1) A control sample with no iron oxide |
2) Modified sample with only yellow iron oxide |
3) Modified sample with only blue iron oxide |
4) Modified sample with only red iron oxide |
5) Modified sample with only black iron oxide |
6) Modified sample with yellow and blue iron oxides |
7) Modified sample with red and black iron oxides |
8) Modified sample with yellow, blue, red, and black, iron oxides |