Tổng hợp zeolite NaA/NaX từ tro trấu không nung bằng phương pháp thủy nhiệt

Abstract

The development of technology and science as well as the growth of population cause the seriously polluted environment, especially the pollution of heavy metals. Synthesis of zeolites and their applications in adsorption, solid catalysts and ion exchange have been concerned. In this study, zeolite was synthesized from the precursor of sodium silicate originated from rice husk ash (RHA) without calcination by using hydrothermal method. The percentage of silica recovery from RHA without calcination was reached at about 90% when the optimal reaction conditions were at the ratio of RHA to NaOH = 1:10 (g/mL), the concentration of NaOH of 5 M, the reaction time of 3 h, the stirring speed of 300 rpm and the reaction temperature of 90oC. The parameters affected zeolite NaA/NaX synthesis such as ratio of SiO2 to Al2O3, the reaction temperature T1 (oC), reaction time t1 (h) and aging time t2 (h) were investigated. The results showed that crystal percentage of zeolite NaA/NaX was obtained at 52,7% during 4 h, 100oC, aging time of 12 h, ratio of Al2O3 to SiO2 of 2,5 and the ratio of Al:NaOH = 1:2 Although the crystal percentage of zeolite NaA/NaX in this study was not as high as that of other published researches, the in-situ synthesis used RHA without calcination and recovery of silica during the synthesis of zeolite NaA/NaX. Therefore, the synthesized process is environmental friendly as well as time and energy savings.