Novel alternative for the purification of kaolin by plant acid extracts

Clay minerals of great purity are scarce; such is the case of kaolin. Many methods currently used for its purification damage some characteristics of industrial interest of the clay mineral, and these methods are aggressive to the environment. For this reason, in this work, the purification of kaolin was carried out using the extracts of Citrus latifolia, Citrus aurantifolia, Opuntia joconostle and Allium sativum. The clay mineral was sifted to obtain a size of ≤38 μm. The liquor obtained after the dissolution of iron was characterized by atomic absorption spectroscopy. A percentage of removal of 91·43% was obtained for C. aurantifolia, 88·76% for C. latifolia, 67·84% for O. joconostle and 62·19% for A. sativum. The clay mineral was characterized before and after iron dissolution by energy-dispersive X-ray spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Plant acid extracts are a viable alternative for the removal of iron from kaolin. The obtained iron removal percentages were higher in comparison with those obtained by other methods currently in use, making this alternative simple and eco-friendly and producing no damage to the morphology of the clay. The percentages of elimination of iron obtained by this method provide acceptable kaolin for use in industries.