ADSORPTION CHARACTERISTICS OF CHLOROFORM ON MODIFIED ZEOLITES FROM GASEOUS-PHASE AS WELL AS ITS AQUEOUS-SOLUTION

Adsorption characteristics of chloroform from its aqueous solution on Na-Y and Li-Na-Y modified by SiCl4, were measured and compared with those on Na-ZSM-5 and Na-Mordenite. No adsorption occurred on Na-Y with high hydrophilicity, while the siliceous faujasites became capable of adsorption and its amount increased with increase in the Si/Al ratio. Adsorption isotherms are of Langmuir type, suggesting that adsorption proceeds by pore filling. The adsorption amounts expressed in volume on Na-Y with high hydrophobicity corresponded to their pore volumes. Adsorption characteristics of chloroform from gaseous phase on Na-Y with different Si/Al ratio were also measured. The adsorption capability decreased with increasing Si/Al ratio. Immersional heats of zeolites into water or chloroform were measured in order to evaluate the surface affinity to both solvents. Immersional heats into water were almost constant (about 500 mJ.m(-2)) for zeolites with their Si/Al ratio below 10. The heats decreased with an increase in the Si/Al ratio above 10, then became almost constant (about 120 mJ.m(-2)) over 30 in their ratio. Heats of immersion of Na-Y series into chloroform were almost constant irrespective of their Si/Al ratio, but decreased slightly when the ratio exceeded 20. Adsorption characteristics of chloroform could be well related to immersional heats into both solvents.