Biosorption of heavy metals by red algae (Palmaria Palmata)

The biosorption of heavy metals from aqueous solutions was investigated, using a cheap and abundant dry biomass of red algae P. palmata. The Freundlich, Langmuir and Brunauer Emmer and Teller (BET) models were used to describe the uptake of lead (Pb\ub2\u207a), copper (Cu\ub2\u207a), nickel (Ni\ub2\u207a), cadmium (Cd\ub2\u207a) and zinc (Zn\ub2\u207a) on P. palmata. The good fits of the Langmuir and BET models to the experimental data reflected that the sorption on P. palmata was a multi-layer sorption, in which a Langmuir equation could be applied to each layer. The highest maximum sorption capacity qmax derived from the Langmuir model was 15.17 mg g\u207b\ub9 for lead and 6.65 mg g\u207b\ub9 for copper (dry weight metal /dry weight biosorbent) at a pH of 5.5-6. The affinity of metals for P. palmata was found to decrease in the order: Pb\ub2\u207a > CO\ub2\u207a > Cu\ub2\u207a > Ni\ub2\u207a. The factors influencing copper and lead uptake were found to be contact time, pH, initial concentration and temperature. Biosorption of copper and lead was a rapid process, with 70% and 100% of the respective uptakes occurring within the first 10 minutes.NRC publication: Ye