关键词: 13X沸石, MCM-41, 水热合成, Cd2+离子, 吸附

Abstract: The 13X zeolite was synthesized hydrothermally by the calcined natural rocks, K-feldspar, from Jixian county, Tianjin, China. The ordered mesoporous molecular sieve material MCM-41 was synthesized by hydrothermal method using fumed silica, NaOH and CTAB. The synthesized 13X zeolite and MCM-41 samples were characterized by XRD, N2 adsorption, SEM and TEM methods. The results show that the MCM-41 has larger pore size (2~4 nm) and higher specific surface area than the microporous 13X zeolite. Moreover, the 13X zeolite and MCM-41 were used to treat Cd2+-containing wastewater. The amounts of Cd2+ adsorbed onto the 13X zeolite and MCM-41 were studied in different adsorbent amounts, pH values and mixing times. Theoretically, the adsorbed amount of Cd2+ onto MCM-41 should be much more than that of 13X-zeolite because of its higher specific surface area and larger pore size. However, it is shown that the 13X zeolite (with the pore size of about 0.7 nm) adsorbs much more Cd2+ than the MCM-41 sample in Cd2+ aqueous solution. The adsorption rate of the 13X zeolite is over 99%, and the adsorption rate is below 80% for the MCM-41. The 13X zeolite can be used for treating the wastewater containing Cd2+ more effectively than the MCM-41 mainly because of their different chemical compositions, pore structures and surface charges, and the 13X zeolite interaction with Cd2+ by ion exchange and the precipitation as well.

Key words: 13X zeolite, MCM-41, hydrothermal synthesis, Cd2+, adsorption