Application of aqai stalks as biosorbent for the removal of Evans Blue and Vilmafix Red RR-2B dyes from aqueous solutions

Abstract

The aqai palm stalk (Euterpe oleracea) is food residue used in its natural form (AS) as biosorbent for the removal of Evans Blue (EB) and Vilmafix Red RR-2B (VR) textile dyes from aqueous solutions. The effects of pH, biosorbent dosage, and shaking time on biosorption capacities were studied. The maximum adsorption of both dyes occurred at pH 2.0. The Avrami fractional-order kinetic model provided the best fit to experimental data compared with pseudo-first-order and pseudo-second-order kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, and Sips isotherm models. For both dyes, the equilibrium data were best fitted to the Sips isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed AS biosorbent for effluent treatment.

Keywords:

• Adsorption kinetics
• Aqai stalk
• Biosorption
• Nonlinear isotherm fitting

Acknowledgments

The authors are grateful to The National Council for Scientific and Technological Development (CNPq, Brazil), The Coordination of Improvement of Higher Education Personnel (CAPES, Brazil), The Academy of Sciences for Developing World (TWAS, Italy), and the Foundation for Research Support in the State of Rio Grande do Sul (FAPERGS, Brazil) for financial support and fellowships. We are also grateful to Center of Electron Microscopy (CME-UFRGS) for the use of the SEM microscope.