Synthesis of a loess-based 4A molecular sieve and its application performance in detergents

Herein, activated loess was obtained via acidification and alkalisation and was mixed with sodium hydroxide, water and aluminium sulphate to prepare a loess-based 4A molecular sieve using the hydrothermal conversion method. The sieve performance was characterised, and the effect of raw materials and reaction conditions on the sieve was investigated. Results showed that it exhibits different microstructures according to its crystallinity and impurity content. Moreover, the amount of sodium hydroxide and the reaction temperature had a substantial influence on its synthesis, while water and the reaction time exhibited less influence. The synthesis method was optimal when the reaction temperature was 90 C-degrees, reaction time was 4 h, pH was similar to 13 and the mixture ratio was SiO2:Al2O3:H2O:NaOH = 1.9:1:213:12. Finally, the application performance of the molecular sieve in detergents was studied. The sieve showed complete adherence to the National Standard of Detergent in China (GB/T 1767-2003).