Activated carbon cloth as adsorbent and oxidation catalyst for the removal of amitrole from aqueous solution

Removal of amitrole from water was studied by adsorption on an activated carbon cloth and by oxidation with hydrogen peroxide using the same activated carbon cloth as catalyst. Study variables included the solution pH, ionic strength, and temperature in the adsorption process and the solution pH and the surface chemistry of the activated carbon cloth in the oxidation process. Results showed that amitrole adsorption on activated carbon cloth was not adequate to remove amitrole from water due to the high solubility and low aromaticity of the herbicide, which reduced its adsorption on the carbon. A higher amitrole removal rate was obtained with the activated carbon/H2O2 system. The best results were obtained on basic activated carbon surfaces at pH 7-10, when hydroxyl radical formation is favored, achieving the removal of 35-45% of the AMT, compared with 20-25% under the best adsorption conditions. Importantly, oxygen fixed on the carbon surface during AMT oxidation must be removed by heat treatment in order to regenerate the surface basicity of the carbon before its reutilization in another oxidation cycle.