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The ZnO nanoparticles were synthesized using marine brown algae (Cystoseira) extract and calcination. For comparison, combustion, and sol–gel methods were employed to synthesize nanoparticles to use as material in dye-sensitized solar cells (DSSCs) photoanode. The produced nanoparticles were characterized using structural and morphological studies by FTIR, SEM, and XRD experiments, respectively. The results revealed that the net hexagonal crystal structure was achieved with a crystal size of less than 100 nm, good purity, spherical shape, and a suitable dimension for fabricating DSSCs. They exhibit enhanced properties due to the variation in their characteristics such as average size, size distribution, and morphology. The ZnO nanoparticles were used to fabricate the DSSCs by the doctor blade method, and the efficacy of each cell was evaluated using voltage–current measurement. The results were in good agreement with the characteristic curve of the commercialized DSSC. The best performance for the fabricated DSSCs was achieved using green synthesized ZnO nanoparticles, because of the influence of their morphology such as smaller crystal size, more grain boundaries, and bigger surface area. The cell’s solar-to-electricity conversion efficiency, short-circuit current, open-circuit voltage, and fill factor were measured as [Formula: see text]1.13%, 3.8[Formula: see text]mA/cm2, 620[Formula: see text]mV, and 54.3%, respectively. The enhanced photovoltaic properties were ascribed to the flower-like morphological structures of the ZnO nanoparticles prepared using the green synthesis method.

Biomass (especially algae) is a renewable energy source that can be a great alternative to fossil fuels. Wet algal biomass converts into products such as solid, aqueous, and gaseous phases as well as biocrude in hydrothermal liquefaction (HTL). The aim of this work was to provide detailed exergy analyses of the production of biocrude from Nannochloropsis sp. by HTL. Physical and chemical exergy of the HTL products, exergy losses, exergy efficiency, and exergy distribution of the HTL process were determined in this research. The highest exergy loss and the lowest efficiency values obtained for the heat exchanger were 65,856.83 MJ/hr and 66.64%, respectively, which was mainly caused by the irreversibility of the heat transfer process. Moreover, the HTL reactor had high efficiency (99.9%) due to the complex reactions that occurred at high temperature and pressure. Also, the optimum operating conditions of the reactor were obtained at 350 °C and 20 MPa by using sensitivity analysis. The high overall exergy efficiency of the process (94.93%) indicated that HTL was the most effective process for the conversion of algae. In addition, the exergy recovery values of the overall exergy input values in the HTL process for biocrude, as well as the aqueous, solid, and gas phases, were nearly 74.88%, 18.42%, 0.86%, and 0.76%, respectively. Exergy assessment provides beneficial information for improving the thermodynamic performance of the HTL system.

Economic estimation of an environmental-friendly biomethanation process based on economic values of consumed and produced gases would be a unique attitude. In this paper, time and space dependent concentration profiles of components involved in a batch process, designed for biomethanation, were predicted through a mass transfer modelling. The reaction terms used in the modeling required bio-kinetic parameters of μmax, m, kL, YC/L, YX/L, and YP/L which were globally optimized via a predefined algorithm using some experimental data as 0.0987 day1, 0.1374 day1, 1.5422 mole m−3, 1.3636, 0.0183, 0.0908. Upon model verification, process income was calculated for a long-term scenario under a variety of factors and maximized through response surface methodology. The maximum income achieved was $-0.4/m3 bioreactor. A term carbon subsidy was considered in the income equation in order to find a break-even income for subsidy value of $363/ton CO2. Sensitivity analysis revealed that the amount of carbon subsidy directly influenced the selection of low or high levels of some process parameters to make the process profitable. In addition, it was found that pressure and liquid volume were the most important factors to achieve maximum income when $30 and $300/ton CO2 carbon subsidy were allocated to the process, respectively.

One of the most advantageous methods for lowering water hardness is the use of low-cost adsorbents. In this research, the effectiveness of natural zeolite (clinoptilolite type), activated carbon, and activated alumina was evaluated. These adsorbents were sequentially modified by NaCl, HCl, and NaCl-HCL to improve their ability to adsorb. The contact time and the amount of adsorbent used in the adsorption process were investigated experimentally to determine their effects. The results indicated that the best contact time for hardness reduction was 90 min, and the best concentrations of adsorbents in drinking water for zeolite, activated carbon, and activated alumina were 40, 60, and 60 g/L, respectively. In addition, for groundwater, these figures were 60, 40, and 40 g/L, respectively. The greatest possible decreases in total hardness under the best conditions by natural zeolite, activated carbon, and activated alumina adsorbents were 93.07%, 30.76%, and 56.92%, respectively, for drinking water and 59.23%, 15.67 %, and 39.72% for groundwater. According to the results obtained from experiments, NaCl-modified zeolite, natural zeolite, and NaCl-HCl-modified activated carbon performed better in terms of parameter reduction. The equilibrium data were well fitted by the Langmuir isotherm model, whereas the kinetic data for the adsorption process were consistent with the pseudo-second-order model. The equilibrium study of the adsorption process by the Morris–Weber model revealed that both chemical and physical adsorption are involved.

This chapter introduces the PVT challenges of gas injection. First, the phase diagram of various gases, oil samples and mixtures of oil and gas are investigated. In the next part, the important PVT experiments are discussed in details. These experiments consist of CCE (constant composition expansion), DL (differential liberation), CVD (constant volume depletion), flash separation and swelling test. Some calculation must be considered for designing the gas injection process as it is discussed in Sect. 2.4. In Sects. 2.5, 2.6 and 2.7, three cases are studied about change of phase behavior due to gas injection, MMP calculation of gas injection and asphaltene precipitation due to gas injection, respectively. The optimum design of gas injection and PVT challenges associated with gas injection are presented in Sects. 2.8 and 2.9, respectively.

After primary and secondary recovery, substantial amounts of hydrocarbon remain entrapped by capillary forces. This phenomenon, known as capillary trapping. Different factors affect the microscopic trapping mechanism such as pore structure, wettability, capillary pressure, interfacial tension, relative permeability, initial saturation, and other properties of the rock and fluids. Understanding the amount of trapped phase is vital for different applications such as enhance oil recovery (EOR), enhanced gas recovery (EGR), and carbon capture and storage (CCS). In EOR and EGR, the purpose is reducing residual oil saturation, while for CCS, it is opposite, i.e. the target is maximising the amount of trapped CO2. There are two main capillary trapping mechanisms, snap-off and by-passing which are described in detail in this chapter. The laboratory methods and empirical mathematical models that are used to measure and predict the trapped phase saturation are discussed in this chapter. Furthermore, there are various techniques for the mobilization of the trapped hydrocarbon phase. Gas injection is one of the effective methods to remove the trapped phase. This chapter discusses some of the key aspects of phase trapping and mitigation methods.

In this study, hydrophilic gilsonite fine particles were produced by reaction of natural gilsonite with a mixture of sulfuric acid and nitric acid followed by a planetary ball mill process. The hyd...

Wax deposition is a common problem in oil pipelines and production systems. In this study, impact of water cut, mixing rate, chemical inhibitor, and time on wax deposition were investigated in a cold finger setup. Effect of different chemical inhibitors on wax appearance temperature (WAT) was studied using viscometry and differential scanning calorimetry techniques. Results suggested that WAT reduced with increasing inhibitor concentration, with 800 ppm being the optimum. Also, chloroform–toluene–ethylene vinyl acetate (EVA) mixture with 30, 30, and 40 wt% had the highest performance and reduced the WAT to 16.7 °C. Mixtures of toluene—EVA with acetone, p-xylene, and disulfide oil (DSO), followed next. Moreover, deposition decreased with increasing temperature difference between oil and pipe at constant cold surface temperature and increased upon increasing temperature difference at constant oil temperature. Wax deposition in two-phase system was lower than in single-phase system, but increased by increasing water cut. EVA–toluene, 2 wt% DSO, 2 wt% acetone, and 2 wt% p-xylene mixtures reduced the deposition to 23.33, 21.71, 32.14, and 12.5%, but addition of 2 wt% of EVA–DSO–acetone mixture reduced deposition to 35.74%. At similar operating conditions, flow turbulence has greater impact on reducing wax deposition, and its effect is enhanced using a proper inhibitor.

In this work, we studied the feasibility of using disulfide oil (DSO) as a solvent for wax prevention in pipelines. Several tests were carried out to determine the effects of DSO, ethylene-vinyl acetate (EVA), acetone, and p-xylene and their mixtures on wax appearance temperature (WAT), deposition mass, and rheological properties of oil samples. The WAT was determined from viscosity in the temperature range of 2–40 °C with 1 °C min−1 cooling rate. Viscoelastic modulus of different samples was measured at temperature intervals of 25–65 °C with 0.5 °C min−1 cooling rate. Results indicated that DSO has a good potential for reducing WAT and wax deposition mass; however, increasing DSO concentration to higher than 800 ppm did not show a significant effect on deposition reduction. It was found that a mixture of inhibitors had higher impact on reducing wax deposition. Using 800 ppm of EVA–DSO–acetone mixture resulted in deposition mass reduction to about 35.74%. It was found that the strong original gel network was considerably weakened by addition of DSO.

Molecular simulation of particles aggregation is a time-intensive computation. In this study, we have developed a computational methodology to simulate the aggregation and fragmentation of particles. Scaling relations are developed that can be used to decrease the number of primary particles towards minimization of the computation time. The developed methodology is applied to reproduce the experimental data of particles aggregation and fragmentation. Results show the capability of the proposed methodology to represent the experimental data. Then, the model is applied to predict the onset of precipitation, the amount of precipitated particles, and their particles size distribution. The simulation results are in agreement with the experimental data. The proposed simulation methodology and the scaling relations find applications in simulation of particles aggregation and fragmentation.

In this research, the influence of a variety of operational factors such as the temperature of the reaction, gas flow rate, concentration of NaCl, and the amount of Ca(OH)2 for reducing the environmental impacts of desalination reject brine using the calcium oxide-based modified Solvay process were investigated. For this purpose, response surface modeling (RSM) and central composite design (CCD) were applied. The significance of these factors and their interactions was assessed using an analysis of variance (ANOVA) technique with a 95% degree of certainty (p < 0.05). Optimal conditions for this process included: a temperature of 10 °C, a Ca(OH)2/NaCl concentration ratio of 0.36, and a gas flow rate of 800 mL/min. Under these conditions, the maximum sodium removal efficiency from the synthetic sodium chloride solution was 53.51%. Subsequently, by employing the real brine rejected from the desalination unit with a 63 g/L salinity level under optimal conditions, the removal rate of sodium up to 43% was achieved. To investigate the process’s kinetics of Na elimination, three different kinds of kinetics models were applied from zero to second order. R squared values of 0.9101, 0.915, and 0.9141 were obtained in this investigation for zero-, first-, and second-degree kinetic models, respectively, when synthetic reject saline reacted. In contrast, according to R squared’s results with utilizing real rejected brine, the results for the model of kinetics were: R squared = 0.9115, 0.9324, and 0.9532, correspondingly. As a result, the elimination of sodium from real reject brine is consistent with the second-order kinetic model. According to the findings, the calcium oxide-based modified Solvay method offers a great deal of promise for desalination of brine rejected from desalination units and reducing their environmental impacts. The primary benefit of this technology is producing a usable solid product (sodium bicarbonate) from sodium chloride in the brine solution.

Flare gas recovery (FGR) is known as an option to reduce greenhouse gases (GHG) from oil and gas refineries. The major concerns about environmental impacts of GHG emission lead refineries to deploy different FGR methods, most of which requiring new equipment and high cost of design and construction. In this paper, feasibility of three methods for FGR is evaluated in a giant gas refinery in Iran. The first two methods considered liquefaction and LPG production by implementing flare gases as feed for existing LPG unit. Different parameters were studied in feed liquefaction and LPG production. The third studied option is using a three-stage compression unit to compress the flare gases. Finally, an economic evaluation was performed to find the most profitable method. Based on simulation results, the 0.75-barg pressure of flash drum leads to maximum LPG production. For FGR, the 1-barg pressure of flash drum recovered the most CO2-equivalent from releasing into the atmosphere, which is more than 205 ton/day. The economic evaluation shows that rate of return (ROR) for liquefaction unit and LPG production unit are more than 200% for different scenarios and are higher than compression.

The elimination of carbon dioxide (CO2) using water-based nanofluids (NFs) in a hollow fiber membrane contactor (HFMC) using polypropylene (PP) membrane was experimented. Gas flows in the shell, while NF flows in the fibers. Metal oxide nanoparticles (NPs) such as aluminum oxide (Al2O3), titanium dioxide (TiO2) and silica (SiO2) in the concentrations of 0.05, 0.1 and 0.2 wt % were used in the experiments. Some factors such as gas flow rates, NPs type, NF temperature, NP concentration, as well as the effect of particle size on the separation were investigated. The results clearly show that the highest flux of CO2 occurred for 0.2 wt % concentration of Al2O3 NFs. Mass transfer flux enhancement (MTFE) was defined as the relative mass transfer flux (MTF) of CO2 in the NFs with respect to the MTF of CO2 in the de-ionized water as the base fluid. MTFE changed from 1.29 to 2.25 for the Al2O3 NFs. Among all the results, the best result was obtained for Al2O3 (40 nm) at 1.6 Lit/min liquid flow rate, 25 °C liquid temperature, 5 Lit/min gas flow rate and 40% inlet CO2 concentration which is 98.9% CO2 removal. Finally, a new correlation was developed for the Sherwood (Sh) number for the CO2 mass transfer in the NFs flowing in the fibers. Sh number was developed based on the NFs Reynolds (Re) number, NPs Reynolds (Renp) number, Schmidt (Sc) number, and NPs volume fraction with an average relative error percent (REP) of 1.6% and R2 of 0.99.

Wettability alteration of the reservoir rock is considered as one of the promising remedies for the condensate blockage. There are key parameters including wettability state (WS), treatment radius (TR), and treatment time (TT) that considerably influence this treatment process. The objective of this paper is to conduct simultaneous optimization of WS, TR, and TT in a supergiant gas condensate reservoir located in Persian Gulf offshore. For this purpose, two distinct optimization methods are used in this research. The Taguchi design of experiment (DOE) method is first used to find the optimal state with a low number of simulation runs. Afterward, a smart optimization approach is developed through integration of the artificial neural network (ANN) and genetic algorithm (GA) techniques; this hybrid method helps to assess more possible combinations of the three key factors. Also, the compositional commercial reservoir simulator ECLIPSE 300 is used to simulate gas production operation, considering different WS, TR, and TT conditions. It was found that both the Taguchi and the hybrid constructed network (ANN-GA) methods lead to the results in agreement with the simulation results so that the magnitudes of average absolute relative error are 0.6397% and 0.0436% for the Taguchi and ANN-GA, respectively, based on gas recovery factor (GRF) data. However, the ANN-GA method estimates a slightly higher GRF at the optimum state, compared to the Taguchi. Nevertheless, Taguchi DOE with only 25 required data points seems a promising and practical option for modeling and optimization purposes. The ANN-GA optimum condition corresponds to 50.64% GRF with intermediate WS, a TR of 12.7 m, and a TT of about 5 months.

Co-sensitization is an effective strategy to achieve panchromatic light-harvesting and to enhance dye-sensitized solar cell performance. In this work, the potential of the extracted natural dyes from Malva verticillata and Syzygium cumini was evaluated as mono and co-sensitizers in DSSCs. The UV–vis absorption spectra revealed that the combination of studied dyes had a high molar extinction coefficient and cumulative absorption properties in a way that its absorption spectra overlapped the spectral domain where the original sensitizers lacked light-harvesting. Moreover, all investigated dyes were characterized using circular dichroism, dynamic light scattering, zeta potential, cyclic voltammetry, and Fourier-transform infrared spectroscopy. The results of zeta potential analysis showed that the pigment aggregation and their colloidal stability, which has implications for the pigment adsorption process on TiO2 nanoparticles, were effectively controlled by varying the pH of the dye extract. Based on the CV results, the studied dyes indicated excellent redox stability and sufficient thermodynamic driving force for efficient electron injection. Based on the photovoltaic results, the acidified cocktail-DSSC had the highest I s c and η of 3.15 mA and 1.84 %, respectively. This superiority could be ascribed to the panchromatic light-harvesting, the excellent optical activity, and the appropriate energy levels of the acidified cocktail. Moreover, the loading of acidified cocktail dyes on the TiO2 surface was enhanced due to their homogeneous dispersion, less steric hindrances, and multi-anchor groups attached to the semiconductor surface. Based on the stability results, the treated cocktail-DSSC retained about 52.51 % of its as-fabricated efficiency after seven days while NDSSCs sensitized with acidified Syzygium cumini, Malva verticillata, Syzygium cumini, and cocktail retained about 26.24 %, 14.80 %, 16.35 %, and 15.25 %, respectively.

Wettability alteration is an important mechanism to increase recovery from oil and gas reservoirs. In this study, effect of fluorine-doped silica coated by fluorosilane nanofluid on wettability alteration of carbonate rock was investigated. The nanoparticle synthesized by sol-gel method was characterized using XRD, FTIR, SEM, and DLS. Adsorption of nanoparticle on rock was characterized by FESEM, and composition of rock after treatment was determined by EDXA. Effect of nanofluid on wettability was investigated by measuring static, advancing, and receding contact angle and surface free energy, imbibition of water, crude oil, and condensate of untreated and treated carbonate rock. Also, stability of contact angle and thermal stability of nanofluid were studied. ‎Results show that contact angles for water, condensate, and crude oil were altered from 37.95°, 0°, ‎and 0° to 146.47°, 145.59°, and 138.24°. In addition, water, condensate, and oil imbibition ‎decreased more than 87, 88, and 80%, indicating...

CO2 miscible injection method combined with surfactants and silica nanoparticles was studied to investigate the effect of these additives on CO2 mass transfer parameters to the light oil, including diffusion coefficient, mass transfer coefficient and solubility. Silica nanoparticles with controlled size distribution were synthesized in isooctane/1-hexanol/CTAB/ammonium hydroxide, a highly-stable reverse micellar system with w o =5. The presence of Si-O-Si and Si-O-H bonds in FTIR spectra of the system revealed that silica nanoparticles are formed by partial hydrolysis of TEOS. Results of DLS indicated that the average size and size distribution of the synthesized nanoparticles were 27.6 nm and 13-76 nm, respectively. Diffusion tests were carried out using CO2 gas and three liquid systems: isooctane/1-hexanol, isooctane/1-hexanol/CTAB reverse micellar system without nanoparticles, and isooctane/1-hexanol/CTAB reverse micellar system with nanoparticles. Results of modeling and optimization of the gas-liquid systems under nonequilibrium interface condition, using pressure decay data show that the presence of surfactants and nanoparticles leads to decreased gas diffusion coefficient; while increased interface mass transfer resistance due to presence of aqueous droplets and nanoparticles as well as lower solubility of CO2 in the light oil are the results of applying these additives, which limits their application. The obtained CO2 diffusion coefficients for isooctane/1-hexanol, reverse micellar system without nanoparticles, and reverse micellar system with nanoparticles are 8.5550×10−8, 8.2216×10−8, and 8.1114×10−8 m2/s, respectively.

Disulfide oil (DSO) mostly burned or stored is known as a low-grade byproduct in gas refining industries. This material is highly perilous to environment. A common way to reduce the environmental impact of DSO is blending in a specific ratio with gas condensate stream in gas refinery. This would improve DSO quality and consequently strengthen its unique application. In this work, density, viscosity and surface tension of DSO and gas condensate mixtures were measured and modeled. Viscosity and density of DSO, gas condensate, and their mixtures were measured in temperature range of 283.15–318.15 K. In addition, surface tension was measured at 298.15 K at different volumetric fractions of DSO–gas condensate mixture. Excess molar volume (V E), viscosity deviation (∆μ), deviation of excess Gibbs free energy (∆G E), and excess surface tension (σ E) were determined based on measured properties. Results showed a positive and negative trend for excess molar volume and excess surface tension, respectively. While fluctuation was observed in viscosity deviation and deviation of excess Gibbs free energy and results showed positive and negative values in different mole fraction. In addition, Redlich–Kister equation is proposed to predict excess properties of DSO and gas condensate mixtures.

Near wellbore condensate blockage phenomena commonly reduce gas production significantly. One efficient method for overcoming such problem is wettability alteration. Such issues as wettability state, treatment radius and time to reach the maximum level of production need be optimized prior to field application. In this paper, impact of these parameters are studied on gas and condensate production enhancement through wettability alteration. To do this, behavior of a well located in supergiant offshore Iranian gas condensate field is simulated and analyzed using a compositional model, single well and radial grid. The real fluid and reservoir properties of the studied well are utilized to construct the model. Different wettability states were defined using various relative permeability curves at various distances from the wellbore along with different treatment times are tested to find the best condition. Results indicate that near-wellbore wettability alteration leads to lower critical condensate saturation which has a significant impact on improving production parameters and reservoir recovery factors. Also, the highest recovery factor is achieved at optimal conditions where wettability is altered from strong liquid-wet to intermediate-wet at the small radius around the production well in early times. Furthermore, the inflow performance relationship curve (IPR) moves upward considerably which represents the magnificent production improvement.

As the ages of most oil fields fall in the second half of their lives, many attempts have been made to enhance oil recovery in an efficient way. Gas injection into oil reservoirs for enhanced oil recovery (EOR) purposes requires relative permeability as a crucial issue in reservoir engineering. In this study, a new method is applied to predict relative permeabilities of gas/oil system related to various rock and fluid types. For this reason, a soft computing technique - multi-gene genetic programming (MGGP) is employed to develop tools for prediction of relative permeability. The new methods are evaluated by experimental data extracted from open literature and are validated by extensive error analysis. The generated smart mathematical equations are able to predict relative permeabilities of gas/oil system with high accuracy and are applicable for various types of rock and fluid as well. In contrary to other reported correlations, the new novel equations require oil API and gas molecular weight as extra input variables to improve their estimating ability for every type of rock and fluid. The proposed technique is promising and encouraging for petroleum and reservoir engineers to be implemented for other gas/oil petro-physical properties.

Scale formation is the major problem in mono-ethylene glycol regeneration units of gas refineries. In this study, the effect of adding different concentrations of silica nanoparticles on the growth rate of salt crystals in a rich mono-ethylene glycol solution is investigated, and the corresponding mathematical model is introduced. To obtain the crystallization kinetics, the particle size distribution was measured in continuous intervals of time and temperature using a dynamic light scattering. Measurements were taken at four temperature levels, in 20-min intervals, and 1, 3, 5, and 9 wt% of silica nanoparticles. Results showed that silica nanoparticles reduced the activation energy needed for nucleation and crystallization by more than 50%. However, increasing the concentration of nanoparticles did not result in a further reduction in the activation energy. Rather, it contributed to the formation of larger primary nuclei that form a larger crystal structure. An increase in temperature from 25 to 50 °C led to an increase of 8.8% in the initial crystal growth. On the other side, increasing the concentration of nanoparticles from 1 to 10 wt% at a constant temperature increased the crystallization growth rate by 3.4%. The proposed mathematical model predicts the kinetics of crystal growth with an acceptable accuracy with the mean relative error of 6.19% for the whole range of concentration and temperature.

One of the major issues in biomethanation studies, especially a batch strategy without mixing, is gaseous substrate mass transfer between gas and liquid phases. The strategy can be assumed as a simplified form of a stagnant underground gas reservoir. Hydrogen gas, as the limiting substrate, plays significant role in biomethanation. Being informed of hydrogen content diffused within the liquid phase for calculating percentage of active volume, help researcher to make a proper decision on bioreactor design or adjusting process parameters. For this purpose, a mass transfer modelling was developed which strengthened with a set of optimized biokinetic parameters. Parameter optimization was accomplished with the help of a predefined optimization algorithm and using a set of experimental data with the source of literature. Active volume calculation was successfully performed via the verified model and response surface methodology was served for maximizing it under variety of process conditions. It was found that the bioreactor height to width ratio significantly affected on active volume followed by pressure and temperature. In addition, working with a bioreactor with a circle cross section, in comparison with a square one, improved the maximum active volume up to 43% due to providing higher surface area for mass transfer. Sensitivity analysis verified the previous findings and revealed that higher pressures and temperatures linearly increased the active volume while increasing the bioreactor height to width ratio exponentially decreased the response. Furthermore, a wide bioreactor have potential to promote active volume up to 72% rather than a vertical one.

At the end of preliminary hydrocarbon production by natural depletion, substantial amounts of hydrocarbon remain entrapped in reservoirs due to their heterogeneity and capillary forces. Knowing the amount of the trapped phase and mechanisms of trapping are crucial in proper designing of oil recovery projects. In this work, we evaluated the different trapping models that represent the relationship between initial and residual saturations and proposed a suitable model for different types of rock and fluids. The accuracy of each model was evaluated by different experimental data, and the model parameters were fitted by curve fitting. Results showed that the Spiteri et al. and Ma and Youngren models could predict residual saturations better than other trapping models. The maximum R2's of the Spiteri et al. and Ma and Youngren models were 1 and 0.99 for oil/brine systems, and 0.95 and 0.97 for gas-brine fluid pairs, respectively, regardless of the type of porous media. These two models accurately fitted the Initial-Residual (IR) experimental data of the gas-oil system that were obtained in this study. The effect of various parameters such as initial oil saturation, porosity, interfacial tension, flow rates, capillary numbers, and porous medium types on trapping in an unconsolidated sand pack were experimentally studied. The results imply that in the water-wet sand pack, the residual saturation increased by increasing the initial saturation and interfacial tension. However, increasing the porosity, mobility of oil phase, flow rate, and capillary number seems to have made for a decrease in the amount of trapped phase. It was also shown that trapping was more likely to occur in unconsolidated sand packs than in carbonate ones.

In this paper, the electrochemical method was used as a rapid and sensitive method to measure the antioxidant activity of Acanthophora red macro-algae (collected from the Persian Gulf coast of Bushehr-Iran). The algae extract was obtained by a combination of maceration and microwave methods, and then the important volatile and bioactive compounds were identified by GC-Mass analysis. To prepare the sensor and improve the electrochemical signal, gold nanoparticles synthesized by the green method were used to modify the electrode surface. Differential pulse voltammetry method (DPV) was used to investigate the inhibitory effect of the extract on ABTS and DPPH radicals. To investigate the ability of the Acanthophora algae extract to prevent DNA damage induced by Fenton reaction, an electrochemical biosensor was designed based on the immobilization of human interleukin-2 (IL-2) gene probe on the surface of gold nanoparticle-modified carbon screen-printed electrode. Then, the protective effect of the algae extract was investigated by electrochemical impedance spectroscopy. Finally, the toxicity effect of Acanthophora algae extract on the HT-29, SKOV3, MCF-7, and SKMES-1 cancer cell lines was evaluated by MTT assay.

The significance of gas compressibility factor in petroleum engineering encourages the researchers to employ the most accurate and precise methods for estimation of this factor. Commonly, empirical correlations due to their simplicity have been referred more than other approaches for prediction of Z-factor. There is no clear and reliable report to address an appropriate combination of correlation and mixing rule for each type of gas. In the present study, combination of several empirical correlations and mixing rules is examined and a decision tree is constructed to suggest best combination for each gas system. For this reason, 2329 experimental data were used for analysis. According to the results, Leland–Mueller mixing rule/Sanjari and Lay correlation is the best combination for sour and natural gas. Also, Van Ness–Abbot mixing rule/Hall–Yarborough correlation, Stewart–Burkhardt–Voo mixing rule/Heidarian correlation and Satter–Campbell mixing rule/Papay correlation are the most appropriate combination for gas condensate, binary and ternary mixtures respectively. For binary mixtures, a robust and novel empirical correlation was developed based on Kay mixing rule to estimate Z-factor. The results employed how good the new correlation is in agreement with the experimental data with significant R-squared 0.9843.

In this study, wound dressings consisting of dexpanthenol (Dex)-loaded electrospun nanofibers were fabricated using polyvinyl alcohol (PVA)/sodium alginate (SA), and chitosan as the core and the shell, respectively. Considering the remarkable properties of chitosan, it was used as a shell against drug release and to improve the thermal stability, and tensile strength of the scaffold. By comparing the thermogravimetric, and tensile strength results of nanofibers with and without shell, it was revealed that the presence of chitosan in the shell side could improve the thermal stability and increased the tensile strength by about three times. The isotherm models of dexpanthenol release from the PVA/SA/Dex-CS scaffold was best described by the Langmuir model. Besides, Fourier transform infrared, scanning electron microscopy, and X-ray diffraction techniques were performed to characterize nanofibers. Furthermore, an in vivo investigation of a wound dressing with dexpanthenol showed better healing compared to the wound dressings without dexpanthenol.

Asphaltene is known as a class of polar poly-nuclear aromatic compounds of crude oil which is extracted by its solubility difference in normal heptane and toluene. Precipitation of this hydrocarbon compound by changing in fluid thermodynamic conditions decelerates flow when passing through up-stream and down-stream processes. In order to understand the thermodynamics of the deposition phenomenon, one needs to pay attention to the kinetics of the aggregation of these nano-particles. In this study, the kinetics phenomenon of aggregation of asphaltene clots in toluene is investigated using dynamic light scattering (DLS) technique. The dynamic light scattering results for super dilute solutions showed that at high and low sonication time, the asphaltene is monomeric and polymeric forms, respectively. Moreover, the experiments revealed that the relationship between the amount of sonication energy given to the solutions and the particle size is logarithmic. The DLS spectra obtained from the lower-sonication solutions were decomposed to the four normal distributions using the deconvolution technique, indicating four different clusters in the solution. The ratio of the area of each normal distribution to the area of the spectrum indicates the fraction of the presence of each cluster in the solution. For the lower and the higher concentrations of the asphaltene solution, the percentage of nano-aggregates is between 8%-41% and 4%–51%, respectively. By assuming the asphaltene molecule to be on a coin-shaped plate and forming a π bond with a minimal coinage overlap, the coin model of asphaltene aggregation kinetics has been developed. The concentration of each nano-aggregates in equilibrium solution is calculated according to the fraction of its presence in the medium and the coin model. Then, these equilibrium concentrations are used to calculate the equilibrium reaction constants. The correlation coefficient between the reaction constants and the diffusion coefficients of the clots in the solutions for all reactions was found to be equal to 0.42. This same value indicates that this coefficient is independent of the concentration of asphaltene in the solution and is dependent on the nature of the solution.

The skin prevents infection and contamination entering the body, and wound dressings are one of the most serious tools in wound healing. In the present work, the biocompatibility and swelling tendency of nanofibers increased by adding alginates to a polymer solution is investigated. Glutaraldehyde was used in different methods to strengthen nanofibers, and it was found that a better cross-link was made from the combination of glutaraldehyde with the polymer solution before electrospinning. As the use of drug accelerates the healing process, dexpanthenol was added to the polymeric composition of polyvinyl alcohol (PVA) and sodium alginate (SA) using a blending method. The resulting composition was then used as the core of the nanofibers, and drug release was controlled by different shells. The results showed that the presence of chitosan 1% (w/v) in the shell side of nanofibers helped better control the drug release. Also, the drug release from dexpanthenol-loaded wound dressing followed the Fickian diffusion mechanism with the Korsmeyer-Peppas model. MTT analysis and cell culture indicated that dexpanthenol-loaded PVA/SA/Triton-Chitosan nanofibers not only were nontoxic to the fibroblast cells but also appropriately affected the cellular attachment and morphology. It was revealed that PVA/SA/Triton-Chitosan nanofibers could be used for tissue engineering applications.

Altering the wettability of a gas-liquid system from liquid-wetting to intermediate gas-wetting is a novel strategy for removing condensate from gas condensate reservoirs. In this paper, the role of a silica nanofluid modified by fluorine groups in the wettability alteration of seven carbonate samples was investigated. An acid test and Energy Dispersive X-ray Spectroscopy analysis were carried out to identify the levels of calcite and dolomite as dominant carbonate minerals and evaluate the coating ability of the proposed chemical used on carbonate surfaces. Contact angle measurements and spontaneous imbibition experiments were conducted before and after wettability alteration. In addition, gas flooding experiments were conducted on three permeable core samples to investigate the effect of the nanofluid on the fluid flow at the core scale. Contact angle measurements demonstrated that the wetting tendency of core samples altered from liquid-wetting into gas-wetting after surface treatment, and a higher contact angle was achieved for carbonate cores with less dolomite than calcite. EDX analysis showed more fluorine and silica adsorption on calcite, compared to dolomite cores. After surface modification, the brine imbibed into carbonate core samples 1 to 7 decreased by 0.104, 0.174, 0.0016, 0.773, 0.355, 0.056, and 0.279, respectively. Core flooding results demonstrated that the recovery factor of three permeable core samples increased from 56.52%, 49.69%, and 65.33%–69.34%, 56.75%, and 76.72%, respectively.

Condensate vaporization in porous media occurs in several processes such as remediation, absorption/adsorption in packed beds, and gas recovery. Most of modeling/simulation investigations on condensate recovery processes assume local equilibrium to model mass transfer rate of components involved in the inter-phase mass transfer phenomenon. This assumption does not seem realistic, since high fluid velocity and limited contact area may result in an appreciable deviation from the equilibrium condition. In this study, vaporization of liquid condensate components into the flowing gas stream is explored through experimental and modeling approaches. We take into account the non-equilibrium inter-phase mass transfer. A key parameter in the non-equilibrium mass transfer is the mass transfer coefficient. Lack of adequate laboratory data concerning the vaporization of condensate components into the gas phase motivated us to conduct a systematic experimental work. Taguchi design of experiment (DOE) is implemented to optimize the experiments in terms of number of runs and process conditions. To accurately estimate the mass transfer coefficient, the diffusion/dispersion and convection mass transfer mechanisms are incorporated in the modeling of condensate vaporization in porous systems for the first time. The statistical tests are also employed to assess the relative importance of diffusion/dispersion and convection mechanisms in the condensate vaporization process. The optimum levels of design factors are found using signal to noise ratio (SNR) plots generated through using the Taguchi DOE. According to the statistical analysis, the diffusion term has no considerable impact on the magnitude of the mass transfer coefficient. The experimental results also reveal that the highest relative significance/contribution (about 36%) belongs to the gas flow rate. The second place is given to the liquid type with 28.83% contribution. The gas type and mean grain size hold the third and fourth ranks with 11.8% and 10.61% contributions, respectively. The experimental results confirm non-equilibrium mass transfer over condensate vaporization event, particularly at high-velocity conditions. Combining the theoretical concepts and experimental data, new empirical mass transfer correlations are suggested in this study that can be incorporated in commercial software packages for obtaining the mass transfer coefficient with a high precision.

Nowadays, the treatment of dimethyl sulfoxide (DMSO) and N, N-dimethylacetamide (DMAC) wastewaters are a serious concern because of the use of these materials as a solvent in various industries such as pharmaceutical, electronic and acrylic fiber manufacturing process. In this research, employing of Fenton process for treatment of DMSO and DMAC wastewaters by considering the effect of operating parameters such as different initial DMSO and DMAC concentration, reaction time, initial pH, and different concentrations of Fenton’s reagent were investigated. Experimental results illustrated that the maximum degradation efficiency for the treatment of synthetic DMSO wastewater was equal to 89.9 %, 89.7 %, 94.5 %, and 97.6 %, for initial concentration of DMSO equal to 250, 500, 1000, and 2000 mg.L−1, respectively. The maximum degradation efficiency of 81.9 %, 92.9 %, 94.8 %, and 95.8 % was reached at best operational conditions of the Fenton process for 250, 500, 1000, and 2000 mg.L−1 initial concentration of synthetic DMAC wastewater respectively. Kinetics study results presented that the kinetic reaction of DMSO and DMAC degradation by the Fenton process at all initial concentrations were well fitted with the BMG model.

The major proportion of dye-sensitized solar cells (DSSCs) fabrication cost is attributed to the pigments. In this study, to increase the performance/cost ratio of DSSCs, we used several wild regional plants of Persian Gulf zone for natural pigment production. At first, the optimum conditions for pigment extraction were obtained for all plants using response surface methodology. The results showed that increasing temperature, as well as extraction time, increased the pigment extraction efficiency while the pH of the solution did not exert a significant effect on the extraction process. Besides, the microwave-assisted method and pure ethanol have the highest extraction efficiency compared to ordinary solvent extraction and water as the extraction method and solvent, respectively. Moreover, all pigments were characterized using circular dichroism, dynamic light scattering, and zeta potential techniques. The results showed that the extracted pigments from Malva verticillata have the highest optical activity while all kinds of pigments tend to make aggregates 12 h after the extraction. Finally, the effectiveness of each pigment was evaluated as a sensitizer in natural DSSCs that fabricated using the doctor blade technique. Based on the photovoltaic results of the DSSCs sensitized with extracted pigments, the open circuit voltage and short circuit current ranged from 0.35 to 0.542 V and 0.802 to 1.702 m A , respectively. The Microwave-assisted Malva verticillata-DSSC owned the highest energy conversion efficiency of 1.702% as well as the comparable open circuit voltage to that of the reference DSSC that made using synthetic sensitizer. This superiority could be attributed to the highest pigments concentration as well as the highest pigments optical activity of Malva verticillata. Moreover, the results showed that the LUMO energy level and the band gap of the extracted pigments from Malva verticillata are better than the other natural pigments for DSSC fabrication. Besides, due to the presence of carbonyl and hydroxyl groups in chemical structures of extracted pigment from Malva verticillata, an effective bond between the pigment and TiO2 surface might be achieved and thereby increasing the energy conversion efficiency.