Study of the involved sorption mechanisms of Cr(VI) and Cr(III) species onto dried Salvinia auriculata biomass

• Published in: Chemosphere (Oxford) Vol. 172; pp. 373 - 383
• Main Authors: Módenes, Aparecido Nivaldo, de Oliveira, Ana Paula, Espinoza-Quiñones, Fernando R., Trigueros, Daniela Estelita Goes, Kroumov, Alexander Dimitrov, Bergamasco, Rosângela
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2017
• Subjects: Adsorption; Algorithms; Biomass; Biosorbent characterisation; Chromium - chemistry; Cr(VI) species uptake; Diffusion; Ferns - metabolism; Gases; Hydrogen-Ion Concentration; Intra-particle diffusion approach; Kinetics; Models, Theoretical; Oxidation-Reduction; Physical-sorption mechanisms; Porosity; Spectrophotometry, Infrared; Spectroscopy, Fourier Transform Infrared; Water Pollutants, Chemical - chemistry; Intra-particle diffusion approach; Physical-sorption mechanisms; Biosorbent characterisation; Cr(VI) species uptake
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2017.01.038

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−1 and 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. [Display omitted] •Biosorbent bulk modification by the presence of Cr(VI) species was verified.•Kinetic data revealed more sorption sites at micro-porous levels by Cr(VI) action.•Cr(VI) species removal was mainly mediated by a redox process.•Functional groups that interacting in the Cr(VI) reduction were identified.•A new insight about the mechanism of Cr(VI) removal by a biosorbent was proposed.