Addition Of Sodium Dodecyl Benzene Sulfonate Research Articles

New insights into the inhibition performance and mechanisms of sodium dodecyl benzene sulfonate (SDBS) on nitrogen removal in activated sludge-biofilm system

To investigate the effect of sodium dodecyl benzene sulfonate (SDBS) on nitrogen (N) removal performance and biological mechanisms, a gradient of SDBS concentrations was introduced into a set of sequencing batch biofilm reactors (SBBRs). The results indicated that a negative correlation was observed between SDBS concentration and the removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N). Compared to the control group, their removal efficiencies were the lowest (decreases of 11.83 %, 12.15 %, and 8.11 %) when SDBS concentration was 1.67 mg (g MLSS) -1 (5 mg L−1). High-throughput sequencing showed that the abundance of Proteobacteria remained stable with SDBS addition, while the abundances of Patescibacteria and Actinobacteria decreased by 0.67–0.70 % and 0.69–3.06 %, respectively. Moreover, SDBS reduced both microbial diversity and richness and hindered the interspecific relationships among microorganisms. It also inhibited N metabolic activities and led to a decrease in the expression of key functional genes involved in N transformation (nifD, nifH, nasA, norB, norC, and nosZ). Additionally, the abundances of key enzymes (EC:1.7.99.1, EC:1.7.2.4, and EC:1.1.1.42) in the N and tricarboxylic acid (TCA) cycles decreased following the addition of SDBS. This study provided insights into the effects of SDBS on N removal in activated sludge-biofilm systems and the adaptive responses of microbial communities to SDBS exposure.

Interaction of Pb(II) with microplastic-sediment complexes: Critical effect of surfactant

In this study, the impact of surfactants on the adsorption behavior of Pb(II) onto microplastics-sediment (MPs-S) complexes was investigated. Firstly, virgin polyamide (VPA) and polyethylene (VPE) were placed in Xiangjiang River sediment for six months to conduct in-situ aging. The results indicated that the biofilm-developed polyamide (BPA) and polyethylene (BPE) formed new oxygen-containing functional groups and different biofilm species. Furthermore, the adsorption capacity of Pb(II) in sediment (S) and MPs-S complexes was in the following order: S > BPA-S > VPE-S > VPA-S > BPE-S. The addition of sodium dodecyl benzenesulfonate (SDBS) promoted the adsorption of Pb(II), and the adsorption amount of Pb(II) increased with the higher concentration of SDBS, while adding cetyltrimethylammonium bromide (CTAB) showed the opposite result. The adsorption process of MPs-S complexes to Pb(II) was dominated by chemical adsorption, and the interaction between MPs-S complexes and Pb(II) was multilayer adsorption involving physical and chemical adsorption when the surfactants were added. Besides, the pH exerts a significant effect on Pb(II) adsorption in different MPs-S complexes, and the highest adsorption amount occurred at pH 6. Noteworthy, CTAB promoted the adsorption ability of Pb(II) when the exogenous FA was added. The binding characteristic of sediment endogenous DOM components and Pb(II) was influenced by the addition of MPs and surfactants. Finally, it confirmed that adsorption mechanisms mainly involve electrostatic and hydrophobic interaction. This study provides a new perspective to explore the environmental behaviors of Pb(II) by MPs and sediments with the addition of surfactants, which was conducive to evaluating the ecological risks of MPs and heavy metals in aquatic environments.

Effect of Surfactants on Eliminating Stable Ultrafine Chalcopyrite Froth.

Chalcopyrite is a primary source of copper in nature. However, with the increasing need to process low-grade and complex chalcopyrite ores, overly stable froth is becoming more and more common and poses operational and safety challenges. No reliable strategy has been developed to address the issue. As a new initiative, this study investigated three different structured surfactants, sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and pentadecafluorooctanoic acid (PFOA), which vary in hydrophobic group, aiming to modify the surfaces of ultrafine chalcopyrite particles and adjust the interfacial tension at the gas-liquid interface to eliminate stable ultrafine chalcopyrite froth. The fundamental hypothesis was that an ideal surfactant structure could adjust the particle surface wettability and interfacial tension to eliminate overly stable froth. Based on contact angle measurements and interfacial tension measurements using a Theta Flow tensiometer by the pendant drop method and the sessile drop method, it was demonstrated that the contact angle played a dominant role in defoaming, while the reduction of gas-liquid interfacial tension had an adverse effect. Additionally, defoaming tests indicated that SDBS had lower defoaming effectiveness than SDS at low surfactant concentrations due to the steric hindrance in its structure, whereas the addition of SDBS could achieve a froth reduction efficiency as high as 93.75% at higher surfactant concentrations due to its stronger hydrophobicity and adsorption capacity to chalcopyrite particles, which could reduce the contact angle from 70 to 37.62°. However, PFOA exhibited lower defoaming effectiveness than both SDS and SDBS due to its lipophobic fluorocarbon tail of PFOA and weaker adsorption capacity to chalcopyrite particles, making it unsuitable for eliminating stable ultrafine chalcopyrite froth.

Surfactant and antibiotic co-occurrence reshaped the acidogenic process for volatile fatty acids production during sludge anaerobic fermentation

The overuse of surfactants and antibiotics has led to their high concentration in waste activated sludge (WAS), and these exogenous pollutants have been shown to pose various influences on the subsequent anaerobic treatment process. Previous works have primarily concerned the impacts of individual pollutants on WAS anaerobic fermentation process. This work revealed the synergetic effects of sodium dodecyl benzene sulfonate (SDBS) and sulfadiazine (SDZ) co-occurrence in WAS on the biosynthesis of volatile fatty acids (VFAs). The addition of SDBS in the SDZ reactor significantly increased VFAs generation, and this increase was correlated with the concentration of SDZ. The VFAs production exhibited a 200.0–211.9 % and 5.9–20.4 % increase in comparison with the sole SDZ and SDBS reactor, respectively. The SDBS and SDZ co-occurrence facilitated the solubilization, hydrolysis, and acidification stages of WAS fermentation synchronously. SDBS was effectively to disintegrate the cemented structure of extracellular polymeric substances and meanwhile improve the SDZ solubilization, which increase the SDZ bioavailability as well as biotoxicity to the anaerobic species. Herein, the anaerobic consortia structure was evidently reshaped, and the keystone microbes Acetoanaerobium and Fususibacter, as well-tolerated hydrolytic-acidogenic bacteria, were greatly enriched. Furthermore, the functional microbial metabolic traits responsible for the substrate extracellular hydrolysis (e.g., glsA and MAN2C1), intracellular metabolism (e.g., ALDO and asdA), and fatty acid generation (e.g., aarC) were all upregulated in the SDBS/SDZ co-occurrence reactor.

Interfacial Wettability Regulation Enables One-Step Upcycling of the End-of-Life Polymeric Microfiltration Membrane

Polymeric membranes, which are typically synthesized from fossil-based polymers, will reach their end of life (EOL) and then be replaced, due to the inevitable accumulation of membrane fouling even though the periodic cleaning is applied. The conventional disposal methods of the EOL membranes are landfilling and incineration, which will lead to additional carbon emission and fossil resource depletion. Herein, we proposed a surfactant-regulated interfacial polymerization strategy, by adding sodium dodecylbenzene sulfonate (SDBS) in the piperazine (PIP) aqueous solution, for the one-step upcycling of the EOL polymeric microfiltration membrane to obtain a thin-film composite polyamide (PA) nanofiltration (NF) membrane. Revealed by the quartz crystal microbalance with dissipation analysis and molecular dynamics simulation, the presence of SDBS reduced interfacial tension (IFT) and regulated interfacial wettability, thereby facilitating adequate and uniform uptake of PIP monomers. The resulting upcycled NF membrane with 4 critical micelle concentration (CMC) of SDBS addition exhibited a favorable pure water permeance (20.1 ± 0.6 L m–2 h–1 bar–1) and a satisfactory Na2SO4 rejection of 98.6 ± 0.4% owing to the formation of a continuous PA layer with high cross-linking degree (89.3 ± 0.5%). The Na2SO4 permeability of the 4 CMC upcycled NF membrane was more than 1 magnitude lower than that of the upcycled NF membrane without SDBS addition. This study provides a facile, rapid, and cost-effective method for the one-step upcycling of EOL polymeric membranes, which thus improves the sustainability of membrane technology.

Inhibitory effect of calcium phosphate-coated high-affinity liposomes on Staphylococcus aureus and its biofilms

The contamination of Staphylococcus aureus (S. aureus) and its biofilm poses a serious challenge to food safety. In this study, a high-affinity liposome coated with calcium phosphate was developed to provide a novel strategy for antibacterial packaging. Litsea cubeba essential oil (LC-EO)-loaded liposomes with various anionic surfactants including sodium deoxycholate (SDC), sodium dodecyl sulfate (SDS), and sodium dodecyl benzene sulfonate (SDBS) were first synthesized using a film-ultrasonic dispersion method, then an attempt was made to coat calcium phosphate (CaP) shell layers on the surface of different anionic liposomes using a sequential deposition method. Anionic liposomes synthesized with the addition of SDBS (SDBS/EO-Ls) were found to be effective precursors for the successful capping of CaP shells. The SDBS/EO-Ls coated with CaP shells (CaP/SDBS/EO-Ls) were then characterized, including physicochemical properties, stability, and antibacterial and anti-biofilm activities. Results showed that the particle size of SDBS/EO-Ls can be increased by about 40 nm after being coated with a CaP shell, and the Zeta potential value can be decreased by about 25 mV. At the same time, the CaP coating helped to prevent the leakage of essential oils during storage. The prepared CaP/SDBS/EO-Ls had a better inhibitory effect against S. aureus and biofilm due to their high affinity. Even when CaP/SDBS/EO-Ls were applied in two different food systems (smoked bean curd and beef), they still had a long-lasting antibacterial effect. The CaP/SDBS/EO-Ls developed in this study could be used to develop a novel antimicrobial packaging additive.

Separation of extremely small indium oxide quantum dots and their highly luminescent properties by dispersing agent

Acquiring extremely small quantum dots (QDs) absorbing and emitting light in the ultraviolet region is challenging because of the difficulty in size control via chemical synthesis. Here, we report that extremely small In2O3 QDs with high crystallinity can be earned from a pristine In2O3 powder of which the average size exceeds the range of QDs. Interestingly, we extracted the extremely small In2O3 QDs by a series of filtration processes of an In2O3 suspension. Transmission electron microscopy images confirmed In2O3 nanoparticles falling within the range of QDs. The tiny In2O3 QDs absorbed light at a wavelength of 220 and 280 nm and exhibited the maximum photoluminescence spectra in the ultraviolet region under the excitation of the wavelengths. Furthermore, we investigated the effect of a surfactant on the optical properties of In2O3 QDs separated from the powder. As a result, the luminescent intensity of In2O3 QDs enhanced drastically with the addition of sodium dodecylbenzene sulfonate. Our findings pave the way to acquiring highly luminescent tiny QDs from other semiconducting powders.

Enhanced Removal of Hydrophobic Short-Chain n-Alkanes from Gas Streams in Biotrickling Filters in Presence of Surfactant.

Emissions of n-alkanes are facing increasingly stringent management challenges. Biotrickling filtration in the presence of surfactants is a competitive alternative for the enhanced removal of n-alkanes. Herein, sodium dodecyl benzene sulfonate (SDBS) was added into the liquid phase feeding a biotrickling filter (BTF) to enhance the removal of various short-chain n-alkanes from n-hexane (C6) to methane (C1). The removal performance of C6-C1 and microbial response mechanisms were explored. The results showed that the removal efficiency (RE) of n-alkanes decreased from 77 ± 1.3 to 35 ± 5.6% as the carbon chain number of n-alkanes decreased from C6 to C1, under the conditions of an n-alkane inlet load of 58 ± 3.0 g/m3·h and EBCT of 30 s. The removal performance of n-alkanes was enhanced significantly by the introduction of 15 mg/L SDBS, as the RE of C6 reached 99 ± 0.7% and the RE of C1 reached 74 ± 3.3%. The strengthening mechanisms were that the apparent Henry's law coefficient of n-alkanes decreased by 11 ± 1.4-30 ± 0.3%, and the cell surface hydrophobicity of microorganisms improved from 71 ± 5.6 to 87 ± 4.0% with the existence of SDBS. Moreover, the presence of SDBS promoted the succession and activity of the microbial community. The activities of alkane hydroxylase and alcohol dehydrogenase were 5.8 and 5.9 times higher than those without SDBS, and the concentration of the cytochrome P450 gene was improved 2.2 times. Therefore, the addition of SDBS is an effective strategy that makes BTF suitable for the removal of various n-alkanes from waste gas streams.

Tribological performance of zeolite/sodium dodecylbenzenesulfonate hybrid water-based lubricants

Water-based lubricants are a low-cost and environmentally-friendly alternative to their oil-based counterparts. Developing novel water-based formulations with improved lubricity is the key to broadening their industrial applications. We report herein two new water-based hybrid lubricants that integrate sodium dodecylbenzene sulfonate (SDBS) with 4A and 13X zeolites respectively. Their tribological performance was assessed using a block-on-ring test. The addition of SDBS mitigated stick–slip motion, leading to the reduction of coefficient of friction (COF), but caused chemical erosion of the steel surface. The addition of zeolite into water led to an increase in COF due to the occurrence of three-body abrasion. The combination of SDBS and zeolite brought about unique and superior lubrication performance attributed to the synergetic interactions between them. The application of 4A + SDBS lubricant led to a 10% reduction in COF and a four-fold increase in material removal compared to water. The angular 4A particles augmented material removal in combination with the corrosive effect of SDBS. The use of 13X + SDBS lubricant, on the other hand, resulted in a 60% reduction in COF and a 94% decrease in wear comparing to water. This can be ascribed to the “lubricated micro-bearing” effect as a result of SDBS attachment on the rounded 13X particles.

Oxygen-vacancy-rich BiOCl with 3D network structure for enhanced photocatalytic CO2 reduction and antibiotic degradation

BackgroundDevelopment of human society has led to various environmental problems and energy crisis. MethodsIn this paper, Bismuth oxychloride (BiOCl) with a 3D network structure was prepared via a simple one-step sodium dodecylbenzenesulfonate (SDBS) assisted hydrothermal method and used for CO2 reduction and antibiotic degradation. Consideration was given to the influence of addition of SDBS in the preparation process on the microscopic morphology and energy band structure of the photocatalyst. Significant findingsThe results of the present study indicate that the formation of the 3D network structure helps to expose the {001} facets of BiOCl and promotes the generation of more oxygen vacancies. As-prepared BiOCl-0.6, i.e., 0.78 g of Bi(NO3)3·5H2O with 0.6 g SDBS, demonstrating the highest photocatalytic reduction performance of CO2. The production of CO by BiOCl-0.6 can reach 59.5 and 20.1 µmol g−1 after 4 h of UV-vis/vis illumination, which is ten times higher than the control BiOCl. In addition, BiOCl prepared with a 3D network structure also showed efficient antibiotic (oxytetracycline hydrochloride, OTC) degradation ability. When the initial concentration of OTC was 20 mg/L, OTC was completely removed after 45 min of UV-vis irradiation, and 77.2% of OTC was removed after 90 min of photocatalytic reaction under visible light. In the photodegradation process, photogenerated holes (h+) and superoxide radical (·O2−) play an important role.

Investigation of the influence of TiO2 distribution on HA/TiO2 composite wetting ability using the dispersant SDBS, high-temperature annealing, and ultrasonication

The use of composites such as hydroxyapatite (HA)/TiO2 in bioapplications has attracted increasing attention in recent years. Herein, for the enhancement wetting ability and biocompatibility, the HA/TiO2 composite was subjected to different treatments to improve nanoparticle (NP) distribution and surface energy with an aim of mitigating nanotoxicity concerns. The treatments included ultrasonication, high-temperature annealing, and addition of a dispersant and surfactant, sodium dodecylbenzenesulfonate (SDBS). Contact angle measurement tests revealed the effect of SDBS addition on the distribution of TiO2 NPs on the HA surface: a decrease in the contact angle and, thus, an increase in the wetting ability of the HA/TiO2 composite were observed. The combination of annealing and SDBS addition treatments allowed for guest TiO2 particles to be uniformly distributed on the surface of the host HA particles, showing a rapid conversion from a hydrophobic to superhydrophilic property. In vitro investigation suggested that the cell viabilities of annealed HA/TiO2, SDBS-added HA/TiO2, and SDBS-added and annealed HA/TiO2 reached 89.7%, 94.7%, and 95.8%, respectively, while those of HA and untreated HA/TiO2 were 80.3% and 86.9%, respectively. The modified composites exhibited lower cytotoxicities than the unmodified systems (HA and HA/TiO2). Furthermore, the cell adhesion behavior of the composites was confirmed through actin-4′,6-Diamidino-2-phenylindole (DAPI) staining, which showed negligible changes in the cytoskeleton architecture of the cells. This study confirmed that a modified HA/TiO2 composite has potential for bioapplications.

Production of phenolic compounds in catalytic pyrolysis of bagasse lignin in the presence of Ca0.5Pr0.5FeO3

Herein, sodium dodecylbenzene sulfonate (SDBS) was used as a template to control the synthesis of Ca0.5Pr0.5FeO3. Its microstructure, composition, and morphology were detected via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The properties of catalyzing bagasse lignin (BL) pyrolysis were determined by thermogravimetric analysis (TG) test and evaluation of a fixed bed alumina microreactor. The results show that the sample Ca0.5Pr0.5FeO3 regulated by SDBS has a cubic crystal phase, and the addition of SDBS does not cause phase transition. Moreover, when the SDBS concentration is 0.10 mol/L, the particle size is 200–500 nm and the specific surface area is 11.26 m2/g. The yields of gas, liquid, and solid products in the BL catalytic pyrolysis are 39.58 wt%, 26.76 wt% and 32.36 wt%, respectively. The contents of CO2 and CO decrease from 54.07% and 4.98% to 45.29% and 3.23%, respectively. The liquid products are mainly guaiacol, syringol, and phenol, and the total selectivity of phenols is 83.67%, accompanied by a small amount of non-aromatic oxygen-containing compounds (five-membered ring (furan) or ester). Compared with the BL pyrolysis and Ca0.5Pr0.5FeO3 catalytic pyrolysis products, the selectivity of guaiacol compounds increases by 43.26%, while those of syringol compounds and phenylketones decrease by 30.08% and 3.39%, respectively. The selectivity of 2,6-dimethoxyphenol is 28.37%. After five catalytic pyrolysis-regeneration cycles, the characteristic peaks of the catalyst do not change significantly and the particles are uniform, suggesting that the catalyst has good crystal phase stability and regeneration stability.

Effects of surfactant addition to draw solution on the performance of osmotic membrane bioreactor

This study investigated the effects of surfactant addition to the draw solution on the performance of osmotic membrane bioreactor (OMBR). Forward osmosis (FO) tests were conducted with the addition of sodium dodecyl benzene sulfonate (SDBS), a representative surfactant, to both inorganic and ionic organic draw solutions, including sodium chloride (NaCl), sodium acetate (NaOAc), and sodium propionate (NaPro), to determine the desirable draw solution for OMBR operation. Results show that SDBS impacts were more notable for inorganic draw solution in comparison to its ionic organic counterparts at the same osmotic pressure (60 bar) in FO operation. In specific, SDBS addition up to 5 mM considerably reduced the reverse diffusion of NaCl draw solute (approximately 69.7%) with insignificant impact on water flux. Thus, salinity build-up in the bioreactor could be effectively mitigated when SDBS was added to the NaCl draw solution in OMBR operation. This mitigation led to stable sludge characteristics and biological treatment to sustain OMBR performance regarding water production (approximately 10 L/m2h) and contaminant removal (e.g. over 90% for pharmaceutically active compounds).

A study on optimum surfactant to multiwalled carbon nanotube ratio in alcoholic stable suspensions via UV–Vis absorption spectroscopy and zeta potential analysis

Common ultrasonication and centrifugation techniques could be utilized for dispersion of carbon nanotubes in solvents. However, there are few studies investigating the effect of concentration of species on stability of surfactant modified suspensions focusing on specific dispersants. Therefore, in this study, UV–Vis absorption spectroscopy, sedimentations tests, zeta (ζ) potential and dynamic light scattering analyses (DLS) were used as tools to estimate the optimal surfactant to multi walled carbon nanotubes (MWCNTs) weight ratio in stable centrifuged suspensions. MWCNTs colloids were prepared via addition of sodium dodecylbenzene sulfonate (SDBS) with ultrasonication and centrifugation in isopropyl alcohol (IPA). Coupling information gathered from overlapped absorption spectra and weighed dried sediments enabled estimation of MWCNTs concentrations in centrifuged suspensions (supernatant). By utilizing sediments weight and zeta potential observations, optimum SDBS/MWCNTs weight ratios were calculated. The results have shown that the SDBS/MWCNTs ratio should be 9 or higher in supernatants in order to obtain stable suspensions. It was also observed that increasing SDBS/MWCNTs concentrations over 9 in supernatants gradually decreased the zeta potentials of studied suspensions. Higher SDBS/MWCNTs ratios, also decreased settling velocities that were attributed to increased viscosity of supernatants. In addition to overlapping spectra technique, which relies on utilization of spectra related to centrifuged and uncentrifuged suspensions only for quantitative analysis, differential UV–Vis spectra were also utilized for the assessment of SDBS/MWCNTs ratios in supernatants. Presence of SDBS in supernatants (prepared by removing contribution of MWCNTs by using COOH modified MWCNTs’ UV–Vis absorption spectrum) exhibited an unexpected hyperchromic shift in maximum wavelength in spectra leading to misleading estimations of surfactant concentrations.

An Artificial Intelligence Approach to Predict the Thermophysical Properties of MWCNT Nanofluids

Experimental data of thermal conductivity, thermal stability, specific heat capacity, viscosity, UV–vis (light transmittance) and FTIR (light absorption) of Multiwalled Carbon Nanotubes (MWCNTs) dispersed in glycols, alcohols and water with the addition of sodium dodecylbenzene sulfonate (SDBS) surfactant for 0.5 wt % concentration along a temperature range of 25 °C to 200 °C were verified using Artificial Neural Networks (ANNs). In this research, an ANN approach was proposed using experimental datasets to predict the relative thermophysical properties of the tested nanofluids in the available literature. Throughout the designed network, 65% and 25% of data points were comprehended in the training and testing set while the other 10% was utilized as a validation set. The parameters such as temperature, concentration, size and time were considered as inputs while the thermophysical properties were considered as outputs to develop ANN models of further predictions with unseen datasets. The results found to be satisfactory as the (coefficient of determination) R2 values are close to 1.0. The predicted results of the nanofluids’ thermophysical properties were then validated with experimental dataset values. The validation plots of all individual samples for all properties were graphically generated. A comparison study was conducted for the robustness of the proposed approach. This work may help to reduce the experimental time and cost in the future.

A new surfactant assisted acid prehydrolysis process for enhancing biomass pretreatment

Prehydrolysis is an essential step for utilizing biomass, particularly in the Kraft-based dissolving pulp process. Once the hemicellulose was effectively extracted, it can not only upgrade the dissolving pulp, but also arise additional revenue by converting value-added products. Herein, sodium dodecyl benzene sulfonate (SDBS) was used to enhance the hemicellulose removal from poplar wood chips during mild acid hydrolysis. SDBS addition could reduce the surface tension, thus increasing the diffusion of hydrogen ion and promoting the hemicellulose and lignin dissolution. The hemicellulose removal was increased from 42.5 to 54.7% by adding SDBS in comparison with the control under condition of 170 °C and 2 h. Additionally, the lignin removal was increased from 9.6 to 19.1%. Gel permeate chronograph, scanning electron microscope, and heteronuclear single quantum coherence spectroscopy support the positive effect of SDBS addition. The properties of dissolving pulp prepared from surfactant assisted pretreatment are comparable/better than that derived from acid pretreatment. It opened a sustainable and economical way to extract hemicellulose from lignocellulose. A new surfactant assisted acid prehydrolysis process for enhancing biomass pretreatment.

Chemical Affinity Modeling of Methane Hydrate Formation and Dissociation in the Presence of Surfactants

Methane hydrate formation and dissociation and its kinetics after addition of sodium dodecylbenzenesulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), and Tergitol in the aqueous phase were investigated experimentally along with its storage capacity. The experiments were carried out with surfactant concentrations varying between 0 and 10 000 ppm in the aqueous phase. The nucleation temperature, pressure, dissociation temperature and point, pressure drop, formation rate, and storage capacity were significantly changed by the addition of surfactants in the aqueous phase during hydrate formation and dissociation. Maximum subcooling was required for nucleation after addition of 5000 ppm SDBS. The hydrate formation rate and rate constants were found to increase with the addition of surfactants, while the same were reduced with time. The formation rate increased 443-fold after addition of 10 000 ppm SDBS in the aqueous phase. The maximum storage capacity was found at 1000 ppm SDBS in the aqueous phase, which then decreased with a further increase in concentration. The chemical affinity model was developed for hydrate formation and dissociation and was employed successfully. Chemical affinity, thermodynamic extent of reaction, and affinity decay rates were calculated using the pressure and temperature data from the hydrate formation and dissociation trace with time. Affinity decay rates were increased after addition of surfactants, and the maximum was observed after addition of 1000 ppm SDBS in the aqueous phase. These results suggested that the surfactants, SDBS, CTAB, and Tergitol, improved the hydrate formation and dissociation effectively. The chemical affinity model can be efficiently employed for a better understanding of the hydrate formation and dissociation kinetics along with thermodynamics.

Experimental evaluation of the effect in the stability and thermophysical properties of water-Al2O3 based nanofluids using SDBS as dispersant agent

Nanofluids are thermo-fluids engineered by dispersing nanosized particles in conventional base fluids used in heat transfer applications. In this experimental study, the temporal stability and thermophysical properties of water-based alumina nanofluids, such as thermal conductivity, surface tension and viscosity, were evaluated at three different concentrations (0.1 wt%, 0.5 wt%, and 1.0 wt%) using sodium dodecyl benzene sulfonate (SDBS) as dispersant agent. The results showed that the nanofluid prepared with 1.0 wt% exhibits thermal conductivity enhancements between 11% and 15% compared to deionized water. Additionally, a pseudoplastic behaviour was identified by means of a rheological study, which increased as the nanoparticle concentration increased. Nevertheless, the nanofluids with SDBS showed a Newtonian behaviour and viscosity values close to those of water, which is suitable to avoid frictional losses in pump processes. In turn, surface tension increases with the amount of DI-water in Al2O3 concentrations, but it decreases with the addition of SDBS, which has an important effect on the boiling applications of nanofluids. This work was carried out to highlight the importance of nanofluids stability in function of the surfactant added and the nanoparticle concentration, in the measurement of significant thermophysical properties such as surface tension, viscosity and thermal conductivity, which could be used to explain the nanofluids behaviour in different thermal devices.

Study on the effects of alcohol-enhanced air sparging remediation in a benzene-contaminated aquifer: a new insight.

In this study, the effects of medium carbon chain alcohol (1-heptanol)-enhanced air sparging (AS) on the remediation of benzene-contaminated aquifers in different media (medium sand, channelized flow; gravel, bubbly flow) were investigated by comparison with a commonly used surfactant (sodium dodecylbenzene sulfonate (SDBS)). The results showed that the addition of 1-heptanol and SDBS significantly increased the air saturation in AS process under different airflow modes. Combined with water retention curves, 1-heptanol had the same effect on reducing the surface tension of groundwater and stabilizing bubbles as SDBS. In the study of benzene pollution removal, when the removal efficiency of the benzene pollutant exceeded 95%, the time required for surfactant-enhanced AS (SEAS) and alcohol-enhanced AS (AEAS) in medium sand was shortened by 28.6% and 52.4%, respectively, and the time required for SEAS and AEAS in gravel media was shortened by 16.7% and 58.3%, respectively, compared with the time required for AS. This finding indicated that the addition of SDBS or 1-heptanol could significantly increase the removal rate of benzene pollutants. Under the same surface tension conditions, the removal effect of 1-heptanol on the benzene pollutant was better than that of SDBS. This difference was due to the disturbance of the flow field during AEAS process causing the 1-heptanol on the gas-liquid interface to volatilize in the carrying gas, thereby inducing Marangoni convection on the interface, enhancing the gas-liquid mass transfer rate, and increasing the removal rate of benzene on the interface. Therefore, 1-heptanol is promising as a new reagent to enhance AS to remediate groundwater pollution.

The mechanism for adsorption of Cr(VI) ions by PE microplastics in ternary system of natural water environment

More attention was paid to the attachment between microplastics and environmental pollutants. The adsorption performance of Polyethylene (PE) beads (a typical type of microplastics) and Cr(VI) ions with the existence of sodium dodecyl benzene sulfonate (SDBS) was investigated in this paper. The adsorption experiments of Cr(VI) ions by PE microplastics were conducted at different conditions, i.e. PE doses, pH and SDBS concentrations, respectively. The adsorption capability of Cr(VI) ions was increased from 0.39 to 1.36 mg⋅g−1 when the dosage of PE microplastics was increased from 2 to 14 g ⋅L−1 at pH of 5 with addition of SDBS, compared with increasing adsorption capability from 0.03 to 0.32 mg⋅g−1 without addition of SDBS. The pH would influence the adsorption capability with and without the addition of SDBS. When the pH was less than 6, the adsorption capability of Cr(VI) would be promoted by the addition of SDBS; however, there was a contrast tendency when the pH was more than 6, which was attributed to that SDBS would compete with CrO42− for occupying the adsorption sites of PE microplastic. The SDBS concentration would affect the adsorption performance of Cr(VI) ions onto PE microplastics. The peak of the adsorption capacity was at SDBS concentration between 1 and 1.5 mM. This research would provide a basis for investigating the influence of SDBS on adsorption performance of heavy metal by PE microplastics to simulate the surface attachment model of those three kinds of pollutants.