title: Biosorption of food dyes onto Spirulina platensis nanoparticles: equilibrium isotherm and thermodynamic analysis.
abstract: The biosorption of food dyes FD&C red no. 40 and acid blue 9 onto Spirulina platensis nanoparticles was studied at different conditions of pH and temperature. Four isotherm models were used to evaluate the biosorption equilibrium and the thermodynamic parameters were estimated. Infra red analysis (FT-IR) and energy dispersive X-ray spectroscopy (EDS) were used to verify the biosorption behavior. The maximum biosorption capacities of FD&C red no. 40 and acid blue 9 were found at pH 4 and 298 K, and the values were 468.7 mg g(-1) and 1619.4 mg g(-1), respectively. The Sips model was more adequate to fit the equilibrium experimental data (R2>0.99 and ARE<5%). Thermodynamic study showed that the biosorption was exothermic, spontaneous and favorable. FT-IR and EDS analysis suggested that at pH 4 and 298 K, the biosorption of both dyes onto nanoparticles occurred by chemisorption.
authors: Unit Operation Laboratory, School of Chemistry and Food, Federal University of Rio Grande, FURG, 475 Engenheiro Alfredo Huch Street, 96201-900 Rio Grande, RS, Brazil. guilherme_dotto@yahoo.com.br
authors: G L
authors: GL
authors: Dotto
authors: E C
authors: EC
authors: Lima
authors: L A A
authors: LA
authors: Pinto
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D004396:Coloring Agents / Q000737:chemistry / Q000302:isolation & purification*; D005505:Food Coloring Agents / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D053758:Nanoparticles / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D053545:Spirulina / Q000378:metabolism*; D013696:Temperature
chemical_list: D004396:Coloring Agents; D005505:Food Coloring Agents