Molecular Weight Surfactants Research Articles

How the designed processing parameters affect the liquid mixture density and viscosity of the tretinoin-loaded niosomes at different temperatures?

The current study was conducted to present novel thermophysical data on tretinoin-loaded niosomes paired with a combination of span 60 and tween 80. Measurements were carried out to analyze the liquid mixture density and viscosity of the mentioned multilayered structures for the first time, with consideration given to the diverse molecular weights of surfactants and various stabilizers at different temperatures. Through the application of equations of state, this study has the ability to set the stage for thermodynamic modeling of solutions that involve niosomes, presenting a promising avenue for further research. So, tretinoin-loaded formulations were prepared by investigating the effects of different co-surfactants, including cholesterol or dodecanol, as well as the impact of surfactant molecular weight limited to 650.525–1090.175 g mol−1. This novel investigation was conducted to assess the superior stabilizing capabilities of dodecanol in comparison to cholesterol, with a specific emphasis on optimized vesicle size, highest incorporation efficiency, and lowest zeta potential. In particulars, the response surface methodology (RSM) was applied to optimize the operative factors and the number of experiments. The experimental evidence clearly indicates that the use of dodecanol in the manufacturing process significantly improves the stability of niosomes, while the inclusion of cholesterol leads to higher liquid mixture density and viscosity in the prepared niosomes.

Stability and characteristics of kerosene-in-water emulsions with xanthate surfactants: Influence of hydrophilic-lipophilic balance and molecular weight

The understanding of emulsion stability is important for several industrial applications including foods, pharmaceuticals, petroleum, personal care products, and in our case mineral processing. Xanthate functional surfactants may be useful to improve mineral recovery through froth flotation by delivering oil to valuable mineral surfaces as they may be used to stabilize kerosene-in-water emulsions. The eco-friendly nature of naturally derived reagents such as vitamin E-based xanthates would be beneficial to the mineral processing industry. In this study, conventional (potassium amyl xanthate (PAX)) and novel xanthate functional surfactants such as α-tocopherol polyethylene glycol 400 succinate (TPGS) xanthates which we synthesized from Vitamin E were investigated as emulsifiers. The creaming and oil phase separation of the kerosene-in-water emulsions produced with the xanthate surfactants were studied. The influence of hydrophilic-lipophilic balances (HLBs) and molecular weights (MWs) of the water-soluble xanthates and other commercial surfactants including polyoxyethylene fatty acid esters (Tweens), sorbitan fatty acid esters (Spans), and polyoxyethylene fatty ethers (Brijs) on the characteristics of the kerosene-in-water emulsions was examined. The experimental results showed that the TPGS xanthate formed the most stable emulsion among the xanthate surfactants considered. The results indicated that HLB is not the only factor influencing the emulsifying properties of surfactants. The chemical structure, particularly the molecular weight of the surfactant has a significant impact on its emulsifying properties. Thus, an emulsion stability chart incorporating the HLB and molecular weight of surfactants is proposed. This stability chart can be used for a better classification of the emulsifying properties of commercially available surfactants and novel reagents.

Effects of surfactant properties on pore wetting of membrane distillation

Pore wetting is a major constraint to the performance of membrane distillation (MD) for hypersaline brine treatment. Despite the existence of surfactants with diverse properties, an explicit relationship between the properties of surfactants and their capabilities of inducing pore wetting has yet to be established. In this study, we perform a comparative analysis of the wetting behaviors of various surfactants with different charges and molecular weights in MD desalination. The induction time of surfactants to initiate pore wetting was correlated to the apparent contact angle and surface tension of the feedwater. Our results show that different surfactants resulting in similar feedwater surface tensions can lead to drastically different wetting potential, suggesting that both charge of the head group and molecular weight of surfactants have a significant influence on membrane pore wetting. Further, we demonstrate that parameters that have been commonly used to indicate wetting potential, including apparent contact angle and solution surface tension, are not reliable in predicting the wetting behavior of MD membranes, which is intricately linked with surfactant properties such as charge and molecular size. We envision that our results not only improve our fundamental understanding of surfactant-induced wetting but also provide valuable insights that necessitate thorough consideration of surfactant properties in evaluating wetting potential and membrane wetting resistance for MD desalination.

Modeling the shear-dependent viscosity of nonionically stabilized waterborne dispersions

The performance of a rheological model that accounts for the effect of the volume fraction, the particle size distribution, and shear rate on the viscosity of water-borne dispersions stabilized with conventional nonionic surfactants and polymeric stabilizers is assessed. The model that contains three parameters fitted well the experimental data. The parameters were independent of the volume fraction, the particle size distribution, and the shear rate. Furthermore, two of them were not affected by the surfactant type and concentration, and temperature. The other parameter increased with the surfactant molecular weight and surface covering, but decreased with increasing temperature.Graphical

Impact Dynamics and Freezing Behavior of Surfactant-Laden Droplets on Non-Wettable Coatings at Subzero Temperatures.

The present study investigates the impact and freezing behavior of the droplets of surfactant solutions on non-wettable coatings at very low temperatures of -10 to -30 °C. Our goal is to elucidate the critical role of concentration, molecular weight, and ionic nature of surfactants on these phenomena. To achieve this goal, we used sodium dodecyl sulfate (anionic), hexadecyltrimethylammonium bromide (cationic), and n-decanoyl-n-methylglucamine (nonionic) at four concentrations ranging from 0 to 2 × CMC (critical micelle concentration). We captured the impact-freezing of the droplets on superhydrophobic alkyl ketene dimer coatings using a high-speed camera at 5000 frames per second. The results show that the ability of the droplets to spread and retract on the coatings is a function of concentration, ionic nature, and molecular weight of the surfactants, as well as the temperature-dependent viscosity of the solutions. Additionally, surfactant-laden droplets generally demonstrated an accelerated freezing compared to pure water. This might be due to the fact that the presence of surfactants can promote both heterogeneous ice nucleation from within the liquid and a larger solid-liquid interfacial area by filling the air pockets of the surface, leading to enhanced heat transfer. The behavior of the cationic surfactant at certain concentrations was, however, an exception leading to a freezing delay, for which a mechanism will be proposed.

Microstructure analysis of porous lead zirconate–titanate films

AbstractPorous ferroelectric lead zirconate–titanate (PZT) films with different internal structures are synthesized using a sol–gel technique and spin‐on deposition on platinized silicon substrates. The films’ porosity is engineered using various structure‐directing agents: polyvinylpyrrolidone with a molecular weight of 360 000 (1–6.6 wt.%) and block copolymer surfactants Brij 30 and Brij 76 (30–60 wt.%). The films’ structures are characterized by transmission electron microscopy. The PVP‐based films contain large, elongated pores with diameters as large as 100 nm. By contrast, the films prepared from solutions with block copolymers exhibit a small pore size depending on the surfactant molecular weight (10–19 nm for Brij 30 and 20–27 nm for Brij 76), with a mostly uniform distribution of channel‐like pores within the film volume. Despite their highly porous structures, all of the films show a columnar‐grain perovskite structure with grains as large as several micrometers and curved grain boundaries. The films demonstrate ferroelectric behavior with dielectric hysteresis, and their permittivity decreases with increasing porosity. Thus, the Brij 30 and Brij 76 copolymer surfactants can be used to engineer fine porous structures in PZT films for various applications in electronics.

Graphene-Anchored Cuprous Oxide Nanoparticles from Waste Electric Cables for Electrochemical Sensing

We demonstrate development of electrochemical nanosensors for planetary health applications using nanocuprous oxide synthesized from recycled materials. Laser-scribed graphene electrodes were enhanced with copper liberated from waste cables, and cuprous oxide nanospheres were synthesized via precipitation at low temperature using lactose as a reducing agent and four different surfactants as capping agents. These laser-scribed electrodes are a low-cost, lithography-free approach to direct synthesis of flexible carbon circuits. Sensors were fabricated by anchoring nanoparticles to flexible graphene electrodes, and then material properties and sensor performance were compared for each surfactant. Surfactant molecular weight and terminal group played an important role in nanoparticle size, band gap, ferromagnetic response, and electron transport. As proof of principle, we show development of catecholamine and mercury sensors for planetary health applications using the best material. Dopamine sensors were line...

Evaluation of adsorption of surfactant at a moving interface of a single spherical drop

Numerical simulations of contaminated bubbles or drops adopt a model of adsorption-desorption kinetics developed for quiescent systems. However, the model has rarely been validated due to the lack of experimental data of surfactant concentration at a moving interface. Hence, we experimentally investigated surfactant concentration at the moving interface of a spherical drop falling in a stagnant liquid containing surfactant using the velocity distributions measured by spatiotemporal filter velocimetry (SFV). The molar flux of surfactant to the interface was also evaluated by substituting the measured velocity and surfactant concentration into the conservation equation of surface concentration of surfactant to examine the applicability of the Frumkin–Levich model to a drop falling in a contaminated system. We confirmed that the evaluation of surfactant concentration using SFV is of great use in understanding adsorption-desorption kinetics at an interface in a contaminated system and for validation of adsorption and desorption models. The measured results showed that the Frumkin–Levich model is not applicable to a moving interface, whereas it is applicable to an immobile interface, that the dependence of the molar flux on the molecular weight of surfactant is not so strong, and that the ratio of the surface concentration of surfactant to the maximum concentration, i.e. the surface coverage, is an appropriate index for judging an applicable range of the Frumkin–Levich model.

Effect of surfactant's molecular weight on the wettability of vinyl polysiloxane impression materials after immersion disinfection

Effect of surfactant's molecular weight on the wettability of vinyl polysiloxane impression materials after immersion disinfection

Synthesis of Surfactants from Alkali Lignin for Enhanced Oil Recovery

With the cheap and abundant resource of alkali lignin as feedstock, surfactants for enhanced oil recovery were synthesized by amination and alkylation reaction of lignosulfonate. The effects of amination conditions, including the ratio of raw materials, amination reagent, temperature, and reaction time, on nitrogen contents and surface tension of the surfactants were investigated. The results showed that ethylenediamine was more suitable for amination, and the molar ratio of alkali lignin, ethylenediamine, and formaldehyde was 1:2:1.5 at 80°C for 5 hours. The structure of synthesized products was characterized by Fourier transform infrared spectrometry. The HLB value of synthesized product was 10. The interfacial tension between Daqing crude oil and synthetic water could be decreased to 10−2 mN/m with synthesized surfactant and NaOH at 45°C. Moreover, the effects of molecular weight of surfactants on interfacial tension were also studied. The synthesized surfactant (Mw > 10,000) showed a better interfacial activity on Daqing crude oil.

Phytotoxicity of Citric Acid and Tween® 80 for Potential Use as Soil Amendments in Enhanced Phytoremediation

Enhanced phytoremediation adding biodegradable amendments like low molecular weight organic acids and surfactants is an interesting area of current research to overcome the limitation that represents low bioavailability of pollutants in soils. However, prior to their use in assisted phytoremediation, it is necessary to test if amendments per se exert any toxic effect to plants and to optimize their application mode. In this context, the present study assessed the effects of citric acid and Tween® 80 (polyethylene glycol sorbitan monooleate) on the development of alfalfa (Medicago sativa) plants, as influenced by their concentration and frequency of application, in order to evaluate the feasibility for their future use in enhanced phytoremediation of multi-contaminated soils. The results showed that citric acid negatively affected plant germination, while it did not have any significant effect on biomass or chlorophyll content. In turn, Tween® 80 did not affect plant germination and showed a trend to increase biomass, as well as it did not have any significant effect on chlorophyll levels. M. sativa appeared to tolerate citric acid and Tween® 80 at the tested concentrations, applied weekly. Consequently, citric acid and Tween® 80 could potentially be utilized to assist phytoremediation of contaminated soils vegetated with M. sativa.

Enhanced Phytoremediation: A Review of Low Molecular Weight Organic Acids and Surfactants Used as Amendments

The contamination of soils with inorganic and organic pollutants is a diffuse environmental issue of significant relevance. Phytoremediation has been proposed as an economically feasible and sustainable remediation technology even if low bioavailability of contaminants constitutes one of the main limitations restricting the success of phytotechnologies. To overcome this constraint the addition of biodegradable amendments has been recently proposed in alternative to synthetic ones. This article presents an overview of two types of biodegradable soil amendments: low molecular weight organic acids and surfactants, evaluating the feasibility of their application in the frame of soil remediation throughout enhanced phytoremediation.

Surfactant and thioacetamide-assisted reflux synthesis of Bi2S3 nanowires

Abstract

Numerical Simulation of Surfactant Adsorption in Micellar Polymer Flooding

Chemical flooding is considered as an attractive alternative to conventional waterflooding. Among chemical flooding approaches, micellar polymer flooding holds a bright future because it can improve the area swept efficiency not only in the macro scale but also in the micro scale. Surfactant adsorption plays an important role in successfulness of the micellar polymer process. Adsorption represents a loss of surfactant agent from solution, and, consequently, a net reduction in the surfactant slug. Therefore, the efficiency of micellar polymer flooding will be significantly diminished not only in technical aspects but also in economics goals if a large amount of surfactant is absorbed in reservoir rock. Unfortunately, numerical simulation of multi-component adsorption is still limited and adsorption process in a polymer/rock system have not yet been well developed; especially for highly heterogeneous reservoir. In this article, the adsorption process was modeled by Langmuir isotherm theory. The simulation results prove that surfactant adsorption strongly depends on surfactant concentration, surfactant molecular weight, salinity, pH, flow rate, reservoir heterogeneities, and alkali. By considering all of those important factors, the optimal design for MP flooding process can be achieved.

Role of surfactant molecular weight on morphology and properties of functionalized graphite oxide filled polypropylene nanocomposites

Various surfactants of different molecular weights, including alkylamine, poly(oxypropylene) diamine (POP), and maleic anhydride grafted polypropylene (PPgMA) oligomers, were used for simultaneous funtionalization and reduc- tion of graphite oxide (fGO). In this study, the effect of molecular weight and compatibility of the surfactants on the mor- phology and properties of the nanocomposites are reported. Wide-angle X-ray diffraction (WAXD) exhibited a definite interlayer thickness for GOA (alkylamine intercalated GO), however, the diffraction peaks were nearly suppressed for fGOs combining ODA with either POP (GOAP) or PPgMA (GOAE). The uniform dispersion of the fGO flakes in the polypropy- lene matrix resulted in the significant increase in both the degradation temperature and the crystallization temperature. A single characteristic melting peak of monoclinic (!) crystalline phase was observed from DSC traces, which was consistent with WAXD results. Dynamic mechanical analysis clearly indicated increase in both the storage modulus and the glass tran- sition temperature of the nanocomposites due to the enhanced affinity between fGO and the polypropylene matrix. How- ever, GOAP composite showed lower E and Tg than GOAE because POP is less compatible with the matrix than PPgMA oligomer. Dielectric analysis also showed significant increase in both dielectric permittivity and dielectric loss at low fre- quency regimes with GOAE showing maximum dielectric properties. The finely dispersed GOAE and its compatibility with polymer matrix manifested the interfacial polarization, which gave rise to much greater # and #$ than other nanocom- posites.

SiO2-supported ferromagnetic catalysts for hydrogen generation from alkaline NaBH4 (sodium borohydride) solution

Ferromagnetic elements Fe, Ni and Co were immobilized on the porous SiO2 to catalyze the hydrogen generation from aqueous alkaline NaBH4 (sodium borohydride). The porous SiO2 was prepared by silica-surfactant self-assembly and the ferromagnetic catalyst was prepared by chemical reduction. The ferromagnetic catalysts were characterized using TG/DTA (Thermogravimetry/differential thermal analysis), BET, XRD (X-ray powder diffraction), ESEM/EDS (environmental scanning electron microscope/energy dispersive spectroscopy), XPS (x-ray photoelectron spectroscopy) and VSM (vibration sample magnetometer) measurements. The surface area of porous SiO2 was affected by the molecular weight of surfactant. The relative catalytic activities in the generation of hydrogen from alkaline NaBH4 solution follow the order Co/SiO2 > Ni/SiO2 > Fe/SiO2. The rates of hydrogen generation using Co/SiO2, Ni/SiO2 and Fe/SiO2 catalysts in 20 ml of 5 wt.% NaBH4 solution at 313 K were 8701, 307 and 130 ml min−1 g−1-metal, respectively. It is found that the degree of metal-oxidation and crystal structure affected the catalytic activity. The hydrogen generation of NaBH4 in alkaline solution increased with increasing cobalt loading, of which the activation energy was 59 ± 2 kJ mol−1.

Catalytic and synergistic effects on thermal stability and combustion behavior of polypropylene: influence of maleic anhydride grafted polypropylene stabilized cobalt nanoparticles

A novel function of polypropylene grafted with maleic anhydride (PP-g-MA) as synergistic additives to effectively reduce the combustion rates of polypropylene (PP) polymer nanocomposites (PNCs) reinforced with in situ synthesized cobalt (Co)–cobalt oxide core–shell nanoparticles (NPs) was reported. Two PP-g-MAs with molecular weights of ∼800 and 2500 g mol−1 have been chosen to demonstrate this function. The combustion behaviors and thermal stability of the PP/Co PNCs were evaluated by micro-scale combustion calorimetry (MCC) and thermal gravimetric analysis (TGA). MCC result illustrated that the combustion behaviors of PP were altered by a reduction of ∼32% in the peak heat release rate (PHRR) with the incorporation of 20.0 wt% Co NPs; more importantly, further reduction in PHRR more than 50% was observed by adding only 5.0 wt% non-flame retardant PP-g-MA into PP/20.0 wt% Co system. This flame retardancy was elucidated through combining MCC with a fast TGA thermal degradation technique. The change of PP thermal degradation pathway by the synergistic and catalytic effects of PP-g-MA and Co NPs in the PP matrix was found to be responsible for the decreased combustion rates of PP. Strong interactions between PP and Co NPs formed by the PP-g-MA was further confirmed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), which favor the decrease of interfacial tension. Differential scanning calorimetry (DSC) and melt rheometry also demonstrated the surfactant molecular weight dependent melting and crystalline properties, and the melt rheological behaviors of the PP matrix.

Nucleate pool boiling heat transfer characteristics of refrigerant/nanolubricant mixture with surfactant

The objective of this paper is to investigate the nucleate pool boiling heat transfer characteristics of refrigerant/nanolubricant mixture with surfactant. In the experiments, three types of surfactants including SDS, CTAB and Span-80 were used. Nanolubricant was formed from Cu nanoparticles and oil VG68. The results show that, the ratio of heat transfer coefficient of refrigerant/nanolubricant mixture with surfactant to that without surfactant (defined as surfactant impact factor, SIF) are within 0.85–1.58, 0.73–1.31, and 0.68–1.24 for SDS, CTAB and Span-80, respectively. The values of SIF increase with the increase of surfactant concentration and then decrease, and increase with the decrease of surfactant molecular weight, nanolubricant concentration and heat flux. A nucleate pool boiling heat transfer correlation for refrigerant/nanolubricant mixture was proposed, and it agrees well with the experimental data of refrigerant/nanolubricant mixture with surfactant and that without surfactant.

Structure and Relative Thermal Stability of Mesoporous (La,Sr)MnO3 Powders Prepared Using Evaporation‐Induced Self‐Assembly Methods

LaMnO3 and (La,Sr)MnO3 were prepared as mesoporous powders using sol‐gel methods that incorporated evaporation‐induced self‐assembly of surfactants as structure‐directing agents. The precursor and surfactant concentrations, surfactant character (mainly molecular weight), aging humidity, and annealing temperature were all found to influence the specific surface area of the powders, which were maximized at 50 and 46 m2/g for LaMnO3 and (La,Sr)MnO3, respectively. Increased metal nitrate contents in the initial sol composition and increased relative humidity during aging led to products having increased specific surface areas owing to increased mesoporosity. The lower molecular weight surfactant CTAB was found to generate higher specific surface area powders than those generated using the larger molecular weight nonionic surfactants P‐123 and F‐127. On the other hand, the relative thermal stability of the mesoporous powders, annealed at 750°C for 100 h, increased with the molecular weight of surfactant. Mesoporous powders having promising thermal stability and surface areas in the 20–25 m2/g range were easily obtainable using P‐123 and F‐127, indicating that high surface area electrocatalysts with mesoporous microstructures can be prepared for high temperature applications.

Effect of surfactant molecular weight on particle morphology of SmCo5 prepared by high energy ball milling

Surfactant-assisted high energy ball milling (HEBM) is a widely used technique for producing nanostructured magnetic materials with oleic acid (OA) being the most commonly utilized surfactant reported in literature to date. No conclusive explanation has been presented for the wide use of OA and only a few studies have deviated from its use. OA has a boiling point of 360 °C which presents issues for complete removal of the surfactant after the HEBM process. Exposing the nanostructured materials to the high temperatures required for surfactant removal is known to result in grain growth and oxidation. In other studies, select surfactant systems, such as octanoic acid or oleylamine, have been used, however, a systematic study examining the dependence of surfactant selection on overall particle (flake) morphology has yet to be performed. In this study, we have qualitatively and quantitatively examined the effects of surfactant selection on the morphology and magnetic properties of SmCo5 utilizing surfactants with lower boiling points that are structurally similar to OA. Our results demonstrate that there was little change in the morphological and magnetic properties for the different surfactants. The implication is that lower boiling point surfactants may be used for HEBM, which require less severe conditions for surfactant removal after milling thereby preserving the integrity of the powders.