Surfactant Sodium Dodecylbenzenesulfonate Research Articles

Heat transfer analysis of triple concentric tube heat exchanger using MWCNT/water nanofluids under parallel flow configurations

In this investigation, heat transfer characteristics of Multi-Walled Carbon Nanotubes/water nanofluids are studied experimentally in a triple concentric tube heat exchanger under parallel flow configurations and compared with water. The Multi-Walled Carbon Nanotubes/water nanofluids are formulated for 0.2, 0.4 and 0.6% nanoparticle volume concentrations using a two-step method by adding sodium dodecylbenzene sulfonate surfactant. At 0.6% particle volume concentration, the Nusselt number is found to be 10% higher compared with water at 7500 Reynolds number. In this experimental investigation, it is found that at Reynolds number 9500, the overall heat transfer coefficient is enhanced by 15% and pressure drop enhanced by 15% compared with water at 6500 Reynolds number and friction factor is enhanced by 16% compared with water at 0.6% Multi-Walled Carbon Nanotubes/water nanofluids concentration.

Enhancement of Heat Transfer Performance of a Heat Pipe by Using Calcium Magnesium Carbonate-Ethylene Glycol/Water Nanofluid with Sodium Dodecylbenzene Sulfonate

In this paper, the effect of using CaMg(CO3)2/Ethylene Glycol-water (50:50%) as a working fluid on the thermal performance of thermosyphon heat pipe was experimentally studied. Nanofluid was prepared by two-step method using 2% concentration of CaMg(CO3)2 nanoparticle and 0.05% surfactant (Sodium dodecylbenzene sulfonate). For the experimental set-up, a straight copper pipe of one-meter length was used. The inner diameter of the pipe is 13 mm, and the outer diameter is 15 mm. Experiments were conducted at three different cooling water mass flow rates (5, 7.5, and 10 g/s) and different heating powers (200, 300, 400 W) to test heat pipe performance. It was observed that the CaMg(CO3)2 nanofluid reduced the average wall temperature of the heat pipe according to the base fluid. Furthermore, the efficiency and thermal resistance of the heat pipe were investigated separately for EG/water and CaMg(CO3)2 nanofluid. The maximum heat transfer enhancement was obtained as 9.55% under 400 W heating power and 10 g/s cooling water mass flow rate conditions and the maximum improvement in thermal resistance was observed as 21% at 200 W and 10 g/s cooling mass flow rate. Viscosity and specific heat of base fluid and CaMg(CO3)2 nanofluid were also determined and compared to each other.

Improving the colloidal stability of PEGylated BaTiO3 nanoparticles with surfactants

Barium titanate, BaTiO3, nanoparticles (NPs) have been widely used as a ferroelectric/piezoelectric/ pyroelectric material in the electronic-optical ceramic industry. However, the stability of BaTiO3 NP suspension is a matter of concern for their advanced applications in wet-ceramic manufacturing, imaging, and electrorheological fluids. In this study, we investigated the effect of three different surfactants (sodium dodecylbenzenesulfonate (anionic), cetyltrimethylammonium bromide (cationic), and sorbitan monooleate (non-ionic)) on the stability of PEGylated BaTiO3 nanoparticles in two solvents (water and ethylene glycol) by means of dynamic light scattering, ζ potential, UV–visible spectroscopy, scanning electron microscopy, and visual observation. Our findings indicate that the anionic surfactant acted as the best stabilizer for BaTiO3 nanofluids, while the cationic surfactant was the least favorable stabilizer in both water and ethylene glycol, due to the balance between attraction and repulsive forces. The results of this research provide a simple and effective approach to control and improve the colloidal stability of BaTiO3 nanoparticles.

(Invited) Toward Nanocarbon Materials-Based Organic and Perovskite Solar Cells

In this presentation, we introduce our recent research progress on organic and perovskite solar cells using functionalized nanocarbon materials. We applied wet-processed scalable single-walled carbon nanotubes (SWCNT) films to transparent and back electrodes in organic solar cells for large area solar cells. Gas-phase growth SWCNT was dispersed with sodium dodecylbenzenesulfonate surfactant in an organic solvent and solution-coated on a treated glass substrate to make a SWCNT film as a transparent electrode. We achieved the first high efficiency e-DIPS/wet-processed SWCNT film electrode in organic solar cells with a best-efficiency of 5.93% through the optimized HNO3 doping methodology.We also report enhanced hole-transporting ability of widely utilized poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) achieved by applying cationic nitrogen-doped graphene (CNG) as a p-type modifier for efficient organic solar cells. The power conversion efficiency of the CNG-coated PEDOT:PSS-applied OSC reaches 2.76% using poly(3-hexylthiophene), which is an increase of 40% compared to that of the pristine PEDOT:PSS-applied OSC (1.96%). This technology improved the efficiency of organic solar cells using a low-bandgap polymer from 6.54% to 7.79%. The significantly enhanced performance is contributed by the increased hole-transporting ability, and the improved interfacial morphology of PEDOT:PSS.

A sensitive photoluminescent sensor based on highly charged monoruthenium(II) complexes for dopamine detection

A sensitive and selective photoluminescent sensor based on the highly charged monoruthenium(II) complex was designed to detect dopamine (DA) in aqueous samples. Two novel highly charged cationic ruthenium(II) complexes [Ru(bpy)2(bpy-N)]X4 (bpy = 2,2′-bipyridine, bpy-N = 4,4′-bis[N,N,N-triethyl-(methylamino)]-2,2′-bipyridine, X− = [PF6]− (1a) or Cl− (1b) and [Ru(bpy)(bpy-N)2]X6 (X− = [PF6]− (2a) or Cl−(2b)) can be assembled with anionic surfactant sodium dodecylbenzene sulfonate (SDBS), leading to an enhancement of photoluminescence intensity. Upon addition of DA to the system, the photoluminescence intensity of the assembled system was quenched due to the energy transfer effect. It exhibited a wide linear range (0.1–50 μM) and low detection limit (10 nM). The sensor demonstrated a high selectivity toward DA, especially in the presence of adrenaline (Adr) and norepinephrine (NE), whose structures are similar to DA in biological systems. With the merits of simple operation, obvious phenomenon and fast response speed, the sensor had a potential application prospect in human urine sample.

Effective removal of humic acid by mesoporous Zr-MOF adjusted through SDBS.

Humic acid (HA) in makeup water is one of the important safety issues of high-parameter power plants. Herein, the Zr-based metal-organic frameworks (NH2-UiO-66) was applied to remove humic acid in water. The mesoporous of NH2-UiO-66 was controlled by surfactants sodium dodecyl benzene sulfonate (SDBS) to increase the adsorption of HA. The adsorption of HA at 25°C and pH 7 increased fast at the first 0.5 h and then gradually reached equilibrium after 10 h. The maximum adsorption capacity was 108.93 mg g-1, which removal efficiency was high as 95.0%. The morphology and adsorption properties of NH2-UiO-66 were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), surface charge, Fourier transform infrared (FT-IR), N2 adsorption-desorption, and adsorption test. The adsorption process of HA accorded with the pseudo-second-order kinetics, while the adsorption isotherm conformed to be the Langmuir model and the adsorption was proved to be monolayer adsorption. Adsorption was the spontaneous and endothermic process (ΔG°<0, ΔH°>0). The accessible surface area provided by mesopores on the 5 different Zr-MOFs was the reason for the enhanced HA adsorption capacity. These results provided useful information for effective HA removing and enhanced our understanding of the adsorption mechanism of HA on NH2-UiO-66.

Simple synthesis of high photocatalytic activity TiO2 nanopowder with sodium dodecylbenzene sulfonate surfactant for photocatalysis of rhodamine B and methyl orange

Simple synthesis of high photocatalytic activity TiO2 nanopowder with sodium dodecylbenzene sulfonate surfactant for photocatalysis of rhodamine B and methyl orange

Impact of Sodium Dodecyl Benzene Sulfonate Concentration on the Stability of the Crude Oil–Mineral Water Interfacial Film: A Molecular Dynamics Simulation Study

The interfacial behavior of surfactants exerts a considerable impact on the chemical flooding-produced liquid treatment project. For circumventing the limitations of model simplification and single-factor simulation of previous molecular dynamics (MD) studies, this paper based on the experimental results of crude oil-phase and water-phase composition constructed different simulation systems of “crude oil/SDBS/mineral water” considering the concentration of sodium dodecyl benzene sulfonate (SDBS). The impact of SDBS concentration on the stability of the crude oil–mineral water interfacial film was explored, and the simulation results were verified by comparing with the simulation system of “crude oil/SDBS/pure water” and interfacial tension experiments. The simulated results showed that the SDBS molecules in the system exist in the form of a monolayer film after dynamic relaxation equilibrium, and with the increase in concentration, the number of SDBS molecules per unit area of the film increases, and the molecular chain bending characteristics are weakened. The order of the effect of inorganic cations on the aggregation degree of SDBS is Ca2+ > Na+ > K+ > Mg2+. When the concentration of SDBS increased from 0.15 to 0.70 mol/L, the total oil water interfacial film thickness increased from 1.433 nm in the crude oil/SDBS/mineral water system and 1.272 nm in the crude oil/SDBS/pure water system to 2.125 nm in the crude oil/SDBS/mineral water system and 2.398 nm in the crude oil/SDBS/pure water system. The absolute value of interface formation energy increased from 1223.59 and 1236.32 to 2739.19 and 3033.64, respectively, which are also basically consistent with the experimental results of interface tension. Furthermore, inorganic ions will weaken the performance of the surfactant SDBS and detrimentally affect the structural strength and stability of interfacial films. These results offer useful insights into the stabilization mechanism of oil–water emulsions. In particular, they provide a basis for the design and optimization of new pathways for oil–water emulsion instability in oilfield development.

Molecular dynamics simulations and experimental study of the effects of an ionic surfactant on the wettability of low-rank coal

The surfactants sodium dodecyl benzene sulfonate, dodecyl dimethyl betaine, and dodecyl trimethyl ammonium bromide were used to study the effect of an ionic surfactant on coal wettability. A lignite-surfactant-water system was constructed using the Wender coal chemical structure model and Materials Studio molecular simulation software, and the static potential of a single molecule was determined by quantum chemical calculations. The initial and equilibrium configurations of the system, relative concentration distribution, and mean-square displacement (MSD) of water molecules were analyzed thoroughly. Additionally, the surface tension and contact angle of aqueous surfactant solutions with different mass concentrations were measured to analyze the relationship between concentration and the rate of reduction of surface tension and of contact angle. The analysis showed that when the surface static potential of the lignite molecule was larger than that of water molecules, the water molecules were easily attracted and exhibited a wetting phenomenon. The water-surfactant-coal system gradually tended from an initial unstable state to a stable state with low energy. Specifically, the hydrophilic groups in the surfactant were tilted toward the water phase and the hydrophobic chains were adsorbed on the surface of coal, which helped enhance the wettability of the coal. The relative concentration distribution range of the SDBS was 26–52 Å, which was wider than the other two surfactants. Additionally, the MSD curve showed that the diffusion coefficient of the water molecules in the water-SDBS-coal system reached a maximum value of 4.23 × 10−2, resulting in accelerated wetting of the coal body. When the SDBS mass concentration was 3%, the surface tension decreased to the minimum value (21.86 mN/m) and the minimum contact angle was 16.12°. Based on the simulation results and experimental test data, the wettability of the three surfactants to lignite was SDBS > BS-12 > DTAB. The findings of this study help to better understand the wetting mechanism of surfactants on lignite, which is conducive to the rapid screening of surfactants with strong wetting ability on lignite, expanding the use of surfactants, and is of great significance to the control and prevention of coal dust pollution.

Sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine oxide (DDAO) in single and mixed systems as corrosion inhibitors of zinc in hydrochloric acid

Abstract The influence of surfactant synergism between sodium dodecyl benzene sulfonate (SDBS) and N,N-dimethyldodecan-1-amine Oxide (DDAO) on zinc corrosion in 0.05 M hydrochloric acid (HCl) solutions at 25 °C was investigated. Firstly, solutions of SDBS and DDAO with mole fractions of 0.00, 0.25, 0.50, 0.75 and 1.00 were prepared and their surface tension and critical micelle concentration (CMC) values in water and in 0.05 M HCl were measured as a function of total surfactant concentration. The SDBS/DDAO mixed system exhibited a strong synergism in 0.05 M HCl with a highly negative interaction parameter β (average β = −23.46), according to regular solution theory. Secondly, the adsorption of single surfactants SDBS and DDAO and SDBS/DDAO surfactant mixture on 2.0% zinc powder was investigated by the depletion method to find out the role of synergism in the adsorption tendency of these surfactants on the zinc surface and thus their corrosion inhibiting effect. The adsorption tendency of single surfactant and the mixed surfactant systems onto 2.0% zinc powder followed the order: SDBS &gt; 0.75 SDBS/0.25 DDAO ≈ 0.25 SDBS/0.75 DDAO &gt; DDAO &gt; 0.50 SDBS/0.50 DDAO. Finally, the corrosion of zinc was investigated using the potentiodynamic polarization technique. It was found that SDBS and DDAO act as efficient corrosion inhibitors for zinc in 0.05 M HCl solution with increasing corrosion inhibition efficiency when they are mixed. Additionally, images of scanning electron microscopy were obtained for zinc sheets in solutions containing single and mixed SDBS/DDAO surfactants in the presence and absence of 0.05 M HCl. The microscopic images show an improvement in the protection of the zinc surface against acid attack in the presence of single and mixed SDBS/DDAO surfactants.

Solidification characteristic enhancement of aqueous nanofluid with different carbon nanotube sizes

In this work, the solidification characteristic of aqueous carbon nanotubes (CNTs) nanofluids with various CNTs sizes and concentrations were experimentally investigated. It is indicated addition of surfactant sodium dodecyl benzene sulfonate (SDBS) keeps suspension stability of CNTs nanofluid after solidification-melt cycle, and shows a positive effect during the nucleation region. The results show that subcooling degree and energy storage duration decrease as increasing CNTs concentration from 50 ppm to 2000 ppm. Furthermore, it is found the size of CNTs has a great influence on solidification characteristics. The subcooling degree depression and storage energy acceleration for aqueous nanofluids are more effective as the smaller diameter and longer length of CNTs. A maximum reduction of 47.3% in subcooling degree and 17.8% in charging speed advance were achieved for the CNTs nanofluid with diameter of <8 nm and length of 10–30 um at 500 ppm compared to the deionized water. Moreover, nucleation free energy for five sizes of nanofluids was studied by heterogeneous nucleation in consideration of contact angle and radius of CNTs. The results show the lower nucleation free energy is relevant to the lower subcooling.

Preparation and characterization of self-crosslinking acrylic emulsion with different fluorocarbon chain lengths

PurposeFluorine materials have received the keen attention of many researchers because of their water repellency and low surface free energy. The purpose of this paper is to prepare self-crosslinking fluorocarbon polyacrylate latexes containing different fluorocarbon chain lengths by semi-continuous seeded emulsion polymerization technology.Design/methodology/approachMethyl methacrylate (MMA), butyl acrylate (BA), hydroxypropyl methacrylate (HPMA) and fluorine-containing monomers were used as main monomers. The fluorine-containing monomers included hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and trifluorooctyl methacrylate (TFMA). Potassium persulfate (KPS) was used as thermal decomposition initiator, non-ionic surfactant alkyl alcohol polyoxyethylene (25) ether (DNS-2500) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS) as mixed emulsifier.FindingsThrough optimizing the reaction conditions, the uniform and stable latex is gained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer. After comprehensively comparing the latexes and films prepared by HFMA, DFMA and TFMA, the performance of DFMA monomer modified is better.Originality/valueThe self-crosslinking acrylic emulsion is prepared via semi-continuous seeded emulsion polymerization, which methyl methacrylate (MMA), butyl acrylate (BA), hydroxypropyl methacrylate (HPMA) and fluorine-containing monomers were used as main monomers. The fluorine-containing monomers were composed of hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and trifluorooctyl methacrylate (TFMA). Potassium persulfate (KPS) was used as thermal decomposition initiator, non-ionic surfactant alkyl alcohol polyoxyethylene (25) ether (DNS-2500) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS) as mixed emulsifier. There are two main innovations. One is that the self-crosslinking acrylic emulsion is prepared successfully. The other is that the effects of monomers containing different fluorocarbon chain lengths on polyacrylate, such as monomer conversion rate, coagulation rate, mechanical stability, chemical stability, emulsion particle size and storage stability, are studied in detail.

Recognition of metallic and semiconductor single-wall carbon nanotubes using the photoelectric method

an innovative application of deep barrier silicon structures for sensory devices with photoelectrical transformation has been suggested. The principal possibility of the photovoltaic transducer implementation for identification of metallic and semiconductor single-wall carbon nanotubes covered with surfactant in water solution was analyzed in detail. The obtained results are qualitatively explained by local electrostatic influence on the parameters of recombination centers at the silicon surface. This influence can be associated with the dipole moment of molecules absorbed at the surface of the nanotube from surfactant sodium dodecylbenzene sulfonate (SDBS). Moreover, the spatial configuration of charged fragments near the defects at the silicon surface can occur. Another possible reason for carbon nanotubes identification is due to the different polarizability of metallic and semiconductor nanotubes. These results are explained in the frame of Stevenson-Keyes's theory. The reported effect can be further applied as the basis for the control and selection of carbon nanotubes with different conductivity types.

Synthesis and characterization of analogues of glycine-betaine surface-active ionic liquids

With the goal of finding sustainable solvents, novel ionic liquids (ILs) with low ecotoxicity features have been a target of research. Among these, ILs with surface-active characteristics play a significant role in the food, cosmetic, pharmaceutical, household cleaning and other detergent industries. Most surface-active ILs reported up to date are imidazolium-based, which may raise some environmental and health-related concerns. Aiming the development of ILs with surfactant properties and low ecotoxicity, in this work, novel surface-active analogues of glycine-betaine ILs (AGB-SAILs) combined with the dodecylbenzenesulfonate ([DBS]-) anion have been synthesized and characterized. The synthesized AGB-SAILs were characterized chemically by elemental analysis and spectroscopic methods. Their thermal properties, critical micellar concentration, micelle diameter and ecotoxicity against Aliivibrio fischeri were determined, being these properties compared with the commercial surfactant sodium dodecylbenzenesulfonate (SDBS). It is shown that all investigated AGB-SAILs are liquid at room temperature and thermally stable. Furthermore, most of them display a lower critical micellar concentration and lower toxicity towards Aliivibrio fischeri than SDBS, thus being good alternatives to the commercial surfactant in a wide range of applications.

Air stability of n-type single-walled carbon nanotube films with anionic surfactants investigated using molecular dynamics

The semiconducting property and air-stability of n-type single-walled carbon nanotube (SWCNT) are important for manufacturing all-carbon thermoelectric generators. We fabricated n-type SWCNT films with different anionic surfactants via drop-casting followed by heat treatment. Among the surfactants used (sodium dodecyl sulfate (SDS), sodium cholate (SC), and sodium dodecylbenzene sulfonate (SDBS)), the SWCNT films with SDBS surfactants exhibited an n-type Seebeck coefficient for 35 days. Structural analyses of the films showed that the SWCNT bundles and SDBS surfactants were homogeneously mixed. To investigate the mechanism behind the air-stability of the n-type property in SWCNT films, molecular dynamics (MD) calculations were performed. The MD calculations revealed that the adsorbability of SDBS molecules to SWCNT was higher than that of the other surfactants, which was consistent with the results of structural analyses. The sodium atoms in the vicinity of the SWCNT surface were vital in imparting n-type properties to the SWCNT. The SWCNT films with SDBS surfactants exhibited n-type properties for a long period of time because the surfactant molecules homogeneously covered the SWCNT surface, which enhanced the transfer of electrons from the sodium atoms to the SWCNT. The findings will aid toward further improving the air-stability of n-type SWCNT films using new surfactants.

Experimental Study on the Wettability of Coal with Different Metamorphism Treated by Surfactants for Coal Dust Control.

Wet dedusting is the main coal dust suppression technique in coal mines, and coal wettability is the main factor affecting dust suppression efficiency. To investigate the main factors affecting the coal wettability and improve it, the coal–water contact angle was used as an index to characterize the coal wettability, and the wettability of six coal samples with different metamorphic degree was studied by analyzing the relationship between the physicochemical properties and the contact angle. To improve the coal wettability, the nonionic surfactant alkyl polyglycoside (APG), anionic surfactant sodium dodecyl benzene sulfonate (SDBS), and polymer surfactant polyacrylamide (PAM) were applied to the coal samples. The results show that SDBS is the most effective surfactant to improve the coal wettability, followed by APG, while the application of PAM would lead to more hydrophobic coal. It is also found that the coal wettability shows a high–low–high trend with the increase in the metamorphic degree. The wettability of long flame coal is the strongest and that of gas coal is the weakest. Moisture is the main hydrophilic factor of coal, while 1,4-dimethylbenzene is the main hydrophobic factor. The main factors affecting the treatment effect of APG, SDBS, and PAM on wettability are the aromatic methylbenzene, hydroxyl, and hydroxyl content of coal, respectively. Therefore, according to the content of hydroxyl in different coals, an SDBS solution can be prepared to improve the coal wettability. For coal with a low hydroxyl content, a higher concentration SDBS solution could be needed.

Effect of SDBS surfactant on gas–liquid flow pattern and pressure drop in upward-inclined pipelines

Liquid loading is a common phenomenon for natural gas gathering and transportation in hilly terrain pipelines, and traditional mechanical pigging technology is usually employed to remove the liquid loading in these pipelines. However, this technology has some obvious limitations and risks in complex pipeline operation conditions. Surfactant injection was presented as an alternative to promote liquid drainage in this study. To further understand the effect of surfactant on the flow characteristics of a gas–liquid flow, an experimental investigation of the flow pattern and pressure drop with and without surfactant was conducted using visual observation and pressure drop measurement methods in the upward-inclined section of a hilly terrain pipeline. The experimental pipeline was made of acrylic glass with an inner diameter of 50 mm and an inclination angle of 10°. Air and deionized water were used as working fluids, and sodium dodecyl benzene sulfonate (SDBS) with concentrations of 100, 400 and 800 parts per million (ppm) was used as surfactant additive in the experiment. The superficial liquid and gas velocities ranged from 0.005 to 0.100 m/s and from 2.0 to 30.0 m/s, respectively. The intermittent flow and segregated flow with and without foam formation were classified into various sub-flow patterns based on the gas–liquid distribution and pressure drop fluctuation characteristics. The distribution of the flow patterns was summarized under different working conditions. The experimental results enhance the understanding of the morphology and evolution process of gas–liquid flow with a surfactant.

Light absorption and hydrophobicity of a polystyrene/multiwall carbon nanotube composite with surface nanostructures

This paper describes an investigation into how combined carbon nanotube doping and surface nanostructuring affects the surface properties of polystyrene. Multiwall carbon nanotubes (MWCNTs) have unique anisotropic electrical properties that can be utilized for light absorption, electromagnetic shielding and nanoscale electostatic forces. Polystyrene was doped with 5 wt% MWCNTs and the resulting composite was wetted onto a porous anodic alumina template to form a nanostructure surface of nanotubes. Scanning electron microscopy revealed a hierarchical surface structure with the composite nanotubes bundled together as the MWCNTs increased the attractive forces between the composite nanotubes. Water droplet testing revealed that this hierarchical surface structure was superhydrophobic. Though the presence of the MWCNTs caused a direct increase in absorption, the hierarchical surface structure increased reflection. The addition of 5 wt% of the anionic surfactant Sodium Dodecyl Benzene Sulfonate to ensure MWCNT dispersal did not significantly change hydrophobicity or light absorption despite the hierarchical surface structure becoming finer. The created composite has potential use as a surface layer on an organic surface cell as it provides reduced cleaning needs and electrical disturbance but further work is required to reduce the reflection.

Effect and mechanism of rheological properties and structure of a novel hydrophobically associating polymer on sand sedimentation rate

With hydrophobic associating polymer (BCG-1) and anionic surfactant sodium dodecyl benzene sulfonate (SDBS) solution as the object, this work studies the different polymer concentration and surfactant concentration on the influence law of fluid properties and examines the sand sedimentation rate and the correlation of fluid properties. After the liquid was tested by electron microscope and rheometer, it was found that the interaction between the surfactant and the polymer is with phases, which provided different angles for revealing the change rule of the deposition rate of sand. When the concentration of SDBS solution is in the second phase (0.05–0.2%), although the system property changes slightly and the microscopic morphology does not change greatly, the deposition rate of sand still decreases significantly. Relaxation time spectrometry explains that the reduction in the sedimentation rate of the sand is caused by the shift of the polymer chain motion mode, whereas the phase angle can clearly manifest this change, and the phase angle is highly correlated with the deposition rate of sand.

Effect of solution pH on removal of anionic surfactant sodium dodecylbenzenesulfonate (SDBS) from model wastewater using nanoscale zero-valent iron (nZVI)

Batch experiments for removal of anionic surfactant sodium dodecylbenzenesulfonate (SDBS) from model wastewater using nanoscale zero-valent iron (nZVI) were conducted to elucidate mechanisms of SDBS removal by nZVI. To clarify the effects of solution pH on removal of SDBS by nZVI, the concentration profiles of Fe ions and dissolved oxygen (DO) were measured besides the concentrations of SDBS and total organic carbon (TOC) at pH of 3, 5, 7 and 9. The SDBS concentration rapidly decreased to less than 4% of the SDBS loadings within 40 min at pH 3, 7 and 9. However, TOC decreases were rather slow and the maximum TOC removal of 62% after 240 min was obtained at pH 7. The XRD patterns confirmed that the main corrosion product was lepidocrocite at pH 5 and 7 while magnetite was dominant at pH 9. The maximum removal of SDBS by nZVI at pH 7 was attributed mainly to the ionic adsorption of anionic SDBS onto the positively charged nZVI surface. The novel kinetic model for dynamic linkage of SDBS removal with concentrations of total eluted iron ions and DO via the formation of iron oxide/hydroxide layer on nZVI surface could simulate the experimental results with the average correlation coefficient of 0.952. The mechanisms of SDBS removal by nZVI at different pH values were clarified and quantified by the proposed kinetic model.