A visual demonstration of removal of methylene blue by the
biochar/c-Fe2O3 composite was conducted by mixing 0.1 g biochar/
c-Fe2O3 with 50 ml methylene blue aqueous solution of
5 ppm in the vessel. The vessel was shaken in the mechanical shaker
for 4 h at room temperature to determine whether the adsorbent
could reduce the color of the solution.