This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004)
funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norteinfo:eu-repo/semantics/publishedVersio

Alves, M. M.

Antunes, A. C.

Lanceros-Méndez, S.

Martins, Pedro Manuel Abreu

Pereira, Luciana

Pereira, M. F. R.

Petrovykh, D. Y.

Silva, Ana Rita Pereira

Soares, O. S. G. P.

Sousa, C.

English

Universidade do Minho: RepositoriUM

Environmental impact of nanomaterials: assessment of toxicity in chemical and biological processes for the degradation of micropollutants.

• Vibrio fischeri has maximum of light emission at ca. 28 h of growth• Vibrio fischeri present rod-shaped cells of 2.2 ± 1 µm• The bacteria’s surface is negatively charged, when growth at pH 6, 7 and 8 orwhen exposed to solutions in this range of pHEnvironmental impact of nanomaterials:assessment of toxicity in chemical and biologicalprocesses for the degradation of micropollutants1Center of Biological Engineering, 2Center of Physics University of Minho, 4710-057 Braga, Portugal3International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal5BCMaterials, Parque Científico y Tecnológico de Bizkaia, Ed. 500, Derio 48160, Spain6Laboratory of Separation and Reaction Engineering − Laboratory of Catalysis and Materials (LSRE-LCM), Faculty of Engineering, University of Porto, Porto, PortugalA.R. Silva1, A.C. Antunes1, P.M. Martins2, C. Sousa3, D. Y. Petrovykh3, S. Lanceros-Mendez2,4, O.S.G.P. Soares5, M.F.R. Pereira5, M.M. Alves1, L. Pereira1IntroductionUniversity of MinhoSchool of EngineeringThis study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004)funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.The exceptional properties of nanomaterials have increased their use in many different areas, including electronics, construction and healthcare [1]. Nanomaterials have also beenproposed on remediation of pollutants as sorbents and as catalysts of their biological and chemical removal. In this study, different nanomaterials have been applied as catalysts in chemicaland biological processes for the degradation of the antibiotic ciprofloxacin (CIP). CIP is one of the most prescribed antibiotic and their persistence in effluents has increased in the lastdecades [2]. UV/Photocatalytic degradation of CIP was performed using TiO2 and ZnO, due to their high photocatalytic activity [3]. CIP biodegradation was performed under anaerobicconditions. The effect of carbon materials (CM), namely Carbon nanotubes, single (CNT) or incorporated with 2% of iron (CNT@2%Fe), as electron shuttles in the process, was studied.Those materials were previously proved to accelerate up to 79-fold the rate of azo dye biodegradation in similar conditions [4]. CIP removal was monitored as well as the toxicity of themedium before and after the treatment. Toxicity assessment is highly important as it is desired that the products formed after the process are not more toxic than the initial compound.Moreover, the evaluation of the possible contribution of nanomaterials used in the process for the final toxic effect of threated solution, is crucial.Vibrio fischeri is a marine bioluminescent bacterium, widely used in acute toxicity tests due to their high sensitivity and fast toxic response to pollutants. The bioassay is based on thechanges in the bacteria natural luminescence when exposed to potentially toxic substances. The reduction of emitted light is related to the toxicity of the tested substance [5].Methods ResultsVibrio fischeri growth➢ Photocatalytic treatment of CIPTOXICITY ASSAYSDarkMorphologyanalysispHinfluenceSurface charge analysis Isolation of Vibrio fischeriLiquid culture Liquid culture in dark observation➢ Biological treatment of CIPChemical and biological processes for the removal of CIP30 min➢ Solution of incubation of TiO2➢ Solution of incubation of ZnO➢ Solution of incubation of CNT➢ Solution of incubation of CNT@2%Fe➢ CIP solution➢ Solution after CIP treatment byphotocatalysis and by biological processesGranular sludge (GS)0 10 20 30 40 50 60 700,05,0x1061,0x1071,5x1072,0x1072,5x107   pH6 pH7 pH8Luminescence (RLU s-1)Growth time (h)500 nmpHGrowth at specified pHa(ζ-potential, mV)Exposed to specified pHb(ζ-potential, mV)6 -40.8 ± 5.9 -18.0 ± 1.26.5 - -37.9 ± 0.87 -44.5 ± 3.9 -38.9 ± 0.77.5 - -37.5 ± 0.68 -45.8 ± 7.4 -38.4 ± 0.9SamplesCIP removal (%)Luminescenceinhibition(%)CNT n.a. 28 ± 1CNT@2%Fe n.a. 35 ± 14CIP solution n.a. 56 ± 10Bio 72 ± 2 30 ± 4Bio+CNT 98 ± 1 19 ± 8Bio+CNT@2%Fe 92 ± 1 26 ± 7Abiotic CNT 100 ± 1 15 ± 9Abiotic CNT@2%Fe 100 ± 1 26 ± 7SamplesTreatmenttime (min)CIP removal (%)Luminescence inhibition (%)CIP solution 0 n.a. 62 ± 1.8CIP treated with TiO215 n.d. 34 ± 8.045 100 70 ± 7.8 CIP treated with ZnO15 n.d. 97 ± 0.2 45 100 98 ± 0.3 TiO2 45 n.a. 38 ± 0.3 ZnO 45 n.a. 97 ± 2.0CIP adsorption to TiO2-30* 85 55 ± 8.6 CIP adsorption to ZnO-30* 63 96 ± 0.5Toxicity - Chemical processToxicity - Biological process• The toxicity of CIP samplesdecreases in the first 15 minof photocatalytic treatmentwith TiO2, but increases afterthat time• ZnO nanoparticles exerthigher toxic effect than TiO2nanoparticles• The toxicity of CIP solutiontreated with ZnO can not beestimated due to the hightoxic effect inherent of theZnO nanoparticles• CNT@2%Fe caused higher toxicitythan CNT, however they areconsidered slightly toxic• The toxicity of CIP solutiondecreases with the biologicaltreatment• In the abiotic processes,detoxification may be a result of CIPadsorption to CM• The slight toxic effect verified afterthe treatment can be related with thepossible formation of by-products,but also the contribution of CMn.a., Non applicable; n.d., Non detectable; -30*, 30 min without UV-radiationConclusionsReferences• CIP removal by photocatalytic processes, TiO2 and ZnO as catalysts, was complete after 45 minof UV-radiation• ZnO nanoparticles exerted almost 3-fold higher toxicity than TiO2 nanoparticles• The toxicity of the treated solution with TiO2 was higher than the initial CIP solution,, probably dueto formed products and also nanomaterials contribution• The use of CM in the biological processes improved the removal of the CIP and also thedetoxification[1] Aitken RJ, Chaudhry MQ, Boxall ABA, Hull M. 2006. Manufacture and use of nanomaterials: Current status in the UK and global trends. Occup Med (Chic Ill) 56:300–306.[2] Liu C, Nanaboina V, Korshin GV, Jiang W. 2012. Spectroscopic study of degradation products of ciprofloxacin, norfloxacin and lomefloxacin formed in ozonated wastewater,Water Res., 46(16):5235–46.[3] Philippopoulos CJ, Nikolaki MD. 2010. Photocatalytic processes on the oxidation of organic compounds in water, p. 242. In Ramov, B (ed.), New Trends in Technologies.INTECH.[4] Pereira L., Dias P., Soares O.S.G.P., Ramalho P.S.F., Pereira M.F.R., Alves, M. M. 2017. Synthesis, characterization and application of magnetic carbon materials as electronshuttles for the biological and chemical reduction of the azo dye Acid Orange 10. Applied Catalysis B: Environmental 212(5):175–184.[5] Behrouzfar A. 2014. Effect of individual toxicants and their mixtures to the marine bacterium Vibrio fischeri. Fac Sci. University of Gothenburg.➢ Control – nanomaterials effect➢ Control – nanomaterials effectToxicity AssayAnalyzed samplesaGrown at the specified pH, then measured in water at pH 7bGrown at pH 7, then measured in water at the specified pHn.a., Non applicable

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Environmental impact of nanomaterials: assessment of toxicity in chemical and biological processes for the degradation of micropollutants.

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