Differences in the removal mechanisms of Undaria pinnatifida and Phragmites australis as biomaterials for lead removal.

This study offers the opportunity to utilize Undaria pinnatifida and Phragmites australis to remove lead from water in permeable reactive barrier (PRB) technology. Its efficacy was tested using batch experiments and PRB column systems. From the batch experiment results, a higher adsorption capacity was observed for Undaria pinnatifida. Nevertheless, Phragmites australis in the column system efficiently removed lead and the breakthrough occurred at the same time for both biomaterials. To dissipate this difference, a sequential extraction for metal speciation analysis was used for both columns. The results have shown that each biomaterial has a dominant mechanism. Phragmites australis removed lead by physical adsorption, whereas Undaria pinnatifida showed a higher tendency to bind lead due to organic matter, primary and secondary minerals.

Lead removal efficiency using biosorbents as alternative materials for permeable reactive barriers.

As alternative materials for heavy metal removal, this study investigated biosorbents to determine their suitability for permeable reactive barriers. The lead removal efficiencies of brown seaweed (Undaria pinnatifida) and reed (Phragmites australis) were determined under different conditions (batch and column system). The experimental results for these biomaterials fitted the Langmuir isotherm with high correlation values. It was verified that the influence of temperature on affinity was higher than that on adsorption capacity. While the lead removal efficiency of U. pinnatifida was higher than of P. australis in the batch experiments, lead removal efficiency decreased for both materials at approximately the same time in the column experiments. This indicates that the dominance of the chemical and physical adsorption mechanisms could result in differences in these systems.