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The lead removal from the wastewater system with Kraft lignin was investigated in this study. The Kraft lignin was characterized through NMR analysis that ion-exchanging functional groups such as phenolic hydroxyl groups and carboxyl groups were observed. The aromatic structure in considered as another adsorption functional group due to its electron quenching ability. Due to the existence of multiple functional groups, a non-ideal adsorption isotherm model was proposed considering the different interaction between Pb(II) and different functional groups. Each two adjacent function groups were grouped up as one active site that is able to adsorb one lead cation. Experimental data performed at different pH and temperature were interpolated with the proposed model. Based on the parameters obtained from the modeling, it was concluded that the ionic bindings of Pb(II) on PhOH and –COOH were not impacted by the changes of temperature. However, the interaction between Pb(II) and aromatic rings was significantly weakened with the increase of temperature.