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.
Storage of CO
2
in deep saline aquifers is a promising techniques to mitigate global warming and reduce greenhouse gases (GHG). Correct measurement of diffusivity is essential for predicting rate of ...transfer and cumulative amount of trapped gas. Little information is available on diffusion of GHG in saline aquifers. In this study, diffusivity of CO
2
into a saline aquifer taken from oil field was measured and modeled. Equilibrium concentration of CO
2
at gas-liquid interface was determined using Henry’s law. Experimental measurements were reported at temperature and pressure ranges of 32–50°C and 5900–6900 kPa, respectively. Results show that diffusivity of CO
2
varies between 3.52–5.98×10
−9
m
2
/s for 5900 kPa and 5.33–6.16×10
−9
m
2
/s for 6900 kPa initial pressure. Also, it was found that both pressure and temperature have a positive impact on the measures of diffusion coefficient. Liquid swelling due to gas dissolution and variations in gas compressibility factor as a result of pressure decay was found negligible. Measured diffusivities were used model the physical model and develop concentration profile of dissolved gas in the liquid phase. Results of this study provide unique measures of CO
2
diffusion coefficient in saline aquifer at high pressure and temperature conditions, which can be applied in full-field studies of carbon capture and sequestration projects.
The gas compressibility factor, also known as Z-factor, plays the determinative role for obtaining thermodynamic properties of gas reservoir. Typically, empirical correlations have been applied to ...determine this important property. However, weak performance and some limitations of these correlations have persuaded the researchers to use intelligent models instead. In this work, prediction of Z-factor is aimed using different popular intelligent models in order to find the accurate one. The developed intelligent models are including Artificial Neural Network (ANN), Fuzzy Interface System (FIS) and Adaptive Neuro-Fuzzy System (ANFIS). Also optimization of equation of state (EOS) by Genetic Algorithm (GA) is done as well. The validity of developed intelligent models was tested using 1038 series of published data points in literature. It was observed that the accuracy of intelligent predicting models for Z-factor is significantly better than conventional empirical models. Also, results showed the improvement of optimized EOS predictions when coupled with GA optimization. Moreover, of the three intelligent models, ANN model outperforms other models considering all data and 263 field data points of an Iranian offshore gas condensate with R2 of 0.9999, while the R2 for best empirical correlation was about 0.8334.
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Recent developments in nanofluids indicate that the addition of nanoparticles to water-based drilling muds can alleviate many drilling problems, including wellbore instability, lost ...circulation, torque and drag force, differential pipe sticking, and low drilling rates. In this study, the addition of hydrophilic Gilsonite nanoparticles (HGNs) to water-based drilling mud was investigated, and its effects upon the well-cleaning process, rheological properties, filtration loss reduction, lubricity characteristics, and, more importantly, on the differential sticking of the base fluid were evaluated. Hence, initially, the HGNs were characterized by means of Fourier transform infrared spectroscopy, the dynamic light scattering technique, as well as thermogravimetric and differential thermogravimetric analysis. The results showed that after the addition of HGNs, the rheological behavior of the base mud before the hot roll process was improved, and, interestingly, after the hot roll at 149 °C and 4 h, the characteristics of the sample mud were significantly retained, compared to those of the base mud. Also, after the hot roll, the plastic viscosity (PV) improved, the yield point (YP) was remarkably maintained, and the ratio of YP/PV was enhanced. On the other hand, the American Petroleum Institute (API) filtration loss was reduced by 36%, and, additionally, after the hot roll process, the filtration loss reduction and the mud cake thickness in high-pressure high-temperature conditions diminished by 79.4% and 50%, respectively. After the hot rolling process, the lubricity coefficient and torque percentage dropped by 15% and 13.63%, respectively. Also, the HGNs reduced the differential sticking coefficient and increased the likelihood of differential sticking release of the base fluid by 61.5%.
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 paper, the efficacy of wild natural dyes as the sensitizer was investigated for the fabrication of natural dye-sensitized solar cells (DSSCs). The natural pigments were extracted from Crocus ...sativus (Saffron), Allium cepa L (red onion), Malva sylvestris (Mallow), and Oregano (Origanum vulgare) using solvent extraction method. Based on the UV–vis results, the extracted solutions have been shown to contain anthocyanin or chlorophylls pigments, which are excellent pigments required for the charge-carriers generation in the energy harvesting process from the sunlight. The efficacy of all sensitizers has been evaluated using the cyclic voltammetry and current-voltage open circuit experiments of the fabricated DSSCs. The photovoltaic performance of DSSCs in terms of efficiency, current, voltage, and filling factors was performed under standard illumination of AM 1.5G having an irradiance of 100mWcm−2. The results showed that the photoelectric conversion efficiency of the fabricated DSSCs were nearly less than 2%, while the open-circuit voltage and short-circuit current density were from 0.43 to 0.55 V and 0.45–0.54 mAcm-2, respectively. The appropriate LUMO energy level and the band-gap of these extracted dyes would enable them to become efficient sensitizer for utilizing in fabricated DSSCs. Therefore, due to the existence of carbonyl and hydroxyl groups in dye's chemical structures, it enable them to bind to the TiO2layer, consequently, improve the electron transfer, and enhance the energy conversion efficiency of the fabricated DSSC.
●Dye extracted from natural native plants used as sensitizer for TiO2 based dye-sensitized solar cells (DSSCs).●The efficiency of fabricated natural-DSSC is comparable with the reference cell.●The potential of dye extraction from four native plants Crocus sativus (Saffron(, Allium cepa L (red onion), Malva sylvestris (Mallow), and Oregano (Origanum vulgare) was evaluated by effectiveness on the fabricated DSSCs.
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.
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•Key bio-kinetic parameters were globally optimized for vast experimental conditions•Pressure linearly influenced on hydrogen diffusion within the liquid phase•Active volume was most affected by height to width ratio and diffusivity parameters•A cylindrical geometry improved percentage of active volume 43% more than a cube one•Higher pressures and temperatures in a wide bioreactor make process more favorable
In this study, the Sargassum angustifolium macroalgae was used as the feedstock of the hydrothermal liquefaction (HTL) process. The effects of operating conditions of temperature, residence time, and ...feedstock concentration on the yield of the HTL products were modeled using the response surface methodology of the Box-Benken design. Based on the proposed model, the maximum biocrude yield was predicted at 350 °C, 35 min residence time, and 8.6 wt% of the feedstock concentration, confirmed by the experiment. The biocrude has a higher heating value of 33.91 MJ/kg, with the main components including ketones and alkanes. Sensitivity analysis of operating conditions revealed that the HTL process temperature has the most effect on the yield of products, and increasing temperature causes an increase in the biocrude and gas phase yields while decreasing the aqueous and solid phase yields. Among the cross-effect of parameters, the temperature-residence time interaction has the highest impact on the biocrude and gas phase yields. A comparison of the structural analysis of the solid phase and the algae showed the solid residue of the HTL process is highly porous and potentially a good candidate as an adsorbent. The physicochemical properties of the aqueous phase revealed its potential application to algae cultivation. Finally, three pretreatment methods of ultrasonication, microwave irradiation, and size variation of the feedstock were used to increase the biocrude yield at both maximum and minimum yield conditions. The results showed that microwave-assisted HTL is the most effective process, increasing the biocrude yield from 26.15 wt% to 34.77 wt%.
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•Sargassum angustifolium macroalga is a suitable species for biocrude production using the HTL process.•Among the operating conditions, the temperature is a more effective parameter in the hydrothermal liquefaction process.•The maximum biocrude yield was 26.15 wt% under 350 °C, 35min residence time, and 8.6 wt% of the feedstock concentration.•The biocrude produced under optimal operating conditions has a suitable quality such as 33.91 MJ/kg higher heating value.•Microwave irradiation is the most effective pretreatment method for increasing the biocrude yield and quality.
In this study, the kinetics of the aggregate behavior of asphaltene particles in a very dilute concentration range of 6.25-50 mg/L in toluene was investigated using the dynamic light scattering (DLS) ...technique. Then, the kinetics of asphaltene aggregation was analyzed by a proposed model based on the mass action law concept. Also, the presence of silica nanoparticles, SiO
2
-NPs, was investigated for the analysis of asphaltene aggregation behavior. The DLS results showed that by selecting the optimum sonication time of 6 min, asphaltene monomers (1 nm) at concentrations of 6.25, 12.5, and 25 mg/L did not incline to form asphaltene nano-aggregates over time. However, at a concentration of 50 mg/L, at the initial moments, the asphaltene particles began to form large clusters and clots. The results obtained by model optimization showed good agreement with experimental data with acceptable accuracy and mean absolute percentage errors of 10.41% and 5.21% for concentrations of 6.25 and 12.5 mg/L, respectively. Also, the results showed that in the mixing ratios of
and
of asphaltene concentration to the concentration of nanofluid, SiO
2
-NPs were placed between the polar particles of asphaltene and created a new structure in the colloidal solution that prevented the self-association of asphaltene molecules and increased the kinetic stability of the asphaltene particles.
This study assesses the energy, exergy, economic, and environmental performance of a gas stabilization unit by employing a new strategy to implement an advanced control system. The advanced process ...control (APC) strategy is established based on the response surface methodology to assess the real-time performance of the process. The RSM-based APC technique targets the energy, exergy, economic, and environmental (4E) performance of the process in unsteady-state operations. A detailed sensitivity analysis is also conducted to evaluate the relative significance of operating parameters on the objective functions, such as exergy efficiency, energy cost, and CO2 emission. The RSM-based APC strategy proposes an algorithm that can readily be implemented in the plant to increase the plant’s energy performance. Implementing this intelligent control system leads to the production of standard products, while production cost, energy consumption, exergy efficiency, and environmental impacts are enhanced. The exergy and sensitivity results indicate that the stabilization tower has the highest potential for process enhancement, and reboiler temperature is the most influential factor among operating parameters. Also, the RSM-based APC improves the exergy efficiency of the plant by 19% and reduces the energy cost by 13%. At the optimal state, 457 kg/h CO2 emission is prevented.
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