ADSOLUBILIZATION AND STABILITY CHARACTERISTICS OF HYDROCARBON AGGREGATES CHEMICALLY BONDED TO POROUS SILICA

The desorption of surfactant may be a problem in the development of ad micellar catalysis for organic synthesis or for wastewater cleanup. Th e formation of hydrocarbon aggregates chemically bonded to mineral oxi de surfaces has been investigated to solve this problem. In this study , octadecyltricklorosilane (ODS) was chemically bonded with silanol gr oups of a silica surface. The adsolubilization capabilities and stabil ity of the bonded ODS were then studied and compared to those of physi cally adsorbed aggregates of cetyltrimethylammonium bromide (CTAB). Th e adsorption of ODS increases with increasing ODS concentration in the bulk phase and reaches a constant value when the equilibrium ODS conc entration is higher than 17 000 mu M. The maximum ODS adsorption of 34 0 mu mol/g is slightly higher than that of CTAB (300 mu mol/g). The cr itical micelle concentration of CTAB is approximately 3000 mu M. The a dsolubilization of two organic substrates, trichloroethylene (TCE) and phenol, was also measured. The adsolubilization of TCE was similar in CTAB and bonded ODS, while the phenol adsolubilized to a greater exte nt in CTAB than in ODS. The bonded ODS was stable under agitation up t o 310 rpm and temperatures below 40 degrees C. The pH value has very l ittle effect on ODS debonding. The rate of oxidation of ODS by ozone i ncreases with increasing ozone concentration, but pH has no effect on ODS oxidation.