Optimization and kinetic analysis of food dyes biosorption by Spirulina platensis

The biosorption of food dyes acid blue 9 and FD&C red no. 40 onto Spirulina platensis was studied. A full factorial design was used to analyze the effects of pH (2-4), stirring rate (50-400 rpm) and contact time (20-100 min) on biosorption capacity. In the best conditions, biosorption kinetics was analyzed and the experimental data were fitted with four kinetic models. The best conditions were: pH 2, 400 rpm and 100 min for acid blue 9, and pH 2, 225 rpm and 100 min for FD&C red no. 40. In these conditions, the biosorption capacities were 1653.0 mg g(-1) for acid blue 9 and 400.3 mg g(-1) for FD&C red no. 40. For both dyes, the Avrami kinetic model was the more appropriate to represent the experimental data. These results showed that the S. platensis is a suitable biosorbent for removal of food dyes from aqueous solutions.