Fig. 3 Sorption–desorption isotherms for am-Fe(OH)3 in 0.01 M NaCl at pH 5.0, showing natural logarithm of Se sorbed as a function of the logarithm of the equilibrium Se concentration: (a) selenate and (b) selenite. The solid concentration was 4.0 g L-1. Desorption was performed following centrifugation of suspensions after a 24-h equilibration for sorption. Each desorption process involved a 24-h equilibration in 0.01 M NaCl at pH 5.0 followed by centrifugation. Numbers in parantheses represent initial selenate concentrations of 4, 6, 8, and 10 mM
