title: Study of the involved sorption mechanisms of Cr(VI) and Cr(III) species onto dried Salvinia auriculata biomass.
abstract: Removal of Cr(VI) species by dried biomass of the aquatic macrophyte Salvinia auriculata was studied in order to understand the involved sorption mechanisms. Kinetic tests were carried out under the conditions such as concentration range of Cr(VI) from 50 to 250 mg L-1and a temperature of 30 °C. Modification of the biosorbent by the presence of Cr(VI) species was assessed by analysis of its porosity, density and infrared molecular absorption spectrum. A series of experimental approaches involving directed chemical modifications on the biosorbent surface was performed. The main functional groups involved in the sorption mechanisms were identified. The gas sorption analyser was applied and proved that a strong chemical effect of Cr(VI) species on the surface took place, resulting in a leaching organic matter with an obvious and significant increase in the porosity parameters. The intra-particle diffusion model revealed different mass transfer zones into the adsorbent during Cr(VI) removal. New combined Langmuir and Dubinin-Radushkevich isotherm was the best to fit the equilibrium data of Cr(VI) species removal. Finally, Cr(VI) removal was mainly mediated by a redox process where Cr(III) species were formed.
authors.affiliation: Postgraduate Program of Chemical Engineering, West Paraná State University, Rua da Faculdade 645, Jd. Santa Maria, 85903-000, Toledo, PR, Brazil. Electronic address: anmodenes@yahoo.com.br.
authors.forename: Aparecido Nivaldo
authors.initials: AN
authors.lastname: Módenes
authors.affiliation: Postgraduate Program of Chemical Engineering, Maringá State University, Av. Colombo 5790, 87020-900, Maringá, PR, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: de Oliveira
authors.affiliation: Postgraduate Program of Chemical Engineering, West Paraná State University, Rua da Faculdade 645, Jd. Santa Maria, 85903-000, Toledo, PR, Brazil.
authors.forename: Fernando R
authors.initials: FR
authors.lastname: Espinoza-Quiñones
authors.affiliation: Postgraduate Program of Chemical Engineering, West Paraná State University, Rua da Faculdade 645, Jd. Santa Maria, 85903-000, Toledo, PR, Brazil.
authors.forename: Daniela Estelita Goes
authors.initials: DEG
authors.lastname: Trigueros
authors.affiliation: The "Stephan Angeloff" Institute of Microbiology-Bulgarian Academy of Sciences, Acad. G. Bonchev str., Bl. 26, Sofia, 1113, Bulgaria.
authors.forename: Alexander Dimitrov
authors.initials: AD
authors.lastname: Kroumov
authors.affiliation: Postgraduate Program of Chemical Engineering, Maringá State University, Av. Colombo 5790, 87020-900, Maringá, PR, Brazil.
authors.forename: Rosângela
authors.initials: R
authors.lastname: Bergamasco
mesh_terms: D000327:Adsorption; D000465:Algorithms; D018533:Biomass; D002857:Chromium / Q000737:chemistry*; D004058:Diffusion; D029624:Ferns / Q000378:metabolism*; D005740:Gases; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D016062:Porosity; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D005740:Gases; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Biosorbent characterisation; Cr(VI) species uptake; Intra-particle diffusion approach; Physical-sorption mechanisms