Studies On The Crystal Structure Stability Of Al-δ-Na₂Si₂O₅ And Ca～(2+), Mg～(2+) Ion Binding Mechanism Of α,β-Na₂Si₂O₅

Layered sodium disilicates(Na₂Si₂O₅) have good ion binding capacity, finealkaline buffer capacity, cooperation with other composition in good method,harmony with enviroment and so on. They were considered as efficientnon-phosphate detergent builder with excellent prospect. Al-δ-Na₂Si₂O₅ is thesame crystal ramification ofδ-Na₂Si₂O₅. Al-δ-Na₂Si₂O₅ has high frameworkstability in hot water, it also has better Ca²⁺ and Mg²⁺ binding capacity, alkalinebuffer capacity and cleaning capacity. Therefore it met the requirements of thespray drying process and solved important technology problem in applicationfield of Na₂Si₂O₅. For further review the crystal structure stability ofAl-δ-Na₂Si₂O₅ and provide basic technical parameter for industrial application.This paper mainly investigated interactional effect of surfactants and inorganicchemicals (main components in detergents) on crystal structure stability ofAl-δ-Na₂Si₂O₅. Ion binding capacity ofα-Na₂Si₂O₅ andβ-Na₂Si₂O₅ was investigated by phase transformation and the residual solid yield in differentsolution (distilled water, tap water, water with Ca²⁺, water with Mg²⁺).According to basic component of detergents, this paper investigated effectof surfactants (LAS, AOS, K12 and AEO-9) on Al-δ-Na₂Si₂O₅ under thecondition near detergent spray drying process. Typical samples werecharacterized by XRD, TG, FT-IR and Ca²⁺ ion binding capacity. Theexperimental results showed that Al-δ-Na₂Si₂O₅ might keep asδphase afterinteracted with LAS. LAS had better protective function to Al-δ-Na₂Si₂O₅.Al-δ-Na₂Si₂O₅ had changed to a mixed phase ofδphase and kanemite afterinteracted with K12 (or AEO-9, AOS). K12 also had better protective functionto the crystal structure stability of Al-δ-Na₂Si₂O₅ though it had changed to amixed phase. AEO-9 had not obviously protective function to the crystalstructure stability of Al-δ-Na₂Si₂O₅. But AOS had destructive function to crystalstructure of Al-δ-Na₂Si₂O₅.According to basic component of detergents, this paper investigated effectof inorganic chemicals on the crystal structure stability of Al-δ-Na₂Si₂O₅.Typical samples were characterized by XRD, TG, FT-IR and Ca²⁺ ion bindingcapacity. The experimental results showed that Al-δ-Na₂Si₂O₅ had changed to amixed phase ofδphase and kanemite after marinating with inorganic chemicals.Na₂SO₄, NaCl and Na₂CO₃ have definite protective function to the crystalstructure stability of Al-δ-Na₂Si₂O₅, NaCl had better protective function toAl-δ-Na₂Si₂O₅ than Na₂SO₄. Water glass had protective function to crystal structure of Al-δ-Na₂Si₂O₅ at m_H2O/m_solid＜1. But water glass had negative effecton the stability of Al-δ-Na₂Si₂O₅ at m_H2O/m_solid＞1.To investigate the mechanism of cation binding, the phase change andresidual solid yield after the hydrolysis ofα,β-Na₂Si₂O₅ in different watersolution (distilled water, tap water, water with Ca²⁺ and water with Mg²⁺) werecharacterized by XRD, FT-IR and SEM. The experimental data showed that apart ofβ-Na₂Si₂O₅ transformed into kanemite with ion exchange ability in tapwater, the other part ofβ-Na₂Si₂O₅ dissolved in water and formed precipitationthrough bonding with Ca²⁺ and Mg²⁺. The data proved that ion bindingmechanism ofβ-Na₂Si₂O₅ has the characteristic of ion exchange and sediment.In distilled water, a part ofα-Na₂Si₂O₅ transformed into an unknown phase,which was similar to other layered material, the other part ofα-Na₂Si₂O₅dissolved in water and formed precipitation through bonding with Ca²⁺ and Mg²⁺.The data proved that ion binding mechanism ofα-Na₂Si₂O₅ has the characteristicof ion exchange and sediment.