title: Experimental evidences for a new model in the description of the adsorption-coupled reduction of Cr(VI) by protonated banana skin.
abstract: This work reports experimental evidences, not previously considered, to evaluate the Cr(VI) removal by protonated banana skin biomass. Variations in the number of hydroxyl groups, quantified by potentiometric titrations, and CO2 evolution during experiments, were attributed mainly to the oxidation of hydroxylic entities present in the studied material. The results indicate that these groups together with the carboxylic moieties are the main functionalities involved on the adsorption-coupled reduction process. The column experiment carried out provides a new approach to obtain the maximum reduction capacity of the material (3.72 mmol g(-1)). Moreover, we hereby propose a model that reports the first evidence for the instant bound of Cr(III) species to the material used, formed after the reduction of Cr(VI) present in solution. The removal process was quantified carrying out experiments under various pHs, biomass doses and Cr(VI) concentrations, and the mechanism underlying chromium removal was identified.
authors.affiliation: Departamento de Química Física e Enxeñaría Química I, Universidade de A Coruña, Rúa da Fraga 10, 15008 A Coruña, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: López-García
authors.forename: Pablo
authors.initials: P
authors.lastname: Lodeiro
authors.forename: Roberto
authors.initials: R
authors.lastname: Herrero
authors.forename: José L
authors.initials: JL
authors.lastname: Barriada
authors.forename: Carlos
authors.initials: C
authors.lastname: Rey-Castro
authors.forename: Calin
authors.initials: C
authors.lastname: David
authors.forename: Manuel E
authors.initials: ME
authors.lastname: Sastre de Vicente
mesh_terms: D000327:Adsorption; D018533:Biomass; D002857:Chromium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D028521:Musa / Q000737:chemistry*; D010084:Oxidation-Reduction; D011199:Potentiometry; D011522:Protons; D012996:Solutions; D013696:Temperature; D013997:Time Factors; D014866:Waste Products
chemical_list: D011522:Protons; D012996:Solutions; D014866:Waste Products; D002857:Chromium; C074702:chromium hexavalent ion