Equilibrium study of the adsorption of molybdenum(VI) on activated carbon
The adsorption of molybdenum(VI) onto activated carbon from aqueous solution has been investigated in the pHc range 1.0-6.5 at 25° in 1.0 mol dm-3 sodium chloride. The molybdenum concentration was varied from 5 × 10-4 to 2 × 10-2mol dm-3. Computer treatment of the distribution data in which all the relevant protonation and condensation equilibria of molybdate were taken into account, led to an adsorption model comprising the three species [HMo2O7]-, Mo(OH)6 and [HMoO4]-, of which [HMo2O7]- predominates by far. The very strong adsorption of [HMo2O7]- is attributed to its small hydration energy and an increase in the coordination number of molybdenum(VI) by bonding to basic surface oxygen atoms analogous to complex formation with e.g. oxalate. © 1988.