Sodium Dodecyl Benzene Sulfonate Solution Research Articles

Dynamics of interfacial layers for sodium dodecylbenzene sulfonate solutions at different salinities

This study investigates the adsorption mechanisms and the dilational surface rheology of the anionic surfactant sodium dodecylbenzene sulfonate (SDBS) at the air–liquid interface, in the presence and absence of NaCl over a wide range of SDBS concentrations. We also evaluate the Langmuir and Frumkin models in order to predict the dynamic adsorption of SDBS solutions. Our results reveal that the equilibrium surface tension of SDBS solutions is a monotonically decreasing function of NaCl concentration. However, the dilational viscoelastic properties of SDBS solutions are found to be a non-monotonic function of NaCl concentration. NaCl manifests opposing effects on the dilational viscoelastic moduli of the gas–liquid interface, depending on the frequency of surface oscillation and surfactant bulk concentration. Our measured dilational surface elasticity and viscosity data show a shift in the surfactant transition concentration, at which the viscoelastic moduli reach their maximum values, towards smaller surfactant bulk concentrations with increasing salt concentration. It is attributed to suppressing the electrostatic repulsion between the hydrophilic head groups of surfactant molecules in the presence of electrolytes. The maximum viscoelastic moduli at different NaCl concentrations is found to be the reflection of the relative impact of enhanced adsorption and increased diffusion exchange between bulk and interface.

Surfactant changes lead adsorption behaviors and mechanisms on microplastics

The impact of surfactant addition on the adsorption performance of lead ion (Pb2+) as a typical heavy metal ion on three microplastics was investigated. The types of microplastics (polyethylene (PE), polypropylene (PP) and polymethylmethacrylate (PMMA)) and surfactants (triton X-100 (TX-100), 1-hexadecylpyridinium bromide (HDPB), and sodium dodecyl benzenesulfonate (SDBS)), adsorption time, concentration of Pb2+, and coexisting ions was systematically investigated, and the characteristics of adsorption of Pb2+ by microplastics were analyzed. The experimental results showed that the adsorption capacity of Pb2+ on three micropalstics was different. The adsorption capacity of Pb2+ on the three microplastics without surfactants was: 4.21 (PMMA) > 2.01 (PE) > 1.57 mg g−1 (PP). The addition of surfactants resulted in a higher hydrophilicity of microplastics, and obviously improved the adsorption ability of microplastics for lead ions. SDBS can significantly enhance the adsorption of Pb2+ on three microplastics compared with other two surfactants (TX100 and HDPB). The highest adsorption capacity of Pb2+ on the three microplastics with addition of SDBS solution was: 7.87 (PMMA) > 7.20 (PE) > 7.02 mg g−1 (PP). With the increase of adsorption time and Pb2+ concentration, the adsorption efficiency of microplastics for Pb2+ first increased and then decreased. The pH of solution had a great influence on the adsorption of Pb2+ by microplastics. The results of coexisting ion experiments demonstrated that when lead ion and copper ion coexist, the two ions have competitive adsorption phenomenon on PP. This research explored the adsorption characteristics of lead ions by microplastics with addition of surfactants, which can provide theoretical basis for further study of heavy metal enrichment and environmental behavior of microplastics in the environment.

Selective adsorption of sodium dodecylbenzenesulfonate from a Cs ion mixture by electrospun mesoporous silica nanofibers

Sodium dodecylbenzenesulfonate (SDBS) is commonly used to remove radioactive nuclides such as Cs ions during decontamination of shut-down nuclear power plants. Potential environmental problems still remain because of the incomplete removal of large amounts of SDBS from radioactive liquid waste. For the first time, mesoporous silica nanofibers (MSFs) were fabricated for an efficient SDBS separation. MSFs were prepared by electrospinning using tetraethyl orthosilicate, a surfactant, and a template polymer; the product had a large surface area, a high pore volume, and a uniform pore size distribution. The internal pores or external surface were modified with quaternary ammonium salt, providing affinity to water and an electrostatic interaction with SDBS. The MSF-based adsorbent had excellent adsorption ability for SDBS (158.98 mg/g) over conventional adsorbents. In addition, the MSF-based adsorbent could selectively adsorb SDBS from a mixed solution of SDBS and Cs ions. Judging from the Freundlich pseuso second-order kinetic adsorption, the adsorption isotherm indicated that the SDBS adsorption was a kind of multilayer physisorption.

Effect of SDBS solution on the surface potential properties of the Zhaozhuang coal

It is of great significance to study the effect of surfactants on the coal surface potential for effective dust suppression in mining faces. The effect of different concentrations of sodium dodecyl benzene sulfonate (SDBS) solution on the surface potential of the Zhaozhuang coal was measured by atomic force microscopy (AFM). The experimental results show that the SDBS solution has significant influence on the surface potential of the Zhaozhuang coal. The electrical characteristics of the coal surface at the nanometer scale are different from those of macroscopic or the mesoscopic level. The surface potential of coal is basically a normal distribution, showing certain electrical characteristics. The mean value of the surface potential of the Zhaozhuang coal is increased with the increase in concentration of the SDBS solution; when the concentration of the SDBS solution is 0.3%, the mean value of surface potential is 5.59 mv, which is about two times of the mean value of the surface potential without SDBS solution added. With the increase of the concentration of the SDBS solution, the maximum value of the surface potential of the Zhaozhuang coal increases, and the minimum value decreases. It shows that the SDBS solution has a significant effect on the potential distribution law and the magnitude of the coal surface. Subsequently, on the basis of the constructed Zhaozhuang coal macromolecule model, xtb and Multiwfn simulation software were used to calculate the molecular surface electrostatic potential value and electron density value of the Zhaozhuang coal molecules after adding water molecules. The variation law for the electrostatic potential surface of the molecule was obtained after adding numbers of water molecules to the surface of the coal molecule. The simulation results show that the area proportion of absolute molecular surface electrostatic potential greater than 10 kcal/mol is increased with the growth in the number of water molecules, while the area proportion of absolute molecular surface electrostatic potential less than 10 kcal/mol is decreased. Because of the free state O─H bond polarity of water molecules, the charges on the molecular surface are rearranged in order to change the electron density on the surface of coal molecules, which affects the overall electrostatic potential of the configuration.

Effect of porous media and its distribution on methane hydrate formation in the presence of surfactant

Hydrates are mainly stored within sediment pores in nature. Therefore, understanding their formation characteristics within the porous space is essential to the transportation of natural gas based on the hydrate-based technology. In this paper, solutions of sodium lauryl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and alcohol ethoxylate (AEO) were used with different-sized porous media to investigate the characteristics (gas storage capacity, formation rate, and formation distribution) of the hydrate formation. The experimental results show that the gas storage capacity was higher in the complex system composed of a small-size porous media. The improvement of hydrate formation in the complex system composed of SDS or SDBS solution was more significant than that in the AEO system which could enhance the hydrate formation. In the three complex systems, the surface of alumina particles was positively charged by hydrolysis, which resulted in a double electron layer consisting of the counter ion in the adjacent liquid phase. The anionic active groups ionized by surfactants (i.e., SDS and SDBS) were aggregated to the surface of particles under Coulomb force. This increased the content of the methane molecules by non-polar adsorption and micellar solubilization. Finally, in the complex system of SDS solution and porous media, the capillary force caused by the pores of porous media could enhance the liquid phase migration in the pores which change the distribution of hydrate formation. This work presents useful insights on the hydrate formation characteristics which are beneficial to the rapid formation of hydrate and its industrial application of both storage and transportation of natural gas in complex porous systems.

High efficiency perovskite solar cells with tailorable surface wettability by surfactant

Perovskite solar cells based on nickel oxide (NiOx) attract tremendous attention and develop rapidly. Nevertheless, they are plagued by charge recombination and extraction loss at interfaces between the perovskite absorber and the charge transport layers. Herein, an ultrathin sodium dodecyl benzene sulfonate (SDBS) film is introduced between the perovskite absorber and the NiOx hole transport layer (HTL) to reduce interfacial and extraction losses. The modification on the NiOx HTL by SDBS surfactant can effectively tailor the quality of the perovskite film with larger grain size and better crystallinity by regulating the wettability of the NiOx surface with varied concentration of SDBS solution. Moreover, the charge separation and extraction in the perovskite/HTL interface are enhanced after SDBS treatment on NiOx HTL characterized by electrochemical impedance characterization. As a consequence, these benefits contribute to high power conversion efficiency (PCE) of 20.15%, in comparison with PCE of 16.26% for the reference device. It is hoped that this work will provide new perspectives for preparing perovskite solar cells with an unprecedented performance and the opportunity for commercialization.

Microwave assisted persulfate induced degradation of sodium dodecyl benzene sulfonate

Microwave assisted persulfate induced degradation of sodium dodecyl benzene sulfonate (SDBS) was investigated, focusing on establishing the best conditions for maximum degradation. The study involving different persulfate based oxidants, such as potassium persulfate (KPS), ammonium persulfate (NH3PS) and sodium persulfate (NaPS), revealed that the extent of degradation as 98.3, 82.2 and 68.2% was obtained for the use of KPS, NH3PS and NaPS, respectively. The study of the effect of SDBS concentration (25–100 mg/L), oxidant loading (0–3 g/L) and power (140–350 W) established that degradation decreased with an increase in the operating parameter beyond the optimum condition. Under optimized conditions using potassium persulfate (KPS) as an oxidant, 51.6% and 98.3% degradation of 50 mg/L SDBS solution was obtained by conventional and microwave assisted chemical oxidation approach, respectively, under optimized conditions of power, oxidant loading, volume and time maintained as 280 W, 2 g/L, 250 mL and 28 min, respectively. Extending the conventional approach for 120 min resulted in degradation of 92.5%, which establishes that microwave helps in reducing the treatment time significantly. Kinetic study revealed pseudo-first-order behavior for degradation of SDBS. Energy per order (EEO) for conventional and microwave assisted degradation was observed to be 840 and 317.33 kWh/m3, respectively. Overall, microwave assisted persulfate induced degradation of SDBS has been established to be promising method giving rapid degradation and better economics.

On-line synergistic stacking in capillary zone electrophoresis featuring field-amplified sample stacking and micelle to cyclodextrin stacking in the determination of two alkaloids in complicated matrix samples.

A novel on-line synergistic proconcentration strategy coupling field-amplified sample stacking and micelle to cyclodextrin stacking for cationic analytes in capillary zone electrophoresis has been proposed and applied for the separation and determination of two alkaloids, matrine, and oxymatrine in complicated matrix samples. The approach was performed by the long injection of sample in a low-conductivity sodium dodecyl benzene sulfonate solution followed by the injection of hydroxypropyl-β-cyclodextrin solution in higher conductivity. The stacking mechanism of this method has been expounded and parameters affecting stacking effect have been optimized in our study. Under the optimum experimental conditions, 169- and 218-fold sensitivity improvements were achieved for matrine and oxymatrine when compared with normal injection. Analytical indicators including linearity, limits of detection, and reproducibility (intra- and inter-day relative standard deviations) were evaluated. Moreover, sample matrix effect was studied using compound flavescent sophora and salicylic acid powder and spiked urine samples. The developed method is an attempt for the combination of micelle to cyclodextrin stacking with other stacking methods. It could be a good alternative choice for the determination of alkaloids in a complex sample matrix.

Adsorption Characteristics of Anionic Surfactant Sodium Dodecylbenzene Sulfonate on the Surface of Montmorillonite Minerals.

The adsorption characteristics of sodium dodecylbenzene sulfonate (SDBS) on the surface of montmorillonite can lay a foundation for obtaining the optimum concentration of the anionic surfactant. The best absorption wavelength of SDBS was determined using an ultraviolet spectrophotometer. The standard curves of concentration and absorbance of SDBS were established. The amount of SDBS adsorbed on the surface of montmorillonite at various concentrations was calculated by stirring adsorption method. Scanning electron microscopy–energy dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD), zeta potentiometer, and Fourier transform infrared (FTIR) spectroscopy were used to observe the changes of the structure, main ions, interlayer spacing, potential, and main functional groups on the montmorillonite surface before, and after, adsorption. The test results of SEM with EDS (SEM–EDS) showed that the surface of the montmorillonite after SDBS adsorption was rougher, and the adsorption capacity of the surface was enhanced as the SDBS concentration increased. The XRD results indicated that SDBS adsorbed on the interlayer of montmorillonite repulsed interlayer water and reduced the interlayer water content. With the increase of SDBS concentration, the interlayer spacing of the montmorillonite available for adsorbing SDBS decreased further. Additionally, interlayer adsorption and surface adsorption exist simultaneously in montmorillonite in SDBS solution. The distribution of total adsorption capacity of SDBS in the layers and on the surface of montmorillonite accords with the adsorption result simulated by a pseudo-second-order kinetic model. The increase in concentration of SDBS adsorbed by montmorillonite is the main reason for the decreased initial adsorption rate. The zeta potential test showed that the addition of H+ to the SDBS solution could reduce electrostatic repulsion and promote the adsorption of SDBS on montmorillonite. The results of this study provide an experimental basis for the study of the mechanism of SDBS adsorption on montmorillonite.

Removal of Sodium Dodecylbenzenesulfonate by Macroporous Adsorbent Resins

Among the surfactants used for removal of radioactive nuclides generated from nuclear decontamination, sodium dodecylbenzenesulfonate (SDBS) is frequently used. A potential environmental problem of incomplete elimination of SDBS from radioactive liquid wastes (RLWs), which contain a high concentration of SDBS and radioactive nuclides, still remains. Removal of SDBS was evaluated by adsorption using commercially available, macroporous polymer-based adsorbents, HP20 and HP2MGL, which are styrene (St)- and methyl methacrylate (MMA)-based crosslinked resin beads, respectively. The effect of the macroporosity and chemical structure of the macroporous adsorbent resins (MARs) on the adsorption behavior was investigated. HP20 did not have any functionality for adsorbing SDBS, but it showed effective adsorption toward SDBS (less than 20 min to reach 90% adsorption), because of the hydrophobic interaction between the phenyl groups in the St unit in HP20 and in the SDBS. The removal of SDBS from a mixed solution of SDBS and Cs ions was investigated to elucidate the adsorption process in an imitation of the sort of RLWs. This investigation suggests that MARs can potentially be used for the removal of SDBS not only from a SDBS solution but also from a mixed solution of SDBS and Cs ions.

Thermoelectric Characterization of Semiconducting Carbon Nanotube Sheets

Key Word: thermoelectric conversion / semiconducting carbon nanotube / electrical conductivity / Seebeck coefficient / thermal conductivity Introduction It is reported that nearly 15 terawatt of energy has been wasted as low temperature heat [1, 2] per year. Thus, conversion of heat into electricity so called thermoelectric (TE) conversion has become an important technology. Typical approach for the TE conversion is to utilize the Seebeck effect that enables the temperature gradient into the carrier movement, resulting in the generation of the electricity. TE efficiency of the materials is usually characterized by the figure of merit (ZT) given by the equation (1) ZT = (σS2/κ) ・ T (1), in which σ, S, κ, T is electrical conductivity, Seebeck coefficient, thermal conductivity and temperature, respectively. To achieve a high ZT value, the material having high σ and S, low κ is desired. Up to date, inorganic semiconducting materials such as Bi2Te3 are used as the thermoelectric materials because of their high ZT value (ZT>1) [3]. However, these materials have problems such as toxicity, high cost and low processability, which prevent these materials from the practical use. In this background, recently, single-walled carbon nanotubes (SWNTs) have attracted strong attention due to the extremely high electrical conductivity as well as their non-toxicity, light weight, mechanical toughness, flexibility and low cost, all of which are advantageous as the thermoelectric material. SWNTs are produced as a mixture of metallic (m-) and semiconducting SWNTs (s-SWNTs) and s-SWNT sheet was proved to have large Seebeck coefficient theoretically and experimentally [4, 5]. However, the improvement of ZT value by separating s-SWNT from the as-produced SWNT mixture is still uncertain. In this study, we characterized the TE properties of s-SWNT sheets with different metal impurity and compared their ZT values with that of unsorted SWNT sheet. Experiment s-SWNTs 2.0 mg (98% Nanointegris) and m-SWNT 1.0 mg (98% Nanointegris) were added to 0.5% SDBS (sodium dodecylbenzenesulfonate) solution and dispersed by bath sonicator (BRANSON, 1 hr) and probe sonicator (TOMY UD-200). The dispersion were filtrated and the free-standing s-:m-SWNT=2:1 sheet was obtained (2:1 mix). s:m-SWNT=4:1 sheet (4:1 mix), s- and m-SWNT sheets were made in the same fashion. In-plane electrical conductivity and Seebeck coefficient were measured by ZEM-3 (ADVANCE RIKO) from 30 to 100 ºC. The specific heat capacity (Cp) was measured by differential scanning calorimetry (DSC) method using EXSTAR DSC 6200 (SII Nanotechnology) at the heating rate of 10 K min-1. In-plane thermal diffusivity (α) were evaluated using a Thermowave Analyzer TA (Bethel Co., Ltd.,). The density of the sheets (ρ) was calculated from the weight and volume of the sheets. Results and discussion Table 1 summarized the in plane σ, S and power factor (PF) of the unsorted SWNT, s-SWNT, m-SWNT and 2:1 mix sheets at 30 ºC. Unsorted SWNT sheet exhibited nearly 1.9 times higher electrical conductivity than the m-SWNT sheet. This was due to the defects induced during the separation process of the m-SWNT, which was confirmed by the larger D band of m-SWNT than that of unsorted SWNT in Raman spectra (data not shown). s-SWNT sheet showed higher Seebeck coefficient, however, the powerfactor (PF) value was similar to that of the unsorted SWNT sheet due to the large decrease of electrical conductivity. In addition, ZT value of s-SWNT was almost comparable with that of unsorted SWNT, which implied the good TE properties of unsorted SWNT in the practical point of view. Reference [1] Hochbaum, A. I. et al, Nature, 451, 163-167 (2008) [2] Ren, Z. F. and Chen, G. et al, Energy Environ. Sci. 5, 5147–5162 (2012) [3] G. J. Snyder and E. S. Toberer et al, Nature Mater., 7, 105-114 (2008). [4] Blackburn, J. L. and Ferguson, A. J. et al. Nature Energy, 1 (2016) [5] Nakai, Y., Maniwa, Y.et al, Applied Physics Express 7, 025103 (2014) Figure 1

Effect of surfactants on the treatment of radioactive laundry wastewater by direct contact membrane distillation

AbstractBACKGROUNDDirect contact membrane distillation (DCMD) was applied to treat the radioactive laundry wastewater produced from nuclear power plants (NPPs), with surfactants.RESULTSThe experimental results show that when 0.08 mmol L‐1 surfactants was added into feed solution, the permeate flux reduced sharply by 3–30% in 1 h, and the largest reduction was found in the case with non‐ionic surfactant. The decontamination factors (DF) of Sr(II), Co(II), and Cs(I) were correspondingly decreased 10–100 times within 4–8 h. Compared with the no salt‐added case, the addition of high concentration salt (100–300 g L‐1) slowed down the reduction rate of the permeate flux caused by sodium dodecyl benzene sulfonate (SDBS). The wetting of membranes by surfactants mainly results from the spontaneous adsorption of surfactant molecules onto the membrane surface and the reduction of solution surface tension. However, the high concentration of NaNO3 in SDBS solution decreases the critical micelle concentration (CMC) of SDBS to less than 0.06 mmol L‐1, and thus SDBS micelles formed, which were hard for the membrane surface to absorb.CONCLUSIONThe study shows that surfactants could cause serious reduction in permeate flux and rejection of nuclides, and thus they should be removed from the feed solution of DCMD process. © 2018 Society of Chemical Industry

Effect of increased groundwater viscosity on the remedial performance of surfactant-enhanced air sparging

The effect of groundwater viscosity control on the performance of surfactant-enhanced air sparging (SEAS) was investigated using 1- and 2-dimensional (1-D and 2-D) bench-scale physical models. The viscosity of groundwater was controlled by a thickener, sodium carboxymethylcellulose (SCMC), while an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), was used to control the surface tension of groundwater. When resident DI water was displaced with a SCMC solution (500 mg/L), a SDBS solution (200 mg/L), and a solution with both SCMC (500 mg/L) and SDBS (200 mg/L), the air saturation for sand-packed columns achieved by air sparging increased by 9.5%, 128%, and 154%, respectively, (compared to that of the DI water-saturated column). When the resident water contained SCMC, the minimum air pressure necessary for air sparging processes increased, which is considered to be responsible for the increased air saturation. The extent of the sparging influence zone achieved during the air sparging process using the 2-D model was also affected by viscosity control. Larger sparging influence zones (de-saturated zone due to air injection) were observed for the air sparging processes using the 2-D model initially saturated with high-viscosity solutions, than those without a thickener in the aqueous solution. The enhanced air saturations using SCMC for the 1-D air sparging experiment improved the degradative performance of gaseous oxidation agent (ozone) during air sparging, as measured by the disappearance of fluorescence (fluorescein sodium salt). Based on the experimental evidence generated in this study, the addition of a thickener in the aqueous solution prior to air sparging increased the degree of air saturation and the sparging influence zone, and enhanced the remedial potential of SEAS for contaminated aquifers.

Investigating the synergic effects of chemical surfactant (SDBS) and biosurfactant produced by bacterium (Enterobacter cloacae) on IFT reduction and wettability alteration during MEOR process

In the current study, a novel approach which takes into account the effectiveness of both convectional surfactants and biosurfactants was investigated. The biosurfactant produced by Enterobacter cloacae strain was utilized concomitant with conventional surfactant (sodium dodecyl benzene sulfonate (SDBS)) to evaluate its capability to reduce the SDBS adsorption on rock surface (biosurfactant acts as sacrificial agent) or synergistically enhance the effectiveness of the SDBS. In this regard, the wettability alteration and interfacial tension (IFT) measurements and calculation of spreading coefficient were performed considering two different scenarios. In the first scenario, SDBS was added to the incubated bacterial solution medium while in the second case, SDBS was added to the bacterial solution before the incubation stage. Based on the obtained results, it was revealed that the wettability altered from original oil wet towards water wet state using bacterial solution, while the addition of SDBS deteriorated this trend for both scenarios. According to IFT measurements, the first scenario was more effective than the individual solution of bacteria and SDBS as well as the second scenario. In conclusion, the measured spreading coefficient demonstrated that the bacterial solution was a more effective EOR agent in comparison to other studied cases.

Micelle-vesicle-micelle transition in aqueous solution of anionic surfactant and cationic imidazolium surfactants: Alteration of the location of different fluorophores

The presence of different surfactants can alter the physicochemical behaviors of aqueous organized assemblies. In this article, we have investigated the location of hydrophobic molecule (Coumarin 153, C153) and hydrophilic molecule (Rhodamine 6G perchlorate, R6G) during micelle-vesicle-micelle transition in aqueous medium in presence of anionic surfactant, sodium dodecylbenzenesulfonate (SDBS) and cationic imidazolium-based surfactant, 1-alkyl-3-methylimidazolium chloride (CnmimCl; n=12, 16).Initially, the physicochemical properties of anionic micellar solution of SDBS has been investigated in presence of imidazolium-based surfactant, CnmimCl (n=12, 16) in aqueous medium by visual observation, turbidity measurement, zeta potential (ζ), dynamics light scattering (DLS), and transmission electron microscopy (TEM). Zeta potential (ζ) measurement clearly indicates that the incorporation efficiency of C16mimCl in SDBS micelle is better than the other one due to the involvement of strong hydrophobic as well as electrostatic interaction between the two associated molecules. Turbidity and DLS measurements clearly suggest the formation of vesicles over a wide range of concentration.Finally, the rotational motion of C153 and R6G has also been monitored at different mole fractions of CnmimCl in SDBS-CnmimCl (n=12, 16) solution mixtures. The hydrophobic C153 molecules preferentially located in the bilayer region of vesicle, whereas hydrophilic R6G can be solubilized at surface of the bilayer, inner water pool or outer surface of vesicles. It is observed that rotational motion of R6G is altered significantly in SDBS-CnmimCl solution mixtures in presence of different mole fractions of CnmimCl. Additionally, the translational diffusion motion of R6G is monitored using fluorescence correlation spectroscopy (FCS) techniques to get a complete scenario about the location and translational diffusion of R6G.

Effects of SDS and SDBS on CO2Hydrate Formation, Induction Time, Storage Capacity and Stability at 274.15 K and 5.0 MPa

AbstractThe CO2 hydratetechnology is growing in relative to CO2 capture, storage and transportation processes. An experimental investigation on CO2 hydrate formation in case of SDS (Sodium dodecyl sulfate) and SDBS (Sodium dodecyl benzene sulfonate) with seven concentrationsi. e.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 g/L was conducted at temperature of 274.15 K and initial pressure of 5.0 MPa. It was found that SDS and SDBS surfactants havelittleinfluence on the total moles of gas consumed in the stirred reactor. The induction time of CO2hydrate formation was approximately 35 minsinboth of 0.5 g/L SDS and 0.3 g/L SDBS solution,while that was 50 minsin pure water. Although the surfactantsreduced the CO2hydrate induction time significantly, they did not show clear influence on the gas storage capacities. The maximum gas storage capacities of CO2 hydrate in pure water, SDS and SDBS aqueous solutions are 89.62, 92.67, 92.62 V/VH, respectively. The difference in decomposition time of CO2 hydrate formed in pure water, SDS and SDBS solutions indicates that SDS and SDBScan greatly enhance the stability of CO2 hydrate.

Removing Sodium Dodecyl Benzene Sulfonate (SDBS) from Aqueous Solutions Using Chitosan

Discharging wastewater containing surfactants such as sodium dodecyl benzene sulfonate (SDBS) to water and soil to follow, problems such as toxicity to humans and animals. Due to the toxicity of biological and non-biodegradable contaminants, sewage containing surfactants need to be refined in terms of public health. The use of absorbent such as chitosan due to advantages such as, low toxicity and good chemical activity is considered to eliminate surfactants from water. In the present study, the removal of SDBS ions was studied from aqueous solutions by chitosan. The latter was dissolved in 1 % acetic acid solution and afterwards the absorption tests was done in a batch system to investigate the parameters of pH, initial concentration of SDBS solution, the amount of absorption and duration of exposure on the adsorption process. The results showed that under optimal conditions, the maximum effectiveness of removal has been 97.3 % at pH 4.

Origin of the Surfactant‐Dependent Redox Chemistry of Single‐Wall Carbon Nanotubes

AbstractThe redox chemistry of single‐walled carbon nanotubes (SWCNTs) was examined by using optical absorption spectroscopy measurements in the presence of sodium dodecyl sulfate (SDS) and its analog surfactants, that is, sodium 1‐undecanesulfonate (SUS) and sodium dodecylbenzenesulfonate (SDBS). Redox reactions of the SWCNTs were observed in the SDS and SUS solutions, whereas such reactions were suppressed in the SDBS solution. Molecular dynamics simulations were performed to investigate the assembly of the surfactants around an SWCNT. SDS and SUS were shown to primarily form single layers on the SWCNT and certain solvent‐exposed areas, whereas SDBS predictably densely coated the SWCNTs. The results suggest that the SDBS layer on the SWCNT surfaces prevents charge‐transfer reactions; in contrast, the sparse layers of SDS and SUS allow the redox chemistry through the charge‐transfer reactions. Interestingly, a positively charged SWCNT as a model for the oxidized SWCNT showed an increase in the number of surfactant molecules around the SWCNT in the SDS and SUS solutions owing to electrostatic interaction, which is related to the chirality‐dependence of the SWCNT colloidal stability.

Modeling of the chemical composition of DC atmospheric pressure air discharge plasma in contact with aqueous solutions of sodium dodecylbenzenesulfonate

The results of calculation of the chemical composition of plasma of the DC atmospheric pressure discharge in air in contact with aqueous solutions of sulfonol (C12H25C6H4SO3Na) in the concentration range of 0–10 g/L at a discharge current of 40 mA are presented. At modeling, the combined solution of Boltzmann equation for the electron gas, equations of vibrational kinetics for ground states of N2, O2, H2O, and NO molecules, equations of chemical kinetics and plasma conductivity equation were used. It was shown that sodium atoms appearing as a result of transfer processes from the liquid cathode affect the chemical composition of the plasma and the characteristics of the electron gas.

On the mechanism of boiling heat transfer enhancement by surfactant addition

In our previous study, bubble jet and bubble explosion around a heated wire were discovered in aqueous cetyltrimethyl ammonium chloride (CTAC) solutions (Wang et al., 2016), in which the bubble explosion process was explained. The bubble explosion phenomenon was proven to be a failed coalescence of unstable bubbles which caused local disturbance and enhanced boiling heat transfer. In this paper, comparative experiments of boiling around a heated wire for different types of surfactant solutions, ethanol and silicone oil were carried out in order to explore the mechanism of surfactant addition enhancing boiling heat transfer. All these fluids had lower surface tensions than that of water. Cationic surfactant of CTAC, anionic surfactant of sodium dodecylbenzenesulfonate (SDBS) and nonionic surfactant of alkyl polyglycoside (APG) were used. Bubble jet and bubble explosion phenomenon were found in all three kinds of surfactant solutions, exhibiting excellent heat transfer effect. For the pool boiling in ethanol, only bubble jet around the heated wire was found, showing better heat transfer efficiency than water. However, weaker boiling heat transfer occurred in silicone oil without bubble jet and bubble explosion. Due to the heat sensitivity characteristics, APG solution had a lower critical heat flux (CHF) than water, while CTAC and SDBS solution had higher CHF. With all phenomena and heat transfer performances, the mechanism of boiling heat transfer enhancement by surfactant addition was confirmed, i.e., the bubble jet and bubble explosion process enhanced the boiling heat transfer in surfactant solution rather than low surface tension.