Browsing by Author "Gumuscu, B."

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Open Access
Complete dissipation of 2, 4, 6-trinitrotoluene by in-vessel composting
(Royal Society of Chemistry, 2015) Gumuscu, B.; Cekmecelioglu, D.; Tekinay, T.
We demonstrate complete removal of 2,4,6-trinitrotoluene (TNT) in 15 days using an in-vessel composting system, which is amended with TNT-degrading bacteria strains. A mixture of TNT, food waste, manure, wood chips, soil and TNT-degrading bacteria consortium are co-composted for 15 days in an aerobic environment. Variations in the TNT degradation rates are assessed when composting reactors are operated at different carbon/nitrogen ratios (C/N), aeration rates, TNT concentrations and TNT-degrading bacteria inoculum loads. Changes in TNT concentrations are measured using high performance liquid chromatography, and C/N are determined using elemental analysis every 5 days. Temperature and moisture of the system are measured every 6 hours. Optimum TNT degradation performance is achieved by combining C/N of 20/1 and a 5 L min-1 aeration rate. Complete removal is achieved for TNT concentrations of 2, 10, and 100 g kg-1 in 15 days by the help of Citrobacter murliniae STE10, Achromobacter spanius STE11, Kluyvera cryocrescens STE12, and Enterobacter amnigenus STE13 bacteria strains. The final products of composting are used to cultivate four different plant seedlings for 10 weeks and showed no toxic effect, which is promising for the potential agricultural use of TNT-contaminated lands after remediation. © The Royal Society of Chemistry.
Open Access
Effective biodegradation of 2,4,6-trinitrotoluene using a novel bacterial strain isolated from TNT-contaminated soil
(2013) Gumuscu, B.; Tekinay, T.
In this environmental-sample based study, rapid microbial-mediated degradation of 2,4,6-trinitrotoluene (TNT) contaminated soils is demonstrated by a novel strain, Achromobacter spanius STE 11. Complete removal of 100mgL-1 TNT is achieved within only 20h under aerobic conditions by the isolate. In thisbio-conversion process, TNT is transformed to 2,4-dinitrotoluene (7mgL-1), 2,6-dinitrotoluene (3mgL-1), 4-aminodinitrotoluene (49mgL-1) and 2-aminodinitrotoluene (16mgL-1) as the key metabolites. A. spanius STE 11 has the ability to denitrate TNT in aerobic conditions as suggested by the dinitrotoluene and NO3 productions during the growth period. Elemental analysis results indicate that 24.77mgL-1 nitrogen from TNT was accumulated in the cell biomass, showing that STE 11 can use TNT as its sole nitrogen source. TNT degradation was observed between pH 4.0-8.0 and 4-43°C; however, the most efficient degradation was at pH 6.0-7.0 and 30°C. © 2013 Elsevier Ltd.
Open Access
Highly sensitive determination of 2, 4, 6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography
(Public Library of Science, 2014) Gumuscu, B.; Erdogan, Z.; Güler, Mustafa O.; Tekinay, T.
In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 μg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation. © 2014 Gumuscu et al.