Biosorption of lead(II) and copper(II) from stormwater by brown seaweed Sargassum sp.: Batch and column studies

This study evaluated the potential use of brown seaweed Sargassum sp to sequester lead and copper (Pb(II) and Cu(II)) from urban runoff based on batch as well as column experiments. The equilibrium data exhibited Langmuir isotherms. The adsorption capacity of this seaweed was found to be 196.1 mg g⁻¹ and 84.0 mg g⁻¹ for Pb(II) and Cu(II), respectively, which are in good agreement with those values obtained for the aqueous solution (188.6 mg g⁻¹ for Pb(II) and 86.9 mg g⁻¹ for Cu(II)). The functional group analysis of the seaweed using FTIR demonstrated that the carboxyl functional groups are mainly responsible for biosorption. The cation exchange capacity of the biosorbent was 2.25 meq/g. This observation suggested that ion exchange mechanism is predominantly responsible for the metal ion uptake. The column study showed that the highest bed height and the lowest flow rate result in a substantial enhancement of the metals uptake with the biosorption uptake capacities being 264.3 mg Pb(II) g⁻¹ and 86.0 mg Cu(II) g⁻¹. In the binary system, the biosorption capacity was observed to be 208.7 mg Pb(II) g⁻¹ and 61.0 mg Cu(II) g⁻¹. The predicted breakthrough curves by the Thomas adsorption model gave a good fit of the experimental data with r² ranging from 0.92 to 0.99.