Biosorption of phenolic compounds by the brown alga Sargassum muticum

Abstract

[Abstract] Phenol, 2-chlorophenol (2-CP), and 4-chlorophenol (4-CP) biosorption on Sargassum muticum, an invasive macroalga in Europe, has been investigated. The efficiency of this biosorbent was studied measuring the equilibrium uptake using the batch technique. A chemical pre-treatment with CaCl2 has been employed in this study in order to improve the stability as well as the sorption capacity of the algal biomass. The influence of pH on the equilibrium binding and the effect of the algal dose were evaluated. The experimental data at pH=1 have been analysed using Langmuir and Freundlich isotherms. It was found that the maximum sorption capacity of chlorophenols, qmax=251 mg g-1 for 4-CP and qmax=79 mg g-1 for 2-CP, as well as that of a binary mixture of both chlorophenols, qmax=108 mg g-1, is much higher than that of phenol, qmax=4.6 mg g-1. Moreover, sorption kinetics have been performed and it was observed that the equilibrium was reached in less than 10 h. Kinetic data have been fitted to the first order Lagergren model, from which the rate constant and the sorption capacity were determined. Finally, biosorption of the phenolic compounds examined in the present study on Sargassum muticum biomass was observed to be correlated with the octanol-water partitioning coefficients of the phenols. This result allows us to postulate that hydrophobic interactions are the main responsible for the sorption equilibrium binding.