Adsorption characteristics of cu (ii) onto blue green algae - modeling and applicability of various isotherms

Adsorption of Cu (II) onto blue green algae (BGA) is studied in this investigation under batch mode at room temperature. It is aimed to determine the maximum adsorption capacity of BGA by varying the initial metal ion concentration from 25ppm to 250ppm under the optimum pH of 6, 2g of biomass loading, 120 rpm of agitation rate and 24 hrs of contact time. To identify the adsorption mechanism and to establish the characteristic parameters for process design, the experimental data are tested with various isotherm models.  In this context; One, Two, Three, Four and Five parameter isotherm models are analysed with experimental data.  The experimental data infers that the isotherm is L shape which indicates, no strong competition between solvent and Cu (II) to occupy the active sites of BGA. Also it indicates that the BGA has a limited sorption capacity for adsorption of Cu (II). Through modeling studies, it is inferred that the Fritz-Schlunder-V isotherm model is highly significant followed by Freundlich and Langmuir model in establishing the mechanism of adsorption of Cu (II) under the conditions employed in this investigation.  The q max obtained by Fritz-Schlunder-V model indicates its relevance more precisely for adsorption of Cu (II) onto BGA (isotherm q max = 34.55 mg/g and experimental q max = 35.79 mg/g). The concurrence of experimental data with Vieth-Sladek isotherm model indicates that the adsorption of Cu (II) onto BGA is influenced both by van der Waals and ionic forces for the entire range of concentration employed in this investigation.