Biosorption of copper and zinc by Cymodocea nodosa.

The adsorption of the two metal ions Cu and Zn in a single-component system by Cymodocea nodosa, a brown alga, under different pH conditions was investigated. The solution pH significantly affected the exhibited uptake, being maximum at a pH value of 4.5. Multi-component mixture biosorption in aqueous solutions is also reported. A comparison was made between the single-component saturation uptake and the multi-component uptakes. To evaluate the two-metal sorption system performance, simple isotherm curves had to be replaced by three-dimensional sorption isotherm surfaces. In order to describe the isotherm surfaces mathematically, three Langmuir-type models were evaluated. The isotherms indicate a competitive uptake with Cu being preferentially adsorbed. In addition, different tests were carried out to compare the process efficiency working continuously in small columns.