Abstract

The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) by two powdered coal activated carbons was studied in aqueous solution. The modelling of the adsorption equilibrium showed that the adsorption of 2,4-D fitted a Langmuir isotherm. Adsorption was influenced by the activated carbon type, adsorbent concentration and solution characteristics. The adsorption was found to decrease with an increase in pH over the range 1.5–9. Maximum adsorption occurred at pH ≈ 2.5, which corresponds to the 2,4-D pK_a value. The amount of 2,4-D adsorbed was also found to depend on the NaCl concentration.