Anionic Surfactant Molecules Research Articles

Applicability of cationic surfactants, anionic surfactants, and nonionic surfactants as foaming agents for foamed concrete: surface activity, foamability, and interaction with cement

Selecting the appropriate surfactant as a foaming agent is crucial in the production of foamed concrete. In this study, multiple technological approaches were employed for the investigation of the effect of three different types of surfactants as foaming agents; the approaches included surface tension measurement, zeta potential analysis, spectrophotometry, and nanoindentation. The results showed that the surface activity, solution viscosity, and environmental pH all influenced the generation and stability of foam in foaming agents. The adsorption process of surfactants onto cement particles was complex and could be effectively explained using the double-layer theory. The adsorption of anionic surfactant molecules on cement particles significantly altered the zeta potential, up to −17 mV, with an adsorption efficiency over 10 times greater than that of cationic surfactants and more than 5 times greater than that of nonionic surfactants. Furthermore, after cement hardening, the mechanical properties of the resulting pores were notably improved due to the presence of adsorbed anionic surfactants, and the maximum compressive strength could exceed 10 MPa.

Effects of organic pollutants on struvite crystallization kinetics and the molecular mechanism of inhibition on crystal growth

The abilities of improving phosphorus (P) resources sustainability and reducing water eutrophication make struvite crystallization technology attract increasing interest in wastewater treatment, but struvite crystallization process may be affected by various impurities in wastewater. In this study, the effects of nine representative ionic surfactants including three types (anionic, cationic and zwitterionic) on crystallization kinetics and product quality of struvite were investigated, and the influencing mechanism was further probed. The results demonstrated that anionic surfactants significantly inhibit crystal growth so as to reduce crystal size especially in a-axis direction, change crystal morphology and decrease P recovery efficiency, and also lead to a slight decline in product purity. In contrast, cationic and zwitterionic surfactants have no obvious influence on the formation of struvite. A series of experimental characterizations and molecular simulations collectively revealed that the inhibition of crystal growth by anionic surfactants is attributed to the adsorption of anionic surfactant molecules on struvite crystal surface and subsequent blockage of active growth sites. The binding ability of surfactant molecules with the Mg2+ exposed on struvite crystal surface was highlighted to be the most essential factor determining the adsorption behavior and adsorption capacity. Anionic surfactants with stronger binding ability with Mg2+ have more intense inhibitory effect, but a large molecular volume of anionic surfactants will weaken the adsorption capacity on crystal surface so as to reduce the inhibitory effect. Contrastively, cationic and zwitterion surfactants without binding ability with Mg2+ have no inhibitory effect. These findings enable us to have a clearer understanding of the impact of organic pollutants on struvite crystallization and make a preliminary judgment on the organic pollutants that may have the ability to inhibit the crystal growth of struvite.

Mitigating the skin irritation potential of mixtures of anionic and non-ionic surfactants by incorporating low-toxicity silica nanoparticles

There has been a notable upswing in the adoption of product formulations based on nanotechnology within the cosmetics industry. By using nanocarriers, such as solid or micellar nanoparticles, the quality and performance of cosmetics can be improved, allowing for better transport of bioactive components into the skin. However, it is important to note that the interaction between these compounds may lead to skin irritation. To mitigate skin irritability, nano-formulation strategies should be implemented in cosmetics. A proof-of-concept study was therefore conducted to investigate if low-toxicity nanoparticles (silica) could be used in combination with a mixture of anionic surfactants and a low-irritant cosurfactant (non-ionic) to develop safer cosmetic formulations that reduce skin damage. The skin irritation potential of the formulations was assessed in vitro using the well-known Zein method.As anticipated, non-ionic surfactants pose the lowest risk for skin irritation. When compared to single anionic surfactants, non-ionic/anionic mixtures were found to decrease skin irritability by 24–67 %. However, when silica nanoparticles (NPs) were added to single surfactants, the potential for skin irritation increased, particularly when the anionic surfactant molecules were arranged in a spherical core-shell structure around the surface of the NPs. On the other hand, incorporating NPs in surfactant mixtures enhanced their formulation stability. While all three-component formulations were found to decrease skin irritability, those that formed spherical core-shell structures demonstrated the most significant reduction, likely related to a reduction in charge density caused by the non-ionic surfactant which may decrease protein solubilisation. Therefore, the inclusion of silica NPs can potentially result in a further reduction of the skin irritation potential caused by mixtures of anionic and non-ionic surfactants.

Synthesis and Evaluation of Mesoporous Silica Nanoparticle and its Application in Chemical Enhanced oil Recovery

AbstractA significant quantity of hydrocarbons remains in the reservoir after production using primary and secondary techniques. Traditional recovery techniques produce about 33 % of the original oil in place. However, the utilization of chemicals such as surfactants and polymers facilitate the additional recovery of one‐third of this oil. Researchers are currently aiming at mixing surfactant and nanoparticles for their potential applications in petroleum industry. In this work, authors claimed to be the first to study usage of synthesized Mesoporous Silica Nanoparticles (MSN) with Sodium Dodecyl Sulphate (SDS) surfactant to understand its applicability in Chemical Enhanced Oil Recovery through evaluation of the surface tension & Interfacial tension, surfactant adsorption, contact angle, and core flooding experiments. Surface tension studies revealed a synergistic interaction between MSN and anionic surfactant molecules. With the introduction of 2500 ppm of anionic surfactant, the surface tension of deionized water reduces to 34.5 mN/m from 72.4 mN/m. The surface tension of the mixture was further lowered by ∼9.8 % with the addition of 300 ppm MSN. The Interfacial Tension results also showed the same trend. When 300 ppm of MSN was introduced, then IFT values decreases from 8.13 mN/m to 3.91 mN/m at 2500 ppm of anionic surfactant. Contact angle measurements after MSN injection went from 77.98° for SDS (2500 ppm) to 73.36°, 66.54°, and 41.95° for 100, 200, and 300 ppm of MSN, respectively. This demonstrates that the shift toward water‐wet behavior increased along with the MSN concentration. Additionally, adding 300 ppm of MSN lowered surfactant adsorption by ∼80 % at a surfactant concentration of 2500 ppm. Up to 72.27 % of the OOIP could be recovered using the chemical slug made of SDS surfactant, polymer, and MSN. The research data suggests that the MSN can increase the effectiveness of the chemical injection approach, which can be used to recover more oil.

Study on the adsorption of cement particles on surfactant and its effect on the characteristics of inorganic curing foam for prevention of coal spontaneous combustion in a goaf

In this paper, the adsorption pattern of cement particles to different surfactants was investigated by Zeta potential method, and the adsorption amounts of cement particles on different surfactants were analyzed by Fourier Infrared Spectrometer. Additionally, the expansion ratio, compressive strength, stacking capabilities, and capacity to avert coal spontaneous combustion of inorganic curing foam (ICF) manufactured by various surfactants were tested to analyze the effects of various adsorption behaviors on the performance of ICF. The findings demonstrated that different surfactants affected cement particle Zeta potential in various ways, which was connected to the mode of adsorption of cement particles to various surfactants. After the addition of surfactant, alterations in the zeta potential of the cement particles led to changes in the zero-shear viscosity of the fresh cement slurry. Furthermore, compared to zwitterionic, nonionic, and cationic surfactant molecules, anionic surfactant molecules were absorbed by cement particles in the greatest amounts. The peak areas of CH2/CH3 of the two anionic surfactants in the IR spectra were 19.5 L/g and 9.82 L/g, respectively, while the peak areas of CH2/CH3 of the other surfactants were below 4 L/g. According to the study on the characteristics of ICF, ICF made using a surfactant that had a lot of adsorption had higher compressive strength, a lower expansion ratio, and worse stacking characteristics. The ICF made with various surfactants all had a cooling effect on the coal fire, and after covering the coal, the temperature of the coal was quickly lowered from 300℃ to 100℃. Meanwhile, the surface temperature of ICF prepared with different surfactants was recorded when extinguishing coal fire, and it was found that the thermal insulation property of ICF was better due to the higher expansion ratio of ICF. The purpose of the study in this paper is to provide a new process for the preparation of ICF to prevent coal spontaneous combustion in a goaf and a theoretical guide for the screening of ICF-blowing agents.

Investigation on the lead adsorption capacity of Iranian natural zeolite: modifications, structural effects, adsorption isotherms, kinetics, and mechanism studies

ABSTRACT Clinoptilolite (NZ) as a natural and cost-effective adsorbent, modified with two different methods. At the first stage, by sodium chloride solution to obtain NaCl-modified natural zeolite (NaCl-MNZ), then sodium dodecyl sulfate (SDS) was used to modify NaCl-MNZ (SDS-MNZ). Along with NZ, NaCl-MNZ, and SDS-MNZ, commercial NaY zeolite was also used for removing lead cations from synthesized wastewater. The adsorption of SDS molecules on the outer surface of zeolite was confirmed by FTIR and the specific surface area of the SDS-MNZ was decreased due to the coverage of smaller pores by anionic surfactant molecules. The zeta potential measurements also revealed that the modification process has decreased the surface charge of the zeolite significantly, which was favorable for the adsorption of Pb2+ cations and improved clinoptilolite performance. The non-linear adsorption kinetics and isotherms are best described by the pseudo-first-order and Sips model, respectively. The maximum adsorption capacity of lead ions were 25.8435, 39.5992, 38.5454, and 101.0240 (mg/g) for NZ, NaCl-MNZ and SDS-MNZ and NaY, respectively. The results indicated that the adsorption capacity of natural zeolites modified with NaCl and SDS were approximately 35% and 33% higher than that of the clinoptilolite alone.

Stability evolution of ultrafine Ag nanoparticles prepared by laser ablation in liquids

Understanding the stability evolution of the silver nanoparticles (Ag NPs) in colloid has great benefits for its controllable preparation, storage and application. Herein, uncapped Ag NPs with diameter of 1.66 ± 0.37 nm are obtained by laser ablation of Ag target in deionized water, corresponding surface plasma resonance (SPR) bands, ζ potential and particle size distribution are monitored to investigate uncapped Ag NPs’ stability evolution. Due to negatively charged surface, uncapped Ag NPs show an excellent dispersion stability in 70 days without any external disturbance. But its dispersion stability and structure stability are destroyed easily by an oscillation treatment, resulting in a tardy growth and the formation of one-dimensional Ag nanochain. In addition, the chemical stability of uncapped Ag NPs is dramatically varied by a displacement reaction with an inserted copper wire. As comparison, two typical cationic and anionic surfactant molecules, N-hexadecyl trimethyl ammonium chloride (CTAC) and sodium dodecyl benzene sulfonate (SDBS) are severally used to prepare surface capped Ag NPs. With same treatment of Ag colloid, both two kinds of capped Ag NPs display better dispersion stability and structure stability than uncapped Ag NPs. Moreover, CTAC capped Ag NPs keep a better chemical stability than SDBS capped Ag NPs.

Molecular modelling as a downstream effort in the discovery of novel anionic sulphate surfactants

Sulphate anionic surfactant is a type of surfactant that is widely used as a cleaning agent. The discovery and development of anionic sulphate surfactant molecule is necessary because it has a huge impact, both in science and economics. Molecular modelling to produce new anionic sulphate surfactant molecules has been carried out. The mathematical equation of the Quantitative Structure-Property Relationship (QSPR) based on Ab Initio has been obtained. Molecules that were candidates for structural modelling and modification were those that have the smallest critical micelle concentration (CMC). The smallest experimental data was C16H33SO4Na with a CMC value = 0.000579 M. The result of this study was CnH3sSO4Na molecules with a theoretical CMC value of 0.000515 M.

Regulating Droplet Dynamic Wetting Behaviors Using Surfactant Additives on High‐Temperature Surfaces

AbstractImpacting the behavior of surfactant droplets impinging upon a heated surface is an intriguing research topic, and is important in spraying cooling processes. Surfactant additives significantly increase nucleate boiling heat transfer by promoting vapor bubble nucleation and foaming. However, it is still not exactly clear how surfactants influence the droplet dynamic behaviors at the heated interfaces, nor is the relationship between the droplet dynamic behaviors and heat transfer performance. Here, three familiar surfactant molecules, i.e., anionic surfactant molecule sodium dodecyl sulfate (SDS), cationic surfactant molecule hexadecylcetyltrimethylammonium bromide (CTAB), and nonionic surfactant molecule poly(ethylene glycol) 1000 (PEG‐1000), are chosen to investigate the dynamic behaviors of the water droplets with surfactant additives on the heated smooth surface with different chemical components. At low temperatures, surfactant‐enhanced spreading of droplets on the hydrophilic and hydrophobic surfaces is achieved due to the surfactant adsorption. At high temperature, bubble jet and bubble explosion processes on the hydrophilic surfaces can generate plenty of bubbles, the bubbles flee away the heated surface and the heat transfer efficiency greatly is improved. SDS and CTAB significantly reduce the Leidenfrost point (LFP) on the hydrophilic and hydrophobic surfaces. PEG‐1000 increases the LFP, which is little affected by variation of concentration.

Synergism effects of coconut diethanol amide and anionic surfactants for entraining stable air bubbles into concrete

Entraining tiny and stable bubbles into cement and concrete is becoming more and more important with the complex composition of cement and concrete. In this work, multi-component surfactants are compounded to improve the air-void stability in fresh concrete. The surface tensions, foam properties of their solutions, and the air contents and air-void parameters of the fresh and hardened cement mortars were tested. The results show that there are strong interactions on the interface of multi-components by calculating the important parameters of surface activity. When coconut diethanol amide molecules are introduced into the interface for co-assembly, the electrostatic repulsion between the anionic surfactant molecules is effectively diminished, thereby decreasing the interfacial free energy and making the interface more stable. The multi-component surfactants induced smaller bubbles with larger amounts in aqueous solutions, which also have higher stability of air bubbles in both cement mortars and concretes. So it is of great practical significance to compound nonionic and anionic surfactants to improve the air-void stability in concrete.

Studies on Interfacial Tensions of Ionic Surfactant and Alkyl Sulfobetaine Mixed Solutions

To expound the mechanisms responsible for reducing interfacial tensions (IFTs) in amphoteric and ionic surfactant mixed systems, the IFTs of mixed solutions containing alkyl sulfobetaine (ASB) and different ionic surfactants against hydrocarbons with different carbon numbers have been investigated by the spinning drop method. For cationic surfactants, the antagonistic effect for reducing IFT appears between cationic and ASB molecules because of electrostatic repulsion, which results in competitive adsorption. On the other hand, the synergistic effect will be observed in ionic and ASB mixed systems as a result of the mixed adsorption caused by the electrostatic attraction. The “chain length compatibility” between the anionic surfactant and ASB molecules leads to a stronger synergistic effect and further reduces IFT. However, “size compatibility” plays the crucial role, and only mixed solutions containing an anionic surfactant with a larger hydrophobic group can produce ultralow IFT against hydrocarbons. Th...

The Role of Electrostatic Repulsion on Increasing Surface Activity of Anionic Surfactants in the Presence of Hydrophilic Silica Nanoparticles

Hydrophilic silica nanoparticles alone are not surface active. They, however, develop a strong electrostatic interaction with ionic surfactants and consequently affect their surface behavior. We report the interfacial behavior of n-heptane/anionic-surfactant-solutions in the presence of hydrophilic silica nanoparticles. The surfactants are sodium dodecyl sulfate (SDS) and dodecyl benzene sulfonic acid (DBSA), and the diameters of the used particles are 9 and 30 nm. Using experimental tensiometry, we show that nanoparticles retain their non-surface-active nature in the presence of surfactants and the surface activity of surfactant directly increases with the concentration of nanoparticles. This fact was attributed to the electrostatic repulsive interaction between the negatively charged nanoparticles and the anionic surfactant molecules. The role of electrostatic repulsion on increasing surface activity of the surfactant has been discussed. Further investigations have been performed for screening the double layer charge of the nanoparticles in the presence of salt. Moreover, the hydrolysis of SDS molecules in the presence of silica nanoparticles and the interaction of nanoparticles with SDS inherent impurities have been studied. According to our experimental observations, silica nanoparticles alleviate the effects of dodecanol, formed by SDS hydrolysis, on the interfacial properties of SDS solution.

Macromolecularly "Caged" Carbon Nanoparticles for Intracellular Trafficking via Switchable Photoluminescence.

Reversible switching of photoluminescence (PL) of carbon nanoparticles (CNP) can be achieved with counterionic macromolecular caging and decaging at the nanoscale. A negatively charged uncoated, "bare" CNP with high luminescence loses its PL when positively charged macromolecules are wrapped around its surface. Prepared caged carbons could regain their emission only through interaction with anionic surfactant molecules, representing anionic amphiphiles of endocytic membranes. This process could be verified by gel electrophoresis, spectroscopically and in vitro confocal imaging studies. Results indicated for the first time that luminescence switchable CNPs can be synthesized for efficient intracellular tracking. This study further supports the origin of photoluminescence in CNP as a surface phenomenon correlated a function of characteristic charged macromolecules.

Corrosion behavior of Ni-P-nano-Al2O3 composite coating in the presence of anionic and cationic surfactants

Ni-P-nano-Al2O3 composite coatings on the mild steel were obtained by adding Al2O3 nanoparticles into the traditional electroless Ni-P bath. Cationic and anionic surfactants were used to prevent the agglomeration of the incorporated nano-Al2O3. Surface morphology, compositions and microstructures of the coating were studied using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) as well. Corrosion resistances of the modified mild steel samples were evaluated in 3.5wt.% NaCl solution by electrochemical impedance spectroscopy (EIS). The results showed that compared to the pure Ni-P coating on the mild steel, the coating formed in the bath with 6g/L nano-Al2O3 performed the highest resistance. Under the optimal conditions, the adding of anionic surfactant (SDBS) improved the anti-corrosion performance of the samples further, while the addition of cationic surfactant led to a worse corrosion resistance. The potential mechanism was that anionic surfactant molecules would contact with active sites of Ni-P composite coating and nano-Al2O3 in the bath, which would improve the dispersion of nano-Al2O3, thus leading to a homogeneous coating with better corrosion resistance.

Charge storage, electrocatalytic and sensing activities of nest-like nanostructured Co3O4

We synthesized nanostructured Co3O4 samples using anionic (SDS), cationic (CTAB) and nonionic (Triton X-100) surfactant molecules in hydrothermal conditions and subsequent calcination. This approach facilitates the synthesis of porous Co3O4 material with bundle-like-sheet, nest-like and flake-like morphologies with specific surface areas in the range of 50–77m2g−1. Among these materials, the nest-like nanostructured Co3O4 material has unique pore architecture, larger pore volume, low solution and charge transfer resistance, and found to be an active material for charge storage, electrocatalytic and sensing applications. The specific capacitance value of the nest-like Co3O4 is 404Fg−1 at a current density of 2Ag−1 with 80% specific capacitance retention. The electrocatalytic oxidation of methanol occurs at lower onset potential on this material with good electrochemical stability. It has good sensing ability for glucose with high sensitivity of 929μAcm−2mM−1, fast response time of ∼0.5s and detection limit as low as ∼1μM. These results show that the nest-like nanostructured Co3O4 material is a versatile candidate for various applications.

Flexible polyelectrolyte conformation in the presence of cationic and anionic surfactants

In this work we have studied the conformation of flexible polyelectrolyte chains in the presence of cationic and anionic surfactant molecules. We developed a simple theoretical model for the formation of the polyelectrolyte–cationic surfactant complexes and mixed micelles formed by cationic and anionic surfactant molecules, in the framework of the Debye–Hückel–Bjerrum–Manning and Flory theories, with the hydrophobic interaction included explicitly as an effective short-ranged attraction between the surfactant hydrocarbon tails. This simple model allows us to calculate the extension of the polyelectrolyte–cationic surfactant complexes as a function of the anionic surfactant concentration, for different types of cationic and anionic surfactant molecules. A discrete conformational transition from a collapsed state to an elongated coil was found, for all surfactant chain lengths we have considered, in agreement with the experimental observations for the unfolding of ​DNA–cationic surfactant complexes.

Determination of micelle aggregation numbers of alkyltrimethylammonium bromide and sodium dodecyl sulfate surfactants using time-resolved fluorescence quenching

Abstract The time-resolved fluorescence quenching method was applied to determine the micelle aggregation number of cationic single-chain surfactants dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS). The concentration dependence of micelle aggregation number was found to be linear for all investigated surfactants in the concentration range 2‒15 × the value of critical micelle concentration of the respective surfactant. The values of micelle aggregation number were found in the range 30‒77. Different trends in the linear concentration dependence of micelle aggregation number were observed for cationic surfactants and for the anionic surfactant SDS. A small slope value was found for cationic surfactants, while the SDS micelle aggregation number concentration dependence showed significantly a larger slope value. The aggregation number increase with the increasing SDS concentration results in the micellar growth. Results from a simple analysis based on computer models of cationic and anionic surfactant molecules with dodecyl chains supports, the formation of intramicellar hydrogen bonding between surfactant molecules in SDS micelle shell.

Cd2+ Counterion-Assisted Synthesis of Uniform CdS Nanospheres Capped with the Anionic Surfactant Sodium dodecylsulfate

Uniform cadmium sulfide (CdS) nanospheres were successfully prepared in the presence of the anionic surfactant sodium dodecylsulfate (SDS) at an appropriate concentration and relatively low temperature. Zeta potential data were collected for the three kinds of CdS particles to verify the existence of the Cd2+counterion on the CdS surface and Charge reversal; this was crucial for the explanation of how the anionic SDS surfactant molecules adsorbed on the negatively charged surface. Moreover, we confirmed that SDS had coated the surface of CdS nanospheres using infrared spectroscopy, and thermogravimetric analysis. An counterion assisted mechanism accounting for synthesis of CdS nanospheres could be widely used in the synthesis of nanomaterials if there is specific adsorption of the counterion. The CdS nanospheres showed good performance for the rapid adsorption of methylene blue.

Aggregation Thermodynamics of Sodium Octanoate Micelles Studied by Means of Molecular Dynamics Simulations

The present work is aimed at studying the computation of the thermodynamic potentials that describe the stability of anionic surfactant molecules in micellar aggregates. We report a set of molecular dynamics simulations of a sodium octanoate micelle in aqueous solution using the umbrella sampling method along with the Jarzynski equality in order to compute the potential of mean force for the dissociation process of one surfactant molecule from a previously assembled micellar aggregate. The Jarzynski average was computed at several different temperatures in order to estimate the Gibbs energy of association for the octanoate anion, which was split into its enthalpic and entropic contributions. We also estimated the contributions arising from the polar head and the apolar tail for each thermodynamic potential, and a detailed picture emerged from these simulations. The aggregation is driven mostly by the Gibbs energy contribution arising from the hydrophobic tail, which was large enough to cancel out the unfavorable contribution from the polar head. Although the association process may be ascribed mostly to the transfer of the apolar tail to the micellar core, it should be noted that the polar head also contributed with a favorable entropic term to the overall Gibbs energy. These findings were rationalized by comparing the energetic and structural patterns of the hydration process of a free monomer in solution to an aggregated molecule. The interaction energy distributions presented at least two discernible populations and each population was related to a different structural pattern, as characterized by the radial distribution functions. Altogether, the changes in both the energy and structure of the hydration layer are consistent with the entropy-driven association of the surfactant into the micellar aggregate.

INFLUENCES OF CATIONS, ANIONS AND SURFACTANTS ON MOLECULAR COIL DIMENSIONS OF PARTIALLY HYDROLYZED POLYACRYLAIMDE

The influences of cations,anions,anionic surfactant and non-ionic surfactant on the molecular coil dimension of hydrolyzed polyacrylamide(HPAM) were studied by using dynamic light scattering(DLS),and ther mechanism was analyzed by applying the Stern-Graham double electrode layer model theory,paternoster model theory and dynamic model.The results show that the influence of anions on the HPAM molecular dimension(D_h) is little,but comparing against anions,the influence from cations is much greater,and the decreasing degree of D_(h)with the cation concentration increasing decreases gradually.The order of action capacity of Ca~(2+),Mg~(2+),K~(+) and Na~+ for D_h is Mg~(2+)Ca~(2+)Na~+K~+.When the anionic surfactant is introduced into polymer solutions,D_h decreases with the concentration of anionic surfactant increasing first,then increases and decreases again.Moreover,because of the powerful electrostatic repulsion,the capacity of anionic surfactant molecules to adsorb on the surface of polymer molecules is weak,and it is difficult to form the "anionic surfactant-polymer" complex.However,the nonionic surfactant can adsorb on the polymer molecular chains in the form of micellar aggregate,forming "nonionic surfactant-polymer" complex,and result in the D_h increasing with the nonionic surfactant concentration increasing.