions, calcium ions and magnesium ions, which contributes to the strong adsorption and ion exchange capacity of zeolite.
Due to the unique structure of the zeolite, it can increase the adsorption capacity of the ammonium ions, potassium ions and others in the soil, reduce nutrient loss, improve fertilizer use rate when applied to the soil。 Zeolite will adsorb heavy metals, passivate the heavy metal ions in the soil, and reduce its impact on organism。
Zeolite is filled with pores and channels, which is much more complicated than the hive with 1 cubic micrometer having one million pores and channels. If compared zeolite to the hotel, then there are one million rooms in this 1 cubic micrometer super hotel, and this hotel can automatically open the door or shut the door of the rooms according to different sex, height, weight, hobbies of the guests (molecules and ions), which will neither let the fat guest go to the room of the thin guest, nor the tall guest share the same room with the short guest, and makes zeolite the unique role of molecular sieve.
With the unique structure, zeolite has big internal specific surface area of 355~1000m2 /gram, which makes it very strong adsorption capacity to ions。 The channels of zeolite shares the similar fixed size, pore size of 0。3 ~ 1。0nm, which can adsorb those with smaller diameter, and exclude those with larger diameter which endows it the proprietary of selective adsorption to ions and molecules。 This selective ion exchange properties of zeolite is one of the theoretical basis for soil improvement。
Currently It has been discovered 43 species of the zeolite in the world and more common species are clinoptilolite, mordenite, analcite, chabazite, heulandite, wherein clinoptilolite, mordenite are of more commercial applications。