Influence Of Different Surfactants Research Articles

Study on the Wettability and Methane Desorption Characteristics of Coal under High Pressure with Different Surfactants.

In the process of coalbed methane extraction, due to the strong hydrophilicity of coal, the surface interaction force between water and the coal matrix is strong. The hydrophobic effect of the coal seam during drainage and pressure reduction is not significant, and adsorbed methane is difficult to desorb. In order to reduce the surface interaction force promoting methane desorption between water and coal, the surfactants NH766, G526, and D001 with a concentration of 0.1% were selected. A pressure of 12 MPa, which is close to that used for the on-site mining of coalbed methane in Baode, was selected as the experimental condition to simulate hydraulic fracturing of high fat coal, and the influence of different surfactants on methane desorption characteristics was analyzed. Combining contact angle experiments and infrared spectroscopy experiments, we explored the changes in wettability of the coal samples. We compared the changes in wettability and methane desorption characteristics and explored the similarities between these changes. The experimental results showed that after NH766 treatment, the content of oxygen-containing functional groups in coal rock decreased by 30%, and the contact angle of the coal matrix surface increased by 10°. Furthermore, its hydrophobicity was enhanced, and the desorption amount increased by 24%. In contrast, the oxygen-containing functional groups in coal rock after G526 and D001 treatments increased by 5% and 16%, respectively, and the contact angle of the coal matrix surface became smaller. Furthermore, its hydrophilicity was enhanced, and the desorption amount was reduced by 12.5% and 20%, respectively. NH766 reduces wettability and promotes methane desorption, and it can be applied to improve CBM extraction efficiency. G526 and D001 enhance wettability and inhibit methane desorption, which make them suitable for dust prevention and gas control in coal mines.

Molecular simulation study of the influence of different surfactants on the wetting characteristics of anthracite

The reduction of dust pollution in coal mines is of great importance both for protection of the environment and for the occupational safety and health of coal mine workers. The reduction of dust from anthracite has been a challenge due to its inherent hydrophobicity and high metamorphism. As a result, surfactants are commonly added to water to improve the wettability of coal, thereby improving the dust reduction efficiency of a water spray system. To clarify from a microscopic perspective the effect of different surfactants on the wettability of anthracite, models for the anthracite-surfactant-water system were established, and adsorption configuration, relative concentration distribution, and the diffusion coefficients of water molecules in the systems were thoroughly investigated with molecular simulations. The results showed the directional arrangement of surfactants in the simulation systems after 150 ps of equilibration, resulting in the reduced surface tension of the water-surfactant solution and enhanced wettability of anthracite. Along the (001) normal direction, the relative concentration of sodium dodecylbenzenesulfonate (SDBS) (15.32), the anthracite-water overlapping area, the diffusion rate of water molecules, and the activity (DSDBS = 0.97 × 10-8 m2·s−1) were maximized, indicating the excellent wettability effect of SDBS. The results of the study are of practical significance for improving the wetting effect of anthracite, improving the dust reduction efficiency, and safeguarding the occupational safety and health of personnel.

Fractal Dimension and Nuclear Magnetic Resonance Characteristics of Surfactants for Coal Gas Desorption

In this paper, the fractal dimension of coal surfaces was calculated using the fractal theory, and the influence of different surfactants on the fractal dimension of coal surface was studied. Six kinds of sustainable and traditional surfactants used in coal gas desorption processes were compared and analyzed. We used mineral gas fertilizer coal from Huainan Liuzhuang, China, as the research object and studied sodium dodecyl benzene sulfonate (SDBS), cohol diethanolamide (CDEA), nonylphenol polyoxyethylene ether (NP-10), tea saponin, sucrose ester and rhamnolipid surfactants used to modify coal. The methane adsorption capacity of coal before and after surfactant modification was measured by low field nuclear magnetic resonance methane adsorption, and Langmuir volume and Langmuir pressure were obtained according to the Langmuir fitting equation. The results showed that from the perspective of fractal dimensions, the best surfactant in the context of sustainability (in order) is rhamnolipid, CDEA, tea saponin, sucrose ester. According to the two important parameters VL and PL in the Langmuir equation, the coal sample modified by sucrose ester had the strongest gas adsorption capacity. According to the numerical analysis of the surface fractal dimension DS of the coal modified by surfactants, the soluble organic matter in the raw coal samples dissolved, and the micropore morphology evolved to become mesoporous or macroporous, which is more favorable for desorption. The coal samples modified by rhamnolipid and SDBS had the strongest gas desorption ability.

Influence of Different Surfactants on Carbon Fiber Dispersion and the Mechanical Performance of Smart Piezoresistive Cementitious Composites

This experimental study presents the effect of different surfactants on micro-scale carbon fiber (CFs) distribution into carbon fiber reinforced cement-based composites (CFRC) in terms of flexural and compressive strength, stiffness, flexural toughness, and strain-sensing ability. Conducting a narrative review of the literature focusing on the fibers’ separation, this paper follows a methodology introducing a combination of mechanical and chemical carbon fibers dispersion, as well as the different mixing processes (wet or dry). Three types of surfactants: Carboxymethyl cellulose (CMC), cellulose nanocrystal (CNC), and superplasticizer (SP), were applied to evaluate the CFs distribution in the cement paste matrix. Compressive and flexural strength, modulus of elasticity, and ductility of the cement-based composites (CFRC) reinforced with 0.5 wt.% CFs were investigated by three-point bending and compressive tests; flexure tests were also conducted on notched 20 × 20 × 80 mm specimens using the Linear Elastic Fracture Mechanics (L.E.F.M.) theory. Moreover, the electrical conductivity and the piezoresistive response were determined by conducting electrical resistance measurements and applying compressive loading simultaneously. The results clearly reveal that the CFs/SP solution or the CFs’ dry incorporation led to a significant enhancement of flexural strength by 32% and 23.7%, modulus of elasticity by 30% and 20%, and stress-sensing ability by 20.2% and 18.2%, respectively. Although the wet mixing method exhibits improved mechanical and electrical conductivity performance, constituting an adequate strain and crack sensor, the authors propose dry mixing as the most economical method, in addition to the enhanced mechanical and electrical responses. The authors recommend an effective method for structural health monitoring systems combining an economical CFs insertion in cementitious smart sensors with great mechanical and self-sensing responses.

Influence of different surfactants on development of nanoemulsion containing fixed oil from an Amazon palm species

Astrocaryum vulgare is an Amazon palm species, popularly known as tucumã. A. vulgare oil has diverse biological purposes, but low solubility in water. Nanoemulsions provide a solution to this problem. This study aimed to evaluate the influence of different surfactants on the development of nanoemulsions. To determine the hydrophilic-lipophilic balance (HLB), the influence of different surfactants on nanoemulsification was determined, the region of nanoemulsion formation on the pseudo-ternary phase diagram was analyzed, nanoemulsions were characterized, and the best candidate was subjected to stability assessment. The HLB was 14, and PPG-5-Ceteth-20 and sorbitan oleate were selected as surfactants. The nanoemulsion had a droplet size of 174.1 nm, a polydispersity index of 0.295, and a zeta potential of 20.7. A. vulgare oil is used in the Amazon for countless pharmaceutical applications. We demonstrate the impact of the chemical structure of surfactants, resulting in the formation of nanoemulsions containing A. vulgare oil.

Influence of different surfactants on morphological, structural, optical, and magnetic properties of α-Fe2O3 nanoparticles synthesized via co-precipitation method

Influence of different surfactants on morphological, structural, optical, and magnetic properties of α-Fe2O3 nanoparticles synthesized via co-precipitation method

Effect of anionic/nonionic surfactants on the wettability of coal surface

To study the effect of different surfactants on the wettability of coal surface, the adsorption simulation of different coal-surfactant-water model systems was carried out by using materials Studio 8.0 molecular simulation software. Combined with the contact angle experiments between different surfactants and coal samples, the effect law of different surfactants on the wettability of three coal samples was obtained. The adsorption simulation results were analyzed from the aspects of adsorption spacing, adsorption sites and “reverse adsorption” phenomenon, and the mechanism of the influence of different surfactants on the wettability of coal surface was revealed from a microscopic point of view. The research results show that: the higher the degree of coal metamorphism, the lower the water absorption and the worse the wettability of coal. Anionic surfactant SDBS has better effect on improving the wettability of Hami (HM) coal with low metamorphic degree, while nonionic surfactant AEO9 has better effect on improving the wettability of Yuwu (YW) and Tunliu (TL) coal with high metamorphic degree. By comparing intermolecular distances, it is shown that nonionic surfactants are more likely to aggregate on the surface of coal molecules and have a greater effect on the wettability of the coal surface. The middle position of the benzene ring structure of coal is the best adsorption site for the hydrophobic tail of the surfactant. By calculating the adsorption energy of different simulation systems, it is confirmed that the phenomenon of “reverse adsorption” between nonionic surfactants and low metamorphic coal is caused by hydrogen bonding. The results of the study provide a theoretical basis for the effective application of different surfactants in coal dust control.

New insights into the “unzippering” mechanism of carbon nanotube dispersion via the “trigger” effect of small charged molecules

In binary systems, the influence of different surfactants in carbon nanotube (CNT) dispersion and the dispersion efficiency remain unclear. This study compared CNT dispersion by sodium dodecyl benzene sulfonate (SDBS, small molecule), Triton X-100 (TX 100, large molecule), and their mixtures in single and mixed surfactant systems. A synergistic effect between SDBS and TX 100 was observed for CNT dispersion. The enhancement adsorption of TX 100 by SDBS indicated that SDBS likely acted as a trigger in the “unzippering” mechanism due to its small molecular size. The actual dispersion efficiency of CNT being higher than the theoretical value also proved the trigger effect of SDBS. However, when TX 100 concentration exceeded its critical micelle concentration, the synergistic effect disappeared. This result indicated that the trigger effect of SDBS probably did not occur because TX 100 directly encapsulated CNT in the form of large micelles.

Two-Dimensional Tungsten Disulfide-Based Ethylene Glycol Nanofluids: Stability, Thermal Conductivity, and Rheological Properties.

Developing stable nanofluids and improving their thermo-physical properties are highly important in heat transfer applications. In the present work, the stability, thermal conductivity, and rheological properties of tungsten disulphide (WS2) nanoparticles (NPs) with ethylene glycol (EG) were profoundly examined using a particle size analyzer, zeta-sizer, thermal property analyzer, rheometer, and pH measuring system. WS2 NPs were characterized by various techniques, such as XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), FESEM (Field emission scanning electron microscopy), and high-resolution transmission electron microscopy (HRTEM). The nanofluids were obtained with the two-step method by employing three volume concentrations (0.005%, 0.01%, and 0.02%) of WS2. The influence of different surfactants (Sodium dodecyl sulphate (SDS), Sodium dodecylbenzenesulfonate (SDBS), Cetyltrimethylammonium bromide (CTAB)) with various volume concentrations (0.05–2%) on the measured properties has also been evaluated. Pristine WS2/EG nanofluids exhibit low zeta potential values, i.e., −7.9 mV, −9.3 mV, and −5 mV, corresponding to 0.005%, 0.01%, and 0.02% nanofluid, respectively. However, the zeta potential surpassed the threshold (±30 mV) and the maximum values reached of −52 mV, −45 mV, and 42 mV for SDS, SDBS, and CTAB-containing nanofluids. This showed the successful adsorption of surfactants onto WS2, which was also observed through the increased agglomerate size of up to 1720 nm. Concurrently, particularly for 0.05% SDS with 0.005% WS2, thermal conductivity was enhanced by up to 4.5%, with a corresponding decrease in viscosity of up to 10.5% in a temperature range of 25–70 °C, as compared to EG. Conversely, the viscoelastic analysis has indicated considerable yield stress due to the presence of surfactants, while the pristine nanofluids exhibited enhanced fluidity over the entire tested deformation range. The shear flow behavior showed a transition from a non-Newtonian to a Newtonian fluid at a low shear rate of 10 s−1. Besides this, the temperature sweep analysis has shown a viscosity reduction in a range of temperatures (25–70 °C), with an indication of a critical temperature limit. However, owing to an anomalous reduction in the dynamic viscosity of up to 10.5% and an enhancement in the thermal conductivity of up to 6.9%, WS2/EG nanofluids could be considered as a potential candidate for heat transfer applications.

Influence of different surfactants on the stability and varying concentrations of TiO2 nanoparticles on the rheological properties of canola oil-based nanolubricants

Influence of different surfactants on the stability and varying concentrations of TiO2 nanoparticles on the rheological properties of canola oil-based nanolubricants

Nanostructure Bi2WO6: Surfactant-assisted hydrothermal synthesis for high sensitive and selective sensing of H2S

Multilayer Bi 2WO6 micro-nano hierarchical structures were prepared via a facile hydrothermal method using sucrose as template in the presence of four kinds of surfactants. The morphologies and phases were determined by SEM, TEM and XRD. All the hierarchical structures Bi 2WO6 are composed of nanocrystals with orthorhombic lattice. The grain size, specific surface areas and pore size vary with the surfactant. And the influence of different surfactants on oxygen vacancy (OV) was investigated by electron paramagnetic resonance (EPR), the sample prepared by F127 has a certain OV concentration and show the highest sensitivity. As gas sensing material, all the hierarchical structures Bi 2WO6 show high selectivity and fast response-recovery characteristic to the H2S at 260 °C. Meanwhile, the sensors presented a favorable linear relationship with the H2S concentration (1∼660 ppm). The sensors based on BWO-F127 exhibit the highest sensitivity to H2S, due to the existed O vacancies, the high specific surface areas and large pore volumes, which can provide potential applications for detecting H2S.

Experimental investigation of surfactants adding effect on the value of the critical heat flux during pool boiling of nanofluids

The influence of different surfactants on the pool boiling of water and water-based nanofluid was experimentally investigated. The concentrations of xanthan gum and polyacrylamide, which were used as surfactants, were varied from 10 mg/l to 200 mg/l. The concentration of silicon dioxide nanoparticles of 25 nm diameter was equal to 0.1 vol. %. The dependences of the value of the critical heat flux on the concentrations of the surfactants were obtained as a result of the experiments. It was shown, that both xanthan gum and polyacrylamide increase the critical heat flux. The increase in critical heat flux value for water with polyacrylamide relative to the clear water was 61%, and for water with xanthan gum was 32%. The increase in critical heat flux values for nanofluids with polyacrylamide and with xanthan gum relative to the nanofluids without surfactants were 36% and 13%, respectively, and relative to clear water were 263% and 200%, respectively.

Effect of surfactants on the properties of a gas-sealing coating modified with fly ash and cement

Gas leakage seriously threatens the safety of workers in coal mines. Spraying the gas-sealing coating is one of the effective methods to relieve gas leakage. However, the hydrophobic property of coal makes it difficult for the gas-sealing coating to penetrate the coal. The effect of surfactants on the properties of the hybrid organic–inorganic, gas-sealing coating was systematically studied. Analysis of the influence of different surfactants on the contact angle of coating and coal shows that the contact angle reduction of tributyl phosphate (TBP) is unaffected by the emulsion concentration. The reduction is more than 30%, which effectively improves the wettability of the coal surface. Further, TBP addition can optimize the micro-morphology, internal microstructure, and bonding strength. TBP addition can also facilitate a close contact on the interface, thus achieving effective penetration within the coal sample and enhancing the gas-sealing performance of the coating. In addition, this study explores preliminarily the curing mechanism and synthetic model of the coating, providing a new theoretical basis for the development of gas-sealing coatings.

Comparing the effect of different surfactants on the aggregation and electrical contact properties of graphene nanoplatelets

We report the influence of different surfactants, Triton X-100, sodium dodecyl sulfate (SDS) and cetrimonium bromide (CTAB), on the suspended graphene nanoplatelets (GNPs) in aqueous solution studied via a single entity electrochemical technique. This method simply requires recording the current responses resulting from the impacts of individual and aggregated GNPs with an interdigitated gold electrode array. Upon impact the nanomaterial can bridge across two interdigitated gold microbands creating an electrical contact. The current magnitude reflects both the agglomeration state of the material and the contact resistance between the gold array and the carbon nanomaterial. The sensitivity of the magnitude of the current steps to the identity of the used surfactant was further evidenced, indicating the influence of these surfactants upon the electrical connectivity of the nanomaterial to the electrode substrate.

Influence of different surfactants on Pickering emulsions stabilized by submicronic silica particles

HypothesisPickering emulsions were prepared using wax and silica submicronic particles (650 nm), as a first step towards the synthesis of Janus particles. Surfactants added to silica particles control the emulsion stability and particles arrangement, i.e. their penetration depth into the wax and their ability to form a monolayer. Thus, a systematic study of surfactants is proposed. ExperimentsZeta potential measurements and sedimentation tests are conducted to evaluate interactions of two cationic (CTAB: hexadecyltrimethylammonium bromide and DDAB: didodecyldimethylammonium bromide) and two polymeric surfactants with silica surface. Surfactants affinity for the wax is estimated by contact angle measurements. Emulsions stability is compared to evaluate the ability of particles to stabilize wax droplets. Through microscopic analyses, the penetration depth into the wax is measured as well as the ability to form a monolayer or multilayers/aggregates. FindingsAll surfactants modify silica surface properties, but only CTAB and DDAB give stable Pickering emulsions. Because of a better affinity for the wax, DDAB presents the best characteristics for Janus particle synthesis, allowing a larger variation of particles penetration depth into the wax.

Influence of Surfactants on Sodium Chloride Crystallization in Confinement.

We study the influence of different surfactants on NaCl crystallization during evaporation of aqueous salt solutions. We found that at concentrations of sodium chloride close to saturation, only the cationic surfactant CTAB and the nonionic surfactant Tween 80 remain stable. For the nonionic surfactant, the high concentration of salt does not significantly change either the critical micellar concentration (CMC) or the surface tension at the CMC; for the cationic surfactant, the CMC is reduced by roughly 2 orders of magnitude upon adding the salt. The presence of both types of surfactants in the salt solution delays the crystallization of sodium chloride with evaporation. This, in turn, leads to high supersaturation which induces the rapid precipitation of a hopper crystal in the bulk. The crystallization inhibitor role of these surfactants is shown to be mainly due to the passivation of nucleation sites at both liquid/air and solid/liquid interfaces rather than a change in the evaporation rate which is found not to be affected by the presence of the surfactants. The adsorption of surfactants at the liquid/air interface prevents the crystallization at this location which is generally the place where the precipitation of sodium chloride is observed. Moreover, sum frequency generation spectroscopy measurements show that the surfactants are also present at the solid/liquid interface. The incorporation of the surfactants into the salt crystals is investigated using a novel, but simple, method based on surface tension measurements. Our results show that the nonionic surfactant Tween 80 is incorporated in the NaCl crystals but the cationic surfactant CTAB is not. Taken together, these results therefore allow us to establish the effect of the presence of surfactants on sodium chloride crystallization.

Ultradeformable Liposomes: a Novel Vesicular Carrier For Enhanced Transdermal Delivery of Procyanidins: Effect of Surfactants on the Formation, Stability, and Transdermal Delivery.

The aims of this work were to develop a novel vesicular carrier, procyanidins, ultradeformable liposomes (PUDLs), to expand the applications for procyanidins, and increase their stability and transdermal delivery. In this study, we prepared procyanidins ultradeformable liposomes using thin film hydration method and evaluated their encapsulation efficiency, vesicle deformability, storage stability, and skin permeation in vitro. The influence of different surfactants on the properties of PUDLs was also investigated. The results obtained showed that the PUDLs containing Tween 80 had a high entrapment efficiency (80.27 ± 0.99%), a small particle size (140.6 ± 19nm), high elasticity, and prolonged drug release. Compared with procyanidins solution, the stability of procyanidins in PUDLs improved significantly when stored at 4, 25, and 30°C. The penetration rate of PUDLs was 6.25-fold greater than that of procyanidins solution. Finally, the results of our study suggested that PUDLs could increase the transdermal flux, prolong the release and improve the stability of procyanidins, and could serve as an effective dermal delivery system for procyanidins.

Influence of different surfactants on the physicochemical properties of elastic liposomes

Elastic liposomes are capable to improve drug transport through the skin by acting as penetration enhancers due to the high fluidity and elasticity of the liposome membranes. Therefore, elastic liposomes were prepared and characterized to facilitate the transdermal transport of bioactive molecules. Liposomes consisted of dimyristoylphosphatidylcholine (DMPC) as the structural component, with different surfactants derived from lauric acid as elastic components: C12E5 (polyoxyethylene-5-lauryl ether), PEG4L (polyethyleneglycol-4-lauryl ester), PEG4DL (polyethylene glycol-4-dilauryl ester), PEG8L (polyethylene glycol-8-lauryl ester) and PEG8DL (polyethylene glycol-8-dilauryl ester). The elastic liposomes were characterized in terms of their phospholipid content, mean diameter, size distribution, elasticity and stability during storage, as well as their ability to incorporate surfactant and permeate through 50 nm pore size membranes. The results showed that the phospholipid phase transition temperature, the fluidity of the lipid bilayer resulting from incorporation of the surfactant and the preservation of particle integrity were factors determining the performance of the elastic liposomes in permeating through nanoporous membranes. The best results were obtained using DMPC combined with the surfactants PEG8L or PEG8DL. The findings demonstrate the potential of using elastic liposomes for transdermal administration of drugs.

Влияние поверхностно-активных веществ разного типа на реологические характеристики водно-гликолевых растворов полиакриловых загустителей

Методом радикальной осадительной полимеризации синтезированы слабосшитые загустители на основе акриловой кислоты. Изучено влияние добавки низкомолекулярных ПАВ разного типа на реологию растворов синтезированных полимеров в смеси пропиленгликоль–вода. Установлено, что растворы пропиленгликоль–вода с добавками гидрофобно-модифицированной полиакриловой кислоты и ПАВ неионогенного типа обладают реологическими характеристиками, позволяющими разрабатывать на их основе противообледенительные жидкости II–IV типов.

Species Specific Differences of CD1d Oligomer Loading In Vitro.

CD1d molecules are MHC class I-like molecules that present glycolipids to iNKT cells. The highly conserved interaction between CD1d:α-Galactosylceramide (αGC) complexes and the iNKT TCR not only defines this population of αβ T cells but can also be used for its direct identification. Therefore, CD1d oligomers are a widely used tool for iNKT cell related investigations. To this end, the lipid chains of the antigen have to be inserted into the hydrophobic pockets of the CD1d binding cleft, often with help of surfactants. In this study, we investigated the influence of different surfactants (Triton X-100, Tween 20, Tyloxapol) on in vitro loading of CD1d molecules derived from four different species (human, mouse, rat and cotton rat) with αGC and derivatives carrying modifications of the acyl-chain (DB01-1, PBS44) and a 6-acetamido-6-deoxy-addition at the galactosyl head group (PBS57). We also compared rat CD1d dimers with tetramers and staining of an iNKT TCR transductant was used as readout for loading efficacy. The results underlined the importance of CD1d loading efficacy for proper analysis of iNKT TCR binding and demonstrated the necessity to adjust loading conditions for each oligomer/glycolipid combination. The efficient usage of surfactants as a tool for CD1d loading was revealed to be species-specific and depending on the origin of the CD1d producing cells. Additional variation of surfactant-dependent loading efficacy between tested glycolipids was influenced by the acyl-chain length and the modification of the galactosyl head group with PBS57 showing the least dependence on surfactants and the lowest degree of species-dependent differences.