THE DETERMINATION OF ACTIVE-FILTER AID ADSORPTION SITES BY TEMPERATURE-PROGRAMMED DESORPTION

Temperature programmed desorption (TPD) was used to evaluate the activ e sites of several filter aids that have been promoted for use by the deep frying industry: activated carbon, aluminas, bleaching earths, di atomaceous earth, silica and synthetic magnesium silicate. TPD analysi s determines both the total surface concentration of the active sites and the details of their intensity distribution. A correlation analysi s was made between the adsorbents' oil treatment performance and the o bserved acidic/basic sites. For some of the adsorbents, the adsorption of free fatty acids and the percent change in the color of the oil wa s shown to relate to the total basic sites and acid sites, respectivel y. The study also showed that other factors might affect these adsorpt ivities.