Alginic acid foams with hierarchical porosity: Promising materials for dyes
Nathalie Tanchoux1*, Asja Pettignano1,2,
Luca Bernardi2, Thierry Vincent3, Eric Guibal3,
1 Institut Charles Gerhardt, CNRS-UM2-ENSC-UM1, 8
Rue Ecole Normale, 34090, Montpellier, France. firstname.lastname@example.org
2 Department of Industrial Chemistry, UNIBO, V. Risorgimento, 4,
40136, Bologna, Italy.
3 Ecole des Mines dAlès, C2MA/MPA, 6 Avenue
de Clavières, 30319, Alès, France.
Keywords: foams, hierarchical porosity,
biopolymers, alginic acid, biocompatible adsorbent
Water pollution due to organic dyes is a
serious environmental problem. Their release, even in low quantities, is highly
undesirable because of their high visibility, low biodegradability and toxic
effects on humans and marine organisms. Among the treatments proposed for water
decontamination, adsorption is a popular method, because of its high efficiency
and low operating cost. Therefore, the development of low-cost adsorbents is
becoming extremely attractive and natural biopolymers are often presented as
abundant, renewable and biodegradable resources for this application.
In our study, alginic
acid, a biopolymer derived from brown algae, has been studied as a
cost-effective replacement for conventional adsorbents. The presence of
hydroxyl and carboxylic groups in its polymeric backbone confers: (a) the
ability to associate, by physical and chemical interactions, with a wide
variety of molecules  and (b) an excellent selectivity towards cationic
dyes. Employing the tremendous manipulability of this polysaccharide, alginate
foams with macro-meso pores have been developed with
a simple procedure. The influence of preparation parameters (alginate
composition, temperature, concentration, acidification procedure) on the final
texture have been studied by SEM microscopy and N2 adsorption, which
confirmed the presence of a hierarchical porosity. The applicability of the
newly developed material have been tested by examining its sorption behavior
towards cationic dyes (such as methylene blue), by
equilibrium and kinetic experiments, proving that alginic
acid foams can be employed as biocompatible, green and low-cost adsorbents for
G. Crini, Prog. Polym. Sci. 2005, 30, 38-70.
F. Di Renzo, E. Guibal, Top. Curr. Chem. 2010, 294, 165-197.