Dodecylbenzenesulfonate Research Articles

Development and mechanism research of hydrophobic associative polymer drag reducing agents

ABSTRACT The challenge of insufficient proppant transportation capacity in slick water remains unresolved. To tackle this concern, a hydrophobically associating water-soluble polymer (HAWP), characterized by a low molecular weight (MW) of 8.11 × 105 g/mol, was successfully synthesized via a photo-initiation method. The drag reduction mechanism of the material was characterized through nuclear magnetic resonance and rheological performance testing. The drag reduction mechanism of the material was characterized through nuclear magnetic resonance and rheological performance testing. The results show that in comparison to conventional drag reducers in slick water with an average MW of approximately 1 × 107 g/mol, HAWP demonstrates significantly reduced MW. The rheological test results indicate that upon addition of sodium dodecyl benzene sulfonate (SDS, 200 mg/L) to the HAWP solution (0.3 wt%), the storage modulus experienced a substantial increase from 0.14 Pa to 7.42 Pa, demonstrating enhanced mechanical properties. Meanwhile, drag reduction (DR) tests showed that the efficiency of drag reduction achieved by the polymer system (PS) drag reducer was comparable to that of conventional linear polymers. This research achievement effectively addresses the challenges of low molecular weight and resistance reduction encountered in previous endeavors.

Synergistic effects of microplastic stability and adsorption rate on co-transport of microplastics and Pb under surfactant

The emergence of microplastics (MPs) and their coexistence with heavy metal contaminants pose potential risks to the safety of the subsurface environment and public health. Therefore, it is crucial to explore the co-transport of MPs (polypropylene (PP), polyethylene (PE), polystyrene (PS), polymethyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE)) with the heavy metal Pb(II) under the surfactant (sodium dodecyl benzene sulfonate (SDBS) and cetyltrimethylammonium bromide (CTAB)). In this study, column experiments were performed to investigate the co-transport of MPs and Pb(II) under surfactants. The co-transport mechanism of MPs with Pb(II) under surfactant was revealed by MPs stability and batch adsorption experiments. Experimental results showed that the presence of Pb(II) did not influence the mobility of MPs under CTAB and SDBS; however, MPs can affect the mobility of Pb(II). Specifically, under CTAB, the MPs increased the recovery rate of Pb(II) from 86% to 87.55%–97.55%. However, under SDBS, the high mobility of PS, PE, and PP inhibited the transport of Pb(II), and the recoveries of Pb(II) decreased from 79% to 57.53%–70.96%. The low mobility of PTFE and PMMA slightly promoted the transport of Pb(II). This could be attributed to two reasons. One aspect is the adsorption rate of Pb(II) by MPs, which plays a pivotal role in influencing the transport tendency of Pb(II) with MPs. Another aspect is the MPs stability, as greater stability enhances their dispersity and accelerates the adsorption rate of Pb(II), thereby facilitating the co-transport of Pb(II) with MPs. This study could provide valuable insights for assessing the transport and environmental impact of MPs and heavy metals in the presence of surfactants.

Synthesis and structure–property relationship of coal-based isomeric alkylbenzene sulfonate surfactants

Using coal resources to synthesize high-value surfactants is effective for clean coal utilization and low-carbon conversion, attracting more attention from academia and industry. Herein, three coal-based isomeric alkylbenzene sulfonate surfactants were successfully synthesized via sulfonation with gas phase SO3 utilizing isomeric alkylbenzenes, derived from the alkylation of benzene and Fischer–Tropsch synthesized α-olefins, as raw materials in a microchannel reactor. Moreover, their surfactant properties were systematically investigated to reveal the structure–property relationship. The results indicated that the equilibrium surface tension (γCMC) for the synthesized surfactants was reduced with the increase of the degree of hydrophobic tails branching, and the order of γCMC was: sodium dodecylbenzene sulfonate (35.67 mN·m−1) > sodium C6 olefin dimer alkylbenzene sulfonate (34.18 mN·m−1) > sodium dihexylalkylbenzene sulfonate (29.94 mN·m−1). Sodium dihexylalkylbenzene sulfonate with the lower γCMC exhibited superior wettability (the contact angle of 50.2 ° at 30 s) and excellent emulsifying capacity (emulsification time of 1337 s) at the corresponding critical micelle concentration. This study provides new insights into rational design of hydrophobic tail architectures of surfactant molecules to meet specific needs in various fields.

Epoxy/polymercaptan microcapsules composite: Synthesis, mechanics, and self-healing behavior

To enhance the longevity of materials, minimize maintenance expenses, and optimize material performance. The wall material employed in this study was urea-melamine-formaldehyde (UMF), and a dual microcapsule self-healing system was established by synthesizing two distinct microcapsules of epoxy resin and polymercaptan via an in situ polymerization technique. Moreover, the reaction conditions were optimized. The reaction parameters were as follows: core-shell ratio of 2:1, surfactant concentration of 0.6 g/L (sodium dodecyl benzene sulfonate (SDBS): Arabic gelatin (GA) = 2:1), polymerization pH = 3.5, stirring rate of 700r/min. Then, the two microcapsules (The mass ratio of the two microcapsules is 1:1) were added to the epoxy resin matrix at 0, 2.5, 5, 7.5, 10, and 12.5 wt% to prepare the resin matrix with self-healing properties. The conical double cantilever beam (TDCB) was used to test the mechanical properties of the matrix. The results showed that the matrix with microcapsule content of 10 wt% had relatively better comprehensive properties, and the self-healing rate was 49.87% at room temperature. These findings provide valuable insights and potential for advancing the development of self-healing materials.

Modulation of metal-organic frameworks by anionic surfactants for rapid adsorption of organic pollutants bisphenol A and chrome black T

With the accelerated development of industry, which generates large quantities of sewage discharged into the aquatic environment, serious impacts on both environmental and human health. Detecting various organic contaminants in water sources has become common, presenting huge challenges for water treatment. Metal-organic frameworks are characterized by their rich porous structures and high chemical activity, making them ideal adsorbents for removing organic pollutants from water. In this study, sodium dodecylbenzene sulfonate is added to the precursor solution of MIL-101(Cr)-Cl2 and synthesized hierarchical porous structure adsorbents MIL-SDBS-X, using hydrothermal synthesis to enhance their adsorption capacity, making efficient and rapid removal of bisphenol A(BPA) and chromium black T(EBT), two common organic pollutants in water, which MIL-SDBS-0.7 was the most effective. MIL-SDBS-0.7 exhibites great potential in the adsorption of BPA and EBT for its high adsorption capacity (260.5 mg-1·g-1 and 272.3 mg-1·g-1) and rapid adsorption (equilibrium could be achieved in 15 minutes), The findings reveal adsorption kinetics aligns with the pseudo-second-order model and the Langmuir equation best fits to study adsorption of MIL-SDBS-0.7 to BPA and EBT. Thermodynamic parameters affirm the exothermic and higher spontaneity behavior of the adsorption process. Moreover, the adsorption mechanism of MIL-SDBS-0.7 was explored, illustrating the crucial roles of effects of hydrogen bonding π-π stacking and pore filling in the adsorption of BPA and EBT. Therefore, this work not only provided a convenient strategy for the preparation of efficient and fast MIL-SDBS-0.7 hierarchical porous material but also highlighted the promising potential of synthesized absorbents as an effective adsorbent for organic pollutants in wastewater treatment and environmental remediation.

Boron-doped reduced graphene oxide as an efficient cathode in microbial fuel cells for biological toxicity detection

Electrodes with superior stability and sensitivity are highly desirable in advancing the toxicity detection efficiency of microbial fuel cells (MFCs). Herein, boron-doped reduced graphene oxide (B-rGO) was synthesized and utilized as an efficient cathode candidate in an MFCs system for sensitive sodium dodecylbenzene sulfonate (SDBS) detection. Boron doping introduces additional defects and improves the dispersibility and oxygen permeability, thereby enhancing the oxygen reduction reaction (ORR) efficiency. The B-rGO-based cathode has demonstrated significantly improved output voltage and power density, marking improvements of 75 % and 58 % over their undoped counterparts, respectively. Furthermore, it also exhibited remarkable linear sensitivity to SDBS concentrations across a broad range (0.2–15 mg/L). Notably, the cathode maintained excellent stability within the test range and showed significant reversibility for SDBS concentrations between 0.2 and 3 mg/L. The highly sensitive and stable B-rGO-based cathode is inspiring for developing more practical and cost-effective toxicant sensing devices.

The effect of modified oily sludge on the slurry ability and combustion performance of coal water slurry

Abstract The aim of this study is to find a solution to the challenging problem of disposing oily sludge (OS). Three different types of modifiers, namely, sodium hydroxide (NaOH), sodium dodecylbenzene sulfonate (SDBS), and polyoxyethylene polyoxypropylene polyether (AE) were employed for the simple modification of OS. The influence of modified OS on slurry ability and combustion performance were investigated. The results showed that OS modified by NaOH and SDBS can increase the concentration of coal OS slurry. However, the influence of AE modification on slurry concentration is intricate. In terms of combustion performance, the change in activation energy results in NaOH and SDBS modifications decrease T i and T h of coal OS slurry, while AE modification increases T i and T h of coal OS slurry.

Performance of a Composite Inhibitor on Mild Steel in NaCl Solution: Imidazoline, Sodium Molybdate, and Sodium Dodecylbenzenesulfonate

Mild steel corrosion is a significant challenge in oil and gas exploitation. Inhibitors are frequently employed to minimize the corrosive impact on mild steel. Mixing corrosion inhibitors is an effective method in reducing the dosage of toxic compounds and expanding the potential applications of inhibitors in NaCl solutions. Herein, a mixed corrosion inhibitor composed of imidazoline (IM), sodium molybdate, and sodium dodecylbenzenesulfonate (SDBS) for mild steel in a 3.5 wt% NaCl solution are investigated by orthogonal experimental design and electrochemical measurement. The imidazoline compound was synthesized and identified using Fourier transform infrared (FTIR) spectroscopy. The inhibitory effect is improved by higher concentrations of sodium molybdate and is further enhanced with the addition of 10 mg/L of SDBS. The electrochemical impedance spectroscopy indicates that the combination of IM (100 mg/L), sodium molybdate (50 mg/L), and SDBS (100 mg/L) results in excellent performance with electrochemical impedance (1.8 kohm·cm2). The mild steel surfaces after electrochemical measurement were analyzed using scanning electron microscopy (SEM). The information can contribute to the development of corrosion inhibitors with high performance or to understand the influence of mixing inhibitors on corrosion processes of mild steels.

PVA/PANI-DBSA Nanomesh Tactile Sensor for Force Feedback.

Touch serves as an important medium for human-environment interaction. The piezoresistive tactile sensor has attracted much attention due to its convenient technology, simple principle, and convenient signal acquisition and analysis. In this paper, conductive beads-on-string polyvinyl alcohol (PVA)/polyaniline doped with dodecyl benzene sulfonic acid (PANI-DBSA) nanofibers were fabricated via the electrospinning technique. Due to the special nanostructure of PVA-coated PANI-DBSA, the tactile sensor presented a wide measuring range of 12 Pa-121 kPa and appreciable sensitivity of 8.576 kPa-1 at 12 Pa~484 Pa. In addition, the response time and recovery time of the sensor were approximately 500 ms, demonstrating promising prospects in the field of tactile sensing for active upper limb prostheses.

Effect of DBSA‐doped PANI on the corrosion protection performance of GO/epoxy coatings

AbstractIn this study, the anticorrosion effect of polyaniline doped with dodecyl benzene sulfonic acid (PANI‐DBSA) in graphene oxide (GO)/epoxy coating is investigated. PANI‐DBSA is effectively synthesized on the surface of GO via chemical polymerization, and its properties are investigated via a series of characterization methods. The PANI‐DBSA/GO hybrid exhibits improved compatibility with organic resin. The anticorrosion performance of PANI‐DBSA/GO coatings is assessed through water absorption tests, electrochemical impedance spectroscopy measurements, and adhesion strength tests. The results indicate that PANI reduces the water absorption of GO, and the favorable compatibility of PANI‐DBSA/GO with epoxy resin minimizes coating defects and enhances the interfacial blocking for diffusion electrolytes. In this work, the PANI has no active function such as passivating the metal surface, it just serves to shield the hydrophilic GO surface and to improve compatibility between GO and the epoxy, attributing its low pigment content.

Tuning the mechanical and thermoelectric properties of self‐standing stretchable PEDOT:PSS/SDBS films

AbstractPoly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has recently attracted significant attention as a potential candidate for small‐scale thermoelectric conversion because of its ease of doping, and solution processability. This study addressed the fabrication of self‐standing PEDOT:PSS films modified with sodium dodecylbenzene sulfonate (SDBS) surfactant, presuming different annealing temperatures. According to the investigation, optimizing the annealing temperature improves crystal quality and increases the efficiency of PEDOT:PSS films. The resulting PEDOT:PSS films showed the highest electrical conductivity of about 623.68 Scm−1 and maximum power factor of 25.87 μWm−1 K−2. In addition to confirming thermoelectric properties; SDBS surfactants are being investigated to plasticize PEDOT:PSS films at different concentrations and annealing temperatures. With an optimization in annealing temperature, the elongation at break value similarly improves; and the highest elongation at break was observed at 0.94 wt% SDBS concentration, reaching 32%. To completely understand the underlying reasons for this dependence, higher‐order structures and electronic states of polymer films have been examined using electronic reflectance spectroscopy and X‐ray diffraction analysis. Overall, the outcomes of this work show how important surfactants and their annealing temperature are for improving the mechanical and thermoelectric characteristics of self‐standing PEDOT:PSS films.

Enzyme stability with essential oils and surfactants. Growing towards green disinfectant detergents

This study investigates the stability of α-amylase and protease in disinfectant formulations incorporating essential oils (EOs), anionic surfactants (linear alkylbenzene sulfonate), non-ionic surfactants (alkylpolyglucosides and ethoxylated fatty alcohols), and mixtures of them, analysing the influence of the composition, temperature, and time using shelf-life assays. EOs reduce α-amylase activity showing first-order deactivation kinetics, and surfactants were found not to significantly affect its activity. However, protease activity increases with the presence of EOs, and it was also observed that the use of surfactants does not significantly affect protease activity either. This work represents a step forward in the development of environmentally friendly multifunctional detergents with high disinfectant and detersive capacity.

Investigation on the enhanced ion impermeability of bipolar corrosion resistant coating prepared with Mg/Al-HT

Hydrotalcite (HT), which contains a large amount of easily exchanged hydroxyl groups, and has attracted great attention in the field of corrosion protection. Taking this aspect into consideration, this study has prepared bipolar corrosion resistant coating with modified magnesium-aluminum synthetic hydrotalcite (Mg/Al-HT), which restrains both the anion and cation migration in the coating. It is achieved by applying sodium dodecylbenzene sulfonate (SDBS) and cetyltrimethylammonium bromide (CTAB) to modify Mg/Al-HT and blending with phenolic epoxy resin. The chemical composition and morphology of the modified Mg/Al-HT are analyzed using SEM, FT-IR, and Raman spectroscopy. The ion selectivity of the prepared coating is evaluated with membrane potential test. Observation of the macroscopic pictures revealed that no corrosion products were observed on the surface of the bipolar coating after 60 days of immersion in 3.5 wt% NaCl solution. The corresponding interfacial impedance behavior is investigated. The typical impedance modulus @0.01 Hz remains constant at about 109 Ω cm2 after 60 days of exposure in 3.5 wt% NaCl solution, which is 102-103 times higher than that of the conventional coating. The mechanism of the enhanced ion impermeability is discussed in the paper.

Comparative study of nanoemulsion and micelle formed by surfactants containing benzene ring for spontaneous imbibition displacement

Nanoemulsion has a wide range of applications in oilfield chemistry due to its unique nanoscale size, excellent kinetic stability and high specific surface area. In this paper, a novel nanoemulsion oil flooding system was prepared using anionic surfactant sodium dodecyl benzene sulfonate (SDBS), the nonionic surfactant alkylphenol ethoxylates (OP-10), kerosene, n-butanol and deionized water. The particle size, Zeta potential, interfacial tension (IFT) and wettability properties were evaluated in the laboratory. The displacement performance of nanoemulsion was evaluated by the spontaneous imbibition experiment. Meanwhile, it compared with the same concentration of SDBS + OP-10 + n-butanol (SOB) system. The results showed that the particle size of the nanoemulsion was 70 ∼ 100 nm. When the concentration of nanoemulsion was 0.10 %, the oil–water IFT could reach 0.091 mN/m. The spontaneous imbibition oil recovery of the nanoemulsion (0.10 wt%) could reach 33.20 %, which was 23.02 % higher than that of SOB system. We also research the spontaneous imbibition displacement mechanism of nanoemulsion and micelle in low-permeability reservoirs. This paper will help to select the best oil displacement agent for the design of enhanced oil recovery (EOR) projects and promote the application of oil displacement agent in oilfield.

Effects of surfactants on the adsorption of norfloxacin onto ferrihydrite: comparison between anionic and cationic surfactants

ABSTRACT There is little information on how widespread surfactants affect the adsorption of norfloxacin (NOR) onto iron oxide minerals. In order to elucidate the effects of various surfactants on the adsorption characteristics of NOR onto typical iron oxides, we have explored the different influences of sodium dodecylbenzene sulfonate (SDBS), an anionic surfactant, and didodecyldimethylammonium bromide (DDAB), a cationic surfactant, on the interactions between NOR and ferrihydrite under different solution chemistry conditions. Interestingly, SDBS facilitated NOR adsorption, whereas DDAB inhibited NOR adsorption. The adsorption-enhancement effect of SDBS was ascribed to the enhanced electrostatic attraction, the interactions between the adsorbed SDBS on ferrihydrite surfaces and NOR molecules, and the bridging effect of SDBS between NOR and iron oxide. In comparison, the adsorption-inhibition effect of DDAB owning to the adsorption site competitive adsorption between NOR and DDAB for the effective sites as well as the steric hindrance between NOR-DDAB complexes and the adsorbed DDAB on ferrihydrite surfaces. Additionally, the magnitude of the effects of surfactants on NOR adsorption declined with increasing pH values from 5.0 to 9.0, which was related to the amounts of surfactant binding to ferrihydrite surfaces. Moreover, when the background electrolyte was Ca2+, the enhanced effect of SDBS on NOR adsorption was caused by the formation of NOR-Ca2+-SDBS complexes. The inhibitory effect of DDAB was due to the DDAB coating on ferrihydrite, which undermined the cation-bridging effect. Together, the findings from this work emphasize the essential roles of widely existing surfactants in controlling the environmental fate of quinolone antibiotics.

An artificial liquid–liquid phase separation-driven silk fibroin-based adhesive for rapid hemostasis and wound sealing

The powerful adhesion systems of marine organisms have inspired the development of artificial protein-based bioadhesives. However, achieving robust wet adhesion using artificial bioadhesives remains technically challenging because the key element of liquid–liquid phase separation (LLPS)-driven complex coacervation in natural adhesion systems is often ignored. In this study, mimicking the complex coacervation phenomenon of marine organisms, an artificial protein-based adhesive hydrogel (SFG hydrogel) was developed by adopting the LLPS-mediated coacervation of the natural protein silk fibroin (SF) and the anionic surfactant sodium dodecylbenzene sulfonate (SDBS). The assembled SF/SDBS complex coacervate enabled precise spatial positioning and easy self-adjustable deposition on irregular substrate surfaces, allowing for tight contact. Spontaneous liquid-to-solid maturation promoted the phase transition of the SF/SDBS complex coacervate to form the SFG hydrogel in situ, enhancing its bulk cohesiveness and interfacial adhesion. The formed SFG hydrogel exhibited intrinsic advantages as a new type of artificial protein-based adhesive, including good biocompatibility, robust wet adhesion, rapid blood-clotting capacity, and easy operation. In vitro and in vivo experiments demonstrated that the SFG hydrogel not only achieved instant and effective hemostatic sealing of tissue injuries but also promoted wound healing and tissue regeneration, thus advancing its clinical applications. Statement of significanceMarine mussels utilize the liquid–liquid phase separation (LLPS) strategy to induce the supramolecular assembly of mussel foot proteins, which plays a critical role in strong underwater adhesion of mussel foot proteins. Herein, an artificial protein-based adhesive hydrogel (named SFG hydrogel) was reported by adopting the LLPS-mediated coacervation of natural protein silk fibroin (SF) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS). The assembled SFG hydrogel enabled the precise spatial positioning and easy self-adjustable deposition on substrate surfaces with irregularities, allowing tight interfacial adhesion and cohesiveness. The SFG hydrogel not only achieved instant and effective hemostatic sealing of tissue injuries but also promoted wound healing and tissue regeneration, exhibiting intrinsic advantages as a new type of artificial protein-based bioadhesives.

Study on the effects of inorganic salts and ionic surfactants on the wettability of coal based on the experimental and molecular dynamics investigations

Through the evaluation and preparation of a novel inorganic salt composite solution consisting of sodium dodecyl benzene sulfonate (SDBS), the nonionic surfactants polyethylene glycol pisooctyl phenyl ether (Triton X-100), and inorganic salt Na2SO4, based on surface tension, contact angle, settling time, wetting rate, and changes in the surface microstructure and functional groups of coal, this study analyzed the wetting behavior of the solution on coal dust and its adsorption capacity on the surface of coal particles. The results demonstrate that the composite solution of inorganic salts can significantly enhance the wettability of coal samples, reducing the contact angle to 21.54° and lowering the surface tension to 26.10 mN/m. After treatment with the solution, the relative content of oxygen-containing functional groups in the microscopic structure of the coal sample increased to 59.6 % and pores more prominent than 25 nm increased to 34.63 %. Molecular dynamics (MD) simulations of the water-inorganic salt composite solution-coal system are conducted using Materials Studio software, revealing that after the addition of the composite solution, the self-diffusion coefficient (D) of water molecules is 6.3 × 10-9 m2/s, the starting point of the composite solution is 15 Å, and the system's interaction energy increase to 14000 kcal/mol. It further elucidated the modification of the surface molecular structure of coal dust by the inorganic salt composite solution, increasing hydrogen bonds, enhancing wetting, and demonstrating a solid adsorption capability of the inorganic salt composite solution on the surface of coal dust.

The magnetic layered double hydroxide/zeolitic imidazolate framework-8 nanocomposite coupled with HPLC-MS/MS for the detection of heterocyclic aromatic amines in thermally processed meat

In this research, a novel magnetic nanocomposite (Fe3O4@Zn/Al-LABSA-LDH/ZIF-8) was synthesized using Fe3O4 as the magnetic core, layered double hydroxide (LDH) with linear alkylbenzene sulfonic acid (LABSA) intercalation and zeolitic imidazolate framework-8 (ZIF-8) as the shell. Benefiting from the intercalation of LABSA into LDH combined with ZIF-8, the multiple interactions, including π-π stacking, hydrogen bonding, and electrostatic interactions, conferred high selectivity and good extraction capability to the material towards heterocyclic aromatic amines (HAAs). Fe3O4@Zn/Al-LABSA-LDH@ZIF-8 was used as an adsorbent for magnetic solid-phase extraction (MSPE) to enrich HAAs in thermally processed meat samples, followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) detection. The method exhibited a low detection limit (0.021–0.221 ng/g), good linearity (R2 ≥ 0.9999), high precision (RSD < 7.2 %), and satisfactory sample recovery (89.7 % -107.5 %). This research provides a promising approach for developing novel adsorbents in sample preparation and improving analytical performance.

Green Surfactant Assisted-Solidified Floating Organic Drop Micro-Extraction (SA-SFODME) for the Preconcentration of Trace Lead with Determination by Flame Atomic Absorption Spectrometry (FAAS)

Determination of trace lead from environmental samples was carried out by solidified floating organic drop microextraction for preconcentration before analysis by flame atomic absorption spectrometry. The determination of lead from environmental samples, even at trace levels, was possible with an ordinary flame atomic absorption spectrometer (FAAS). The lead formed a hydrophobic complex with the anionic surfactant sodium dodecyl benzene sulfonate (SDBS), and this hydrophobic complex was extracted into the 1-dodecanol drop. Parameters affecting analytical performance have been studied. The optimum pH value was 3.5. The optimum sample volume, SDBS concentration, and extraction solvent volume were 75 mL, 50 mM in dodecanol, and 75 µL, respectively. The optimum extraction time was determined as 30 min, the optimum extraction temperature was 45 °C, the optimum mixing speed was 650 rpm and the ideal extraction phase volume was 0.50 mL. Methanol has been shown to be effective when used as a diluent. Using the optimum conditions, the enhancement factor was 106, and the limit of detection (3s) and precision were 3.3 ng/mL and 2.3% (n = 9,15 ng/mL), respectively. The limit of quantification (LOQ) (10s) was 10 ng/mL and the linear working range was 15-100 ng/mL. The accuracy was evaluated by certified reference material analysis. The optimized method was applied to the determination of Pb(II) from environmental water samples. This method follows the principles of green analytical chemistry.

Preparation and Tribological Performance of Multi-Layer van der Waals Heterostructure WS2/h-BN

Van der Waals heterostructures with incommensurate contact interfaces show excellent tribological performance, which provides solutions for the development of new solid lubricants. In this paper, a facile electrostatic layer-by-layer self-assembly (LBL) technique was proposed to prepare multi-layer van der Waals heterostructures tungsten disulfide/hexagonal boron nitride (vdWH WS2/h-BN). The h-BN and WS2 were modified with poly (diallyldimethylammonium chloride) (PDDA) and sodium dodecyl benzene sulfonate (SDBS) to obtain the positively charged PDDA@h-BN and the negatively charged SDBS@WS2, respectively. When the mass ratio of PDDA to h-BN and SDBS to WS2 were both 1:1 and the pH was 3, the zeta potential of PDDA@h-BN and SDBS@WS2 were 60.0 mV and −50.1 mV, respectively. Under the electrostatic interaction, the PDDA@h-BN and SDBS@WS2 attracted each other and stacked alternately along the (002) crystal plane forming the multi-layer (four-layer) vdWH WS2/h-BN. The addition of the multi-layer vdWH WS2/h-BN (1.0 wt%) to the base oil resulted in a significant reduction of 33.8% in the friction coefficient (0.104) and 16.8% in the wear rate (4.43 × 10−5 mm3/(N·m)). The excellent tribological property of the multi-layer vdWH WS2/h-BN arose from the lattice mismatch (26.0%), a 15-fold higher interlayer slip possibility, and the formation of transfer film at the contact interface. This study provided an easily accessible method for the multi-layer vdWH with excellent tribological properties.