Normal Paraffin Hydrocarbons Research Articles

Potentiality of Azolla pinnata R. Br. for Phytoremediation of Polluted Freshwater with Crude Petroleum Oil

The pollution of freshwater resources with crude petroleum oil is a major environmental issue in oil-producing countries. As a result, the remediation of polluted aquatic ecosystems using eco-friendly and cost-effective technology is receiving increased global attention. In this study, the ability of Azolla pinnata R. Br. to remediate petroleum-polluted freshwater was assessed. The remediation potentiality was determined by evaluating the total petroleum hydrocarbon degradation percentage (TPH%) and changes in the molecular type composition of saturated and aromatic hydrocarbon fractions. TPH% was estimated gravimetrically, and changes in the molecular type composition of saturated and aromatic fractions were measured using gas chromatography and high-performance liquid chromatography, respectively. The results reveal that A. pinnata has the potential to phytoremediate freshwater polluted with low levels (up to 0.5 g/L) of petroleum hydrocarbons (PHs). After seven days of phytoremediation, the degradation rate of total PHs was 92% in the planted treatment compared with 38% in the unplanted positive control. The highest breakdown of PHs for the normal paraffinic saturated hydrocarbon fraction occurred in the presence of A. pinnata combined with Anabena azollaea (A-A), which showed a moderate degradation capacity toward total aromatic hydrocarbons (TAHs) and total polycyclic aromatic hydrocarbons (PAHs). The results indicate that A. pinnata effectively removed C18, a saturated PH, and acenaphthene (Ace), an aromatic PH. Therefore, this study suggests that A. pinnata is a useful tool for the remediation of freshwaters contaminated with low pollution levels of crude oil.

Identification of hydrocarbon compositions of diesel fractions and assessment of their effect on fuel operational characteristics

Using the chromatography-mass spectrometric method of analysis the group hydrocarbon compositions of straight-run and hydro-dewaxed diesel fractions have been determined. The effects of hydrocarbons on the physicochemical and operational properties of the fractions were analyzed and compared with the requirements of the standard for winter diesel fuels. The molecular-mass distribution of normal paraffin hydrocarbons was considered in detail, as well as their relationship with the low-temperature properties of the fractions. The aromatic compounds were analyzed in the two-dimensional chromatography method. It was found that naphthalene hydrocarbons predominated in the straight-run diesel fraction, and benzene and indan derivatives dominated in the hydro-dewaxed fraction. It was proved by chromatographic analysis. For the straight-run and hydro-dewaxed diesel fractions optimal concentrations of a cetane-raising additive have been determined, which enable to achieve the requirements of standards for diesel fuels.

Effect of Nature of Nonpolar Hydrocarbon Solvents on Adsorption Capacity of Synthetic Fatty Acids, Amines, and Amides

The sorption of surface-active substances (surfactants), namely, C18–C21 synthetic fatty carboxylic acids (distillation residues of their production), a number of amines, and amides from films of pure, normal paraffinic hydrocarbons such as heptane, octane, nonane, decane, and pentadecane deposited on St3 steel immersed in 0.5 M NaCl solution, has been studied. Concentrations have been obtained at which the degree of surface filling with surface-active substances approaches unity. It is shown that surfactant adsorption takes place on an energetically inhomogeneous surface, and it seems that in a number of cases it is realized by the donor-acceptor interaction mechanism.

Modeling and simulation of diluent recovery unit in PUREX solvent regeneration system

The presented work details the modeling and simulation of distillation column for the separation of tributyl phosphate (TBP) and normal paraffin hydrocarbon (NPH) which is an integral unit in the PUREX solvent regeneration system. The vapor liquid equilibrium data of TBP + NPH system at 5.5 torr and 7.5 torr were experimentally generated using an ebulliometer and the data were subjected to thermodynamic consistency test using Herington's method. The experimental VLE data were correlated using Wilson and non random two-liquid (NRTL) models and the binary interaction parameters regressed from the data are reported. The distillation column simulation was carried out using an algorithm involving separate solver/corrector loops for the MESH variables and the NRTL model was used for predicting the vapor liquid equilibrium of TBP-NPH system. Validity of the developed code was tested by comparing the simulation outputs with the experimental results from PUREX solvent regeneration plant.

Kinetics of Extraction of Tributyl phosphate (TBP) from Aqueous Feed in Single Stage Air-sparged Mixing Unit

Abstract The mass transfer studies involving kinetics of extraction of Tributyl phosphate (TBP) saturated in 0.3 M nitric acid using different organic extractants viz. normal paraffinic hydrocarbon (NPH), kerosene, dodecane etc. have been performed in a novel air-sparged single stage mixing unit. Based on the mechanism, a simple kinetic model (analogous to first order) is proposed and experimental data was analyzed. The optimization studies including the effect of diluent, % TBP in NPH, Organic to Aqueous phase (O/A), air flowrate and the nitric acid concentration in aqueous phase have been performed. The experimental and modeled kinetic results suggest that the optimized conditions for the extraction of TBP (174 ppm to 65.5 ppm) from aqueous 0.3 M HNO3 feed are found to be, 3 % TBP in NPH as extracting solvent, O/A is 1/1 and volumetric air flowrate is 15 LPM. However, if pure NPH used as an extractant with these operating conditions 100 % removal can be obtained.

The Dynamic Change of Microbial Communities in Crude Oil-Contaminated Soils from Oil Fields in China

ABSTRACTTo study the biodegradability of microbial communities in crude oil contamination, crude oil-contaminated soil samples from different areas of China were collected. Using polyphasic approach, this study explored the dynamic change of the microbial communities during natural accumulation in oil field and how the constructed bioremediation systems reshape the composition of microbial communities. The abundance of oil-degrading microbes was highest when oil content was 3–8%. This oil content is potentially optimal for oil degrading bacteria proliferation. During a ∼12 months natural accumulation, the quantity of oil-degrading microbes increased from 105 to 108 cells/g of soil. A typical sample of Liaohe (LH, oil-contaminated site near Liaohe River, Liaoning Province, China) was remediated for 50 days to investigate the dynamic change of microbial communities. The average FDA (a fluorescein diacetate approach) activities reached 0.25 abs/hr·g dry soil in the artificially enhanced repair system, 32% higher than the 0.19 abs/hr·g dry soil in natural circumstances. The abundance of oil-degrading microbes increased steadily from 0.001 to 0.068. During remediation treatment, oil content in the soil sample was reduced from 6.0% to 3.7%. GC–MS analysis indicated up to 67% utilization of C10–C20 normal paraffin hydrocarbons, the typical compounds that undergo microbial degradation.

Kinetics of extraction of nitric acid into binary mixture of tri-n-butyl phosphate and normal paraffin hydrocarbon

The extraction kinetics of nitric acid with tri-n-butyl phosphate (TBP) dissolved in normal paraffin hydrocarbon (NPH) was investigated. Experiments were carried out in a constant area stirred cell. Influences of stirring speed, temperature, specific interfacial area and concentrations of extractant and nitric acid on the extraction rate of nitric acid were studied. The objective of the present study was to identify the reaction location, extraction reaction regime and to determine intrinsic rate constant of the reaction and mass transfer coefficients. A systematic approach was adopted for the determination of these rate parameters. Based on experimental results, it is concluded that the liquid-liquid reaction takes place at the interface and the overall rate is controlled by both the intrinsic kinetics as well as the mass transfer of the species involved.

Removal of tributyl phosphate from aqueous stream in a pilot scale combined air-lift mixer-settler unit: Process intensification studies

This work reports the removal of tributyl phosphate (TBP) from aqueous stream using organic solvent in an industrial scale combined air-lift mixer-settler unit (CAL-MSU) having 10 stages. The solute i.e., TBP is transferred from aqueous continuous (0.3M HNO3 saturated with TBP) to organic dispersed phase i.e., normal paraffin hydrocarbon (NPH). Effect of phase flow ratios on steady state, number of stages as well as mass transfer coefficient on TBP removal and mass transfer coefficient, is observed. The maximum TBP extraction efficiency of about 96% (201ppm to 8ppm) and maximum overall volumetric mass transfer coefficient of 13.3×10−5s−1 was observed at continuous phase flowrate 36 LPH and dispersed phase flowrate 24 LPH. For optimized operating parameters, the energy input per unit volume for 10-stage CAL-MSU and similar configuration 10-stage pump-mix mixer-settler are found to be 37.0kJ/m3 and 77.7kJ/m3, respectively.

Effect of Radiolysis in Altering the Physiochemical and Metal Retention Properties of Solvent-Diluent-Acid Systems

Systematic studies were performed on radiolytic degradation of Tri-n-Butyl Phosphate diluted with n-Dodecane or Normal Paraffin Hydrocarbon in the presence/absence of nitric acid as a function of absorbed gamma dose. Viscosity and phase disengagement time increased with absorbed dose but interfacial tension decreased gradually. The extent of damage caused during radiolysis was estimated by Zr retention in the organic phase. The effectiveness of carbonate wash in restoring the quality of the solvent was evaluated. Comparison of the IR spectra for the neat and the degraded samples revealed the formation of nitro alkanes at absorbed dose above 20 MRad.

Removal of dissolved tri-n-butyl phosphate from aqueous nitric acid solutions: kinetic studies

The present work deals with the kinetic study for the removal of dissolved TBP from aqueous nitric acid solutions using Normal Paraffin Hydrocarbon (NPH) as the solvent. Effect of different parameters like type of solvent, concentration of organic phase, concentration of aqueous phase, organic to aqueous phase (O/A) ratio and temperature on the extraction of TBP, has been successfully optimized. Around 62% of dissolved TBP was extracted from aqueous feed solution containing 0.3M HNO3 with 3% TBP in NPH as the solvent and O/A ratio of 1:1 in only 5 min at 35°C. The graphical representation of the kinetic expressions for different parameters predicted that the extraction of TBP follows the first-order behaviour. The rate constants values obtained from the first-order equation have also verified the optimized parameters. This study will provide an aid in development of a robust and effective process for removal of dissolved TBP with minimum waste generation.

Mass Transfer Studies in Pulsed Sieve Plate Extraction Column for the Removal of Tributyl Phosphate from Aqueous Nitric Acid

Removal of a saturated amount of tributyl phosphate (TBP) from a nuclear reprocessing aqueous waste stream is very important as far as economy of process as well as waste disposal is concerned. The present research work describes the detailed mass transfer studies for the removal of TBP from aqueous stream in a geometrically optimized pulsed sieve plate extraction column (PSPEC). The original industrial system, viz., 0.3 M nitric acid–TBP–normal paraffinic hydrocarbon (NPH), was used for the mass transfer studies. The effect of operating parameters such as continuous to dispersed phase velocity ratio and pulsed velocity on the volumetric mass transfer coefficient was investigated. The effect of operating parameters on the variation in axial concentration and holdup profile is also studied to evaluate the dynamic operation of the column for the attainment of steady state. The experimental results indicate that pulse velocity has a strong effect on the volumetric mass transfer coefficient, while the effect ...

Liquid–liquid extraction studies for the separation and recovery of plutonium from acidic medium with novel ligand Benzodioxodiamide (BenzoDODA)

Detailed liquid–liquid extraction studies of Pu(IV) with BenzoDODA have been carried out to evaluate the efficacy of BenzoDODA in the separation and recovery of Pu(IV) from acidic solutions. Acid uptake constant (KH) was determined to be 0.44. Incorporation of tertiary butyl group in the aromatic moiety of BenzoDODA resulted in the increase in extractability of Pu(IV) but at the expense of decrease in the selectivity for Pu(IV) vis a vis other metal ions. Among the various diluents studied, the normal paraffinic hydrocarbons, namely, n-dodecane/kerosene were found to be the most preferred diluents. BenzoDODA was found to be stable in radiation environment, with good extraction ability up to 20MRad. Number of stages required for the effective recovery of plutonium from the feed solution has been determined by McCabe Thiele’s plot. It was found that even at higher loadings of Pu(IV), there is no third formation which is remarkable since at these loading TBP/n-dodecane solvent system has shown considerable third phase formation. Thus, BenzoDODA/n-dodecane solvent system can be used for recovery of Pu(IV) from concentrated processing streams as well.

Non-Dispersive Solvent Extraction of Uranium from Nitric Acid Medium by Several Amides and their Mixture with TODGA using a Hollow Fiber Contactor

Non-dispersive solvent extraction (NDSX) of uranium from nitric acid feed solutions was studied using three dialkyl amides, viz. N,N-di-n-hexylhexanamide (DHHA), N,N-di-n-hexyloctanamide (DHOA), N,N-di-n-hexyldecanamide (DHDA), and their binary mixtures with TODGA (N,N,N’,N’-tetra-n-octyldiglycolamide) in normal paraffinic hydrocarbon (NPH) as the carrier solvents. The feed solution usually contained 10.6 g/L of uranium in 3 M HNO3 and the extraction studies were carried out using a commercial hollow fiber contactor operating in recirculation mode at a flow rate of 3 L/h. In a separate set of experiments, the stripping studies were carried out in the NDSX mode using the U loaded organic extract and 0.01 M HNO3 or 1 M Na2CO3 as the strippant. Use of TODGA along with the amides resulted in faster mass transfer rates though the extraction and stripping efficiencies of the dialkylamides were reversed in the mixture as compared to that observed in the absence of TODGA.

Mechanisms of the oxidation and combustion of normal paraffin hydrocarbons: Transition from C1–C10 to C11–C16

Mechanisms of the oxidation and combustion of normal paraffin hydrocarbons: Transition from C1–C10 to C11–C16

Liquid–Liquid Equilibria for Dipropylene Glycol–Hydrocarbon Binary Systems: Experimental Data and Regression

Propylene glycols (mono- and di-) have an important potential as solvents in liquid–liquid extraction of aromatics and in azeotropic distillation. Literature and databases provide few accurate experimental data on liquid–liquid and vapor–liquid equilibria in systems consisting of propylene glycols and hydrocarbons (paraffinic, naphthenic, and aromatic hydrocarbons). However, an increasing interest in this field can be observed in recent years. This paper reports the results of an experimental study on the liquid–liquid equilibria in binary systems consisting of dipropylene glycol and paraffinic, naphthenic, and aromatic hydrocarbons with six, seven, and eight atoms of carbon. The experimental data were obtained in a high-precision thermostatic equilibrium cell. The first and most important result was that all normal paraffinic and naphthenic hydrocarbons are partially miscible with dipropylene glycol (4-oxa-2,6-heptanediol), whereas aromatics are completely dissolved. To obtain the binary interaction para...

Comparison of normal phase operation and phase reversal studies in a pulsed sieve plate extraction column

The hydrodynamic characteristics of a pulsed sieve plate extraction column (PSPEC) was studied experimentally using two different liquid phase systems, namely water/kerosene and 30%TBP (tributyl phosphate) in NPH (normal paraffin hydrocarbon)/0.3M HNO3. The aqueous phase as the dispersed phase and the organic phase as the continuous phase (phase reversal) and vice versa (normal phase operation) studies in a pulsed sieve plate extraction column 0.076m in diameter and 1m height are presented in this paper. The hydrodynamic properties like drop size and holdup are characterized as a function of various operating parameters namely pulse velocity, dispersed phase and continuous phase velocity and duty cycle of pulsing. Flooding in the column was also investigated for the changes involving flow ratio of continuous phase to that of the dispersed phase for both insufficient and excessive pulsing. It has been observed that phase reversal mode of operation is not efficient as compared to normal phase operation for the PSPEC.

Comparative studies on the determination of di-n-butyl phosphate in degraded solvent of PUREX process by ion chromatography and gas chromatography methods

This paper describes comparative studies on the determination of di-n-butyl phosphate (DBP) by ion chromatography (IC) and gas chromatography (GC) techniques in spent solvent of PUREX process used for the reprocessing of spent nuclear fuels. The ion chromatography method involves the separation of DBP from 30% TBP–NPH (tri-n-butylphosphate diluted in normal paraffin hydrocarbon) containing heavy metal ion like uranium and nitric acid by extraction of DBP into alkaline medium. DBP was subsequently eluted by ion-exchange separation in ion chromatography column and followed by suppressed conductivity detection. DBP is quantified to a lower limit of about 1 ppm with 3% RSD. However, in order to determine DBP by gas chromatography technique DBP is first quantitatively converted into its volatile and stable derivatives by using diazomethane prior to analysis by GC. Results obtained with ion chromatographic technique are compared with those of obtained by standard gas chromatographic technique. It was observed that IC technique involves minimum steps and is much faster than GC analysis. The effect of mobile phase flow rate on the detector response, retention time, and column pressure are also investigated.

Accumulation of water-soluble gas by degasification: One of important mechanisms of large gas accumulations in the Xujiahe Formation, Sichuan Basin

Abstract In recent years, a lot of lithologic/structural-lithologic gas reservoirs were found in the Xujiahe Formation, Upper Triassic, Sichuan Basin, and most of the reservoirs contain water. We have carried out the study of the properties and characteristics of the fluid, and found the changes of natural gas components and carbon isotope which confirm the accumulation of water-soluble gas with degasification, namely, such accumulation far away from gas source features high methane, high drying factor, high ratio of isoalkane to normal paraffin hydrocarbons, and heavy carbon isotope in methane and ethane. Accumulations of water-soluble gas with degasification with reduction of pressure & temperature for strata uplift and with reduction of pressure & temperature for lateral migration of soluble gas along layer are the main forming mechanisms. The strong ground uplift, fluid decompression and reduction of temperature, local concentration of water salinity, and a wealth of water-soluble gas resources are the favorable conditions for the accumulation. We conclude that the accumulation of water-soluble gas with degasification is not only one of the important mechanisms of development of large lithologic gas reservoirs and large gas accumulations in Central Sichuan, but also a key reason for poor source rocks in the Xu1 Member but large gas accumulation in the Xu2 Member in the Hechuan-Anyue area.

Oxidation and combustion mechanisms of paraffin hydrocarbons: Transfer from C1-C7 to C8H18, C9H20, and C10H22

At the present time, detailed kinetic mechanisms (DKMs) for higher hydrocarbons, which include hundreds of particles and thousands of reactions, are proposed. These DKMs have a number of undoubted advantages because they aspire to description of a wide class of phenomena. However, their application, e.g., for modeling of turbulent combustion, is difficult due to their extreme inconvenience. In addition, they are limited to a certain degree and cannot be considered to be comprehensive. As an alternative to such DKMs, we construct no maximum mechanism in this work, but an optimum mechanism of high- and low-temperature oxidation and combustion of normal paraffin hydrocarbons. This mechanism, in accordance with the previously proposed algorithm, contains only general processes that govern the reaction rate and the formation of basic intermediate and final products. A such mechanism has the status of an nonempirical DKM because all parts, including elementary reactions, have kinetic substantiation. The mechanism itself has two features: (i) Reactions of so-called double addition of oxygen (first, to the alkyl radical, then to the isomerized form of the formed peroxide radical) are lacking because the first addition is considered to be sufficient; (ii) Isomeric compounds and their derivative substances as intermediate particles are not considered, because this means of oxidation is slower than through molecules and radicals of the normal structure. The application of the algorithm results in sufficiently compact mechanisms that are important for modeling chemical processes with the participation of paraffin hydrocarbons C n with large n. Previously, this was done for propane, n-butane, n-pentane, n-hexane, and n-heptane; in the present article, it was done for n-octane, n-nonane, and n-decane. The major feature of all the mechanisms is the appearance of stages, viz., cold and blue flames during low-temperature spontaneous ignition. The direct comparison of the calculation and experiment results is carried out.

Electro-oxidative process for the mineralization of solvent and recovery of plutonium from organic wastes

Mediated electrochemical oxidation is a promising technique for the destruction of organic compounds. Destruction of tributyl phosphate (TBP) in normal paraffin hydrocarbon (NPH) in nitric acid medium containing electro-generated Ag(II) was studied. Initially, the effect of uranium, presence of DBP along with uranium in the organic phase and direct electrochemical oxidation without catalyst (Ag) on the destruction of 30% TBP/NPH system was evaluated. For a comparison, the rate of destruction of NPH alone was studied. Further, radioactive laboratory waste solution was tested for the destruction of organic waste under similar experimental conditions. The electrolyte used in the system was 0.5 M AgNO3 in 8 M HNO3 at 333 K. The uniqueness in all these experiments is the use of a double end open porcelain diaphragm for the isolation of electrodes. Though there would be a slight reduction in the efficiency, two major hurdles viz., reduction in the concentration of nitric acid and reduction in the volume of catholyte resulting in an increase in cell voltage were avoided. The problem of the migration of Ag+/Ag2+ and accumulating at the cathode site was overcome by using double end open diaphragm and thorough mixing. The results revealed that the rate of destruction of organics is favoured in the presence of uranium in organic phase and with increase in temperature.