Addition Of Surfactant Research Articles

Enhancing the physicochemical properties of nickel cobaltite catalyst for oxygen evolution reaction in anion exchange membrane water electrolyzers

Hierarchical hollow urchin-like nickel cobaltite (NiCo2O4) was synthesized using a two-step hydrothermal method. The effects of metal composition and surfactant addition on the morphology, structure, and electrochemical performance toward oxygen evolution reaction (OER) were investigated. The addition of cetyltrimethylammonium bromide (CTAB) reduced particle aggregation, resulting in a higher electrochemical active surface area and electrical conductivity. Lowering the Ni content from 1.0 to 0.25 did not alter the morphology and structure of the product to any extent. However, the crystallite size slightly increased. Among the spinels with different Ni and Co compositions, NiCo2O4 exhibited a superior OER electrocatalytic activity, achieving a 380 mV overpotential at 10 mA/cm2 current density. It also delivered a good performance in an anion exchange membrane water electrolyzer (AEMWE) using 1 M NaOH at 60 °C, reaching a current density of about 420 mA/cm2 at a cell voltage of 1.95 V.

Effect of Polyoxyethylene-Based Nonionic Surfactants on Chemical–Mechanical Polishing Performance of Monocrystalline Silicon Wafers

The use of surfactants is crucial in the chemical–mechanical polishing fluid system for silicon wafers. This paper examines the impact of the functional group structure of polyoxyethylene-based nonionic surfactants and the variation in the polyoxyethylene (EO) addition number on the polishing performance of monocrystalline silicon wafers, to achieve the appropriate material removal rate and surface quality. The results demonstrated that the straight-chain structure of fatty alcohol polyoxyethylene ether (AEO-9) exhibited superior performance in wafer polishing compared to octylphenol polyoxyethylene ether (OP-9) and isoprenol polyoxyethylene ether (TPEG) and polyethylene glycol (PEG). By varying the number of EO additions of AEO-type surfactants, this study demonstrated that the polishing performance of monocrystalline silicon wafers was affected by the number of EO additions. The best polishing effect was achieved when the number of EO additions was nine. The mechanism of the role of polyoxyethylene-type nonionic surfactants in silicon wafer polishing was derived through polishing experiments, the contact angle, abrasive particle size analysis, zeta potential measurement, XPS, and other means of characterization.

Simulation and experimental study on amphiphilic modified graphene oxide for EOR

The application of nanosheet in enhanced oil recovery (EOR) offers a practical approach to resolving some surface-related problems. In this study, theoretical calculation and experiment were combined to study the interfacial behavior and mechanism of amphiphilic modified graphene oxide. Octadecyl amine and aspartic acid were successfully grafted onto graphene oxide nanosheets by starch template method. The stability of the modified structure was verified by IR, XRD and SEM. The change of microstructure in molecular simulation can enhance the understanding of the structure of amphiphilic modified nanosheets under SEM. The contact angle experiment directly shows its amphiphilicity, which shows that the contact angle of hydrophilic surface is 34.6° and that of hydrophobic surface is 103.5°. The interfacial elasticity experiment shows that the interfacial film formed by synthetic GOTA has certain elasticity. When the concentration increases, the interfacial film formed in the adsorption process can effectively separate the oil and water phases. Based on the interfacial tension value, the ability of graphene oxide and modified graphene oxide with different concentrations to reduce the interfacial tension between distilled water and diesel oil was investigated successively. The mechanism of GOTA action was explained from the aspects of molecular structure and energy by molecular simulation. The results show that the interfacial tension fluctuates around 16 mN/m when the GOTA concentration is 0.005%, and the average interfacial tension is 17.48 mN/m when the GOTA concentration (molecular number percentage) is 0.004% in the simulation process, which is highly consistent. Further studies have shown that the interface formation energy of the system is significantly reduced after the addition of zwitterionic surfactants, and the interfacial tension can be reduced to 11.95 mN/m. With the help of molecular simulation, the adsorption mechanism of GOTA on the interface is explained from the aspects of microstructure change, interaction energy, cohesion energy, interface density and conformation. The adjustment of these interactions will directly affect the oil-water interface morphology and interfacial tension.

Effects of substrate (track-etched filter) properties on the performance of forward osmosis membranes

Highly permeable membranes can improve the validity of water treatment using forward osmosis (FO) membranes. This study aims to identify the effects of substrate (track-etched (TE) filter) properties on the permeability of FO membranes. The polyamide active layer properties of three types of TE filters with similarly-sized pore diameters (0.2 μm) were observed to be equivalent regardless of the substrate porosity (13.7%–15.8 %) and substrate thickness (10–25 μm). Under the same fabrication protocol using 1.5 wt% m-phenylenediamine (MPD) solution with 0.25 wt% sodium dodecyl sulfate (SDS) addition, the increased porosity of the TE filter increased water flux. This suggested that further reduction in thickness and increase in porosity can enhance the water flux. The addition of SDS to an MPD solution was crucial in maximizing the water flux of TE filter-based FO membranes, and the other approaches (no surfactant addition or the addition of Tween80 or hexadecyltrimethylammonium bromide) produced lower water flux. The optimized fabrication protocol presented the highest water flux of 43 L/m2h and reverse salt flux of 10 g/m2h with the draw (1.0 M NaCl) and feed (pure water) solutions. This study determined the best approach for forming a highly permeable PA active layer on TE filters.

EFFECT OF POLYMER CONCENTRATION AND SURFACTANTS ON PHYSICAL CHARACTERISTICS, DRUG RELEASE AND ANTIOXIDANT ACTIVITY OF GLUTATHIONE-KAPPA CARRAGEENAN NANOSPHERES

Objective: Glutathione is one of the antioxidants widely used as an antiaging and skin lightener. Glutathione at a dose of 250 mg/d orally proved useful as an antiaging. At the same time, glutathione topical night cream is effective at a dose of 0.1% for the skin of Indonesian women. Glutathione is one of the antioxidants that has easily oxidized properties in storage. Research purpose to optimize the concentration of kappa carrageenan polymer and surfactan to obtain the optimal physical characteristics of nanosphere system analyzed based on size, PDI, yield, drug loading, entrapment efficiency, dissolution and antioxidant activity. Methods: The most commonly used method of making nanospheres is ionotropic gelation because it has proven effective, easy, and easy to apply. Ionotropic gelation is depend on the tendency of polyelectrolytes to cross connect to develop hydrogel beads often called gelispheres in the existence of counter ions. Nanospheres were prepared by aerosolization ionotropic gelation technique followed by freeze-drying. This method uses carrageenan polymers of 0.5% and 1.0% with the addition of surfactant as a stabilizer. Evaluation parameters are particle size, entrapment efficiency, drug loading, drug release and antioxidant activity. Results: The results of the nanospheres obtained were tested physically and drug activity. Nanospheres successfully formed, with size 382.67±52.24 nm, F2 325.20±4.62 nm, F3 495.39±30.61 nm, and F4 409.80±4.11 nm. The greater the polymer concentration, the greater the value of entrapment efficiency and drug content in the nanosphere. The morphology of the nanosphere is quite good, spherical, with a smooth surface. The release profile shows that glutathione release is quite good but takes a long time, namely F1 73.91±2.17%, F2 75.91±2.76%, F3 78.56±2.82%, and F4 79.56±1.34% in 480 min or 8 h. Antioxidant activity of glutathione-Kappa carrageenan nanospheres with the DPPH method showed that nanospheres have medium or medium category antioxidant activity. Conclusion: The most optimal formula is F4 with 1% kappa-carrageenan concentration and 0.6% KCl.

The Effect of Surfactant on the Stability of Inorganic Salt Hydrated Phase Change Material Containing Graphene Nanoplatelet: An Experimental Investigation

The use of nano phase change material (PCM) as a heat transfer agent has spread and expanded as its thermal conductivity is higher than the base PCM, so its use has been increased in PVT systems. In this study, inorganic salt hydrated PCM was used as a base material and Graphene nanoplatelet (GNP) as an additive to improve the thermal conductivity of the resulted nano-PCM and its stability was studied using Cetyl Trimethyl Ammonium Bromide (CTAB) surfactants. The main objective of the present study was to investigate the effect of surfactant on the stability of different GNP concentration in CaCl2.6H2O PCM. The nano-PCM has been prepared using two-step method. The stability of nano-PCM depends on the surfactant used to slow the sedimentation of nanoparticles in the base PCM. The sedimentation process significantly reduces the thermal conductivity of nano-PCM and thus reduces heat transfer. The study results indicated that the employment of surfactant significantly affected the stability of nanoparticles added in the base PCM. The stability test ascertained the effectiveness of the surfactant applied in phase change material. With successive addition of surfactant, the stability of GNP in PCM was further enhanced to +49.3 mV of Zeta potential value.

Weakly agglomerated NANO/MICRO-particles of Gd2O3:Tb3+: Structure, luminescence and thermometry

Gadolinium oxide nanostructures have been actively studied as multimodal materials for both technical applications and biomedical research. Doping of this oxide structure with a given concentration of chosen rare earth ions allows one to obtain predefined optical properties. Weakly agglomerated nanoscale and submicron Gd2O3:Tb3+ particles were synthesized by a modified Pechini method in a single chemical process. The nanoscale fraction was transferred into aqueous solution without the addition of surfactant. Zeta potential of this solution was found to be about −17 (±1) mV. The crystal structure of cubic gadolinium oxide is confirmed for the large and small size fraction. The optimal concentration of terbium ions, at which the highest luminescence is observed, was 1.2 at.%. The concentration quenching mechanism for Tb3+-doped Gd2O3 samples was determined as a dipole–quadrupole energy migration with subsequent quenching on impurities. The luminescence properties of sub-micron and nanoparticles, including lifetimes, were found to be almost identical. The effect of temperature on both steady-state and kinetic luminescent properties was studied. Gd2O3:Tb3+ phosphors were found to be promising as lifetime-based luminescent thermometers.

Evaluation of surfactant-aided polycyclic aromatic hydrocarbon biodegradation by molecular docking and molecular dynamic simulation in the marine environment

Marine oil spills directly cause polycyclic aromatic hydrocarbons (PAHs) pollution and affect marine organisms due to their toxic property. Chemical and bio-based dispersants composed of surfactants and solvents are considered effective oil spill-treating agents. Dispersants enhance oil biodegradation in the marine environment by rapidly increasing their solubility in the water column. However, the effect of dispersants, especially surfactants, on PAHs degradation by enzymes produced by microorganisms has not been studied at the molecular level. The role of the cytochrome P450 (CYP) enzyme in converting contaminants into reactive metabolites during the biodegradation process has been evidenced, but the activity in the presence of surfactants is still ambiguous. Thus, this study focused on the evaluation of the impact of chemical and bio-surfactants (i.e., Tween 80 (TWE) and Surfactin (SUC)) on the biodegradation of naphthalene (NAP), chrysene (CHR), and pyrene (PYR), the representative components of PAHs, with CYP enzyme from microalgae Parachlorella kessleri using molecular docking and molecular dynamics (MD) simulation. The molecular docking analysis revealed that PAHs bound to residues at the CYP active site through hydrophobic interactions for biodegradation. The MD simulation showed that the surfactant addition changed the enzyme conformation in the CYP-PAH complexes to provide more interactions between the enzyme and PAHs. This led to an increase in the enzyme's capability to degrade PAHs. Binding free energy (ΔG‌‌Bind) calculations confirmed that surfactant treatment could enhance PAHs degradation by the enzyme. The SUC gave a better result on NAP and PYR biodegradation based on ΔG‌‌Bind, while TWE facilitated the biodegradation of CHR. The research outputs could greatly facilitate evaluating the behaviors of oil spill-treating agents and oil spill response operations in the marine environment.

Effects of surfactant types on anthracite dust wettability: Experimental and molecular simulations

To study the wetting mechanism of surfactants at the solid–liquid interface of anthracite, a combination of experiments and molecular simulation was used to explore the adsorption and wetting processes of four surfactants, namely, fatty alcohol polyoxyethylene ether N = 9 (AEO9), Triton X-100, rapid penetrant T (PRT), and sodium alkyl ether sulfate (AES) on anthracite. The wetting mechanism of surfactants on anthracite was analyzed at both macroscopic and microscopic levels by surface tension, contact angle, settling time, and changes in surface morphology and functional groups on the anthracite surface. The presence of OH-π and C = O was determined to significantly enhance anthracite wettability. The anthracite/surfactant/water system was constructed from a microscopic perspective, and the interaction energies, relative concentration distributions along the Z-axis, diffusion coefficient (D) of water molecules, radial distribution functions (RDF) of hydrophilic groups and water molecules, and coordination numbers of the components were analyzed. The results show that the wetting effect depends on the adsorption state of the surfactant at the anthracite/water interface and the strength of the interaction between the surfactant and water molecules. The addition of surfactants enhances the adsorption thickness of water molecules along the Z-axis and generates more hydrogen bonds, which play a role in fixing water molecules and lead to a decrease in the D of water molecules. RPT forms the highest number of hydrogen bonds with water molecules and has the lowest D of 0.479 × 10-5 cm2/s, indicating strong wetting ability. The RDF of O atoms in surfactants and water molecules shows a similar trend, with two peaks one strong and one weak. The coordination numbers are 1.356, 1.057, 1.003, and 0.903, respectively. The final wettability of the surfactant on the anthracite depends on the synergistic interaction between the oxygen functional groups (OGs) as compared to the coordination number of the individual OGs.

Selective additions of dopants, Co-catalyst and surfactant on the hydrothermally synthesized BiVO4 semiconductors for outstanding photoelectrochemical water oxidation behavior

The present study describes the significant improvement of the PEC performance through modifications via co-doping of Mo/W and optimizing the level of surfactant (Triton-X 100; TX-100) addition to the hydrothermally synthesized BiVO4 photoanode. The photoelectrochemical performance is improved when the precursor solution contains an optimized 5 % TX-100 surfactant level. The visible light responsiveness of the semiconductor photocatalyst has been confirmed using linear sweep voltammograms under periodic chopped illumination of UV–vis and visible irradiation for H2O → O2 oxidation. Adding an optimized level of Mo and W to the precursor solution leads to modifications of the crystallites, which facilitates the water oxidation reaction and exhibits the highest photo-current of ∼0.61 mA cm−2. Selective loading of oxygen evolution catalyst (OEC) in the surface boosts the PEC performance to 1.05 mA cm−2 and significantly increases photon current conversion efficiency.

Dedusting and inhibition of methane-coal dust hybrid explosion by ultrafine water mist containing SDS surfactant

The dust reduction and inhibition effects of ultrafine water mist containing SDS anionic surfactant on methane-coal dust explosion were experimentally investigated. Compared with pure ultrafine water mist, the Pmax and (dP/dt) max of 0.5% SDS water mist were reduced by 9.18% and 27.2%, respectively, and the explosion induction period was prolonged from 102 ms to 205 ms. SDS water mist can effectively inhibit the intensity and propagation of the flame, forming the formation of irregular fronts and unevenly colored orange flames after multiple extinguishments in the explosion induction period. In addition, the addition of SDS surfactant promotes the formation of liquid bridges between water mist and coal dust particles. The contact angle of coal dust is reduced by 38.9% and the sink time is reduced to 30 ms. This paper presents a new direction and choice for achieving simultaneous dust reduction and explosion suppression in coal mines.

Surfactant Effects in Porous Electrodes for Microemulsion Redox Flow Batteries

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

Optimization of nano-emulsion production in ultrasonic microreactors: The effects of pre-homogenization, circulating ratio and hybrid frequency application

The study first investigated the effects of individual ultrasound and high-speed shearing on emulsification, both obtaining emulsions with average sizes of approximately 1 μm. Subsequently, a combined strategy to utilize shearing instrument producing coarse emulsion for ultrasonic microreactor was proposed. Immiscible liquids were drawn into the stirring chamber by rotating paddles, where they underwent strong shearing and thorough mixing. The pre-mixed liquids were introduced into microchannel and subjected to further processing by oscillating cavitation bubbles. Through optimization of experimental parameters such as residence time and recycle ratio, the average emulsion size was significantly reduced to 522 nm. Finally, a dual-frequency strategy using ultrasound frequencies of 20 and 40 kHz consecutively further reduced the emulsion size to 307 nm. In comparison with conventional sonoreactors and high-pressure homogenizers, this dual-frequency approach demonstrated superior emulsification performance with less surfactant addition and energy input, indicating its high applicability on continuous emulsification process with proper design and optimization.

Unique behavioral patterns of wandering colonies of Brevibacillus thermoruber on agar plates.

Brevibacillus thermoruber strain Nabari cells grow as widely spreading dendritic colonies on reasoner's 2A-agar (1.5%) plates at around 55°C but as small motile colonies at 37°C. Motile colonies can be divided into colonies that move in straight or curved lines over long distances (wandering colonies), and colonies that rotate at a fixed location (rotating colonies). The addition of surfactant to the agar medium greatly increased the frequency of wandering colonies and facilitated the study of such colonies. The morphology of the wandering colonies varied: circular at the tip and pointed at the back, lemon-shaped with pointed ends, crescent-shaped, bullet-shaped, fish-like, and so on. A single colony may split into multiple colonies as it moves, or multiple colonies may merge into a single colony. The most surprising aspect of the movement of wandering colonies was that when a moving colony collides with another colony, it sometimes does not make a U-turn, but instead retreats straight back, as if bouncing back. The migration mechanisms of wandering colonies are discussed based on optical microscopic observations of swimming patterns of single cells in water and scanning electron microscopy of the arrangement of bacterial cells in wandering colonies.

Sustainable nanodemulsifiers for enhanced demulsification of water and saline in crude oil emulsions: Synthesis and application

Nanoparticles have been used as important materials for various applications in the oil industry. Among these applications, the use of nanoparticles as demulsifiers has gained considerable attention. In this study, sustainable nanodemulsifiers including cellulose nanocrystals (CNC) and cellulose nanocrystals/PEG (CNC-PEG) composites derived from low-cost cotton, are synthesized. These demulsifiers were characterized by the Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectra (XRD), thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). The impact of various parameters, including demulsifier concentration, additives, salinity, demulsification time, temperature, and surfactant addition, on the performance of these demulsifiers was investigated. According to the results, the composite nanodemulsifier exhibited superior performance with a demulsification efficiency of 90%, outperforming CNC and PEG alone for both water and saline in crude oil emulsions. Also, the results indicated that by adding surfactant to these demulsifiers, the demulsification efficiency increased to 100%. These findings offer valuable insights into the development of sustainable and efficient demulsifiers for the oil industry.

Mechanisms of CO2-rich industrial waste gas enhanced shale oil recovery in kerogen slit based on adsorption behavior, gas flooding and surfactant synergy study

Enhanced oil recovery (EOR) by injection of CO2-rich industrial waste gas has been proposed as an energy-efficient and environmentally friendly method for shale oil reservoirs, in which the waste gas can be utilized and sequestered to reduce greenhouse gas emissions. In this work, the adsorption behaviors of shale oil and waste gas components in kerogen slits and the effects of gas flooding on EOR were investigated using molecular dynamics (MD) method, which can provide technical guide for shale oil development. In terms of the adsorption behaviors, an intensity decrease of oil adsorption is observed in kerogen slits after the injection of the waste gas components. Desorption of shale oil during injection of SO2 and CO2 is more pronounced in shallow reservoirs, whereas it is more evident for NO and N2 in deep reservoirs. The desorption efficiency can be 10.91 % for pure CO2 injection and 9.09 % for NO injection at a depth of 1000 m, and the relative stability ratios of CO2 and NO sequestration are 77.09 % and 76.06 %, respectively. For gas flooding, the existence of pressure difference provides favorable conditions for gas molecules to pass through the oil zone, and waste gas can be more effective than pure CO2 as driving gas. For the waste gas injection, the percentage of CO2 retained in the kerogen nanopores is much higher than that of pure CO2 injection, suggesting that more CO2 molecules can enter into kerogen matrix to take part in the displacement process. Furthermore, the effect of surfactants on oil desorption and displacement was also investigated and the interaction energy of the surfactant/oil/gas system was calculated and analyzed, finding that addition of the oil-soluble surfactants can be beneficial to shale oil displacement. This work can provide a comprehensive evaluation of the feasibility of CO2-rich industrial waste gas application for EOR, which is of great significance in the effective production of shale oil and the sequestration of waste gas in shale reservoirs.

Why Carbon Nanotubes Improve Aqueous Nanofluid Thermal Conductivity: A Qualitative Model Critical Review

Media thermal conductivity is important in various heat-transfer processes. Many conventional fluid conductors suffered low conductivity and environmental issues. Therefore, research was active in finding out alternative systems, mostly relying on aqueous liquids that are low-cost and ecofriendly. After the emergence of carbon nanotubes (CNTs), with their many special structural, electrical and thermal properties, they have been examined for many applications, including heat-transfer processes. Adding CNTs to water yields CNT aqueous nanofluids that have been widely investigated as heat-transfer media. The literature shows that CNT addition improves water thermal conductivity and other water properties, such as viscosity, surface tension, freezing point and boiling point. The literature also shows that nanofluid thermal conductivity improvement is affected by CNT type and concentration, in addition to other factors such as surfactant addition. All these subjects were widely described in literature, focusing on experimental, modelling and theoretical accounts. Despite the wide literature, there exist inconsistencies and discrepancies between reports that need to be justified. In addition to technical papers, many reviews were published on various aspects of the subject including experimental results and mathematical modeling. However, the very basic question here is as follows: Why does adding CNT to water affect its thermal conductivity? In spite of the wide published literature, this issue was not targeted in a simple qualitative approach. This review provides a clear understanding of how CNTs improve thermal conductivity of aqueous nanofluids. A qualitative model is presented to explain mechanisms behind improvement as presented in the literature. CNT type effects are discussed with other factors such as aspect ratio, Reynold number, dispersion quality, composition, temperature and additives. CNT functionalization is described. Relations to estimate nanofluid thermal conductivity are discussed. The model will help specialists to tailor CNT aqueous nanofluid characteristics as desired by varying types and concentrations of CNT and surfactant, and other factors.

Effect of irradiated nonionic surfactant on drug-protein binding

In this work, the effect of γ-irradiated surfactants on drug–protein binding has been assessed. Irradiated aqueous solutions of Pluronic F-127, Pluronic L-35, Tween 20, and Tween 80 surfactants were used. Gamma irradiation was carried out for three different doses, to these four surfactants viz., 6, 30, and 36 kGy. Two drugs, Ornidazole (ONZ) and Telmisartan (TMS) were used for the binding study. The effect of four irradiated surfactants in the presence of drug – Bovine serum albumin (BSA) protein was analyzed. The drug solutions in methanol-aqueous media were combined with BSA in the initial step. In the next two succeeding steps, drug–BSA interaction in the presence of unirradiated and irradiated surfactants were carried out. The results of drug-BSA due to addition of irradiated and unirradiated surfactants were compared. The interaction processes were assessed through UV Spectroscopy, DLS, zeta potential, turbidity, and docking studies. Improved binding was observed for both the drugs and four surfactants for irradiated surfactants as determined from the binding constant values using UV spectroscopic studies. The DLS measurements demonstrated no general trend of increase or decrease in micellar size with absorbed dose. The binding and change in the size of micelles were observed to be highly drug and surfactant-specific. Among the four surfactants, irradiated Pluronic F-127 showed higher binding affinity. To the best of our knowledge, this is the first report on the effect of γ-irradiated surfactant on drug–BSA interaction. This can be applied to other drug–protein systems to tune their interaction to the required level. Communicated by Ramaswamy H. Sarma

Study of the Effect of the Surfactant Linear Alkylbenzene Sulfonate (LAS) on the Coagulation of Aged Microplastic

Objective: Evaluate the effect of linear alkylbenzene sulfonate (LAS) surfactant on the coagulation of aged microplastic. Theoretical Framework: Chemical coagulation is one of the steps adopted in water treatment that can help remove microplastics. During coagulation, suspended particles agglomerate, increasing the efficiency of removing these particles in the sedimentation stage. However, when coagulation occurs in the presence of surfactants, evidence points to deficits in removal capacity. Method: Using Jar Test tests, the optimal parameters for microplastic removal were determined with aluminum sulfate as a coagulating agent in the presence and absence of the surfactant linear alkyl benzene sulfonate (LAS). The LAS concentrations studied were in the range of 20 mg/L to 300 mg/L. Microplastic removal efficiency was evaluated by measuring turbidity. Results and Discussions: The combination of pH and coagulant concentration values that best suited the system were 5.0 and 4.25 mg/L, respectively. Due to the addition of surfactants, a decrease in removal efficiency was observed, with an average value ranging from 94.79% to 76.50% due to the interaction of polyethylene spheres with the surfactant. Research Implications: As explained, due to the coexistence of microplastics and surfactants in the aqueous environment, studies that describe chemical coagulation under these conditions have great value for optimizing treatment systems and technologies. Research Originality/Value: The use of aged microplastics aims to approximate their natural occurrence.

Secondary Atomization and Micro-Explosion Effect Induced by Surfactant and Nanoparticles on Enhancing the Combustion Performance of Al/JP-10/OA Nanofluid Fuel.

Aluminum/tetrahydrodicyclopentadiene/oleic acid (Al/JP-10/OA) nanofluid fuel is considered a potential fuel for aircraft powered by aviation turbine engines. However, an optimized formula for an Al/JP-10/OA system inducing a secondary atomization and micro-explosion effect and improving the burning performance needs to be developed. With this aim, in this work, the combustion characteristics of pure JP-10, JP-10/OA, JP-10/Al, and Al/JP-10/OA were experimentally tested, and a comparative analysis was conducted. Specifically, the influence of the surfactant and nanoparticle concentrations on the combustion characteristics of Al/JP-10/OA nanofluid fuel, including the flame structure, the flame temperature, the burning rate, the secondary atomization and micro-explosion effect, etc., were evaluated in detail. The results demonstrate that the addition of OA surfactant and Al nanoparticles had a significant effect on the burning rate of fuel droplets. The OA had an inhibition effect, while the Al nanoparticles had a promotion effect. As both OA and Al nanoparticles were added to the JP-10, the synergetic effect had to be considered. At the optimum ratio of OA to Al for the best suspension stability, there is a critical Al concentration of 1.0 wt.% from promotion to inhibition with increases in the Al concentration. The addition of OA and Al nanoparticles induced the secondary atomization and micro-explosion, resulting in an unsteady combustion and chaotic flame structure. The transient flame temperature of hundreds of Kelvins increased, the high-temperature flame zone widened, and thus, the energy release was elevated. Therefore, the combustion performance and energy release of Al/JP-10/OA nanofluid fuel can be improved through the secondary atomization and micro-explosion effect induced by the surfactant and nanoparticles.