Table 1.

XRF analysis on the RHA before and after adsorption of Fe(II) and Mn(II) (%).

Element	Unloaded biomass	Fe(II)-loaded biomass	Mn(II)-loaded biomass
O	26.650	24.530	24.183
Na	0.040	—	—
Mg	0.301	0.090	0.057
Al	0.132	0.014	0.012
Si	29.433	27.538	27.276
P	0.511	0.054	0.054
S	0.102	0.154	0.069
Cl	0.190	0.342	0.097
K	2.123	0.338	0.290
Ca	0.942	0.061	0.048
Mn	0.183	0.187	0.293
Zn	0.011	0.002	0.003
Fe	—	0.175	0.013
Cu	—	0.003	0.004