Nonionic Surfactant Research Articles

Coal-Based Branched Vicinal Diol Ethoxylates Versus Guerbet Alcohol Ethoxylates: Role of Tertiary Hydroxyl Groups.

Branched surfactants exhibit a lower surface tension, excellent low defoaming performance, and better wetting ability compared with linear surfactants, making them promising for applications in industrial cleaning. In this study, 2-hexyl-1-decene (C8 olefin dimer), obtained from the dimerization of 1-octene, was used as the hydrophobe to synthesize branched nonionic surfactants via hydroxylation and ethoxylation. The hydroxylation of the C8 olefin dimer to synthesize 2-hexyldecane-1,2-diol (C8 BD) using H2O2 and HCOOH was investigated systematically. Under the optimal reaction conditions (H2O2/C8 olefin dimer molar ratio: 1.5, HCOOH/C8 olefin dimer molar ratio: 4.0, reaction time: 10 h, reaction temperature: 50 °C), the conversion of the C8 olefin dimer and selectivity toward C8 BD were found to reach 99.96 and 79.89%, respectively. Further, branched nonionic surfactants (C8 BDEn) were synthesized via ethoxylation of C8 BD with ethylene oxide and characterized using FTIR, LCMS, 1H NMR, and 13C NMR techniques. The presence of a tertiary hydroxyl group in C8 BD increases the reactivity of the primary hydroxyl group, leading to a narrower range of products and lower residual substrate content. The physicochemical properties and surface properties of C8 BDEn with different degrees of ethoxylation at various concentrations were investigated and compared with those of commercially available Guerbet alcohol polyoxyethylene ethers (C8 GAEO9 and C6 GAEO9). The results show that, compared with C8 GAEO9 and C6 GAEO9, C8 BDE6 displayed a higher surface activity with a lower equilibrium surface tension (27.14 mN·m-1), superior wettability with a smaller contact angle (39.2°), better emulsification performance with a longer emulsification time of 548 s, and excellent foaming properties (initial foam volume of 11.6 mL). This strategy of utilizing coal-based α-olefins for the synthesis of branched nonionic surfactants presents a route to prepare value-added fine chemicals from coal-based resources.

High-efficiency triplet-triplet annihilation upconversion microemulsion with facile preparation and decent air tolerance.

Current research of triplet-triplet annihilation upconversion (TTA-UC) faces difficulty such as overuse of organic solvents and quenching of excited triplet sensitizers by molecular oxygen. Herein, we propose an efficient and facile preparation strategy of TTA-UC microemulsion to overcome these issues. With simple device and short preparation process, air-stable TTA-UC with a high upconversion efficiency of 16.52% was achieved in microemulsion coassembled from TritonX114, tetrahydrofuran and upconverting chromophores (platinum octaethyl-porphyrin and 9,10-diphenylanthracene). This is comparable to the highest UC efficiency ever reported for TTA-UC microemulsion systems. The excellent UC performance of TX114-THF could be attributed to two perspectives. Firstly, small-size micelle accommodated chromophores up to high concentrations in organic phase, which promoted efficient molecular collision. Additionally, high absorbance at 532nm ensured full use of excitation light, getting more long wavelength photons involved in the TTA-UC process. Moreover, air-stable TTA-UC also performed well in microemulsion with various surfactants, including nonionic surfactants (Tween 20, Tween 80, Triton X-110, Triton X-114), ionic surfactants (sodium dodecyl sulfate, cetyltrimethyl ammonium bromide) and block copolymers (pluronic F127, pluronic P123), through three conjectural assembly models according to the structural characteristics of surfactant molecules (concentrated, uncompacted and scattered). These discoveries could provide estimable reference for selection of surfactants in relevant fields of TTA-UC.

Studies on the properties and molecular dynamics simulations of nonionic surfactants based on succinic acid derivatives

AbstractNonionic surfactants have proven useful in various applications such as wastewater treatment, enhanced oil recovery, dyeing, and cosmetics. Novel nonionic surfactants such as PEMP, BEMP, HEMP and BEEP were synthesized based on succinic acid derivatives and using L‐isoleucine as the linking group and four polyether alcohols as the hydrophilic group. First, the structures of the four nonionic surfactants were studied using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectra. Then the critical micelle concentration (CMC) and surface tension at CMC (γCMC) of the four nonionic surfactants in aqueous solution were tested. γ‐lg c curves determined the relationships of their surface properties as BEEP > PEMP > BEMP > HEMP. In order to expand the range of applications for nonionic surfactants, we evaluated the salt‐resistant properties of four such surfactants. Our findings demonstrated that this class of surfactants indeed has superior salt‐resistant properties. Molecular dynamics (MD) simulations were used to study how surfactant molecules aggregate in the interfacial film. The study investigated the trend of solvent accessible surface area (SASA) over time. Results showed that the surfactant molecules interacted well with solvent molecules in the equilibrium state. This study investigates the performance differences among four types of surfactants using the electrostatic potential (ESP) distribution of their molecules. The study employed both experimental and computational simulations to provide a more comprehensive understanding of surfactant properties. The results offer insights into the theoretical research and application extension of this class of surfactants.

Physicochemical investigations of nootropic drug piracetam for enhanced solubilization as nano drug carrier under the influence of single and mixed micellar formulations: An optimized approach towards drug delivery

Nonionic surfactants have drawn tremendous attention for micellar solubilization, sustained release of the drug, encapsulation of pharmaceutically active ingredients, and permeabilization due to their distinct physicochemical characteristics. Concise solubility investigations are required for the appropriate selection of nonionic surfactant that is to be used for a formulation. In the present research, a cluster of micelles was developed that relies on trapping and stabilizing piracetam by balancing the hydrophilic and hydrophobic forces of nonionic surfactants. Tween 80 and Triton-X 100 and a mixture of these surfactants were used to clarify the drug-surfactant interaction in an aqueous and micellar medium. The interaction was investigated in premicellar, micellar, and post-micellar regions by using UV/Visible spectroscopy. Spectroscopic parameters were calculated to determine the degree of solubilization in terms of the partition coefficient (Kx), binding constant (Kb), and their respective energies in terms of Gibbs free energy of partition (ΔGp) and Gibbs free energy of binding (ΔGb) for piracetam. The solubilization of piracetam is enhanced by mixing an adequate amount of both nonionic surfactants. The obtained results demonstrated that solubilization is spontaneous and entropically favorable and the cluster of micelles in both single and mixed micellar mediums are stable due to the presence of a much more hydrophobic and hydrophilic culture which provides a synergistic link between the two surfactants.

A Comprehensive Review on Niosomes as a Tool for Advanced Drug Delivery.

Over the past few decades, advancements in nanocarrier-based therapeutic delivery have been significant, and niosomes research has recently received much interest. The self-assembled nonionic surfactant vesicles lead to the production of niosomes. The most recent nanocarriers, niosomes, are self-assembled vesicles made of nonionic surfactants with or without the proper quantities of cholesterol or other amphiphilic molecules. Because of their durability, low cost of components, largescale production, simple maintenance, and high entrapment efficiency, niosomes are being used more frequently. Additionally, they enhance pharmacokinetics, reduce toxicity, enhance the solubility of poorly water-soluble compounds, & increase bioavailability. One of the most crucial features of niosomes is their controlled release and targeted diffusion, which is utilized for treating cancer, infectious diseases, and other problems. In this review article, we have covered all the fundamental information about niosomes, including preparation techniques, niosomes types, factors influencing their formation, niosomes evaluation, applications, and administration routes, along with recent developments.

Pseudoternary Phase Diagram and Antibacterial Activity of Microemulsion-Based Citronella Oil

Citronella oil (CTO) is extracted from citronella leaves by maceration or steam distillation process, which has antibacterial and insect-repellent activities. However, the use of CTO is limited and requires modification in other formulations, such as microemulsion (ME), to increase its bioactivities. ME consists of oil, water, surfactant and/or cosurfactant and is commonly applied in food and beverages, cosmetics, and carrier for drug delivery applications. CTO was used as the oil phase for ME with nonionic surfactant and ethanol as a cosurfactant for lowering interfacial tension between oil and water phase. Subsequent observations regarding stability and antibacterial tests were carried out on ME formulations with surfactant/cosurfactant mixture of 2 due to its largest ME area. A hydrodynamic diameter analysis was also carried out to see the stability of the ME within a period of 50 d. ME with 10% CTO, 30% surfactant mixture, and 60% water showed the best formulation observed from the consistent hydrodynamic diameter measurement. In addition, ME with different formulations could inhibit the growth of Escherichia coli and Staphylococcus aureus by more than 90%. From this research, CTO-based ME potentially improve and develop drug carrier applications, especially via topical route.

Interaction mechanisms between fibers and bubbles during foam forming

It is critical to understand the interaction mechanism of fiber-bubble before the foam-forming technique is used to disperse the long fiber and tailor the material microporous structure. Herein, the adhesion behavior of ionic and nonionic surfactants with different concentrations on five fibers was investigated, and the effect of electrostatic force and adhesion driving force on the interaction between fibers and bubbles was analyzed. In addition, the fiber dispersion mechanisms and the response mechanism of the fiber orientation and tensile strength of foam-formed paper on the interaction strength between fiber and bubble were clarified. The results show that the adhesion ability between hydrophobic fibers with weak surface polarity and cationic and amphoteric surfactants is more obvious. Though electrostatic repulsion weakens the interaction strength of fibers with anionic surfactants, the adhesion ability can exist when the adhesion driving force is larger than 6.6 mN/m. Furthermore, the bridge effect between ethoxylated surfactant headgroups with the acylamino on the aramid fiber surface also propels the adhesion behavior of bubble-fiber. The fiber dispersion mechanisms were proposed based on the adhesion effect of the fiber-bubble, electrostatic elimination, and high-viscosity (≥95 mPa∙s) properties of the “foam-fiber” slurry. Eventually, under the gradually decreased interaction strength between fibers and bubbles, the fiber orientation in the Z direction of foam-formed NBSKP fiber paper turned from −20°-20° to −60°-40°, and the tensile strength decreased from 693 KPa to 537 KPa. This work has implications for improving the long fiber dispersion and regulating the structure of foam-formed fiber composites.

An experimental study of foam-oil interactions for nonionic-based binary surfactant systems under high salinity conditions

A key factor affecting foam stability is the interaction of foam with oil in the reservoir. This work investigates how different types of oil influence the stability of foams generated with binary surfactant systems under a high salinity condition. Foam was generated with binary surfactant systems, one composed of a zwitterionic and a nonionic surfactant, and the other composed of an anionic and a nonionic surfactant. Our results showed that the binary surfactant foams investigated are more tolerant under high salinity conditions and in the presence of oil. This was visually observed in our microscopic analysis and was further attributed to an increase in apparent viscosity achieved with binary surfactant systems, compared to single surfactant foams. To understand the influence of oil on foam stability, we performed a mechanistic study to investigate how these oils interact with foams generated with binary surfactants, focusing on their applicability under high salinity conditions. The generation and stability of foam are linked to the ability of the surfactant system to solubilize oil molecules. Oil droplets that solubilize in the micelles appear to destabilize the foam. However, oils with higher molecular weights are too large to be solubilized in the micelles, hence the molecules will have less ability to be transported out of the foam, so oil seems to stabilize the foam. Finally, we conducted a multivariate analysis to identify the parameters that influenced foam stability in different oil types, using the experimental data from our work. The results showed that the oil molecular weight, interfacial tension between the foaming liquid and the oil, and the spreading coefficient are the most important variables for explaining the variation in the data. By performing a partial least square regression, a linear model was developed based on these most important variables, which can be used to predict foam stability for subsequent experiments under the same conditions as our work.

Effect of Edge Activator Combinations in Transethosomal Formulations for Skin Delivery of Thymoquinone via Langmuir Technique

Thymoquinone (TQ), a bioactive compound found in Nigella sativa seeds, possesses diverse therapeutic properties for skin conditions. However, formulating TQ presents challenges due to its hydrophobic nature and chemical instability, which hinder its skin penetration. Transethosomes, as a formulation, offer an environment conducive to enhancing TQ’s solubility, stability, and skin permeation. To optimize TQ transethosomal formulations, we introduced a combination of ionic and nonionic surfactants, namely Tween 20 and sodium lauryl sulfate (SLS) or sodium lauroyl glutamate (SLG). Surfactants play a crucial role in stabilizing the formulation, reducing aggregation, improving biocompatibility, and minimizing potential toxicity. We fine-tuned the formulation composition and gained insights into its interfacial behavior using the Langmuir monolayer technique. This method elucidated the interfacial properties and behavior of phospholipids in ethosome and transethosome formulations. Our findings suggest that monolayer studies can serve as the initial step in selecting surfactants for nanocarrier formulations based on their interfacial dilational rheology studies. It was found that the addition of surfactant to the formulation increased the elasticity considering the capability of transethosomes to significantly decrease their radius when permeating the skin barrier. The results of the dilational rheology experiments were most relevant to drug permeation through the skin for the largest amplitude of deformation. The combination of Tween 20 and SLS efficiently modified the rheological behavior of lipids, increasing their elasticity. This conclusion was supported by in vitro studies, where formulation F2 composed of Tween 20 and SLS demonstrated the highest permeation after 24 h (300.23 µg/cm2). Furthermore, the F2 formulation showed the highest encapsulation efficiency (EE) of 94%, surpassing those of the control and ethosomal formulations. Additionally, this transethosomal formulation exhibited antimicrobial activity against S. aureus, with a zone of inhibition of 26.4 ± 0.3 mm. Importantly, we assessed the cytotoxicity of both ethosomes and transethosomes at concentrations ranging from 3.5 µM to 50 µM on HaCaT cell lines and found no cytotoxic effects compared to TQ hydroethanolic solution. These results suggest the potential safety and efficacy of TQ transethosomal formulations.

Influence of Non-Ionic Surfactant and Silver on the Photocatalytic Activity of TiO2 Films for Degradation of Dyes in Distilled and Tap Water

Influence of Non-Ionic Surfactant and Silver on the Photocatalytic Activity of TiO2 Films for Degradation of Dyes in Distilled and Tap Water

Mitigating strategy and mechanism of cement slurry contamination caused by oil-based mud: Macro-micro experiments, molecular dynamics simulation and dissipative particle dynamics simulation

During the cementing process, the oil-well cement (OWC) inevitably comes into contact with oil-based mud (OBM), which contaminates the OWC due to the incompatibility between OBM and the OWC. As a solution, hydrophilic surfactants can reduce interfacial tension and enhance the wetting compatibility of oil and water. Therefore, adding surfactants to the OWC is expected to alleviate contamination caused by OBM. In this study, a new strategy was proposed to combine non-ionic surfactants and anionic surfactants to form a composite surfactant (OP-S2), which overcomes the defect that excessive use of anionic surfactants deteriorates the performance of the OWC—showing great potential in adjusting the compatibility between OBM and the OWC and reducing cement contamination. The mechanism of contamination alleviation during the cementing process was elucidated by comparing the anticontamination properties of a single non-ionic surfactant (OP-S1) and OP-S2. In addition, molecular dynamics (MD) and dissipative particle dynamics (DPD) simulations were used to verify the mechanism of different types of surfactants in removing contamination further, providing theoretical guidance for future research on anti-contamination agents.

Rheology and surface active properties of sodium N-lauroyl sarcosinate in mixed surfactant system

Anionic surfactant sodium N-lauroyl sarcosinate (SNLS) forms elongated wormlike micelles with cocamide monoethanolamine (CMEA) and lauryl glucoside (LG) a nonionic surfactants in the pH range 5.5–6.0. The total surfactant concentration was examined between 10% and 20% wt/v, and the pH was lowered from 7.5 to 4.5. The presence of CMEA/LG diminishes electrostatic repulsion amid SNLS head groups and prompts micellar transition displaying moderate viscosity. The viscosity peak of each system occurred in the pH range 5.5–5.8, close to the system’s pKa. This might prove to be a novel approach for SNLS surfactant formulation which otherwise was difficult to thicken. Additionally, mixed surfactant systems of SNLS/CMEA/LG portrays high surface activity, enhanced foaming behavior and improved skin mildness. Further, this study demonstrated a cost-effective and thickener-free method for cleansing compositions with the desired viscosity.

Adsorption of spray droplets reduced adsorption of dicamba spray droplets on leaves as droplet size increases

Abstract Off-target movement of growth regulator herbicides can cause severe injury to susceptible plants. Apart from not spraying on windy days or at excessive boom heights, making herbicide applications using nozzles that produce large droplets is the preferred method for reducing herbicide drift. Although large droplets maintain a higher velocity and are more likely to reach the leaf surface in windy conditions, their ability to remain on the leaf surface is poorly understood. Upon impact with the leaf surface, droplets may shatter, bounce, roll-off, or be retained on a leaf surface. We examined how different nozzles, pressures, and adjuvants impact spray droplet adsorption on the leaf surface of common lambsquarters and soybean. Plants were grown in a greenhouse and sprayed in a spray chamber. Three nozzles (XR, AIXR, and TTI) were evaluated at 138, 259, and 379 kPa. Dicamba (0.14 kg ae ha⁻¹) was applied alone and with methylated seed oil (MSO), a non-ionic surfactant, silicone-based adjuvant, crop oil concentrate, or a drift reduction adjuvant. A 1, 3, 6, 8-pyrene tetra sulfonic acid tetra sodium salt was added as a tracer. Dicamba spray droplet adsorption when using the XR nozzle, which produced the smallest spray droplets, was 1.75 times greater than when applied with the TTI nozzle with the largest spray droplets. Applying dicamba with MSO increased adsorption on leaf surfaces nearly four times the amount achieved without an adjuvant. The lowest application pressure (138 kPa) increased dicamba spray volume adsorbed more than 10% compared to the higher pressures 259 and 379 kPa. By understanding the impacts of these application parameters on dicamba spray droplet adsorption, applicators can select application parameters, equipment, and adjuvants that will maximize the amount of dicamba spray volume retained on the target leaf surface while minimizing dicamba spray drift.

Synthesis of narrow-distributed Guerbet dodecyl alcohol ethoxylates on Ca(OAc)2 catalyst and theirs surface properties

Despite significant breakthroughs that have been made in the application performance of traditionally distributed Guerbet alcohol ethoxylates (GAEO), research on the characteristics of their narrow distribution products remains relatively limited. Herein, a series of hydrophilic and hydrophobic nonionic surfactants have been synthesized via the ethoxylation of 2-butyl-octanol with ethylene oxide. Ca(OAc)2 was employed as a narrow distribution (NRD) catalyst, while KOH served as a broad distribution (BRD) catalyst. The synthesized products were characterized using Fourier-transform infrared (FT-IR), 1H and 13C nuclear magnetic resonance (1H, 13C NMR) spectroscopy. In addition, a comprehensive assessment of the physicochemical and surface properties of the NRD GAEO surfactants was conducted through systematic investigations. The results were then compared to conventionally distributed GAEO surfactants. The study has demonstrated that NRD GAEO surfactants exhibited lower critical micelle concentration (CMC) values, which have the higher efficiency of the surfactant application. In addition, the NRD products have superior wettability performance, reduced foaming capacity in foam properties, and improved rapid defoaming capacities. In regarding their other properties, they closely mirrored the performance of BRD products. These findings will contribute to a comprehensive understanding of the properties of NRD ethoxylates and have substantial practical implications in optimizing personal care and household cleaning products.

Modulating protein unfolding and refolding via the synergistic association of an anionic and a nonionic surfactant

HypothesisNonionic surfactants can counter the deleterious effect that anionic surfactants have on proteins, where the folded states are retrieved from a previously unfolded state. However, further studies are required to refine our understanding of the underlying mechanism of the refolding process. While interactions between nonionic surfactants and tightly folded proteins are not anticipated, we hypothesized that intermediate stages of surfactant-induced unfolding could define new interaction mechanisms by which nonionic surfactants can further alter protein conformation. ExperimentsIn this work, the behavior of three model proteins (human growth hormone, bovine serum albumin, and β-lactoglobulin) was investigated in the presence of the anionic surfactant sodium dodecylsulfate, the nonionic surfactant β-dodecylmaltoside, and mixtures of both surfactants. The transitions occurring to the proteins were determined using intrinsic fluorescence spectroscopy and far-UV circular dichroism. Based on these results, we developed a detailed interaction model for human growth hormone. Using nuclear magnetic resonance and contrast-variation small-angle neutron scattering, we studied the amino acid environment and the conformational state of the protein. FindingsThe results demonstrate the key role of surfactant cooperation in defining the conformational state of the proteins, which can shift away or toward the folded state depending on the nonionic-to-ionic surfactant ratio. Dodecylmaltoside, initially a non-interacting surfactant, can unexpectedly associate with sodium dodecylsulfate-unfolded proteins to further impact their conformation at low nonionic-to-ionic surfactant ratio. When this ratio increases, the protein begins to retrieve the folded state. However, the native conformation cannot be fully recovered due to remnant surfactant molecules still adsorbed to the protein. This study demonstrates that the conformational landscape of the protein depends on a delicate interplay between the surfactants, ultimately controlled by the ratio between them, resulting in unpredictable changes in the protein conformation.

Surfactant Synergistic Effect and Interfacial Properties of Microemulsions Compounded with Anionic and Nonionic Surfactants Using Dissipative Particle Dynamics

Surfactant Synergistic Effect and Interfacial Properties of Microemulsions Compounded with Anionic and Nonionic Surfactants Using Dissipative Particle Dynamics

Influence of Surfactant on the Skin Permeation of Methylisothiazolinone and Methylchloroisothiazolinone.

Patch tests are often used in safety evaluations to identify the substance causing skin irritation, but the same substance can sometimes give positive or negative results depending on the test conditions. Here, we investigated differences in the skin penetration of two test compounds under different application conditions. We studied the effects of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant polysorbate 80 (PS) on skin penetration of the preservatives methylisothiazolinone (MT) and methylchloroisothiazolinone (MCT), which are used in cosmetics such as shampoos. The skin permeation of MT was enhanced by SDS but was unchanged by PS. Skin impedance decreased in the presence of SDS whereas PS had the same effect as the control aqueous solution, suggesting that SDS reduction of the barrier function of skin affects the permeation of MT, a hydrophilic drug. Application of a mixture of MCT and MT in the presence of SDS did not affect the skin permeation of MCT whereas the permeation of MT was enhanced by SDS, indicating that the skin permeation of MCT is less affected by SDS than is MT. Thus, attention should be paid to the possible effect of co-solutes, especially hydrophilic drugs.

Development and characterization of dexamethasone nanodispersion for the effective treatment of diabetic retinopathy

Diabetic retinopathy is the most common complication of diabetes and remains the leading cause of vision loss worldwide. The potent glucocorticoid based anti-inflammatory drug dexamethasone (DEX) chosen for the present work is long-acting with half-life of 37–72 h extensively metabolized in to 6-hydroxy-dexamethasone (6-OH-DEX). The present work aimed to develop dexamethasone loaded nanodispersion (DEX-ND) by improving its solubility, half-life, and bioavailability in biological system thereby this formulation may be afforded economically. With the concept that polymeric surfactant improves the solubility of challenging water insoluble drug the present work has been hypothesized to improve its solubility using polyvinyl pyrrolidone (PVP-K30) polymer and polysorbate 80 (Tween 80) hydrophilic non-ionic surfactant, thereby the bioavailability is expected to get enhanced. By varying the PVP K30 and Tween 80 concentrations three different formulations were developed. The developed DEX-ND was further characterized for its compatibility, particle size, zeta potential, morphology, and in vitro release behavior. The results of Fourier transform infrared spectrometric analysis indicate the compatibility nature of DEX-ND along with other excipients/drug used in the formulation. The developed formulations showed spherical morphology, particle size ranging from 550.46 ± 107.82 to 3560 ± 284.29 nm, zeta potential ranging from −29.23 ± 1.09 to −7.793 ± 1.01 mV. The amount of DEX present in the DEX-NDs was found to be 0.95–3.93 mg. The in vitro release studies as performed by dialysis bag method showed a sustained release pattern. The results of ex vivo corneal permeation studies indicates that the developed DEX- NDs has some exposure to the posterior segment of the eye.

The effect of anti-agglomerant tween on the thermal and rheological properties of TBAF semi-clathrate hydrate slurry used for cold storage systems

Hydrate, as a phase change cold storage material, can form the slurry with certain fluidity, enabling convective heat transfer during both the heat absorption and heat release stages (cold storage or refrigeration), with high heat transfer efficiency. However, high viscosity and significant flow pressure losses are the principal challenges limiting its advancement. The paper selected four non-ionic surfactants as hydrate anti-agglomerants (Tween 20, 40, 60, 80) and utilized DSC to examine their effects on the thermal properties of TBAF semi-clathrate hydrate slurry at three theoretical hydrate concentrations (with mass fraction of 0.60, 0.70, and 0.80). Additionally, it measured the viscosity variation during the endothermic dissociation stage of the TBAF hydrate slurry and calculated the flow pressure losses in hydrate slurries within various pipe diameters. The results revealed that the presence of Tween increased the hydrate growth within the slurry, resulting in a higher available phase change enthalpy. Tween 80 demonstrated the most significant increase in enthalpy increasing effect, with an available phase change enthalpy ranging from 128.08 to 170.03 kJ/(kg·slurry) and an increase in enthalpy of 52.14 % to 91.62 %. For TBAF hydrate slurries with the theoretical hydrate mass fraction of 0.60, the addition of Tween 20 or Tween 80 significantly reduced viscosity, dropping to between 57.6 mPa·s and 116 mPa·s, and reducing viscosity by 43.4 % to 71.9 %. Furthermore, most flows with anti-agglomerants were in the laminar regime. The addition of Tween 20 and Tween 80 achieved the maximum reduction in flow pressure loss per unit length, with the highest reduction being 80.2 % (0.11 kPa/m) and 71.1 % (0.15 kPa/m), respectively. Both the phase change enthalpy of the hydrate and the viscosity of the hydrate slurry impacted the flow pressure drop within pipes. Increasing phase change enthalpy and reducing viscosity are effective strategies for mitigating flow pressure drop.

Effects of promoter and dedoping process on electrorheological response of polyaniline-graft-chitosan copolymer

In this study, electrorheological (ER) properties of biodegradable and conducting polyaniline-graft-chitosan (PAni-g-CS) copolymer particles were investigated. For this purpose, PAni and PAni-g-CS particles were synthesized by using in situ oxidative radicalic polymerization method. At first, PAni and PAni-g-CS/silicone oil (SO) ER suspensions (15% V/V) were subjected to external electric field and they exhibited low ER activity. When the external electric field strengths ([Formula: see text] were increased, both the suspensions showed electrical breakdown. Therefore, virgin PAni and PAni-g-CS were first subjected to dedoping process by treating with 1.0 M NaOH(aq) and non-ionic surfactant Triton X-100 (T-X) surfactant to enhance the expected ER activity and prevent the electrical breakdown. But we observed that the addition of T-X as promoter had no significant effect on the ER activity. On the other hand, electric filed-induced viscosities of both the suspensions were observed to enhance after the dedoping (DD) process and electrical breakdown prohibited. After the DD process, DD PAni-g-CS/SO ER system exhibited the highest electric field-induced viscosity by reaching 400[Formula: see text]Pa[Formula: see text]⋅[Formula: see text]s at [Formula: see text][Formula: see text]kV/mm. The highest ER efficiency was also obtained for DD PAni-g-CS/SO system at 15% (V/V) as 79. Additionally, typical shear thinning non-Newtonian viscoelastic behavior was observed under externally applied E. The conduction model of DD PAni-g-CS/SO system was determined to well fit the conduction model by showing a slope of [Formula: see text] calculated from the E vb. yield stress graph. In conclusion, conducting and biodegradable-dedoped PAni-g-CS particles would be a good candidate for potential ER applications as dry-based ER materials having high colloidal stability of 76%.