Fig. 2. (a) Amounts of DNA adsorbed on Al– or Fe–M–HA as a function of the cation-exchange capacity (CEC) of the complexes. Data were obtained by interpolating the best-fitting Langmuir, Freundlich, or linear equations, as reported in Table 3. (b) Percentage of DNA adsorbed on Al– or Fe–M–HA as a function of the organic C content of the complexes.