Application of Taguchi L32 orthogonal array design to optimize copper biosorption by using Spaghnum moss

• Spaghnum sp. was used to biosorp Cu+2 ions from aqueous solutions.
• Taguchi experimental design was applied to optimize biosorption process.
• Higher is better approach was followed to calculate S/NS/N ratios.
• Thermodynamic parameters were in good accordance with Taguchi model.
• Biosorption process followed pseudo-second-order kinetic model.

In this work, Taguchi L32 experimental design was applied to optimize biosorption of Cu2+ ions by an easily available biosorbent, Spaghnum moss. With this aim, batch biosorption tests were performed to achieve targeted experimental design with five factors (concentration, pH, biosorbent dosage, temperature and agitation time) at two different levels. Optimal experimental conditions were determined by calculated signal-to-noise ratios. “Higher is better” approach was followed to calculate signal-to-noise ratios as it was aimed to obtain high metal removal efficiencies. The impact ratios of factors were determined by the model. Within the study, Cu2+ biosorption efficiencies were also predicted by using Taguchi method. Results of the model showed that experimental and predicted values were close to each other demonstrating the success of Taguchi approach. Furthermore, thermodynamic, isotherm and kinetic studies were performed to explain the biosorption mechanism. Calculated thermodynamic parameters were in good accordance with the results of Taguchi model.