TẨY TRẮNG CAO LANH BẰNG OXALIC ACID VỚI SỰ HỖ TRỢ CỦA SIÊU ÂM

Tóm tắt

The bleaching process of kaolin mined in Lam Dong province, Vietnam, was carried out by the reaction
between kaolin mineral and oxalic acid to remove iron in the raw material with the help of temperature and
ultrasound. CIE L*a*b* colorimetric method was used to evaluate the whiteness of kaolin samples before
and after treatment. XRF, XRD, FTIR, and SEM analyses were performed to assess the phase composition
and structural morphology. The results showed that this process could remove 96.5% of the Fe2O3 content in
the original kaolin sample and improved the whiteness of the kaolin sample from 63.5% to 96.3% on a scale
of 100% being the whitest, bringing the application value of kaolin to manufacture high-end ceramic
products. Bleaching kaolin only removed the unwanted component, the iron-containing mineral phase,
without affecting the main mineral phases presented in the original kaolin raw material sample.