On the removal of hexavalent chromium by olive stones coated by iron-based nanoparticles: Equilibrium study and chromium recovery. (20th July 2018)

• Record Type: Journal Article
• Authors: Vilardi, Giorgio; Ochando-Pulido, Javier Miguel; Verdone, Nicola; Stoller, Marco; Di Palma, Luca
• Is Part Of: Journal of cleaner production. Volume 190(2018)
• Page Start: 200
• Page End: 210
• Publication Date: 2018-07-20
• Subjects: Waste-reuse -- Coated-biomass -- Chromium-recovery -- Circular-economy; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2018.04.151
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: In this work hexavalent chromium, Cr(VI), removal in aqueous solution by olive stones coated by zero-valent iron and magnetite nanoparticles was investigated. The Cr(VI) removal test results showed that the coated biomass adsorption capacity significantly increased (2.54 and 4.11 mg Cr g −1 ) when compared to the uncoated one (1.48 mg Cr g −1 ). Optimal removal conditions were reached by fixing the operating parameter values for pH, mass concentration and contact time equal to 3, 2.5 g L −1 and 120 min for the uncoated and equal to 2, 1.5 g L −1 and 120 min for the coated biomasses, respectively. Both Cr(VI) and Cr(III) recovery, after 5 cycles of use, was investigated using different solvents and operative conditions (with and without sonication), showing that remarkable Cr recovery was possible using the more environmentally friendly washing procedure. A possible Cr(VI) removal mechanism will be here proposed and discussed, considering both reduction and adsorption contribution towards Cr(VI) removal in aqueous medium and capable to justify the obtained results. Graphical abstract: Image Highlights: nZVI and nMG were used to modify the surface of olive stones particles. Coated materials show noticeable Cr(VI) removal capacity at concentration = 1.5 g L −1 . DW + sonication allowed to recover 82% Cr and to preserve adsorbent surface activity. The Cr(VI) removal mechanism comprised both adsorption and reduction processes. The adsorbent Cr(VI) removal efficiency decreased of 30% after 5 cycles of reuse.