Ppm Of Phenanthrene Research Articles

Development of Potentiometric Sensors for C₂H₄ Detection.

Gas exhaust emissions in vehicles are increasingly restrictive in EU and USA. Diesel engines are particularly affected by limitation in hydrocarbons and NOx concentrations. This work presents a screening of working electrode materials to develop a potentiometric sensor, with the most promising material to detect being C2H4 at 550 °C. The device consists of a dense 8YSZ (8 mol% Y2O3 stabilized ZrO2) disk as oxide-ion conducting electrolyte, whereas platinum is screen-printed in the back face as reference electrode. As working electrode, several materials such as Fe0.7Cr1.3O3, ZnCr2O4, Fe2NiO4, La0.8Sr0.2CrO3−δ (LSC), La0.8Sr0.2MnO3 (LSM), and NiO+5%wt Au were tested to detect C2H4. Sensor voltage was measured for several concentrations of C2H4 and CO as these are two of the major oxidizable compounds in a diesel exhaust gas. Fe0.7Cr1.3O3 was selected as the most promising material because of its response to C2H4 and CO. Not only is the response to the individual analytes important, but the C2H4 cross-sensitivity toward CO is also important. Fe0.7Cr1.3O3 showed a good performance to C2H4, with low cross-sensitivity to CO. In addition, when 0.16 ppm of phenanthrene is added, the sensor still has a slightly better response to C2H4 than to CO. Nevertheless, the sensor exposure to high concentrations (>85 ppm) of polycyclic aromatic hydrocarbons led to signal saturation. On the other hand, the operation in wet conditions induces lower sensor sensitivity to C2H4 and higher cross-sensitivity toward CO increase, i.e., the sensor response becomes similar for C2H4 and CO.

Isolation and characterization of catechol 2,3-dioxygenase genes from phenanthrene degraders Sphingomonas, sp. ZP1 and Pseudomonas sp. ZP2

Two bacterial strains, Sphingomonas sp. ZP1 and Pseudomonas stutzeri sp ZP2, were identified as having phenanthrene-degrading ability and were characterized. The activity of catechol-2,3-dioxygenase (C23O) of both strains was measured. With degradation of phenanthrene with an initial concentration of 250 ppm, the C23O activity of both strain ZP1 and ZP2 increased. The ZP1 strain consumed all phenanthrene at day 6, and strain ZP2 degraded 250 ppm of phenanthrene at around day 5; C23O activity in strain ZP1 reached its peak of 6.92 U at day 6, and C23O activity in strain ZP2 achieved 7.80 U as its peak at day 5. After all phenanthrene (250 ppm) was consumed, C23O activity in both Sphingomonas sp. ZP1 and Pseudomonas stutzeri ZP2 decreased. Analysis of the C23O gene sequence indicated that gene PhnZP1 from strain ZP1 has close sequence similarity with the C23O gene from the nearest strain Sphingomonas. sp. KMG 425 (98% identity), 97% similarity with the C23O gene catA from S. paucimobilis sp. TZS-7, and 94% similar with catE gene from S. sp. HV3. The sequence of the C23O gene PhnZP2 of strain ZP2 has 98% similarity with the cmpE gene from strain S. sp., 92% similarity with the phnE gene from P. sp. DJ77 strain, and 90% similarity with all selected C23O genes from Pseudomonas genus strains.

Phenanthrene Biodegradation in Soils Using an Antarctic Bacterial Consortium

ABSTRACT Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in Antarctic soils is limited by low temperatures, lack of adequate levels of nutrients, low number of PAH-tolerant members in the autochthonous microbiota and low bioavailability of contaminants. In the present work, microcosms systems (performed in 1-L glass flasks containing Antarctic soil supplemented with 1744 ppm of phenanthrene) were used to study (i) the effect of biostimulation with a complex organic source of nutrients (fish meal) combined with a surfactant (Brij 700); (ii) the effect of bioaugmentation with a psychrotolerant PAH-degrading bacterial consortium (M10); (iii) the effect of the combination of both strategies. The authors found that combination of biostimulation and bioaugmentation caused a significant removal (46.6%) of phenanthrene after 56 days under Antarctic environmental conditions. When bioaugmentation or biostimulation were applied separately, nonsignificant reduction in phenanthrene concentration was observed. Microtox test showed a low increase in toxicity only in the most efficient system. Results proved that “in situ” bioremediation process of phenanthrene-contaminated soils is possible in Antarctic stations. In addition, inoculation with a psychrotolerant PAH-degrading bacterial consortium in association with a mix of fish meal and a high-molecular-weight surfactant improved phenanthrene removal and should be the selected strategy when the number of hydrocarbons degrading bacteria in the target soil is low.