Marine and freshwater mussels secrete proteinaceous adhesive materials for adherence to the substrates upon which they reside. It is well known that 3,4-dihydroxyphenylalanine (DOPA) is the key to ...understanding these mussel adhesive proteins (MAPs). In order to gain a better understanding of their complex formation and quick recovery upon rupturing, novel water soluble copolymers of N-isopropylacrylamide and dopamine methacrylate were synthesized in such a way that they have 1, 2.5, and 5 mole percent dopamine monomer with respect to the NIPAM monomer on average. The statistical distribution of DOPA-functionalities along the chain makes the material a close synthetic equivalent of the byssal thread proteins of mytili. At acidic pH, the aqueous copolymer solution behaves like an unentangled copolymer solution, but at basic pH, these catechol functionalities form a dicomplex with H sub(3)BO sub(3), thereby crosslinking two chains, proven by super(11)B-NMR and gelation. The polymer solution is thermosensitive with a pH-dependent lower critical solution temperature (LCST) between 21 and 33 degree C, depending on the DOPA-content. If 2 or more functionalities per chain are present, a gel is formed that is self-healing with very quick recovery from sustained damage. The moduli of the gels depend on the concentration of functionalities. Hence, triple stimuli responsive copolymers were obtained.
Wellbore instability because of poor rheological properties, high fluid loss volume and shale swelling is the leading challenge faced by the petroleum sector. Therefore, the success of any drilling ...activity is fundamentally governed by the characteristics of the drilling mud. The main scope of this study is to observe an increase in the performance of water-based mud (WBM) after the addition of synthesized GO/TiO
2
nanoparticles. In the first part, properties of WBM are analyzed after the addition of GO/TiO
2
and anatase-TiO
2
nanoparticles. Each particles as a separate entity is added in different three concentrations
0.75
,
1.5
,
2.25
g
in the WBM. In the second part, the influence of salt, polymer and synthesized nanoparticles on inhibiting the shale swelling is observed. For the first part, the results reveal that the rheological properties of all the six samples are in the API recommended window. However, plastic viscosity, yield point, gel strength (10 s/10 min), and transport index of the base mud substantially improves with the addition of GO/TiO
2
nanoparticles than anatase-TiO
2
nanoparticles. Furthermore, the GO supports TiO
2
through oxygen-bearing functional groups, which eventually improves the adsorptivity of GO/TiO
2
particles in the micro and nanopores and decreases the filtrate loss volume. Thin and compacted mud cake with lower permeability is obtain from GO/TiO
2
nanoparticles. For the second part, full factorial design of experiment technique is implemented on the shale swelling behavior. The result of this segment indicates that GO/TiO
2
nanoparticles are the most influential factor in reducing the shale swelling behavior. The shale surface becomes hydrophobic after its interaction with the GO/TiO
2
nanoparticles. Moreover, these particles are responsible for developing strong interparticle hydrogen bonds between themselves, which prevents the fluid migration into the shale pellets. On the other hand, the impact of KCl and PAC on the shale swelling is relatively small. The polymer PAC is dehydrated in the presence of monovalent cations, which impacts their performance in minimizing the shale swelling.
Application of titanium dioxide nanomaterial having different crystal forms has been extensively studied in various fields. However, as a drilling fluid additive it is still an unexplored area. ...Changing the composition of TiO
2
morphology, leads to substantial improvements in the environmental and energy sector. These enhancements are based on the chemical and physical interaction of the crystal structure. In the current work, the carbon supported anatase TiO
2
particles are used as a drilling fluid additive to improve the efficiency of water-based mud systems. For the first time, the effect of the crystal system is considered on the drilling fluid performance. Three carbon supported particles in the form of MWCNT/TiO
2
, GO/TiO
2
and activated carbon/TiO
2
are used in drilling fluid. Each particle was added in the mud system with concentration ranging from (0.35 g, 0.875 g, 1.75 g, 2.625 g, 3.5 g,) respectively. The rheology, filtration, stability, and shale inhibition characteristics of the samples was performed. Improvement in electrochemical characteristics of the mud system was recorded after the incorporation of carbonaceous TiO
2
particles. Moreover, the gelation and filtration characteristics of the muds were also enhanced after the synergy of carbonaceous material with TiO
2.
This interaction leads to better cutting suspension and provides smooth and compacted mud cake. In addition, all the mud samples interacted with Ranikot formation to observe its stability behavior. Substantial improvement in hydrophobic nature of the shale sample was recorded after interacting with the carbon supported TiO
2
nanoparticles. These carbon supported particles are extremely potential in plugging the nano-pores of Ranikot shale and are responsible for maintaining the shale integrity.
Limited studies are performed in the petroleum sector on titanium dioxide (TiO
2
) nanoparticles and its crystal form. Moreover, no study is reported up till now that studied the combination of ...carbonaceous material and TiO
2.
In the current work, the rheological and filtration characteristics of water-based mud was investigated after the addition of polyanionic cellulose grade-L and AC/TiO
2
nanoparticles. To verify the impact of these two particles on the rheological and filtration behavior, central composite design was implemented, which further validates the experimental results. According to the research, concentration of particles was a significant parameter in maintaining rheological properties and minimizing the fluid loss volume. The AC/TiO
2
nanoparticle was mainly responsible for keeping the plastic viscosity, yield point and gel strength within API standards. On the other hand, when the concentration of PAC-L goes beyond the critical concentration, the PV of the mud sample goes beyond API protocols; however, yield point and gel strength were not affected. The effect of these particles on API low-pressure low-temperature filtrate press test was also examined. The fluid which shows the maximum fluid loss volume and greater mud cake thickness was Sample 4. This sample had the least concentration of polymer and nanoparticles. The performance of PAC-L in filtration control yields a negative response. This polymer was unable to control the fluid loss effectively. The presence of K + ions in the base mud was responsible for this lower performance, as it dehydrates the polymeric material. On the other hand, the AC/TiO
2
nanoparticle was mainly responsible for controlling the fluid loss volume and minimizing the mud cake thickness. Furthermore, the addition of AC/TiO
2
nanoparticles in water-based mud system was effective in mitigating the shale swelling behavior. The concentration of this particle demonstrated strong negative correlation. This particle was responsible for the delamination effect, as it ensures the covering of clay surface and preventing the movement of water molecules in the nano-spacing present in clay structure. All the experimental work were also validated by ANOVA analysis. Overall, the AC/TiO
2
nanoparticles proved to be an extraordinary drilling fluid additive as compared to less potential PAC-Lin improving the properties of water-based mud.
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.
Plastic manufacturing industry is the fastest growing industry as the demand for plastic products is exponentially growing worldwide. Poly (methyl methacrylate) (PMMA), also known as acrylic glass, ...is a transparent and rigid thermoplastic. PMMA is highly resistant to UV light. Weathering has an excellent light transmission and unlimited coloring options compared to other transparent plastic and has been used in wide applications such as architecture, automotive and transportation, lighting (LED lights), medical and healthcare, and furniture. Injection molding is the widely used plastic manufacturing process to produce plastic products for various applications. The quality of the plastic products depends on the injection molding parameters, viz. melting temperature, injection speed, and pressure, holding and cooling time, and holding pressure. Therefore, it is important to control injection molding parameters to reduce injection molding defects or parts. Hence, the main objective of this research is to optimize the injection molding parameters, including the amount of mold releasing agent, to avoid the crazing marks in PMMA which is a long-standing problem in the production of PMMA products or parts such as motorbike headlight lenses. Three different holding pressures (65, 75, and 85 kg/cm2) were varied against three different injection pressures (70, 80, and 90 kg/cm2). The injection speed (60 %), cooling time (4 s), and barrel zones temperature (185-205: 185-205: 190-210: 195-215) were kept constant not to disturb the production cycle, a constraint from the production industry. The minimum criteria required for the motorbike headlight lens selection was based on the LUX intensity test, density, and crazing demanded by the Japanese standard throughout this research. The optimized injection molding parameters and amount of mold releasing agent (Nabakem mold release R2) were 70 kg/cm2 (injection pressure), 65 kg/cm2 (holding pressure), and 1.18 g, respectively. The motorbike headlight lens produced with optimized injection molding parameters showed no crazing. In addition to the desired LUX intensity, density, and no crazing criteria, the motorbike headlight lens also showed improved impact properties and no substantial changes in mechanical properties when compared to virgin PMMA or literature. Hence, it is concluded that the optimized injection molding parameters (thermo-mechanical history) did not much affect the molecular weight and morphology of the PMMA.
Carbonaceous nanocomposite hydrogels are prepared with an aid of a suspension polymerization method and are used as anodes in microbial fuel cells (MFCs). (Poly N‐Isopropylacrylamide) (PNIPAM) ...hydrogels filled with electrically conductive carbonaceous nanomaterials exhibit significantly higher MFC efficiencies than the unfilled hydrogel. The observed morphological images clearly show the homogeneous dispersion of carbon nanotubes (CNTs) and graphene oxide (GO) in the PNIPAM matrix. The complex formation of CNTs and GO with NIPAM is evidenced from the structural characterizations. The effectual MFC performances are influenced by combining the materials of interest (GO and CNTs) and are attributed to the high surface area, number of active sites, and improved electron‐transfer processes. The obtained higher MFC efficiencies associated with an excellent durability of the prepared hydrogels open up new possibilities for MFC anode applications.
Hydrogels with carbonaceous fillers are synthesized and used as anode for microbial fuel cells (MFCs). While carbon nanotubes and graphene oxide alone improve electrical properties and MFC efficiency, only the hydrogel incorporating both fillers shows optimized properties, allowing for improved MFCs.
In past decade, electrochemical energy storage gained undivided attention with the increase in electrical energy demand for the usage of new technology such as moveable electronics. Li-ion batteries ...(LIB) have been the most successful energy storage system with their long-life cycle and efficiency, lower energy density, and notable cost effectiveness with small-scale energy storage. However, with large-scale energy storage and for long duration, work still needs done to make LIB efficient on such a scale as well. Recently Li–air batteries have been suggested as potential energy storage systems that can provide the solution for large- and long-term electrical energy storage. The Li–air battery utilizes the catalyst-based redox reaction, and still, it is not applicable commercially due to low current density, poor life cycle, and energy efficiency. Generally, such problems are associated with the materials used as an electrocatalyst and on the selection of the electrolyte. Herein, we briefly review the current advancements in the field of electrocatalysts for Li–air batteries which hinders their improvement toward commercial applications, and this review also provides an outlook for future Li–air battery systems.
This research study aims to conduct a rigorous comparative performance analysis of four different kinetic models used to predict asphaltene adsorption kinetic on nanoparticles. The models included in ...this study were zero-order kinetic model, pseudo-first-order model, pseudo-second-order kinetic model and the Elovich model. The models were implemented on published experimental datasets present in the literature. The study discusses the working and behaviour of kinetic models while predicting asphaltene adsorption kinetic rates on three different concentrations (taken as three cases) of fumed silica nanoparticles. The model prediction results are analysed both through statistical parameters (MAE and
R
2
) and graphically through cross-plots and relative plots. In all cases, it was observed that experimental kinetic adsorption data generated in later times of the experiment satisfy models more precisely as compared to the experimental data yielded in earlier times. This study also proved and confirmed by validation dataset that the pseudo-second-order kinetic model is the best kinetic model (
R
2
of 0.999) followed by the pseudo-first-order model and then the Elovich model. The last rank concerning accuracy was achieved by zero-order kinetic model.
Superabsorbent hydrogels constitute a group of polymeric materials with three-dimensional network structure, which can swell to absorb an enormous amount of water or aqueous solutions. This property ...enables various commercial applications of hydrogels such as water holding capability in agriculture and superabsorbent material for baby diapers. Several novel superabsorbent hydrogels based on acrylic acid-co-acrylamide copolymers were synthesized under variation of copolymer compositions through free radical polymerization. N,N’methylenebisacrylamide (MBA) was used as a water soluble crosslinker and potassium persulphate (KPS) as an initiator. Effect of varying the copolymer composition, change in crosslinker concentration, and effect of environmental parameters (pH, temperature, and ion concentration) on both swelling capacity and swelling rate were examined. These gel shows maximum swelling at neutral pH-7, whereas increasing salt concentration in water decrease the swelling capacity. It was found interesting that an increase in crosslinker concentration from 0.020% to 0.16%, the swelling capacity decreases up to 70% while the swelling rate increases from 0.007g water/g dry hydrogel sec to 0.024g water/g dry hydrogel sec, respectively because there is a compromise exists between entropic spring forces between network connection points and the hydrostatic pressure of the water diffusing into the gels. Dynamic swelling curve obtained were fitted to the three different kinetic models namely Peleg’s kinetic model, pseudo 1st order as proposed by Lagergen and pseudo 2nd order kinetics. All these models provided a good agreement with the experimental data; However on the bases of statistical parameters (RMSE, R2 and X2) the Peleg’s model was selected as the most appropriate model for this study. Analyzing rate constant for Peleg’s models at different swelling temperatures disclosed that increasing temperature could only increase the swelling rate without affecting the swelling capacity of the hydrogels. Experimental values for rate constant k1 of Peleg’s model at different temperature shows a sharp decrease from 0.57545 at 30 oC to 0.1535 at 75 oC that contemplated the rate of swelling at 75 oC was 65% faster than that of 30 oC. The diffusion mechanisms in hydrogels were proven to be tailorable by increasing cross-linker concentration and temperature, leading towards the Fickian type diffusion behavior. The synthesized superabsorbent hydrogels were also tested for water retention applications in agriculture.
