Interactions between Phosphoric/Tannic Acid and Different Forms of FeOOH

Table 2

The state and color of reaction products.

Phosphoric acid/tannic acid	-FeOOH	-FeOOH	-FeOOH
3T-10P	Gray powder	Gray powder	Gray powder
3T-20P	Gray powder	Yellow powder	Less product, blue-gray
3T-30P	Less product, beige	Yellow powder	Yellow powder
5T-10P	Gray powder	Blue-gray, yellow	Blue-gray powder
5T-20P	Gray powder	Yellow powder	Blue-gray powder
5T-30P	Less product, beige	Less product, blue-gray	Yellow powder