Phenol sorption by organoclays having different charge characteristics

Abstract

This work attempts to elucidate how charge characteristics of clay affect the mechanistic function of the organoclay in nonionic organic compound (NOC) sorption. Organosmectites are synthesized by placing quaternary ammonium surfactants, benzyltrimethylammonium (BTMA) ion and hexadecyltrimethylammonium (HDTMA) ion, on smectites by cation exchange. Sorption isotherms for phenol on various organosmectites were measured. Results of this study indicate that the exchanged organic cations affected the sorptive behavior of smectite in some manner that appeared to be related to the size and molecular arrangement of the exchanged organic cations in the clay. The organic phases formed by HDTMA on the high-charge smectite (HCS) were more effective than that on low-charge smectite (LCS) for phenol uptake due to enhanced nonpolar interactions of the alkyl groups of HDTMA on high charge density surface. BTMA ions intercalated at low charge density smectite forms a more effective organic phase for phenol adsorption presumably due to the availability of free area between BTMA ions. Consequently, high-charge smectite should be used for preparing organoclay intercalated with organic cations with long alkyl chain and low-charge smectite should be used for preparing organoclay intercalated with organic cations with short alkyl chain. Results from this work will provide valuable information on using organoclay as a sorbent for purifying NOC contaminated water.