Oil Drop Research Articles

Coalescence Frequency in O/W Emulsions: Comparisons of Experiments with Models.

We have studied the coalescence of oil in water emulsions under the influence of gravity. The emulsions were made with alkane oils and surfactants with varying physical chemistry. We chose cationic alkyl trimethylammonium bromides of different chain lengths and nonionic surfactants of ethylene oxide and sugar head groups, including polymeric surfactants. We observed phase separation in two steps. Creaming of the oil drops is followed by their rapid coalescence, increasing the average drop size and resulting in complete surfactant surface coverage of the interfaces. Full phase separation occurs after much longer times Tc when the emulsion drops coalesce dramatically. We have used a model by Dinh et al. to relate Tc to the coalescence frequency and hence to the activation energy for the rupture of the films between two neighboring drops. Our results support the view that the coalescence of stable emulsions (stable at least for a few hours) is a thermally activated process and is controlled by the surface compression elastic modulus. This modulus was determined using surface tension measurements and calculations using the Gibbs adsorption equation. The observed differences between ionic and nonionic systems are attributed to a two-step film rupture process in the case of ionic surfactants, which is not found in nonionic systems.

Microscopic Remaining Oil Classification Method and Utilization Based on Kinetic Mechanism

In reality, the remaining oil in the ultra-high water cut period is highly dispersed, so a thorough investigation is required to understand the microscopic remaining oil. This will directly influence the technological direction and allow for countermeasures such as enhanced oil recovery (EOR). Therefore, this study aims to investigate the state, classification method and utilization mechanism of the microscopic remaining oil in the late period of the ultra-high water cut. To achieve this, the classification of microscopic remaining oil based on mechanical mechanism was developed using displacement CT scan and micro-scale flow simulation methods. Three carefully selected mechanical characterization parameters were used: oil–water connectivity, oil–mass specific surface and oil–water area ratio. These give five types of microscopic remaining oil, which are as follows: A (capillary and viscous oil cluster type), B (capillary and viscous oil drop type), C (viscous oil film type), D (capillary force control throat type), and E (viscous control blind end type). The state of the microscopic remaining oil in classified oil reservoirs was defined after high-expansion water erosion. Based on micro-flow simulation and analysis of different forces during the displacement process, the main microscopic remaining oil recognized is in class-I, class-II and class-III reservoirs. Within the Eastern sandstone oilfields in China, the ultra-high water-cut stage is a good indicator that the class-I oil layer is dominated by capillary and viscous oil drop types distributed in large connected holes. The class-II oil layer has capillary and viscous force-controlled clusters distributed in small and medium pores with high connectivity. In the case of the class-III oil layer, it enjoys the support of capillary force control throats that are mainly distributed in small holes with high connectivity. Integrating mechanisms of different types of micro-remaining oil indicates that, enhancing utilization conditions requires increasing pressure gradient and shear force while reducing capillary resistance. An effective way to improve the remaining oil utilization is to increase the pressure gradient and change the flow direction during the water-drive development process. Hence, this forms a theoretical basis and a guide for the potential exploitation of remaining oil. Likewise, it provides a strategy for optimizing enhanced oil recovery in the ultra-high water-cut stage of mid-high permeability oil reservoirs worldwide.

Oil recovery and cooling for underground salt cavern oil storage: Insights from coupled flow and thermal model

Petroleum reserve in salt caverns is paying more attention to oil cooling to prevent dissolved gas release from heated crude oil. This work introduced a method for oil recovery in conjunction with cooling, along with a matching flow and heat transfer model taking changes in crude oil thermophysical parameters into consideration. An average error of 3.43% was observed between the model results and filed monitoring data. It was found that after being cooled by the heat exchanger, the temperature of extracted crude oil drops from 39.5 °C to 26.8 °C, demonstrating the effectiveness of this approach for oil cooling. Sensitivity analysis indicates that the season is the primary determining factor for the cooling efficacy of crude oil. Even worse, cooling will be useless when the ambient temperature exceeds 35 °C. However, increasing brine temperature will reduce the surface pumping pressure from 7.60 MPa to 5.17 MPa, with a decrease of up to 31.97%. A special focus was given to the brine injection rate, which seemed to have less impact on the cooling efficiency but became more significant in the pressure profile. In addition to providing further insights into the flow and thermal performance of strategic petroleum reserves in the salt cavern, this study could also be a powerful tool for determining the best process parameters to ensure the delivery temperature of crude oil and the stability of the salt cavern.

Protein folding: Funnel model revised

The spatial structure of proteins, largely determined by their amino acid sequences, is also dependent on the environmental conditions under which the folding process takes place. In aqueous environments, exposure of polar amino acids is the driving factor, whereas protein stabilization in amphipathic membranes requires exposure to hydrophobic residues. This observation can be extended to all other environmental conditions under which proteins exhibit biological activity and, most importantly, to the folding process. The fuzzy oil drop (FOD) model assumes a centric location of hydrophobic residues (hydrophobic core) with exposure of polar residues towards the aqueous environment, as the influence of the aqueous environment is extended to include the contribution of other non-aqueous factors, enabling the assessment of their influence on protein structuring. The application of the modified FOD model (FOD-M) we have developed allows the environment to be represented as an external force field in the form of a continuum. The role of environmental conditions allows modification of the funnel model expressing the localization of the energy minimum as dependent on external conditions expressed by the K scale, where K measures the degree of other than polar water factors participating in folding process.

Modulating outcomes of oil drops bursting at a water–air interface

Recent studies have shown that capillary waves generated by the bursting of an oil drop at the water–air interface produces a daughter droplet inside the bath, while a part of it floats above it. Successive bursting events produce next generations of daughter droplets, gradually diminishing in size until the entire volume of oil rests atop the water–air interface. In this work, we demonstrate two different ways to modulate this process by modifying the constitution of the drop. First, we introduce hydrophilic clay particles inside the parent oil drop and show that it arrests the cascade of daughter droplet generation preventing it from floating over the water–air interface. Second, we show that bursting behavior can be modified by a compound water–oil–air interface made of a film of oil with finite thickness and design a regime map, which displays each of these outcomes. We underpin both of these demonstrations by theoretical arguments providing criteria to predict outcomes resulting therein. Finally, all our scenarios have a direct relation to control of oil–water separation and stability of emulsified solutions in a wide variety of applications, which include drug delivery, enhanced oil recovery, oil spills, and food processing, where a dispersed oil phase tries to separate from a continuous phase.

Water interaction with MCC powder exposed to wetting–drying cycles: Comparison of capillary imbibition techniques

We investigate how wetting-and-drying (WD) cycles change the properties of microcrystalline cellulose (MCC) powder (Avicel PH101), due to hornification, by performing the following experiments: (i) drop absorption in a slightly compressed powder bed, (ii) capillary imbibition in a packed powder column, and (iii) drop absorption into tablets obtained by direct compression. We use the MCC powder as received, as well as the powder obtained after one or more WD cycles. In each case, the powder is sieved and fractionated into two samples, with different particle size distribution. First, we perform drop absorption experiments using both water and silicone oil (Polydimethylsiloxane - PDMS) drops. We observe that WD cycles increase the absorption time for water, a particularly marked effect after the first cycle, for both particle size distributions. Comparing the absorption times of water and oil drops we obtain a parameter β that characterizes the water-MCC interaction in lieu of the contact angle, and accounts for both capillary and swelling phenomena. We observed that the main effect is produced after the first WD cycle exhibited by a large (more than 50%) reduction in the β value. Column imbibition experiments performed using water and PDMS show that, initially, water penetrates at a larger rate than PDMS. This initialing faster water uptake is more significant for larger particles and fewer WD cycles. A power law regime is obtained in each case with a ζ exponent. In particular, a Washburn-like imbibition regime with ζ=0.5 is recovered at long times for both liquids. In the last experimental technique, we study the absorption of water drops deposited on tablets obtained by direct compression of the full distribution of powder particle sizes. We observe that absorption time increases with increasing number of WD cycles of the MCC powder. This is quantified by the 30% reduction of the ζ exponent that models the penetration rate of the drop.In summary, we use three kinds of experiments that cover a wide range of characteristic time scales to quantify the effect of WD cycles on the interaction of water with a swelling powder like MCC. The importance of comparing responses under different timescales is that the swelling phenomenon modifies the properties of the material in time, while imbibition happens. It is shown by this study that in some cases, the phenomena can be decoupled (droplet absorption in porous media) while in other cases it cannot be (droplet on tablets and intermediate times in capillary rise). Finally, at long times in capillary rise, even when the swelling and imbibition effects are not decoupled, it is possible to estimate the permeability ratio, χ, and its dependence with the WD cycles when the results are used in combination with the ones from the droplet absorption on powder test. The permeability decreased about 8 times for no WD cycles, and it decreased much less (2 and 3 for small and large particles respectively) for one and two WD cycles. We were able to quantitative characterize the effects of water-MCC interaction and this is important in order to predict how some pharmaceutical processes, like wet granulation, will be affected.

Probing the Interfacial Interaction Mechanisms of Nitrogen with Dodecane/Toluene: Implications for Foam Flooding.

Interfacial interactions between deformable bubbles and oil drops have attracted much attention in foam flooding. However, interactions involving nitrogen bubbles have not been reported. In this work, the interaction forces between nitrogen and dodecane/toluene in aqueous solutions were quantified using the atomic force microscopy bubble probe technique. The effects of the solution pH, ionic type, and solution concentration on the interactions were analyzed. The van der Waals (vdW), electric double layer (EDL), and hydrophobic (HB) interactions were involved in the low-concentration solutions. The EDL repulsion in NaCl increased with solution pH, while in CaCl2 and MgCl2, the EDL repulsion in general decreased and then increased with pH, attributed to the adsorption of OH- and divalent cations and their hydration products. The adsorption of divalent cations at the toluene/water interface was pronounced by cation-π interactions. At pH 10, precipitated divalent cation hydroxides at the bubble/water and oil/water interfaces adsorbed more cations, causing the increase of the surface potential. At high salinity, the EDL interaction was suppressed and the vdW repulsion became predominant. The vdW force of nitrogen with toluene was stronger than that with dodecane. Under all of the solution conditions, the attractive interaction could not overcome the total repulsive interaction at the minimum separation, and thus no bubble attachment was observed, which implied that a stable bubble/liquid/oil film was essential for maintaining foam stability. This work provides useful insights into the interfacial interaction mechanisms in nitrogen foam flooding. The findings can be readily extended to other engineering systems such as oil flotation and bubble-oil-water emulsions.

Unveiling the antimicrobial and antibiofilm potential of biosurfactant produced by newly isolated Lactiplantibacillus plantarum strain 1625.

The present study aimed to characterize the biosurfactants synthesized by lactic acid bacteria (LAB) obtained from fermented foods, optimize the conditions for increasing the yield of biosurfactants and explore their antimicrobial and antibiofilm potential. Out of the 26 LAB isolates, isolate BS2 showed the highest biosurfactant production as indicated in the oil displacement test, drop collapse and emulsification activity. BS2 was identified as Lactiplantibacillus plantarum 1625 using 16S-rRNA gene sequencing and phylogenetic analysis. The biosurfactant produced by BS2 was identified as an anionic glycol-lipo-proteins by employing Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The biosurfactants produced by L. plantarum 1625 demonstrated strong antibacterial and antibiofilm characteristics against pathogenic strains such as Staphylococcus aureus MTCC 1049, Escherichia coli MTCC 1587, and Pseudomonas putida MTCC 1655. The minimal inhibition concentration value of antibacterial activity was found to be 0.1 mg/mL with the inhibition percentage ranging from 90 to 95%. Further, the effect of temperature, pH, and substrate composition on biosurfactant production was also studied to enhance it production using the Box-Behnken Design approach of Response surface methodology (RSM). Application of biosurfactant led to a considerable decrease in biofilm-forming harmful bacteria, as proven by scanning electron microscopy analysis. The results highlight the potential uses of biosurfactants in distinct industries, and biotechnological contexts, especially in the creation of new antimicrobial and antibiofilm agents.

Chameleon Sequences-Structural Effects in Proteins Characterized by Hydrophobicity Disorder.

Repeated protein folding processes both in vivo and in vitro leading to the same structure for a specific amino acid sequence prove that the amino acid sequence determines protein structuring. This is also evidenced by the variability of structuring, dependent on the introduced mutations. An important phenomenon in this regard is the presence of a differentiated secondary structure for chain fragments of identical sequence representing distinct forms of the secondary-order structure. Proteins termed chameleon proteins contain polypeptide chain fragments of identical sequence (length 6-12 aa) showing structural differentiation: helix versus β-structure. In the present paper, it was shown that these fragments represent components matching the structural status dictated by the physicochemical properties of the entire structural unit. This structural matching is related to achieving the goal of the biological function of the structural unit. The corresponding secondary structure represents a means to achieving this goal, not an end in itself. A selected set of proteins from the ChSeq database have been analyzed using a fuzzy oil drop model (FOD-M) identifying the uniqueness of the hydrophobicity distribution taken as a medium for recording the specificity of a given protein and a given chameleon section in particular. It was shown that in the vast majority, the status of chameleon sections turns out to be comparable regardless of the represented secondary structure.

Modelling and predicting lift force and trans-membrane pressure using linear, KNN, ANN and response surface models during the separation of oil drops from produced water

This study aims to improve the efficiency and reliability of membrane filtration systems used to treat produced water by accurately predicting lift force, transmembrane pressure (TMP), and total resistance (TR) using ML models, namely linear, K-nearest neighbors (KNN), and artificial neural networks (ANN). The dataset was split into training, validation, and test sets, allowing for comprehensive training and evaluation of model performance. Linear, KNN and ANN models achieved high R-squared scores (R2) of 0.998, 0.996, and 0.999 and low mean squared error (MSE) values of 0.0000046, 0.0002763, and 0.000004621 for Lift force prediction, respectively. For TMP prediction, these models showed R2 values of 0.801, 0.90, and 0.72 and MSE values of 0.01236, 0.109, and 0.283, respectively. Similarly, these models predicted TR with R2 scores of 0.76, 0.78, and 0.78 and MSE values of 0.2087, 0.025, and 0.22, respectively. These results indicate that KNN is particularly efficient in accurately predicting the membrane parameters and could be a robust tool to optimize membrane filtration processes. Response surface modelling (RSM) elucidates the relationship between input and output parameters. Initially, the increase in drop size and shear has a minimal impact on the lift force. Beyond a drop size of 0.3 μm and shear rate 1200 S−1, lift force rises significantly. TMP initially increases with shear rate, peaking at a value of 1200 S−1, then decreases with higher shear rates. Optimal conditions identified are higher shear rates and drop sizes >0.3 μm to maintain lower TMP and effective filtration. Findings from the study suggest that employing predictive modelling can significantly enhance the efficiency and reliability of produced water treatment, by improving contaminant removal, reducing energy consumption and cost, potentially reducing environmental impacts, and improving sustainability in the oil and gas industry.

The outer-membrane componentof the multi-drug efflux system –a structural analysis based onhydrophobicity distribution

The structure of a multi-drug efflux system (specifically the outer membrane part) is the focus of our analysis. The role of electrostatic interactions in the efflux process is well understood. The distribution of hydrophobicity in the periplasmic and membrane domains plays a significant role in both stabilisation within the membrane and in tunnel formation, which facilitates the transport of antibiotics. The analysis presented in this paper reveals the specificity of hydrophobicity distribution in relation to biological activity, as well as a possible mechanism for the folding process of proteins involved in multi-drug efflux. Our analysis is made possible by the application of the fuzzy oil drop model in its modified form (FOD-M).

The impact of lavender essential oil inhalation on fatigue and stress of mothers of premature infants

Background and aimThe hospitalization of premature infants can lead to fatigue and stress for mothers. This research aimed to investigate the impact of inhaling lavender essential oil on fatigue and stress levels of mothers with premature infants in the neonatal intensive care unit. Materials and methodsThis study was conducted in Valiasr and Shariati hospitals on 72 mothers of premature infants from 2022 to 2023. In the intervention group, the mothers inhaled two drops of lavender essential oil for 30 min every other day for four weeks. No intervention was implemented for the control group. we used demographic questionnaires, the Multidimensional Fatigue Inventory, and the Parental Stressor Scale in the Neonatal Intensive Care Unit. two weeks after the intervention, and four weeks after the intervention. The collected data were analyzed using SPSS 26, independent t-, Fisher's exact, chi-square, and analysis of covariance tests. ResultsThe independent t-test revealed no statistically significant differences in fatigue and stress before the intervention (P-value>0.05). However, two weeks after the intervention, the analysis of covariance indicated significant differences in fatigue and stress between the two groups. Similarly, four weeks after the intervention, there were significant differences in fatigue and stress between the two groups(P-value<0.05). ConclusionThe study results indicated that inhaling lavender essential oil was effective in reducing fatigue and stress levels among mothers of premature infants.

Effects of different temperatures on the embryonic development of the Lebranche mullet Mugil liza.

We herein investigated the influence of temperature on theembryonic development (from fertilisation to hatching) of Mugil liza larvae. For this purpose, oocytes (>600 μm) and sperm were obtained from breeding stock at the laboratory of marine fish culture (LAPMAR). After fertilisation, 1200 eggs were distributed in 12 cylindrical experimental units of 400 mL under four different temperatures 18, 22, 26 and 30 ºC, all in triplicate. Every 15 min until hatching, about 10 eggs were randomly sampled in each treatment. The eggs were visualized and photographed, and the classification of embryonic stages was performed. Temperature influenced the main events of the embryonic development of M. liza. More accelerated development was observed according to the increase in temperature until the gastrula phase. At temperatures of 22 and 26 °C, embryonic development occurred from fertilisation to hatching of the larvae. In the 18 °C treatment, it was verified that most of the embryos ceased development during the final phase of cleavage and the beginning of blastula formation, while in the 30 °C treatment patterns of embryo malformation were also verified, with erratic divisions of the blastomeres, resulting in irregular cells. Unlike what was observed at a temperature of 18 °C, none of the embryos incubated at 30 °C reached the blastopore closure phase, stopping in the gastrula. The larvae hatched in the treatments at 22 and 26 °C were viable and exhibited intense swimming, with a large amount of reserve material (yolk) and an evident drop of oil.

Fabrication of pea protein isolate-stabilized oil-in-water emulsions with high freeze-thaw stability: Effect of high intensity ultrasonic on emulsions and interfacial protein structure

The poor freeze-thaw stability of plant protein-based emulsions posed a major challenge for their application in the cold chain foods. The present study successfully prepared oil-in-water emulsions stabilized solely with pea protein isolate (PPI) with excellent freeze-thaw stability using a facile high intensity ultrasonic (HIU)-assisted method. The optimized emulsion can endure three freeze-thaw cycles without stratification or oil leakage, maintaining oil droplet sizes at the nanometer scale. Furthermore, changes of interfacial protein structure induced by HIU were systematically investigated to reveal the stabilizing mechanism. The freeze-thaw stability of emulsions treated under varying intensities was evaluated based on changes in the appearance and oil drop size distribution. The results showed that the oil drop size of emulsions decreased from micron to nanometer and the freeze-thaw stability was significantly enhanced with the increase of HIU intensity. The emulsion exhibited optimized freeze-thaw stability under 800W. Subsequently, the effect of HIU on the structure of interfacial protein was analyzed through SDS-PAGE, –SH/S–S contents, UV spectrum, surface hydrophobicity, protein adsorption percentage, emulsifying activity and interfacial dilatational rheology. It was found that HIU triggered crosslinking of disulfide bonds among interfacial PPI molecules and enhanced the strength of the interface layer. Additionally, HIU promoted the unfolding of interfacial PPI structure, resulting in the improvement of surface hydrophobicity, emulsifying activity, and interfacial adsorption percentage of PPI. The study demonstrated the feasibility of using HIU to improve the freeze-thaw stability of oil-in-water emulsions stabilized with PPI and provided references for the fabricating of plant protein-based frozen emulsion foods.

Bursting of Underwater Oil Drops.

For decades, two main facets of underwater oil spills have been explored extensively-the rise of oil drops and resulting evolution of the oil slick at the air-water interface. We report on the bursting of rising oil drops at an air-liquid interface which precedes slick formation and reveal a counterintuitive bulge reversal that releases a daughter oil droplet inside the bulk as opposed to upward-shooting jets observed in bursting air bubbles. By unraveling the underlying physics we show that daughter droplet size and bulk liquid properties are correlated and their formation can be suppressed by an increase in the bulk viscosity.

About the 3D virtualization of the Millikan oil drop experiment

Abstract Robert Millikan’s experiment, conducted in 1909, aimed to measure the charge of the electron. This experiment holds immense significance in the fields of electricity and magnetism and is widely performed by physics and chemistry students worldwide. While there are simplified two-dimensional recreations of this experiment available, obtaining measurements that closely resemble reality through a three-dimensional recreation is not easily accessible. This article delves into the development process of this three-dimensional recreation, achieved through reverse engineering of the original experiment using the Unity video game engine. Additionally, it incorporates laboratory equipment, user manuals, and a student guide to ensure a comprehensive experience. By comparing the data obtained from the virtual recreation with that of the real experiment, it was observed that the precision of the virtual experiment resulted in a mere 7% error. Consequently, the virtual experiment can be used as a substitute for the real experiment when circumstances prevent its execution, without compromising the hands-on experience.

Penerapan Intervensi Kombinasi Aromaterapi Lemon dan Guided Imagery dalam Asuhan Keperawatan pada Klien dengan Diagnosis Medis Post Operasi Open Reduction Internal Fixation Fraktur Ekstremitas Hari Ke-1 di Bangsal Bedah RSUD Sleman

Background: Bone fracture is one of the most common injuries with a global prevalence in 2020 reaching 2.7% with 1.3 million fracture cases occurring annually in Indonesia. Postoperative pain is one of the impacts felt by patients. One pain management that can be done is non-pharmacological management by providing combination therapy between aromatherapy and guided imagery. However, this pain management needs to be studied further because differences in patient characteristics influence the response to each therapy given. Objective: To find out the application of combination therapy between aromatherapy and guided imagery in reducing pain levels. Case Report: This study is a case report with a 21-year-old male patient who came to the emergency department due to a traffic accident. The nursing diagnosis made in this patient was acute pain related to physical injury agents and the medical diagnosis was post-operative open reduction internal fixation (ORIF) cruris and right clavicle. The non-pharmacological management provided is in the form of aromatherapy using a diffuser containing 50 ml of water and 5 drops of lemon aroma essential oil, as well as guided imagery. Pain level evaluation was carried out before and after the intervention. Results: The application of lemon aromatherapy and guided imagery is effective in reducing post-operative pain, as evidenced by the pain scale being reduced from 8 to 3. Conclusion: The application of combination therapy between aromatherapy and guided imagery is effective in reducing pain levels in post-operative patients.

Comprehensive analysis of 19 cannabinoids in commercial CBD oils: concentrations, profiles, and safety implications

Nineteen cannabinoids, including Δ9-THC (tetrahydrocannabinol) and CBD (cannabidiol), were quantified in 22 CBD oils, 2 CBG (cannabigerol) oils, and 2 CBN (cannabinol) oils, marketed as food supplements, aroma oils, or cosmetic preparations. Analyses were conducted using high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The declared concentrations of CBD (or CBG, CBN) in the oils ranged from 2.5 to 20%. Actual concentrations compared to declared concentrations ranged from 81 to 226%. CBD concentrations of up to 9 mg per drop were found. Δ9-THC was detected in 20 of 26 samples, with concentrations ranging from 5 to 1576 mg/kg (mean = 536 mg/kg). Considering the highest daily intake suggested by one manufacturer (20 drops) and a body weight of 70 kg, the measured Δ9-THC concentration in 50% (n = 13) of the products would exceed the acute reference dose (ARfD) of 1 µg/kg body weight (bw) derived for Δ9-THC by the European Food Safety Authority (EFSA). For 7 samples, only 2 drops of oil would be sufficient to exceed the ARfD of Δ9-THC.

Mechanism of Crude Oil Biodegradation in Bioreactors: A Model Approach

Oil-degrading bacteria have the ability to degrade alkanes present in crude oil because of a special enzymatic system, the alkane hydroxylase complex (AlkH). The mechanism for the transport and degradation of alkanes present in crude oil remains unclear, especially related to the first step in hydrocarbons oxidation. In this work, we present a novel model of the crude oil biodegradation mechanism by considering the contact between the oil drop and the cell and calculating the mass transfer coefficients in three oleophilic bacteria (B. licheniformis, P. putida and P. glucanolyticus). The mass transfer coefficients are evaluated under critical time conditions, when the kinetics and mass transport are in balance, and the difference in the values obtained (kL α = 1.60 × 10−3, 5.25 × 10−4 and 6.19 × 10−4 m/d, respectively) shows the higher value of the mass transfer coefficient and higher biodegradation potential for B. licheniformis. Because the morphology of the cells has been analyzed by optical and electron microscopy, in the proposed model, the increase in the size of the cells in P. glucanolyticus compared to P. putida exhibits higher values of the mass transfer coefficients and this is attributed, as a novel statement, to a bigger window for alkanes transport (contact area) when the external area of the cell is bigger.

Research on the blocking mechanism of oily sewage reinjection based on microfluidic technology

Reinjection into reservoirs to displace oil is an environmentally friendly and efficient way to treat and use produced oily sewage. However, the permeability damage to the reservoir by the small oil droplets in the oily sewage (usually called oil-in-water, OIW) is a huge challenge in oil industry. In this work, microfluidic device is designed to qualitatively and quantitively evaluate the OIW damage using both micro-homogeneous model and micro-heterogeneous model together with core flooding experiments. The results show that OIW can cause serious permeability damage (more than 60%) to the porous media after 50 PV sewage injection due to the adsorption and accumulation of oil drops in four main forms: oil droplet blockage, column oil blockage, cluster oil blockage, and blind oil blockage. To relieve the OIW damage, according to the composition of oil in the produced water, a new oily blockage removal system, which is composed of organic solvent, surfactant, and alcohol, is developed to solve the problem of pore blockage caused by OIW. The three components in blockage removal system cooperate with each other can effectively remove the blockage in pores caused by OIW, and the permeability recovered to more than 96% of the initial permeability values after 20 PV injection of blockage removal system.