Adsorption of Manganese(II) from Aqueous Solution by Activated Carbon Granules

The adsorption kinetics of Mn²⁺ ions by AG-3 activated carbon granules is investigated. It is found that the pseudo–first-order Lagergren kinetic model describes manganese adsorption for only 300 min. By contrast, the pseudo–second-order model proposed by Ho and McKay describes the entire process. The role played by diffusion through the sorbent pores in limiting the rate of Mn²⁺ ion extraction is estimated by the Weber–Morris method, on the basis of the isotherms of Mn²⁺ ion adsorption by activated carbon granules. With a high degree of correlation (R² ~ 0.96–0.99), the equilibrium of Mn²⁺ ion adsorption is described by the Langmuir equation. The limiting adsorption capacity of a sorbent monolayer is calculated at various temperatures. When using the adsorptional equilibrium temperature, the thermodynamic parameters of the process are determined. The sorptional extraction of metal ions is greater at higher temperatures. The adsorption of metal ions at the carbon surface is described by means of IR spectroscopic data.