Biosorption of copper ions from aqueous solution using Chlorella pyrenoidosa: Optimization, equilibrium and kinetics studies

The heavy metals biosorption from aqueous solution using microalgae has attracted attention, but studies related to the process of copper biosorption by C. pyrenoidosa are scarce. The present work aimed to characterize, verify thermodynamic viability and optimize the copper biosorption by C. pyrenoidosa using a Box-Behnken factorial design. The adsorbent had a particle diameter ranging from 14.13 to 123.6 mu m, with macropores of 1.868 +/- 0.337 mu m. The infrared spectra suggested a physical adsorption mechanism that was later proven by the enthalpy change (48.318 kJ.mol(-1)) and the parameters obtained from Temkin and Dubinin-Radushkevich isotherms. Furthermore, the process was best described by the Langmuir isotherm and a pseudo second order kinetics. The model optimization was achieved in order to maximize the percentage of copper removal, corresponding to 83.14% when the algae concentration was 1.28 g.L-1, 5 mg.L-1 of copper ions and pH 6.33.