Interaction between chromate and zeolite under the influence of sorbed cationic surfactant

摘要

Zeolite aggregates with particle sizes of ＜0.4, 0.4-1.4, 1.4-2.4, and 3.6-4.8 mm were studied for its interaction with chromate under the influence of sorbed cationic surfactant. Batch results showed that raw zeolite had no affinity toward chromate. However, in the presence of sorbed surfactant the chromate sorption capacity on zeolite increased with an increase in surfactant loading. Chromate sorption capacity reached 330,840, 1230, and 1580 mg/kg for the zeolite with particle sizes of 3.6 - 4.8, 1.4-2.4, 0.4-1.4 and ＜ 0.4 mm with maximum surfactant loading, respectively. The enhanced chromate sorption was attributed to the surface charge reversal by surfactant bilayer formation on zeolite. Column tests with an input chromate concentration of 11 mg/L revealed that zeolite had no retardation of chromate at all. In contrast, the observed chromate retardation factor of zeolite in the presence of sorbed surfactant increased to 80 for the columns packed with 1.4-2.4 mm zeolite with maximum surfactant bilayer loading.