Phenanthrene removal

Strain PI5 was grown on phenanthrene by a known pathway in which salicylate is an intermediate. Pre-incubation with phenanthrene and downstream intermediates through salicylate stimulated PAH dioxygenase activity and initial rates of phenanthrene removal, suggesting that salicylate was the inducer of this activity. 

Park et al (2007) introduced two nonionic surfactants, APG and Brij30, and one anionic surfactant, SDS, to remediate phenanthrene-spiked kaolinite. These authors found that APG produced the highest electroosmotic flow and showed the best removal efficiency among tested surfactant solutions. An electrokinetic test using Brij 30 showed relatively low phenanthrene removal because of low electroosmotic flow, even though the surfactant showed better solubilization than did APG. However, electroosmotic flow using Brij 30 could be enhanced by addition of acetate buffer, thus enhancing removal efficiency. 

After these feasibility test data appeared (Li, Cheung, and Reddy, 2000), n-butylamine was employed in several electrokinetic tests as a flushing solution (Reddy and Ala, 2006 Reddy et aL, 2006 Maturi and Reddy, 2008). In a study by Maturi and Reddy (2008), the concentration of n-butylamine greatly influenced the amount of electroosmotic flow as well as phenanthrene mobility. When n-butylamine was present at 20%, greater phenanthrene removal was seen than when the cosolvent was present at 10% because of increased phenanthrene solubiUzation. Electroosmotic flow decreased, however, with increases in cosolvent concentration, resulting in an overall rather limited removal of phenanthrene. Therefore, optimization of cosolvent concentration is required to increase contaminant solubilization while permitting sustained electroosmotic flow. 

When 0.001-0.1 MNaCl solutions were employed as electrolytes, most tests showed maintenance of low electrical potential gradients under constant current conditions with consequent decreases in power consumption. However, because increments in ionic strength induce decreases in soil surface zeta potential, the electroosmotic flow decreased, and phenanthrene removal was barely enhanced... 

Similarly, in tests with dredged sediment and gas plant soil, substantial electroosmotic flow was produced because of high acid buffering capacity, but phenanthrene removal efficiency was very low because PAHs were strongly adsorbed to organic matter. The organic matter proportions were 19% and 4% in the sediment and gas plant soil, respectively (Reddy and Ala, 2006 Reddy et al, 2006). Particularly, in tests with cyclodextrin solution, it was found that the low PAH removal efficiency was caused by adsorption of cyclodextrin-PAH complexes onto minerals and organic matter in the sediments (Reddy and Ala, 2006). 

Ju L, Elektorowicz M (2000). In-situ phenanthrene removal provoked by electrokinetic transport of on-site prodneed biosnrfactants. Annual conference abstracts, Canadian Society for Civil Engineering, May, London, ON, p. 135. 

The distribution of phenanthrene in the soil for cells C3, C4, C5, and C6 showed, 76%, 70%, 72%, and 74% average removal of phenanthrene between reactive membranes, respectively. It can be concluded that coupling the supply of surfactant with electrokinetics enhanced the mobility of phenanthrene. The highest removal of phenanthrene was achieved in cell C3. The surfactant was supplied for a longer period in this cell. No impact of the duration of the selected test on the phenanthrene removal was observed. All systems demonstrated an insignificant capture of phenanthrene on membranes. 

Otherwise, when the experiment was run with the RVC-Ti02 anode (Figure 7) the presence of smaller peaks it is practically null also, an opposite phenomena is observed since in this case the higher residual concentration was about 0.9 A.U., while the lower one is not less than 0.6 A. U., this last takes place at the 0.3 cm position (near the anode). In general, with this option phenanthrene removal was lower than the one attained with the bare RVC electrodes. 

Correlating these results with corresponding pH data it can be affirmed that keeping a shorter difference in pH wells, as it hapvpens with bare RVC electrodes, it favors a soil alkaline condition which, even though produces a slower liquid movement, so far this is good enough for phenanthrene removal since it provides a higher residence time. 

Up to here, it was shown that inclusion of one catalytic specie, like anatase, in the anode allowed increasing the oxidant specie production and the electroosmotic flow rate, but obtained phenanthrene removal was lowered. So next step is to analyze what happen if the catalytic activity is maintained at the anode, but cathode is chosen between different materials. Experimental set-up objective was data collection for two different cathode materials, and also to clarify how much the system becomes affected by inclusion of additional physical barriers like a thick filter paper. 

Increased removal of phenanthrene from soil columns spiked with the rhamnolipid mixture synthesized by Pseudomonas aeruginosa UG2 has been demonstrated, and shown to depend both on the increased desorption of the substrate and on partitioning into micelles (Noordman et al. 1998). However, the addition of the biosurfactant from the same strain of Pseudomonas aeruginosa UG2 or of sodium dodecyl sulfate had no effect on the rate of biodegradation of anthracene and phenanthrene from a chronically contaminated soil. 

Noordman WH, W Ji, ML Briusseau, DB Janssen (1998) Effects of rhamnolipid biosurfactants on removal of phenanthrene from soil. Environ Sci Technol 32 1806-1812. 

Human activities have resulted in exposure of Antarctic fishes to petroleum-derived PAHs (McDonald et al. 1992). Fish captured near Palmer station on the Antarctic peninsula had induced EROD activities and elevated concentrations of biliary PAH metabolites of phenanthrene and naphthalene when compared to conspecifics from reference sites (McDonald et al. 1995). Artificial reefs consisting of oil and coal flyash stabilized with cement and lime in Florida waters near Vero Beach contained elevated PAH levels ranging from as high as 1.2 mg fluoranthene/kg and 0.25 mg naphthalene/kg. But there is negligible leaching because seawater is not an effective medium for removing PAHs from reef bricks or the ash (Frease and Windsor 1991). 

The specific rate of removal of benzo [a]pyrene was at least two orders of magnitude lower than that of the four-ring compounds and nearly five orders of magnitude lower than that of phenanthrene. 

The feasibility of a one-pot consecutive removal of the pyridinium moiety by reducing the products electrochemically in the same cell has been shown, thus providing a convenient synthetic route to 1-methylthio-acenaphthylene and 9-methylthio-phenanthrene (Eq. 19) [128]. 

The solubility of fuel oil no. 2, particularly the alkane and isoprenoid fractions, in seawater is increased by the presence of fulvic acid, although the solubilities of phenanthrene or anthracene, both polycyclic aromatic hydrocarbons, are unaffected by the presence of humic materials (Boehm and Quinn 1973). Unfiltered Narragansett Bay water was able to dissolve 1,560 g/L of fuel oil no. 2, although removal of... 

Isolation of Oxidation Products. After oxygen absorption had ceased, or reached the desired value, the oxidates were poured into water. In many cases the reaction product could be removed by filtration in high yield. In this manner xanthone (m.p. 172-174°C.), was isolated from oxidations of xanthene or xanthen-9-ol thioxanthone (m.p. 208-210°C.), from thioxanthene acridine (m.p. 107-109°C.), from acridan anthracene (m.p. 216-217°C.), from 9,10-dihydroanthracene phenanthrene (m.p. 95-99°C.), from 9,10-dihydrophenanthrene pyrene (m.p. 151-152.5°C.) (recrystallized from benzene) from 1,2-dihydropyrene and 4-phenan-throic acid (m.p. 169-171 °C.) (recrystallized from ethanol) by chloroform extraction of the hydrolyzed and acidified oxidate of 4,5-methyl-enephenanthrene. 

A. Purification of phenanthrene. 1. By azeotropic distillation.2 A mixture of 300 g. of commercial phenanthrene (Note 1), 90 g. of maleic anhydride, and 600 ml. of xylene, contained in a 2-1. round-bottomed flask, is heated under reflux for 20 hours (Note 2). The initially yellow solution rapidly turns to a dark brown on heating. This solution is cooled to room temperature and filtered by suction to remove any insoluble adduct. The filtrate is then extracted with two 100-ml. portions of dilute sodium hydroxide, and the basic extracts are discarded. The organic phase is next washed with water and saturated sodium chloride solution, and finally is filtered through a layer of anhydrous magnesium sulfate. The excess xylene is removed by distillation, first at atmospheric pressure then the final portions are removed at reduced pressure. The residue, while still hot, is poured into a large mortar and, after solidification, is powdered to a convenient size. The yield of crude phenanthrene is 230-240 g. 

---