Effect of humic acid on adsorption of methylparaben from aqueous solutions onto commercially available granular activated carbons

The adsorption of methylparaben (MP) on Calgon carbon (F400) and Norit-type granular activated carbons (GACs) from aqueous solutions was examined. The influence of humic acid (HA) on adsorption of MP under different pH conditions was evaluated. The adsorption isotherm results are well described by Freundlich model. The MP adsorption capacity on F400 and Norit GACs was found to be of 150 mg/g. In the presence of 2.357 mg/L HA total organic carbon (TOC), the maximum MP adsorption capacity on F400 GAC at pH 7 was increased to 2.2 folds. The Norit-type GAC had a comparatively higher uptake capacity of MP than F400 GAC. The key mechanism for MP adsorption onto the F400 GAC was through the hydrogen interaction between –OH functional group of the MP molecules. The MP adsorption capacity on Norit GAC was increased from 5 to 100 mg/g at pH 7.