Progress of Cryogenics and Isotopes Separation

Newsflash

The National Conference with international participation on New Cryogenic and Isotope Technologies for Energy and Environment - EnergEn 2018 is organized by the National Research-Development Institute for Cryogenic and Isotopic Technologies - ICSI Rm. Valcea with the scientific participation of the University of Pitesti and the University of Craiova and will be held at Baile Govora, in 2018.

REDUCTIVE DECHLORINATION OF α-HEXACHLOROCYCLOHEXANE BY IRON SULFIDE NANOPARTICLES IN BATCH EXPERIMENTS MIMICS ITS ANAEROBIC BIODEGRADATION IN ENVIRONMENT - PRELIMINARY RESULTS Print

 

REDUCTIVE DECHLORINATION OF α-HEXACHLOROCYCLOHEXANE BY IRON SULFIDE NANOPARTICLES IN BATCH EXPERIMENTS MIMICS ITS ANAEROBIC BIODEGRADATION IN ENVIRONMENT - PRELIMINARY RESULTS

Silviu-Laurentiu Badea*, Diana Ionela Popescu, Violeta-Carolina Niculescu, Stanica Enache, Amalia Soare,

Roxana Elena Ionete

National Research and Development Institute for Cryogenics and Isotopic Technologies – ICSI Rm. Valcea, 4 Uzinei Street, P.O. Box Râureni 7, 240050 Rm. Valcea, Valcea, Romania

 

ABSTRACT

Iron sulfide (FeS) is a reductive mineral naturally occurring in many anoxic environments. It is associated with sulfate-reducing bacteria that grow in anoxic aquifers and sediments. Many previously studies have reported the capacity of FeS for reductive dehalogenation of various halogenated organic pollutants. Therefore, a new method for FeS nanoparticles synthesis was developed in this study, to be used in reductive dechlorination of α-hexachlorocyclohexane (α-HCH), mimicking its transformation pathways in anoxic environments. To synthesize the FeS nanoparticles, a solution of 0.2M Na2S was added over a solution of 0.2M FeSO4, under a N2 flow. The XRD analysis showed an almost amorphous phase of FeS nanoparticles, while the Raman and FTIR spectra were in accordance with the ones of FeS phases from the literature. The dehalogenation reaction was performed by mixing 1g of FeS nanoparticles with 100 mL N2 flushed-water and by adding α-HCH from a stock solution in acetone to a final concentration in water of 9.80 mg/L. The dechlorination reaction was performed for 20 days in an incubator at 30°C and 125 rpm. For sampling, 14 mL aliquots of α-HCH solution were taken with syringes at determined intervals for gas chromatography-mass spectrometry (GC-MS) analysis. The degradation products identified by GC-MS were β-pentachlorocyclohexene, benzene and 1,2,4 trichlorbenzene, showing that the dehydrochlorination is the main degradation pathway of α-HCH by FeS. The experiment highlighted that the synthesized FeS nanoparticles degraded the α-HCH to an extent of about 53%, demonstrating their potential in dehalogenation of HCH isomers.

Keywords: Reductive dechlorination, iron sulfide, anaerobic degradation


___________________

*Corresponding author: Silviu-Laurentiu Badea, e-mail: silviu.badea@icsi.ro