A novel solid-phase activization approach to activate kaolinite-rich soil for LTA zeolite synthesis

This study introduces a novel and green solid-phase activization technology, which could significantly enhance the chemical reactivity of Si and Al species within kaolinite for zeolite synthesis. Based on this technology, a cost-free kaolinite-rich soil is successfully transformed into A-type zeolite (LTA), a famous and highly productive commercial zeolite. Specifically, solid-phase activization only comprises a green solid-phase ageing step at room temperature and a straightforward heating step at 100°C, showing a progressive activization characteristic. Firstly, the aluminosilicates are fully encapsulated and eroded by the deliquescent NaOH colloids during solid-phase ageing process, occurring preliminary depolymerization. Then upon heating operation, the depolymerization strength of aluminosilicates would be dramatically enhanced, transforming most original Q 3 Si and Al VI species within the soil into Q 0 , Q 1 Si, and Al IV species that are highly desired for zeolite synthesis. Finally, through conventional hydrothermal reaction, the activizated soils could be seamlessly converted into LTA. Compared to the current activization technologies, solid-phase activization exerts superior advantages in terms of activization efficacy, NaOH consumption, energy expenditure, and equipment requirements. Overall, this work shows a novel activization approach for greener aluminosilicate depolymerization and cost-effective LTA synthesis. More remarkably, it significantly broadens the diversity and source options of Si and Al raw materials for zeolite preparation, profoundly enhancing the application potential of silica-alumina minerals within soil and fostering a vast horizon for industries reliant on activizated Si and Al species.