Li-air batteries attract abundant attention in recent years with superior performance, and have largely replaced traditional methods of energy storage. The main objective of Li–air battery is to ...provide long-range electric-vehicles, while functioning as an environmentally friendly and compact energy storage solution. They offer the highest theoretical energy density (3500 Wh/kg), almost 20% higher than the ordinary Li-ion batteries. Nonetheless, Li-air batteries still face numerous issues, the most serious of which are high overpotential and parasitic reactions. Several redox mediators (RM) have been studied in order to reduce the high overpotential and the influence of side reactions. RM function in the electrolyte as soluble catalysts, limiting the formation of singlet oxygen while promoting the formation of discharge product Li2O2. This research primarily focuses on the optimization of Li-air cells with different redox mediators in conjunction with appropriate electrolyte, as a result reducing overpotential, parasitic byproducts and increasing efficiency. Under standard electrolytic conditions, ruthenocene exhibits high stability by completing 83 cycles, thus outperforming the other mediators being investigated. Further, di-tert-butyl-1,4-benzoquinone is more commonly used for discharge reaction and has been shown to increase the capacity of Li–O2 batteries by 80 times. This study reconfirms lithium bis(trifluoromethylsulfonyl) imide in tetraethyleneglycol dimethylether as the most stable electrolyte.
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•LABs offer high energy density but pose overpotential and parasitic reactions.•Redox mediators or soluble catalysts are studied to reduce overpotential issues.•Ruthenocene is highly stable and outperforms all other mediators.•DBBQ is commonly used for discharge and increases the capacity of LABs 80 times.
Energy may be generated in large quantities from fossil fuels, but this comes with environmental concerns. Thus, renewable resources like biogas, comprising carbon dioxide and methane, should be used ...alone or in combination with fossil fuels to mitigate the environmental footprints of energy generation systems. In this study, a new concept of hybrid solvent was presented, which combines 1-octyl-3-methylimidazolium tetrafluoroborate with aqueous mono diethanolamine for biogas upgrading process to provide high purity (≥ 99 wt%) and recovery (≥ 99 wt%) of biomethane. The process was simulated in ASPEN Plus® V.11. The thermodynamic framework was validated against experimental data, and rigorous regression was conducted to obtain binary parameters. To establish the efficacy of the suggested hybrid solvent, three scenarios were studied by altering the concentration of ionic liquid (5–20 wt%) linked with amine and compared to aqueous mono diethanolamine as the base case (50 wt%). The results showed that a hybrid solvent with 5 wt% 1-octyl-3-methylimidazolium tetrafluoroborate could increase CH4 purity to 99% (mol%). The hybrid solvent led to an energy saving of 64.94% compared to the amine-based system. Thermodynamic irreversibilities showed that 5 wt% 1-octyl-3-methylimidazolium tetrafluoroborate improved exergy efficiency by 54% over the amine-based procedure. Environmentally, the hybrid solvent system also achieved a higher capture rate (99%) and lower emissions (0.017 kW/kmol). Comparing the economic prospects, 5 wt% 1-octyl-3-methylimidazolium tetrafluoroborate saved 56% on total capital cost, making it competitive from an investment perspective.
The study proposes a novel integrated process in which ionic liquid is utilized to control carbon dioxide (CO2) emissions from the natural gas combined with a single mixed refrigerant-based ...liquefaction process to assist safe transportation over long distances providing a sustainable and cleaner energy. Commercially amines are utilized for CO2 sequestration, but amines entail energy-intensive regeneration with elevated process costs. The present study offers a solvent screening mechanism based on important parameters such as heat of dissolution, viscosity, selectivity, working capacity, vapor pressure, corrosivity, and toxicity. The selected solvents’ performance is computed by sensitivity analysis suggesting imidazolium-based cation 1-hexyl-3-methylimidazoliumHmim functionalized with tricyanomethanide(tcm) as anion a potential natural gas sweetening solvent in comparison with commercially used solvent monoethanoloamine(MEA), conventional ILs 1-butyl-3-methylimidazolium hexafluorophosphate BmimPf6 and 1-butyl-3-methylimidazolium methyl sulfate BmimMeSO4. The obtained sweet gas is liquefied using a single mixed refrigerant-based process providing 0.99 mol fraction of liquefied CH4 with less overall specific compression power requirement of 0.41 kW/kg of natural gas. Moreover, an exergy analysis demonstrates that the Hmimtcm based process has lower total exergy destruction of 7.49 × 103 kW and is found to utilize less overall specific energy consumption 0.49 kWh/kg of NG in contrast to other studied solvents. Furthermore, a detailed economic analysis establishes Hmimtcm-based CO2 integrated with liquefaction technology offers 50.7%, 74.4%, and 85.8% of total annualized cost (TAC) savings compared with the MEA-,BmimPf6-, and BmimMeSO4, respectively. Hence, Hmimtcm for CO2 removal and integration with liquefaction process will incur unit cost based on the total annualized cost to be $2.2 × 104/kmol of purified NG.
•CO2 removal from natural gas integrated with single mixed refrigerant.•Tricyanomethanide functionalized ionic liquid led to 99 wt% CH4 recovery.•Hmimtcm-based IL offers Specific thermal load of 0.43 kWh/kg natural gas.•Unit cost for upgrading and liquefaction processes to be $ 2 × 104/kmol of NG.•$ 2.2 × 104/kmol of purified NG rich in CH4.
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An analytical method was developed and validated for the determination of fludioxonil in rice samples. Rice samples for the study were collected from different regions of Pakistan. ...The method was based on safe and cost-effective extraction of fludioxonil from rice grains using acetone and methanol (1:1), efficient clean-up through homogenous mixture of acidic aluminium (12 g) and activated charcoal (1 g) followed by liquid chromatographic determination with UV detection. Quantification was performed on Prospher Star C18 (5 µm, 25 × 0.46 cm) column maintaining the temperature 40 °C and detector wavelength 212 nm using mobile phase 50:50 v/v methanol-water (pH 3.3) employing flow rate 1.0 mL min−1 and 20 µL injection volume. The method showed linearity (0.01–16 mg−1) with correlation coefficient greater than 0.998. The proposed method was precisely validated for rice sample of all regions, showing recoveries higher than 98%. Rice samples collected from Badin, Multan, Hyderabad, Lahore, Jahania and Sarghoda was found to have fludioxonil residues 0.046, 0.045, 0.043, 0.040, 0.024 and 0.016 mg Kg−1 respectively, all below the maximum residual limit (MRL) level i.e. 0.05 mg Kg−1 whereas samples collected from Khanewal and Gularchi showed fludioxonil residue above MRL i.e. 0.065 and 0.058 mg Kg−1 respectively. However, fludioxonil residues was not detected in rice sample collected from city Makhdumpur.
Shale is a sedimentary rock that comprises clay minerals in different proportion. These clay minerals tend to swell when they come in contact with water-based drilling fluid (WBDF); as a result, ...severe wellbore instability problems develop, which compromises the integrity of the wellbore. In order to find the shale swelling behavior, various researchers have worked on different modeling techniques. Of all the approaches, very recently our group formulated a scaling swelling model to validate the swelling results obtained from linear dynamic swell-meter (LDSM). However, splitting of the dataset at the end of the steeper slope is the complexity associated with scaling swelling model. Hence, to resolve this challenge, an alternative approach was proposed which comprises logarithmic function. Certainly, the use of this operator makes the scaling swelling equation more useful, as it eliminates the splitting part of the swelling dataset. The new approach was compared with scaling swelling model that was not split at the end of the steeper slope. It was observed that for scaling swelling model, the percentage of statistical error sources was almost thrice of what the new approach produces. Moreover, during analysis of variance (ANOVA) it was observed that the variance of LDSM data was similar to the variance of new model, while the previous scaling swelling model shows higher dispersion with a larger value of variance. Conversely, when the splitting was performed, the new approach and scaling swelling model behave almost in a similar manner. In addition, in both the cases the final swelling result was 10.77%, which is almost similar to the experimental LDSM result. This shows that the new approach is extremely efficient in validating the LDSM experimental results, as the intricacies related with the splitting of the dataset are removed.
Nanoparticle adaption in comparison with micron particles reveals a relatively conducive impact on the stability of the drilling mud. Hence, the use of these particles can be a solution for the ...improvement of shale inhibition along with the rheological properties of water-based drilling fluid (WBDF). Salt polymer–based mud and five other samples with varying concentration of graphene oxide (GO) ranging from 0.1 to 0.5 wt% was analyzed as a shale swelling inhibitor during this study. Influence of these nanoparticles on rheological properties, filtrate volume loss, shale stability, and swelling was investigated during the experimental work. Results revealed that at different temperatures, improvement in the rheological properties of the samples was observed as the concentration of graphene oxide increases. However, at 0.5 wt%, a critical limit was observed, which indicates that further increase in the concentration of nanoparticles beyond this limit causes poor cutting carrying capacity of the mud system. Furthermore, coefficient of friction was also found to reduce at 0.4 wt% concentration. This clearly shows the formation of a slippery layer onto the interface after the addition of this particle. The results also demonstrate an improvement in shale immersion and swelling test after the addition of the GO. The sample exhibits less possibility of erosion, cracks, and disintegration after it established contact with GO mud. Additionally, an improvement in overall bulk hardness was further observed by the used of this particle. During the swelling test, it was found that the swelling characteristics of the shale sample mitigated to a great extent with the use of GO. A decrease of almost 12% in swelling was observed when the fluid system was changed from fresh water to nanoparticle mud system and change in 3% swelling, when this particle is added in the based mud system. Overall, graphene oxide proves to be a better option in improving the WBDF characteristics.
The chemical interaction between the shale formation and water-based drilling fluid has some profound influence on the wellbore stability. Formation swelling, disintegration, bit balling, or even ...abandonment of the wellbore are some severe consequences after this interaction. Hence, it is extremely important to understand the dynamics of the water molecules as it penetrates into the nano-platelets of the shale formation. At the macroscopic level, the diffusion of water molecules is primarily dependent on the size of the clay pore, while at the microscopic level, it is predominantly the function of the clay surfaces. Hence, during this study, three Pakistan shale formations, namely Ranikhot, Murree, and Talhar, were experimentally investigated in a linear dynamic swell-meter, and then the effects of mineral content on water diffusion mechanism were analyzed. As the weight (%) of clay minerals increases, the swelling tendency of these formations increases in the order of
Ranikhot
>
Murree
>
Talhar
. Three diffusion models specifically; the Higuchi model, Peppas model, and Peppas and Sahlin model were then used to investigate the diffusion characteristics of the respective shale samples. It was found that the performance of all the diffusion models suffers substantially in Ranikhot formation, with the highest weight percentage of clay mineral. The models exhibit the transient state throughout the course of experimentation. However, Higuchi model was extremely useful during the transient state of this formation, but an over-estimation of the swelling % was observed during the equilibrium state. Overall in Ranikhot formation, Peppas model was consider the most efficient, with MAE values below 1 and smaller percentages of relative errors. On the other hand, in both Murree and Talhar formations, Peppas and Sahlin’s model was the most efficient in terms of modeling the flow behavior and swelling (%), as the MAE value was below 0.5. All these formations exhibit a Fickian type diffusion mechanism with adjustable parameter “
n
” < 0.5. However, the characteristics of Fickian behavior increase with a decrease in clay content.
Swelling of shale potentially occurs when it is exposed to water-based drilling fluid. The migration of hydrogen ions (H
+
) in the nano-interlayered platelets of the shale rock is utterly ...responsible for the swelling behavior in the shale. Conventionally, swelling behavior of any shale formation can be experimentally determined by linear dynamic swell meter. However, it is extremely important to validate these experimental results; hence, this research study aims in conducting a comparative performance analysis for different kinetic models, namely Peleg’s model, first-order exponential association equation and pseudo-second-order kinetic model, and a newly developed scaling swelling model in estimating the experimental results of three different shale samples, namely Talhar, Ranikot and Murree, obtained from different regions of Pakistan. It was found that the performance of the scaling swelling model was the most accurate in predicting the experimental swelling results with accuracy greater than 95% in all the three samples. Peleg’s model is found to be the most inaccurate with
p
values
<
α
(
0.05
)
in all the three formations. The equilibrium state in all the three samples was unable to attain by the use of this model. This clearly shows that the transient states continue throughout the course of experimentation, thus demonstrating a higher water activity in the shale samples. Moreover, when comparison was made between the two remaining kinetic adsorption models, it was perceived that pseudo-second-order kinetic was far superior to first-order exponential association equation with
mean
model
≃
mean
experiment
and less dispersion in the dataset. Nevertheless, the performance of this model also suffers with the increase in clay content. Furthermore, all these analyses were further validated by different statistical error analysis that includes MAE, APRE% and ANOVA.
One of the most significant problems in oil and gas sector is the swelling of shale when it comes in contact with water. The migration of hydrogen ions (H
+
) from the water-based drilling fluid into ...the platelets of shale formation causes it to swell, which eventually increases the size of the shale sample and makes it structure weak. This contact results in the wellbore instability problem that ultimately reduces the integrity of a wellbore. In this study, the swelling of a shale formation was modeled using the potential of first order kinetic equation. Later, to minimize its shortcoming, a new proposed model was formulated. The new model is based on developing a third degree polynomial equation that is used to model the swelling percentages obtained through linear dynamic swell meter experiment performed on a shale formation when it comes in contact with a drilling fluid. These percentages indicate the hourly change in sample size during the contact. The variables of polynomial equation are dependent on the time of contact between the mud and the shale sample, temperature of the environment, clay content in shale and experimental swelling percentages. Furthermore, the equation also comprises of adjustable parameters that are fine-tuned in such a way that the polynomial function is best fitted to the experimental datasets. The MAE (mean absolute error) of the present model, namely Scaling swelling equation was found to be 2.75%, and the results indicate that the Scaling Swelling equation has the better performance than the first order kinetics in terms of swelling predication. Moreover, the proposed model equation is also helpful in predicting the swelling onset time when the mud and shale comes in direct contact with each other. In both the cases, the percentage deviation in predicting the swelling initiation time is close to 10%. This information will be extremely helpful in forecasting the swelling tendency of shale sample in a particular mud. Also, it helps in validating the experimental results obtained from linear dynamic swell meter.
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