Effect Of Surfactant Addition Research Articles

Surfactant Effects in Porous Electrodes for Microemulsion Redox Flow Batteries

The effect of surfactant additives on electrochemical behavior in porous electrodes was investigated using vanadium redox flow battery half-cells and the dependence of volumetric kinetics and mass transport on electrolyte, surfactant, and electrode type was explored. Without surfactant added, carbon paper electrodes demonstrated greater kinetics and transport compared to carbon felt, for a given electrolyte. Additionally, posolyte kinetics are greater than negolyte kinetics by one to three orders of magnitude, depending on the electrode type. Addition of surfactant increased electrode wettability and possibly electrochemical surface area. However, this was accompanied by a decrease in volumetric mass transport, due to stronger electrolyte-electrode interactions. The presence of sodium dodecyl sulfate (SDS) influenced posolyte and negolyte kinetics differently. Kinetics showed a dependence on electrode type and surfactant. On carbon felt, volumetric kinetics decreased for both posolyte and negolyte with SDS addition. On carbon paper, SDS decreased volumetric kinetics for the posolyte but increased (>2X) kinetics for the negolyte! This kinetic enhancement depends on surfactant chemistry: cetyltrimethylammonium bromide, a cationic surfactant, failed to increase kinetics. Furthermore, SDS did not increase areal specific resistance. These findings show the superior performance of carbon paper compared to carbon felt and suggest SDS as a possible VRFB negolyte additive.

Stability enhancement of Al2O3, ZnO, and TiO2 binary nanofluids for heat transfer applications

Abstract Primary goal of this research is to enhance stability of nanofluids which is vital for maintaining consistent thermophysical properties during various applications. Nanofluid stability is essential for obtaining the uniform thermophysical properties during its application. X-ray diffraction and zeta potential were performed to characterize three nanoparticles, namely TiO2, Al2O3, and ZnO. Experimental work was carried out under several trials to enhance the stability of nanofluids. Initially, deionized water was used as base fluid for stability analysis, but nanoparticles agglomerate within after 5 h. Second, alkaline water was selected as base fluid at different pHs ranging from 7 to 14 to analyze the stability of the nanofluids. Finally, the effect of surfactant addition on the stability of prepared nanofluids was also investigated. Observations revealed that at pH 11, nanoparticles exhibited enhanced stability compared to other pH levels. This stability can be attributed to the high zeta potential, fostering electrostatic repulsion between individual particles. It was concluded from the results that zeta potential increases in cases of (TiO2 + ZnO) and (Al2O3 + ZnO) from −44.2 to −47.8 mV and −42.4 to −44.1 mV with the addition of surfactant, respectively. In the case of (Al2O3 + TiO2), zeta potential decreases slightly from −47.7 to −44.9 mV with the addition of surfactant.

Effect of surfactant addition on the biofiltration of siloxane-contaminated gas streams

Biogas contains low levels of volatile methyl siloxanes (VMS), which are responsible for severe damage to turbines or internal combustion engines during energy recovery. In this study, we investigated the removal of the linear octamethyltrisiloxane (L3) and cyclic octamethylcyclotetrasiloxane (D4) from gas by using two biofilters (BFs) filled with either woodchips and compost (WC) or perlite (PER). To overcome the mass transfer limitation, the addition of a synthetic (Tween 80) and a biological (Quillaja saponin, QS) surfactant on the removal of VMS in both BFs was studied. Tween 80 (added at × 1 critical micelle concentration, CMC) and QS (also at × 1 CMC) enhanced VMS removal in both BFs. Specifically, the performance of both BFs increased from an average VMS elimination capacity (EC) of 0.07 ± 0.04 g VMS m−3 h−1 to 0.24 ± 0.08 g VMS m−3 h−1 (Tween 80) and 0.43 ± 0.02 g VMS m−3 h−1 (QS). However, higher concentrations of Tween 80 ( × 3 CMC) did not further improve VMS removal. The WC BF exhibited a higher maximum EC of 0.63 g VMS m−3 h−1 (0.37 g D4 m−3 h−1 and 0.26 g L3 m−3 h−1), with a VMS RE of 28.4 ± 2.0% (D4 RE = 30.4% and L3 RE = 26.5%). The PER BF obtained a maximum EC of 0.52 g VMS m−3 h−1 (0.28 g D4 m−3 h−1 and 0.23 g L3 m−3 h−1), along with a VMS RE of 32.0 ± 0.8% (D4 RE = 31.2% and L3 RE = 32.8%). The most abundant genera in the WC BF were Mycobacterium (7.5–1.8%), Rhodococcus (1.1–7.2%), and Planctomicrobium (5.1–2.9%). However, given the high microbial diversity present in WC BF and the complex structure of VMS, their removal was most likely due to the joint activity of several microorganisms with VMS-degrading capacity, such as Bacillus (0.58–0.39%), Pseudomonas (0.07–0.04%), Dokdonella (0.50–0.10%), Microbacterium (0.5%), Novosphingobium (0.02%), Gordonia (0.5–0.1%), and Sphingopyxis (0.07%).

Influence of drying and granulation process conditions on the characteristics of micronutrient chelates granules

Abstract Fluidized-bed spray granulation (FBSG) enables manufacturing particles with desired characteristics, including particle size distribution (PSD), density, or dust content. This study investigated the effect of selected factors on the granules obtained in a continuous FBSG of chelated fertilizers for foliar applications. The effect of surfactant addition to the solution sprayed into the bed and perturbations of operating parameters on PSD and granules morphology was studied. The experiments were supplemented with calculations based on a population balance equation (PBE). It was shown that granules manufactured with the tenside addition are more regular in shape, and thus less prone to mechanical wear. It was demonstrated that increasing rotational mill speed does contribute to a slight increase in the amount of dust, but in the long term, it does not disturb the regular agglomeration process. The computational results confirm that, despite the complexity of the process, its description with PBE is feasible.

Effect of surfactant addition on leaching process of weathered crust elution-deposited rare earth ores with magnesium sulfate

Surfactants were proposed to be added into magnesium sulfate solution to improve the leaching process of weathered crust elution-deposited rare earth ores (WREOs). Effects of surfactants and their concentration on the seepage of leaching solutions and the leaching efficiency of rare earth (RE) and aluminum (Al) were investigated, and the leaching kinetics, the mass transfer process, the adhesion work and the adhesion work reduction factor were analyzed to reveal its strengthening leaching mechanism. The results show that cetyltrimethylammonium bromide (CTAB) has a better strengthening effect on the leaching process than dodecyl trimethyl ammonium bromide (DTAB), sodium dodecyl sulfate (SDS), sodium oleate and oleic acid. In the presence of 0.04% CTAB in 0.2 mol/L solution, the permeability coefficient of WREOs increases from 0.945×10−5 to 1.640×10−5 cm·s−1, and the leaching efficiency of RE increases from 80% to 90%, confirming the promotion of surfactants on the leaching process of WREOs. Kinetic analysis shows that the leaching process conforms to the inner diffusion control model, and the leaching kinetics equations of RE and Al related to CTAB content are obtained. Mass transfer discussion shows a smaller height equivalent to theoretical plate (HETP) of RE and Al at CTAB content of 0.04%, suggesting the higher mass transfer efficiency here. According to the interfacial properties of leaching solutions, the calculated adhesion work and the adhesion work reduction factor further demonstrate the strengthening leaching effect of CTAB on the leaching process of WREOs.

Size dependence of magnetic properties of Fe, Co and Ni nanoparticles prepared by the chemical-metallurgical method using surfactants

The present study focuses on the synthesis of Fe, Co and Ni nanoparticles (NPs) by the chemical-metallurgical method with surfactant additives at the precipitation stage. The effect of surfactant additives on the dispersion, morphology and magnetic properties of the Fe, Co and Ni NPs was studied. The size characteristics of the NPs were measured by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and the Brunauer–Emmett–Teller method. Sodium dodecyl sulfate (SDS) and ethylenediaminetetraacetic acid disodium salt (EDTA) were used as surfactants in this study. Application of SDS and EDTA amounting to 0.1 wt% yielded an increase of 1.5–3 times the specific surface area of the reduced NPs. No surfactant traces were found in the reduced samples according to energy dispersive X-ray analysis. The mechanism of surfactant action is proposed. The surfactants reduce the critical radius of hydroxide clusters and prevent their growth and coagulation. The use of more dispersed hydroxides as precursors leads to the formation of NPs with a smaller particle size. The NPs with a diameter close to the critical size of the single-domain state for each material were obtained due to application of the surfactants. It was found that the saturation magnetization values of the Fe, Co and Ni NPs synthesized using surfactants are close to the values of micron-sized samples. This makes them suitable for many applications in mechanical engineering and technological industries.

Effect of surfactant addition on disperser disintegration of water hyacinth: a new insight to overcome the inhibitory effects of lignin on methanogenesis and improve the energy and economic aspects

A cost- and time-saving strategy for the recovery of biomethane from water hyacinth using an energy-efficient combined pretreatment.

Thermal conductivity and dispersion properties of SDBS decorated ternary nanofluid: Impacts of surfactant inclusion, sonication time and ageing

Ternary nanofluids are now under the limelight of research communities due to their thermo-physical and heat transfer characteristics. In this scientific contribution, the effect of surfactant concentration, ageing, and sonication period on the thermal conductivity of ternary nanofluidis presented. A water-based Ternary nanofluid at weight concentration of (φ) of 0.06 % was prepared using SiO2, TiO2, and ZnO nanoparticles by ultrasonication. Sodium Dodecylbenzene Sulfonate (SDBS) was introduced as a surfactant. The stabilities of the samples were analysed by visual inspection, Dynamic Light Scattering (DLS), and Zeta potential analysis. The thermal conductivity of nanofluid was measured and the effects of surfactant addition, sonication time, and ageing on the stability and thermal conductivity of ternary nanofluid were examined. By increasing SDBS concentration from φ= 0–1.18 %, the thermal conduction and dispersion increased. Thermal conductivity was enhanced by surfactant addition up to 2.71 % with φ = 1.18 % at 55 °C. Surfactant concentration at φ =1.18 % showed an adverse effect on thermal conductivity enhancement. A maximum of 6.85 % enhancement in thermal conductivity can be obtained by increasing sonication duration up to 6 h at 65 °C. Old nanofluids exhibited larger thermal conductivity than newer ones. The 20 days old nanofluid showed 4.66 % enhancement with φ= 1.18 % at 35 °C. Finally, the authors recommended for an optimization study of surfactant concentration and sonication duration.

Effect of Surfactant Additives on Water-based Ink Properties

Effect of Surfactant Additives on Water-based Ink Properties

Effects of surfactant additives during ball milling on the microstructural, electrical, and piezoelectric properties of 0.4Ba(Zr0.2Ti0.8)O3-0.6(Ba0.7Ca0.3)TiO3 ceramics

Effects of surfactant additives during ball milling on the microstructural, electrical, and piezoelectric properties of 0.4Ba(Zr0.2Ti0.8)O3-0.6(Ba0.7Ca0.3)TiO3 ceramics

The Effects of Surfactant on the Stability of SiO2 nanofluid Prepared by Bead-milling Method

Typical nanofluid containing metal or non-metallic nanoparticles dispersed in water with high surface energy. This condition causes aggregation and leads to the instability of the nanofluid dispersion in media. The inclusion of surfactants during the bead-milling process can increase the amount of dispersion stability of nanofluids with bigger particle sizes. The aim of this study was to determine the optimum surfactant in stabilizing SiO2 nanofluid and investigate the effect of surfactant addition during the bead-milling process since the effect of different types of surfactant in the bead mill remains unclear and varied. The sol-gel method was used to synthesize SiO2 particles from waterglass. The preparation of SiO2 nanofluid began with screening surfactants to determine the optimum surfactant concentration. Then, the SiO2 nanofluid was prepared by using a bead mill with the addition of the surfactant. The Zeta potential analysis and particle size analyzer (PSA) were used to visualize the dispersion stability of all the prepared nanofluid samples. The results showed that adding 0.1 weight percent of PEG 6000 as a nonionic surfactant increased the stability of the dispersion, producing an average particle distribution of 502.7 nm and a zeta potential of -48.9 mV. The average value of particle size can be reduced using bead mill down to 241.7 nm (aggregate size) with 39.8 nm primary particle resulting in -45 mV zeta potential.

Effect of Surfactant Addition on Organic Transparent Conductive Films Fabricated by Inkjet Printing Method

Recently, active research has been conducted on the development of flexible electronic devices. Hence, the transparent conductive film (TCF), an essential component of the device, must also be flexible. However, the commonly used indium tin oxide (ITO) TCF lacks flexibility and contains rare metal, making resource depletion an issue. Therefore, we focused on poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS), which has high flexibility and conductivity. Flexible TCFs have been fabricated by coating PEDOT:PSS on polyethylene naphthalate substrates using an inkjet printer. However, the current issue in such fabrication is the effect of the interface state on the transparency and conductivity of the thin film. In this study, we investigated the effect of surfactant in addition to polar solvents on the properties of thin films fabricated with PEDOT:PSS ink. Although the electrical conductivity was reduced, the transmittance remained above 90%. Thus, these results are comparable to those of ITO TCFs for practical use in terms of optical properties.

Effect of Adding Surfactants to a Solution of Fertilizer on the Granulation Process

Granulated chelates are innovative fertilizers that are highly effective and versatile, and they ensure the best start-up effect for plants. The final properties of granules are influenced by the method of their preparation and the used substances. The diameters of the obtained granules, their size range, and the final costs of the produced fertilizer are of great importance. The paper describes granules that were produced using an agglomeration of ZnIDHA in a fluidized bed with the aid of an aqueous solution of this substance with a high dry matter content. The aim of the study was to evaluate the effect of surfactant addition to the solution on the evolution of granule size distribution during the process carried out in a batch mode and to access the possibility of describing the process dynamics using population balance approach. A sieve analysis was performed in order to determine the size of the granulate, and numerical calculations were performed to determine the value of the constant aggregation rate. Based on experimental studies, it can be seen that the increase in the diameters of granules is mainly caused by the agglomeration process, and to a lesser extent by the coating process. The addition of surfactant increased the median size of the granules in the initial granulation stage, and also lowered the surface tension. This in turn enables a lower spraying pressure to be used. A comparison of different aggregation kernels constituting an integral part of the population balance model proved that the physically motivated equipartition kinetic energy kernel performs best in this case. Moreover, the computational results show an increase in the aggregation rate when the surfactant additive is used and confirm that population balance allows the extraction of physical information about the granulation.

Effect of surfactant addition and viscosity of the continuous phase on flow fields and kinetics of drop formation in a flow-focusing microfluidic device

Droplet formation in a flow focusing microfluidic device was studied for capillary numbers between 10−4 and 10−1. The addition of a cationic surfactant to the dispersed phase and the effect of the continuous phase viscosity on droplet size, neck kinetics and flow fields inside the drop was investigated. Dropletsize decreased with an increase of the capillary number following a power law with an exponent dependent on drop confinement. At 1–3 ms before pinch-off, the neck thinning rate is dependent onsurfactant concentration and increases closer to pinch-off. Forthe 96 mPa s continuous phase, the two-fluid Stokes regime is observed with an effective interfacial tension smallerthan the equilibrium value, suggesting a negative contribution of Marangoni stresses. During necking, velocities along the neck interface for the surfactant laden cases are smaller due to Marangoni phenomena. During expansion, increased fluid velocities and recirculation are observed.

Dispersion stability of nano additives in lubricating oils – an overview of mechanisms, theories and methodologies

ABSTRACT With the advancement in the field of nanotechnology, various researchers have reported an improvement in the friction and wear behaviour of different lubricating oils by the addition of different nano additives. However, the stability of these nano additives remains a challenge. In this paper, the dispersion stability of various nano additives in lubricating oils has been studied in detail. The paper aims to summarize various dispersion stability theories and several methods reported in the literature to improve dispersion stability. Apart from this, a special focus has been laid to highlight the various surfactants used to improve the dispersion stability, particularly the tribological properties. The literature suggests that although a number of studies have been carried out to study the effect of surfactant addition on dispersion stability, however, future developments could be focused to improve the dispersion stability of the existing mono and hybrid nano fluids and their underlying mechanisms. Abbreviations: SWCNH, single-walled carbon nano-horns; PAO, poly alpha olefin; MoS2, molybdenum di sulphide; H, Hamaker constant, MWCNTs, multi-walled carbon nanotubes; GNF, graphene nanoflakes; DLVO, Derjaguin and Landau Verway and Overbeek; DLS, dynamic light scattering; HLB, hydrophobic lyophilic balance; FERTEM, freeze etching replication transmission electron microscope; SDS, sodium dodecyl sulphate; PTFE, polytetrafluoroethylene; FTIR, Fourier-transform infrared spectroscopy; TBAAc, tetra butyl ammonium acetate; THF, tetrahydrofurane; UV–Vis, ultraviolet visible light; SEM, scanning electron microscope; TEM, transmission electron microscope

Surfactant head group and concentration influence on structure and dynamics of gellan gum hydrogels: Crossover from stretched to compressed exponential

AbstractIn the present study, we have investigated the effects of surfactant addition on the structure and dynamics of gellan gum hydrogels. A strong interaction is seen between gellan gum and oppositely charged cationic surfactant, hexadecyltrimethylammonium bromide (CTAB) whereas rather weak or minimal interactions are observed when either anionic surfactant, sodium dodecylsulfate (SDS), or nonionic surfactant, Triton X‐100 is added to the system. The dynamics of the hydrogels was studied, using dynamic light scattering measurements and the heterodyne method was used for data evaluation. The correlation function of parent hydrogel was fitted with a stretched exponential function, while a single plus stretched exponential function was employed to study the dynamics of hydrogel with surfactants and the corresponding relaxation times were appropriately analyzed. An interesting crossover from stretched to compressed exponential was seen when CTAB was added beyond critical micellar concentration to the system, which was not evidenced for the other two surfactants. Ensemble averaged intensity was also analyzed and the general picture that emerges is that the oppositely charged surfactant has the strongest ability to form large associations as oppose to nonionic and like‐charged surfactants. The rheological measurements were carried out to determine the elastic response of the gels over a wide range of frequencies. It was seen that the elastic modulus was dependent on both the surfactant concentration and type. Cationic surfactant increased the elastic modulus markedly as opposed to the nonionic and anionic surfactants. These results may have implications for the use of polymer surfactant systems as potential products.

Effect of Surfactant Addition on The Physico-Chemical Properties and Stability of Virgin Coconut Oil Nanoemulsions

<p>Virgin coconut oil (VCO) is high quality coconut oil and categorized as the healthiest oil and functional foods. Based on these benefits, the development of a VCO in emulsion product might increase the human consumption of coconut oil because consumers dislike the only taste of pure VCO. The aim of this study was to develop the water compatible form of VCO through nano-emulsification. The effect of different types and amounts of surfactants (Tween 80 and Span 80) on the physio-chemical characteristic of emulsion containing VCO was investigated. VCO based emulsions were prepared with the aid of Ultra-Turrax homogenizer. Emulsions were developed by adding and mixing VCO with surfactants. The ratio of Tween 80 and Span 80 used were 0:10, 2.5:7.5, 5:5, 7.5:2.5, and 10:0. The droplet size of nanoemulsions consisting of Tween 80:Span 80 (0:10, 2.5:7.5, 5:5, 7.5:2.5, and 10:0) were 1.343, 0.606, 0.829, 1.439, and 2.506µm, respectively. Based on the TEM analysis and polydispersity index (PDI) >0.5 showed the oil droplets are in not uniform shape, indicating a unstable emulsion. VCO emulsion with ratio Tween 80:Span 80 (0:10) obtained a homogeneous emulsion (stable) compare than that of others and w/o type emulsion. The stability of emulsion is evaluated by turbidity measurement using UV-VIS spectrophotometer with wavelength 502 nm. A combination of treatments (ambient condition, thermal treatmeant (40°C)), and centrifuge) of VCO emulsion has resulted on thermal treat, the turbidity measured from the emulsion was higher than the other emulsion, reflecting the presence of the smaller droplets in this emulsion.</p>

Strength Indicators Of Cement Systems With Additives Of Surface - Active Substances

In the article, the study was to establish the effect of surfactant additives on the strength characteristics of cement systems. The determinations were carried out on cements of various mineralogical composition, freshly ground and stale, on cement-sand mortars and concretes. For control samples and with additives, the same plasticity was chosen, and the water-cement ratio than for various additives fluctuated within certain limits.

Effect of cationic surfactant addition on the electrokinetics and stability of silica/kaolinite suspensions in copper hydrometallurgy conditions

The presence of small particles at operating conditions of the hydrometallurgy process forming the crud is a complicated issue. These particles, most often silica and clays, remain in the suspension or float to the top. A potential solution for their elimination could be to promote the sedimentation of the solids by the addition of surfactant. However, such a procedure in these complex systems, with different kinds and sizes of particles, requires the evaluation of the composition and optimal dose of surfactant. In this work, we explore the use of dynamic electrophoretic mobility for indirectly evaluating the adsorption of CTAB on silica/kaolinite mixtures at low pH, high ionic strength, and particle concentration above 3%. The electroacoustic technique (ESA) shows to be suitable to predict the effect of surfactant addition on the individual particles of silica and kaolinite and mixtures of them. The conclusions were in agreement with sizes and sedimentation rate determinations. Moreover, scanning electron microscope (SEM) images confirm the evolution of aggregates and the formation of structures between particles by the addition of CTAB. Since the final aim is the identification of the optimal doses of surfactant in which the described suspensions flocculate and separate from the continuous phase, this investigation can potentially contribute to solve operational problems associated to the generation of crud in the hydrometallurgy process.

Effect of surfactant addition to Guar Gum and protection of mild steel in hydrochloric acid at high temperatures: Experimental and theoretical studies

Guar Gum (GG) is an established green inhibitor for mild steel (MS) corrosion in acidic media. The inhibitor action of GG is enhanced by the synergistic interaction with two non-ionic surfactants (Tween -80 and Triton-X). The synergistic pairs were investigated for MS corrosion in 0.5 M HCl using weight loss and electrochemical methods. The synergistic interactions were monitored via theoretical calculations using NBO analysis implemented in Gaussian-09 packages. AFM, SEM, and XPS spectra were carried out to understand the surface events. Computational calculations (DFT and Monte Carlo simulation) were performed to ensure the synergistic action of GG and surfactants. Experimental results revealed that GG:Tween -80 offers 97.13% and GG:Triton-X has 95.50% inhibition efficiency when used in 800: 5 ppm ration at 303 K. The synergistic pairs exhibited remarkable efficiencies at elevated temperatures also.