Quantitative arrangement of Si/Al ratio of natural zeolite using acid treatment

Acid treatment is an effective way to arrange SiO2/Al2O3 ratio of natural zeolite. However, limited researches have been done on quantitative regulation of SiO2/Al2O3 ratio of natural zeolite. In this paper, an orthogonal test was designed to optimize the acid treated conditions. Acid concentration, treated time and temperature were then employed to quantitatively arrange the SiO2/Al2O3 ratio of natural zeolite, respectively. The results showed that the primary and secondary factors of acid treatment were acid treated time, acid concentration and acid treated temperature, respectively. The extent of dealumination of zeolite and its corresponding SiO2/Al2O3 ratio of natural zeolite could rise up to 98.4% and 372.7 under the optimized condition for 48 h, 8M and 70 degrees C, respectively. Acid concentration, treated time and temperature could effective quantitatively arrange the extent of dealumination of zeolite and SiO2/Al2O3 ratio of natural zeolite. The as-prepared acid treated zeolites with different SiO2/Al2O3 ratio regulated by acid concentration had higher specific surface area, micropore volume, silanol group content and hydrophobicity than those for the natural zeolite.