Main Article Content
Aims: Preparation of the new metals-polymeric composite, Metx-EPS (I), to be used as a green catalyst in water or in two-phase aqueous conditions.
Study Design: Recovery and valorization of polymetallic wastes to obtain directly new catalysts using a microorganism to explore their application in removal of difficult and dangerous chemical pollutants present in aqueous environment.
Place and Duration of Study: Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Venezia Mestre, Italy; University of Nova Gorica, Nova Gorica, Slovenia, Institut Jozef Stefan, Ljubljana, Slovenia and Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia, between February 2018 and January 2019.
Methodology: For the preparation of Metx-EPS (I), the metals source was an exhausted catalytic converter that was grinded and treated with an acidic solution at 20-25°C. After filtration, the solution was concentrated, neutralized and added to a broth of Klebsiella oxytoca DSM 29614 to produce (I) where metals are embedded in a peculiar polysaccharide structure. The composite was easily recovered from the fermentation broth and purified. The process protocol was verified many times and was shown to be reproducible satisfactorily. The % recovery of metals, originally present in the converter, was good as determined by atomic absorption. The morphology and the chemical state of main metals in (I) were investigated by X-ray absorption spectroscopy methods (XANES and EXAFS). No metallic alloy seems to be evident.
Results: As first application of (I) as catalyst, the hydrodechlorination treatment of polychlorinated biphenyls (PCBs) was studied in water/methanol. A significant removal of higher chlorinated congeners was observed working at 1MPA of hydrogen and 60°C. This result improves significantly and surprisingly the methodology, previously studied by us using mono- or bi-metals embedded in the same polysaccharide moiety, indicating that positive synergies among the different metals were operating.
Conclusion: The preparation of this new polymetallic species embedded in a polysaccharide moiety starting from spent catalytic converters represents an alternative valorisation of metallic wastes. Moreover, a synergic effect was exerted by the different metals when the catalyst Metx-EPS (I) was used in the hydrodechlorination treatment of polychlorinated biphenyls (PCBs) in water/methanol. Finally, a promising preliminary proof of concept for the removal of polychlorinated aromatic pollutants even in contaminated aqueous sites was carried out.
Izatt RM, Izatt SR, Bruening RL, Izatt NE, Moyer BA. Challenges to achievement of metal sustainability in our high-tech society. Chem. Soc. Rev. 2014;43:2451-2475.
Baldi F, Marchetto D, Paganelli S, Piccolo O. Bio-generated metal binding polysac-charides as catalysts for synthetic applications and organic pollutant trans-formations. New Biotechnol. 2011;29:74-78.
Arčon I, Paganelli S, Piccolo O, Gallo M, Vogel-Mikuš K, Baldi F. XAS analysis of iron and palladium bonded to a polysaccharide produced anaerobically by a strain of Klebsiella oxytoca. J. Synchrotron Rad. 2015;22:1215- 1226.
Baldi F, Gallo M, Paganelli S, Tassini R, Sperni L, Piccolo O, et al. Hydrode-chlorination of aroclor 1260 in aqueous two-phase mixture catalyzed by biogenerated bimetallic catalysts. Int. Res. J. Pure & Appl.Chem. 2016;11:1-9.
Ravel B, Newville M. Athena, Artemis, Hephaestus: Data analysis For X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Rad. 2005;12: 537-541.
Rehr JJ, Albers RC, Zabinsky SI. High-order multiple-scattering calculations of x-ray-absorption fine structure. Phys. Rev. Lett. 1992;69:3397-3400.
Tieuli S, Baldi F, Arčon I, Vogel-Mikuš K, Gallo M, Sperni L, et al. Alternative recovery and valorization of metals from exhausted catalytic converters in a new smart polymetallic catalyst. Chemistry Select. 2019;4.
Papageorgiou SK, Kouvelos EP, Favvas EP, Sapalidis AA, Romanos GE, Katsaros FK. Metal–carboxylate interactions in metal–alginate complexes studied with FTIR spectroscopy. Carbohydr. Res. 2010; 345:469-473.
Tan L, Dong H, Liu X, He J, Xu H, Xie J. Mechanism of palladium(II) biosorption by Providencia vermicola. RSC Adv. 2017;7: 7060-7072.
Leone S, De Castro C, Parrilli M, Baldi F, Lanzetta R. Structure of the iron‐binding exopolysaccharide produced anaerobi-cally by the gram‐negative bacterium Klebsiella oxytoca BAS‐10. Eur. J. Org. Chem. 2007;5183-5189.
Wong J, Lytle FW, Messmer RP, Maylotte DH. K-edge absorption spectra of selected vanadium compounds. Phys. Rev. B 1984; 30: 5596-5610.
Arčon I, Kodre A, Abra RM, Huang A, Vallne JJ, Lasič DD, Colloid Surface B 2004;33:199-204.
Meng W, Xiao D, Wang R. Enhanced production of tetramethyl-pyrazine in Bacillus licheniformis BL1 by bdhA disruption and 2,3-butanediol supple-mentation. World J. Microbiol. Biotechnol. 2016;32:32-46.
Kozjek Škofic I, Padežnik Gomilšek J, Kodre A, Bukovec N, Sol Energ Mat Sol C. 2010;94:554-559.
Bouvier P, Djurado E, Ritter C, Dianoux AJ, Lucazeau G. Low temperature phase transformation of nanocrystalline tetragonal ZrO2 by neutron and Raman scattering studies. Int. J. Inorg. Mater. 2001;3:647-654.
Coey JMD. The crystal structure of Rh2O3. Acta Cryst. 1970;B26:1876-1877.