Effects of operational parameters and ultrasonic pretreatment on supercritical CO2 extraction of diesel fuel from soil

Supercritical fluid extraction (SFE) using CO2 was performed on soil material artificially contaminated with diesel fuel. Raising the temperature from 313 K to 343 K caused the recovery efficiency to increase from 52 to 76%. Pressure and CO2 flow rate were found to be less important. As expected, increasing extraction time resulted in higher recoveries. Ultrasonic pretreatment of the soil material was found to be very effective, possibly due to disrupting the strong interaction bonding between soil matrix and contamination

The biodegradation of benzene, toluene and phenol in a two-phase system

A two-phase aqueous-organic system was used to degrade benzene, toluene and phenol, individually and as mixture by Pseudomonas putida F1 (ATCC 700007). In the first stage of the work, the effect of the phase ratio (0-1, v/v) and the agitation rate (150 and 200 rpm) on the biodegradation process was investigated in an orbital shaker using 2-undecanone as the solvent and the most suitable phase ratio and agitation rate were found to be 0.0625 (v/v) and 200 rpm, respectively. P. putida F1 was added into the aqueous phase of the two-phase system, which consisted of a 40 ml aqueous phase and 2.5 ml 2-undecanone. Experiments were carried out at pH 7 and 30 degreesC. Benzene, toluene and phenol individually were consumed completely below concentrations of 4400 mg l(-1) benzene, 4200 mg l(-1) toluene and 600 mg l(-1) phenol according to the aqueous phase volume. The presence of the second phase (organic phase) not only prevented the inhibition effect of the substrates, but also decreased the biodegradation time. The maximum overall biodegradation rates of benzene, toluene and phenol were obtained as 183, 197 and 18 mg l(-1) h(-1), respectively. In the biodegradation experiments using mixtures, the presence of phenol did not change the biodegradation times of benzene and toluene and, the presence of benzene and toluene decreased the biodegradation times of phenol

Kinetics model for growth of Pseudomonas putida F1 during benzene, toluene and phenol biodegradation

The effect of adaptation of Pseudomonas putida F1 ATCC 700007 (Pp F1) to the biodegradation of benzene (B), toluene (T) and phenol (P) was studied. The adaptation of microorganism to BTP decreased the biodegradation time from 24 to 6 It for benzene (90 mg/1) and toluene (90 mg/1), and from 90 to 18 It for phenol (50 mg/1). Andrews kinetics model for single substrate was solved to obtain maximum specific growth rates, half saturation and substrate inhibition constant. Cell growth using toluene (mu(max.T) = 0.61) and benzene (mu(max.B) = 0.62) as carbon sources were better and faster than the growth in phenol (mu(max.P) = 0.051). For the substrate mixtures, a sum kinetics model was used and the interaction parameters were determined. These models provided an excellent prediction of the growth kinetics and the interactions between these substrates. Toluene inhibited the utilization of benzene (I-T, B = 5.16) much more than benzene inhibits the utilization of toluene (I-B.T = 0.49). Benzene (I-B.P = 0.27) and toluene (I-T.P= 0.14) enhance the biodegradation of phenol, and phenol inhibits the biodegradation of benzene (I-P.B = 1.08) and toluene (I-P.T = 1.03)

Substrate interactions during the biodegradation of benzene, toluene and phenol mixtures

Benzene, toluene and phenol were degraded completely at high initial concentrations by Pseudomonas putida F I ATCC 700007. Two hundred and fifty milligram per litre benzene, 225 mg/l toluene and 200 mg/l phenol were degraded individually in 19, 14 and 3 5 h, respectively. The biodegradation times increased on increasing the substrate concentration. The maximum biodegradation rates were 149 mg benzene/g dry cell h for 60 mg/l benzene, 44 mg toluene/g dry cell h for 110 mg/l toluene and 102 mg phenol/g dry cell h for 100 mg/l phenol. The specific growth rates were 0.530/h for 30 mg/l benzene, 0.410/h for 28 mg/l toluene and 0.037/h for 50 mg/l phenol and decreased on increasing the concentration of these compounds. Cell growth using toluene and benzene as carbon source was better and faster than growth in phenol. These substrates were also biodegraded as binary and tertiary mixtures. The presence of toluene, phenol and toluene-phenol binary mixture increased the biodegradation time of 60 mg/l benzene from 6 to 8, 11 and 8 h respectively. The presence of benzene and/or phenol did not affect significantly the biodegradation time of 55 mg/l toluene. The presence of benzene, toluene and benzene-toluene binary mixture decreased the biodegradation time of 200 mg/l phenol from 35 to 18, 15 and 16 h, respectively. (C) 2002 Published by Elsevier Science Ltd

Biodegradation of BTEX compounds by a mixed culture obtained from petroleum formation water

The biodegradation of BTEX compounds (benzene, toluene, ethyl benzene, and o,m, p-xylenes) by a mixed culture obtained from the formation of water, produced from the petroleum wells of the Turkish Petroleum Corporation (TPAO) in the Adiyaman region (southeast Turkey), and the effect of biomass concentration on the biodegradation rate of BTEX compounds, both alone and as a mixture, were investigated. The mixed culture, identified as Pseudomanas stutzeri and Vibrio mimicus, was grown on a brain heart infusion enriched medium at 30degreesC before its use in the biodegradation experiments. The biodegradation experiments were carried out using nonadapted, benzene-adapted, and toluene-adapted microorganisms. It was found that the mixed culture obtained degraded all BTEX compounds, both alone and as a mixture, and the overall specific biodegradation rates of BTEX compounds individually were higher with toluene-adapted microorganisms (both benzene and toluene: 4.27 mg/g biomass-day) than with the nonadapted (benzene: 0.096; toluene: 1.355 mg/g biomass-day) and benzene-adapted microorganisms (benzene: 3.4; toluene: 1.6 mg/g biomass-day). Similar results were obtained for BTEX compounds in a mixture. When the initial biomass concentration increased from 0.42 g/L to 2.34 g/L, the time required for complete biodegradation of both benzene and toluene decreased from 3 to 2 days with toluene-adapted microorganisms

Response surfaces of hazelnut oil yield in supercritical carbon dioxide

Response Surface Methodology was used to determine the effects of solvent flow rate (1, 3 and 5 g/ min), pressure (300, 375 and 450 bar) and temperature (40, 50 and 60 degreesC) on hazelnut oil yield in supercritical carbon dioxide (SC-CO2). Oil yield was represented by a second order response surface equation (R-2 = 0.997) using Box-Bhenken design of experiments. Oil yield increased with increasing SC-CO2 flow rate, pressure and temperature. The maximum oil yield was predicted from the response surface equation as 0.19 g oil/g hazelnut (34% of initial oil) when 4 g hazelnut particles (particle diameter < 0.85 mm) were extracted with 5 g/min SC-CO2 flow rate at 450 bar, and 60 degreesC for 10 min. Total extraction time at these conditions was predicted to be 35 min

Hydrate Formation Conditions of Methane Hydrogen Sulfide Mixtures

The objective of the study is to determine hydrate formation conditions of methane-hydrogen sulfide mixtures. An experimental work is carried out with different H2S concentrations and both brine and distilled water. The Black Sea conditions, which are suitable for methane-hydrogen sulfide hydrate formation, are examined. Effects of H2S concentration and salinity on the hydrate formation conditions are also obtained during the study. It is concluded that an increase in the salinity shifts the methane-hydrogen sulfide hydrate equilibrium condition to lower equilibrium temperatures at a given pressure. With an increase in H2S concentration, the methane hydrogen sulfide hydrate formation conditions reach higher equilibrium temperature values at a given pressure

Black Sea Hydrate Formation Conditions of Methane Hydrogen Sulfide Mixtures

The objective of the study is to examine hydrate formation conditions of methane-hydrogen sulfide mixtures providing the Black Sea conditions. An experimental work is carried out by using a system that contains a high-pressure hydrate formation cell with different H2S concentrations and both brine and distilled water. Hydrate equilibrium conditions, the number of moles of free gas in the hydrate formation cell, and rate of hydrate formation are determined. Effects of H2S concentration on the hydrate formation conditions are also obtained during the study. It is observed that with an increase in H2S concentration, the methane hydrogen sulfide hydrate formation conditions reach higher equilibrium temperature values at a given pressure. According to the experimental results, it is concluded that the Black Sea has suitable conditions for hydrate formation of methane hydrogen sulfide mixtures