Acid-leaching and consequent pore structure and bleaching capacity modifications of egyptian clays

Adsorption of Gossypol from Cottonseed Oil on Oxides

“…• C (12,13,18,19). There are discrepancies about the respective influence of the SiO 2 and Al 2 O 3 contents of adsorbents and their efficiency (14,15,18,19).…”

“…9). Zaki et al (18) found an optimum pore size of 10 to 12 nm for adsorption of pigments by Egyptian clays from cottonseed oil. The data presented above show that the optimum pore size is determined by the surface area accessible to gossypol, which is the surface area developed by pores larger than about 3 nm.…”

“…There are discrepancies about the respective influence of the SiO 2 and Al 2 O 3 contents of adsorbents and their efficiency (14,15,18,19). Acid activation of clay generally leads to an improvement of bleaching capacity (17,18,21).…”

“…Acid activation of clay generally leads to an improvement of bleaching capacity (17,18,21). However, few authors (17)(18)(19)(20) characterized the texture of the adsorbents; Zaki et al (18) found that the bleaching capacity of activated natural clays varied with pore size and an optimum was observed at a pore diameter of 10 to 12 nm.…”

Effect of Alumina Content and Surface Area of Acid‐Activated Kaolin on Bleaching of Rice Bran Oil

“…Results from SEM/EDX analysis of the Ranong kaolin in previous studies indicated that hot sulfuric or oxalic acid treatments of the ground sample resulted in the formation of products with globular morphology [25]. Upon acid activation, specific surface area, porosity and number of acid centers are also changed in the activated clay due to the leaching of alumina and other mineral impurities [28,[32][33][34][35][36][37][38][39][40]. The increase in surface area and surface acidity of the activated clays largely affect their bleaching properties.…”