EQA - Escola de Química e Alimentos
URI permanente desta comunidadehttps://rihomolog.furg.br/handle/1/1610
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3 resultados
Resultados da Pesquisa
- ItemEquilibrium and thermodynamics of azo dyes biosorption onto Spirulina platensis(Abeq, 2013) Dotto, Guilherme Luiz; Vieira, Mery Luiza Garcia; Esquerdo, Vanessa Mendonça; Pinto, Luiz Antonio de AlmeidaThe equilibrium and thermodynamics of azo dye (tartrazine and allura red) biosorption onto Spirulina platensis biomass were investigated. The equilibrium curves were obtained at 298, 308, 318 and 328 K, and four isotherm models were fitted the experimental data. Biosorption thermodynamic parameters (ΔG, ΔH and ΔS) were estimated. The results showed that the biosorption was favored by a temperature decrease. For both dyes, the Sips model was the best to represent the equilibrium experimental data (R2>0.99 and ARE<5.0%) and the maximum biosorption capacities were 363.2 and 468.7 mg g-1 for tartrazine and allura red, respectively, obtained at 298 K. The negative values of ΔG and ΔH showed that the biosorption of both dyes was spontaneous, favorable and exothermic. The positive values of ΔS suggested that the system disorder increases during the biosorption process.
- ItemKinetic studies on the biosorption of phenol by nanoparticles from Spirulina sp. LEB 18(2013) Dotto, Guilherme Luiz; Costa, Jorge Alberto Vieira; Pinto, Luiz Antonio de AlmeidaA kinetic study on the biosorption of phenol by nanoparticles from Spirulina sp. LEB 18 was carried out. The Spirulina sp. nanoparticles were prepared and characterized. Kinetic curves of phenol biosorption were obtained in batch system, being verified the effects of initial concentration (50, 150, 250 and 450 mg L 1) and stirring rate (50, 200 and 400 rpm). The models of pseudo-first order, pseudo-second order, Elovich, Bangham, general order and Weber–Morris were used for the kinetic interpretations. Spirulina sp. nanoparticles were stable, monodisperse, spherical with mean diameter of 230 nm. The phenol biosorption was a relatively fast process, being favored at higher values of initial concentration and stirring rate. Pseudo-second order and general order models showed satisfactory fit with the experimental data and the maximum biosorption capacity was around 101 mg g 1. From the Weber– Morris analysis, it was found that external mass transfer and intraparticle diffusion occurred during the phenol biosorption on Spirulina sp. nanoparticles. The externalmass transfer was faster at higher values of initial concentration and stirring rate, and the intraparticle diffusion was favored at high initial concentrations.
- ItemAnalysis of mass transfer kinetics in the biosorption of synthetic dyes onto Spirulina platensis nanoparticles(2012) Dotto, Guilherme Luiz; Pinto, Luiz Antonio de AlmeidaIn this research, the mass transfer kinetics for the biosorption of synthetic dyes (acid blue 9 and FD&C red no. 40) by Spirulina platensis nanoparticles was analyzed under different experimental conditions. The external mass transfer model (EMTM) and the homogeneous solid diffusion model (HSDM) were employed to study the mass transfer kinetics and also to estimate the values of external mass transfer coefficient (kf) and intraparticle diffusion coefficient (Dint). The Biot number (Bi) was used to verify the importance of external mass transfer in relation to intraparticle diffusion. The values of external mass transfer coefficient (kf) ranged from 1.67 × 10−6 to 11.40 × 10−6 cm s−1 and the intraparticle diffusion coefficient (Dint) ranged from 0.70 ×10−14 to 4.30 ×10−14 cm2 s−1. The Biot numbers (0.53 ≤ Bi ≤ 10.33) showed that, for both dyes, the biosorption onto S. platensis nanoparticles was controlled simultaneously by external mass transfer and intraparticle diffusion.