Addition Of Anionic Surfactant Research Articles

Treating boron-containing wastewater by electrocoagulation-flotation (ECF) process with the stepwise addition of anionic surfactants

This study presents an innovative approach for boron removal from industrial wastewater, especially from coal-fired power plants and hydraulic fracturing processes, through an advanced electrocoagulation-flotation (ECF) method. This method, enhanced by the stepwise addition of anionic surfactants, effectively reduces the sludge-volume ratio (SVR) while ensuring efficient boron removal. Anionic surfactants, due to their compatibility with the positively charged boron‑aluminum hydroxide co-precipitates, enhance coagulation and solid-liquid separation. The research highlights the correlation between the hydrophobicity of the surfactant's carbon chain and reduced sludge volume and residual turbidity. Importantly, the stepwise addition of surfactants optimizes the dosage, maintaining low residual turbidity and SVR, even in high-conductivity (30.1 mS cm−1) wastewater from actual coal-fired power plants. Further, the study shows that longer reaction times and higher surfactant doses in a mono-polar electrode reactor can significantly improve boron removal and solid-liquid separation, marking a substantial advancement in wastewater treatment technologies.Boron is a common pollutant in wastewater of coal-fired power plants and the hydraulic fracturing process. It can be effectively removed by electrocoagulation (EC). However, the boron‑aluminum hydroxide particles after EC are too tiny to settle by sedimentation, and therefore, the sludge-volume ratio (SVR) is extremely high. By adding surfactants, the solid-liquid separation mechanism of EC can be shifted from settling to flotation (known as the electrocoagulation-flotation (ECF) process), effectively reducing the SVR without affecting boron removal. Due to the positively charged nature of boron‑aluminum hydroxide co-precipitates, anionic surfactants work better than cationic surfactants as coagulants. The higher the hydrophobicity of surfactant's carbon chain, the lower the sludge volume and residual turbidity. A stepwise addition method significantly reduced the surfactant dosage without causing an increase in the residual turbidity or SVR. The efficiencies of boron removal and solid-liquid separation by ECF in actual coal-fired power plant wastewater were significantly reduced due to the extremely high conductivity (30.1 mS cm−1). A stepwise addition method was also useful when treating real wastewater. The efficiencies of boron removal and solid-liquid separation were significantly be improved by a longer reaction time and a higher SDS dose by ECF with a mono-polar electrode reactor.

Wettability, flowability and core bending strength of wet silica sand particles based on the interfacial properties of liquid silicate binders

The flowability of wet silica sand particles containing liquid binders, which are among the new moulding materials for green casting, must be further improved. Herein, we conducted an in-depth study on the interface characteristics of silicate binders with the addition of anionic surfactants. Through particle flow experiments and sand core bending fracture experiments, the influence of anionic surfactants on the flow characteristics of wet sand particles and the mechanical properties of silicate-bonded sand was explored. The experimental results showed that the addition of 0.10 wt% of an anionic surfactant significantly reduced the surface tension and contact angle of solutions, from 78.99 to 28.53 mN/m, and from 49.9° to 34.4°. Moreover, compared with unmodified wet particles, the flowability of wet particles modified with 0.10 wt% of the anionic surfactant was improved to some extent. However, the flexural strength of silicate-bonded sand was also reduced to a certain extent.

Diffusion kinetics of molecular probe in thin poly(vinyl alcohol)-based films

We investigated the diffusion characteristics of a molecular probe in organic films of poly(vinyl alcohol) (PVA) that replicate formulations used as packaging materials. Diffusion kinetics of Rhodamine B (RhB) was measured in thin films of PVA containing glycerol and surfactants of various headgroup chemistry (cationic/nonionic/anionic) using fluorescence recovery after photobleaching and atomic force microscopy. Here we show how diffusion is determined by both molecular arrangement within the film and the nature/magnitude of intermolecular interactions. Addition of glycerol could improve the flexibility of PVA chains initially but imposed steric inhibition once the concentration exceeded the threshold of 44 wt%. In all investigated formulations, RhB exhibited diffusion-coupled mechanism. The presence of surfactants (at 6 wt%) reduced the diffusivity of RhB in PVA matrix for all types of surfactants used (by 30 %, 61 %, and 88 % for cationic, nonionic, and anionic surfactant addition compared to control sample, respectively). We conclude that steric inhibition effects underpin the diffusion of RhB in PVA thin films doped with nonionic surfactant. However, for PVA films with the addition of cationic or anionic surfactant, interactions between surfactant and fluorophore are likely responsible for the change in diffusivity of the molecular probe.

A study on surfactant modified polypyrrole nanostructures and its applications in supercapacitors

Nanocomposites of Polypyrrole (Ppy), were synthesized by chemical oxidative polymerization of pyrrole, in the presence of mono and mixed‐surfactant solutions using ammonium persulfate as an oxidant and were investigated for its applications in super capacitors. The surfactants used in the experiments included anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS) and cationic surfactants, tetradecyltrimethylammonium bromide (TTAB) as well as cetyltrimethylammonium bromide (CTAB). The morphology and structure of the resulting Ppy were investigated in detail with FESEM and FTIR, respectively. The addition of anionic surfactants produced globular morphology. The results showed that the interaction between the different surfactants and the interaction between the surfactants and the polymer influenced the morphology, structure and conductivity of the resulting polymer to different degrees. Apart from these, XRD, UV-Vis spectroscopy and cyclic voltammetry (CV) were also performed to characterize the prepared composites. In comparison with the results for mono surfactant solutions, the polymerization of pyrrole in mixed‐surfactant solutions shows significant changes in morphologies and electrochemical properties of Ppy. The results of CV show that the specific capacitance values of Ppy samples with anionic surfactants are greater than cationic surfactants. In case of mixed surfactants, sample with SDBS + TTAB posses highest specific capacitance of 204 Fg−1 at scan rate 100 mVs−1. The good electrochemical properties can be attributed to the highly porous structural advantage of the Ppy sample prepared using SDBS + TTAB. It indicates the energy holding capacity or capacitance of the prepared samples and can be utilized in sensing applications like supercapacitors.

Regulatory effects of different anionic surfactants on the transformation of heavy metal fractions and reduction of heavy metal resistance genes in chicken manure compost

Surfactants are widely used as a passivating agent in heavy metal passivation process, but their effect on transformation of heavy metal fraction and reduction of heavy metal resistance genes (MRGs) in composting process is still unknown. The aim of this study was to compare the effects of two anionic surfactants (rhamnolipid and sodium dodecyl sulfate) on heavy metal passivation and resistance gene reduction in chicken manure composting. The results showed that the addition of surfactant can effectively enhance degradation of organic matter (OM). Both surfactants could effectively reduce the bioavailability of heavy metals (HMs) and the relative abundance of resistance genes, especially rhamnolipids. The potential functional bacteria affecting heavy metal passivation were identified by the changes of microbial community. Redundancy analysis (RDA) showed that protease (PRT) activity was the key factor affecting the fractions of the second group of HMs including ZnF1, CuF1, CuF2, PbF1 and PbF3. These findings indicate that addition of anionic surfactants can reduce the bioavailability of HMs and the abundance of resistance genes in compost products, which is of guiding significance for the reduction of health risks in the harmless utilization of livestock and poultry manure.

Montmorillonite swelling properties with various surfactants based on molecular simulation

The clay swelling is extremely harmful to the reservoir during tight oil and shale oil extraction. In order to prevent the interaction between clay and surfactants from making the clay to hurt reservoir during oil recovery, this paper studies the effects of different surfactants on reservoir clay. Clay-surfactant swelling experiments were conducted to observe the macroscopic effects of different surfactants on clay swelling and to summarize the rules, and molecular simulations were then used to explain this phenomenon. The results show that different surfactant groups have different tendencies to move toward the clay in water, with cationic groups moving toward the montmorillonite layers and anionic groups moving away from the montmorillonite layers, and nonionic does not have a significant effect. Cationic surfactant and amphoteric surfactant whose mechanism of inhibiting swelling action is directly reducing the negative electrical properties of the montmorillonite layers when Na+ outflow from montmorillonite layers, thus preventing electrostatic repulsion between montmorillonite layers to repel each other and move far away. In contrast, the nonionic surfactant, because it is not charged, cannot prevent the hydration of montmorillonite although there are surfactant molecules adsorbed on the layers due to van der Waals force; and the addition of anionic surfactant cannot suppress the negative electrical properties between the layers, which makes the diffusion of sodium ions between the layers augmented and promotes the swelling and dispersion of montmorillonite. This study is expected to provide benefits to oil production area by reducing the damage of surfactant imbibition fluid.

Nanocomposite Co-nSiC coatings electrodeposited from cobalt-gluconate bath via pulse reverse plating technique with anionic surfactant

The co-deposition of silicon carbide nanoparticles (50 ± 5 nm diameter) in an electrodeposited metallic cobalt matrix has been investigated under pulse reverse plating (PRP) conditions with the inclusion of an anionic surfactant. The effect of variable anionic surfactant content in the plating solution with a particle content of 5 g L−1 was evaluated using both direct current (DC) plating and PRP. The particle content of the coatings was investigated by varying the cathodic cycle during PRP by varying the cathodic cycle time between 30 and 240 s per pulse whilst maintaining a fixed anodic charge. The coatings were assessed by SEM and EDX in cross section to determine the effect of PRP parameters and anionic surfactant content on the particle content of. With no anionic surfactant, all coatings produced contained a similar particle content. Addition of anionic surfactant affected the SiC content of DC and PRP coatings. PRP combined with anionic surfactant to produce an electrophoretic nanoparticle delivery mechanism increasing the SiC content of coatings compared to DC coatings. Higher SiC content was observed at shorter cathodic cycle times.

Liquid Crystals as Multifunctional Interfaces for Trapping and Characterizing Colloidal Microplastics.

Identifying and removing microplastics (MPs) from the environment is a global challenge. This study explores how the colloidal fraction of MPs assemble into distinct 2D patterns at aqueous interfaces of liquid crystal (LC) films with the goal of developing surface-sensitive methods for identifying MPs. Polyethylene (PE) and polystyrene (PS) microparticles are measured to exhibit distinct aggregation patterns, with addition of anionic surfactant amplifying differences in PS/PE aggregation patterns: PS changes from a linear chain-like morphology to a singly dispersed state with increasing surfactant concentration whereas PE forms dense clusters at all surfactant concentrations. Statistical analysis of assembly patterns using deep learning image recognition models yields accurate classification, with feature importance analysis confirming that dense, multibranched assemblies are unique features of PE relative to PS. Microscopic characterization of LC ordering at the microparticle surfaces leads to predict LC-mediated interactions (due to elastic strain) with a dipolar symmetry, a prediction consistent with the interfacial organization of PS but not PE. Further analysis leads to conclude that PE microparticles, due to their polycrystalline nature, possess rough surfaces that lead to weak LC elastic interactions and enhanced capillary forces. Overall, the results highlight the potential utility of LC interfaces for rapid identification of colloidal MPs based on their surface properties.

Spreading Behavior and Wetting Characteristics of Anionic Surfactant Droplets Impacting Bituminous Coal.

Spraying water-based materials on the coal surface is a common means of coal dust suppression. There are obvious dynamic wetting behaviors during droplets impacting coal. To explore the spreading behavior and wetting characteristics of anionic surfactant droplets on bituminous coal, three anionic surfactants, which are sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDDS), and sodium dodecyl benzene sulfonate (SDBS), were used for the droplet impact experiment and molecular dynamics (MD) simulation. The results show that the addition of anionic surfactants can promote the wetting behavior of the droplet, and the difference between the head group and the tail group of the surfactant molecules can affect the wettability of the droplet. The dimensionless spreading coefficient shows the rule of SDBS > SDS > SDDS. When the concentration does not reach critical micelle concentration (CMC), the surface tension decreases and the dimensionless spreading coefficient of droplets increases with the increase of concentration. When the droplet concentration reaches the CMC, surface tension is no longer an effective indicator to evaluate the wettability of droplets. The dimensionless spreading coefficient can effectively evaluate the macroscopic spreading wetting behavior of droplets, and it is better than the surface tension. MD simulation results show that the interaction between anionic surfactants and coal molecules can affect the adsorption behavior, and the interaction energy and adhesion work are shown as the rule of SDBS < SDS < SDDS. The results of MD simulation and the impact experiment show that the intermolecular adsorption behavior has a significant influence on the spreading process. The results of MD simulation further explain the results of the droplet impact experiment.

Effect of additives on hydrogen release reactivity of magnesium hydride composites

Magnesium hydride, a compound potentially applicable as a hydrogen carrier and energy storage material, releases hydrogen via hydrolysis or thermolysis.Ball-milled MgH2 composites were studied to optimize the kinetics and yield of the dehydriding process. Milling MgH2, under inert atmosphere increased the susceptibility to oxidation: the amount of MgO produced following air exposure of pulverized MgH2 was found to be proportional to the milling duration.Incorporation of protective coatings to avoid undesirable oxidation was studied: addition of anionic surfactants or expanded graphite as milling aids reduces the susceptibility of MgH2 to oxidation, presumably via formation of a protective layer. Such coatings minimize the access of oxygen to the particle surface upon exposure to air and facilitate manipulations, such as performing analysis, under ambient atmosphere.Improved dehydriding efficiency of oxidation-protected milled composites was demonstrated.Hydrolysis of pristine magnesium hydride and MgH2-composites with aqueous hydrolysates containing aprotic polar solvents demonstrated a significant increase of dehydriding efficiency.

Surface Planarization of CdZnTe Wafers: Effect of Slurry Formulation and CMP Processing Parameters on Surface Planarity

This study investigates the effect of chemical mechanical planarization (CMP) processing parameters such as platen velocity, the concentration of the oxidizer and abrasive nanoparticle, slurry pH and surfactant types on the surface roughness of cadmium zinc telluride (CdZnTe) substrate. It was found that these parameters have a significant effect on the quality of the polished surfaces. It was found that lower platen velocity, lesser concentration of abrasive particles, basic slurry pH, and addition of anionic surfactant (SDS) into the CMP slurry solution showed improved surface planarity. Optical Surface Profiler and atomic force microscopy (AFM) techniques were used to monitor the surface topography before and after polishing. A notable root-mean-square surface roughness, (Rq), ∼0.9 nm, has been obtained on the polished CdZnTe (CZT) surface over a scan area of 481 × 361 μm2 under the optimized conditions of 60 rpm relative velocity, slurry pH of 9, 3.75 vol% of oxidizer (H2O2) and 1.25 wt% of abrasive (SiO2 nanoparticle). A probable mechanism of the present CMP surface planarization of CZT substrate has been proposed. Unlike the conventional surface planarization processes, which involve two-step lapping followed by CMP for the CZT surfaces, we have developed a single step CMP process to obtain good surface planarity.

Addition of surfactants to Low Salinity Waterflooding in microfluidics system to increase oil recovery

This study was conducted to investigate the phenomenon of oil removal from inside pores using a self-designed microfluidic test kit. An artificial micromodel chip as a representation of porous rocks has been created with a uniform pore structure design and made of PMMA (Polymethyl Methacrylate) material. The micromodel chip has a porosity of 27.8% as well as a permeability of 2.7 Darcy. By using the microfluidic test kit, this study has investigated how low salinity water (LSW) injection with MgCl2 divalent ions and the addition of anionic surfactant, linear alkylbenzene sulfonate mixed with nonionic surfactants, nonylphenol ethoxylate (NP-10) affects to oil recovery. The injection of LSW and surfactant solution was carried out with different injection stages, injection rates and surfactant solutions concentrations. Visual images during the injection process are recorded for analysis, which is the advantage of dynamic testing using this microfluidic test kit over conventional coreflooding. From this study, it is indicated that the selection of ions contained in LSW affects the success of LSW injection. Reducing the surfactant injection rate from 50 μL/min to 20 μL/min can increase the oil recovery from 1.27% to 4.29%. Oil recovery was also higher on surfactant injection which resulted in lower interfacial tension of the system based on the calculation of interfacial tension obtained from the Chun-Huh and Ghosh equations from the Winsor test. From all injection scenarios carried out in this study, the highest increase in oil recovery of 26.87% OOIP was obtained by injecting surfactant solutions directly in the secondary stage without prior LSW injection.

Electrooxidation of tetracycline antibiotic demeclocycline at unmodified boron-doped diamond electrode and its enhancement determination in surfactant-containing media

In this paper, for the first time, the study of voltammetric determination of tetracycline antibiotic demeclocycline was conducted. The oxidation of compound was investigated using a commercially available boron-doped diamond electrode pretreated electrochemically (anodic and subsequent cathodic). Addition of anionic surfactant, sodium dodecylsulfate (SDS) and cationic surfactant, cetyltrimethylammonium bromide (CTAB) to the demeclocycline-containing electrolyte solution at pH 2.0 and 9.0, respectively, was found to improve the sensitivity of the stripping voltammetric measurements. Employing square-wave stripping mode (after 30 s accumulation at open-circuit condition) in Britton-Robinson buffer, the limits of detection were found to be 1.17 μg mL−1 (2.3 × 10−6 M) for 4 × 10−4 SDS-containing buffer solution at pH 2, and 0.24 μg mL−1 (4.8 × 10−7 M) for 1 × 10−4 CTAB-containing buffer solution at pH 9.0. The feasibility of the developed approach for the quantification of demeclocycline was tested in urine samples.

Increased Electrical Conductivity of PANi: Anionic Surfactant Addition during Emulsion Polymerization

AbstractElectrically conductive polyaniline (PANi) doped with anionic surfactants is successfully synthesized and characterized. The conductive PANi is prepared by chemical oxidation polymerization reaction with the addition of two types of anionic surfactant solutions respectively 1% Sodium Octyl Sulfate (NaC8H17SO4, SOS) and Sodium Dodecyl Sulfate (NaC12H25SO4, SDS), followed by doping with a strong perchloric acid (HClO4). The addition of each surfactant solution has increased the electrical conductivity value of surfactant free PANi from 0.089 to 1.16 S cm−1 (SOS) and 1.12 S cm−1 (SDS) respectively. The viscosity value of surfactant free PANi is 1.97 mPa s which is much lower when compared with those of PANi containing surfactants in which the value is 3.58 and 4.20 mPa s for 1% of SDS added PANi each. The chain length of anionic surfactant has no major effect on the conductivity of PANi. The latter is only affected by the presence of SO3− group in hydrophobic part of surfactant.

Formation and surface-stabilizing contributions to bare nanoemulsions created with negligible surface charge

The stabilization of nanoemulsions, nanosized oil droplets dispersed in water, is commonly achieved through the addition of surfactants and polymers. However, nanoemulsions in the absence of emulsifiers have been observed to acquire a significant negative charge at their surface, which ultimately contributes to their stability. While the source of this negative charge is disputed to this day, its presence is taken as an inherent property of the aqueous-hydrophobic interface. This report provides a look at the molecular structure and bonding characteristics of bare aqueous-hydrophobic nanoemulsion interfaces. We report the creation of bare nanoemulsions with near zero surface charge, which are marginally stable for several days. The process of creating these low-charge nanoemulsions (LCNEs) required rigorous cleaning procedures and proper solvent storage conditions. Using vibrational sum-frequency scattering spectroscopy, we measure the structure and bonding of the interfacial aqueous and hydrophobic phases. The surfaces of these LCNE samples possess a measurable free OH vibration, not found in previous studies and indicative of a clean interface. Tuning the nanoemulsion charge through addition of anionic surfactants, modeling potential surface-active contaminants, we observe the free OH to disappear and a reorientation of the interfacial hydrophobic molecules at micromolar surfactant concentrations. Notably, the free OH vibration provides evidence for stronger dispersion interactions between water molecules and the hydrophobic phase at the LCNE surface compared with similar planar water-alkane interfaces. We propose the stronger bonding interactions, in addition to an ordered interfacial aqueous layer, contribute to the delayed droplet coalescence and subsequent phase separation.

Solution properties and electrospinning of poly(galacturonic acid) nanofibers

Poly(galacturonic acid) (PGuA) is an important natural biopolymer, however its potential has not been realized due to its anionic nature and rigid structure, which limits its processability into fine films and fibres. This study aims at modifying the solution properties of PGuA in alkaline medium (aq. sodium hydroxide) to enable their conversion into electrospun nanofibers. Addition of anionic surfactants was found to play an important role in individualizing the PGuA chains that lead to formation of small spindle shaped fibers of length ranging from 2 to 10 μm and diameter from 287 to 997 nm. However, continuous fibers were not formed even at concentrations higher than the critical concentration. Addition of small amount (10–30%) of high molecular weight PVA resulted in formation of continuous fibers. Correlation of fiber diameters of PGuA/PVA with the rheological properties suggested a strong dependence of diameter with the elasticity of the blend solutions. Such PGuA based fibers may be utilized in various biomedical applications.

Effect of modified fibre flour wood on the fresh condition properties of cement-based mortars

The effect of wood fibre flour in a studied Portland cement material shows interesting mechanical properties. The objective of this work is the elaboration new composite materials by emulsion. The dispersion of wood fibre and compressive strength was studied. The results showed an improvement in compressive strength of over 40% with 2% added wood fibres flour. The chemical modification of the wood fibres into their surfaces changes from the hydrophilic state to the hydrophobic state which makes it necessary to reduce the amount of water absorbed by the sample. The addition of anionic surfactant in the mixing water further improves the surface of the samples by minimising the pore size, hence the reduced water absorption. The dispersion of the wood fibres is controlled and assumed by an anionic surfactant as an emulsion phenomenon, the elaborate Maserati has thermal properties can be used as phase change materials (PCMs).

Effect of modified fibre flour wood on the fresh condition properties of cement-based mortars

The effect of wood fibre flour in a studied Portland cement material shows interesting mechanical properties. The objective of this work is the elaboration new composite materials by emulsion. The dispersion of wood fibre and compressive strength was studied. The results showed an improvement in compressive strength of over 40% with 2% added wood fibres flour. The chemical modification of the wood fibres into their surfaces changes from the hydrophilic state to the hydrophobic state which makes it necessary to reduce the amount of water absorbed by the sample. The addition of anionic surfactant in the mixing water further improves the surface of the samples by minimising the pore size, hence the reduced water absorption. The dispersion of the wood fibres is controlled and assumed by an anionic surfactant as an emulsion phenomenon, the elaborate Maserati has thermal properties can be used as phase change materials (PCMs).

Surfactant assisted CaO-based sorbent synthesis and their application to high-temperature CO2 capture

The concern of carbon dioxide (CO2) emissions, a main contribution of greenhouse gases, has been emerged as an important issue for environmental impact. Adsorption of CO2 by porous solid materials is proven to be one of efficient techniques for CO2 capture technologies. In the present work, attempted has been made to improve property of porous solid materials, CaO-based sorbent, applied for high-temperature CO2 capture. CaCO3 and CaO-based alumina was synthesized using precipitation technique with the addition of sulfonic single chain (SDS) and gemini (12-carbon hydrophobic chains and 3-carbon alkyl spacer, 12-3-12) surfactants for controlling/modifying physical properties. Our studies showed that the addition of anionic surfactants affected phase formation and polymorph of CaCO3, where stronger effect was observed with gemini surfactant. The synthetic CaCO3 was derived to form CaO and applied for capturing CO2 at 600 °C, 15% v/v CO2 (N2 balanced). The results showed that CaO synthesized with adding gemini surfactant offered higher CO2 sorption capacity than single chain surfactant. By incorporating calcium with alumina using co-precipitation technique, the addition of gemini surfactant showed a good impact on CO2 capture performance as an increase in CO2 sorption capacity was observed. However, sintering effect was still not yet be resolved with the addition of gemini surfactant as CO2 sorption capacity decreased upon multiple cycles of CO2 capture.

Correction to "Role of Ion-Dipole Interactions in Nucleation of Gamma Poly(vinylidene fluoride) in the Presence of Graphene Oxide during Melt Crystallization".

The crystallization behavior and crystalline structure of poly(vinylidene fluororide) (PVDF) in the presence of graphene oxide (GO) platelets were investigated using time-resolved Fourier transformation infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), as well as differential scanning calorimetry (DSC). It is shown that GO platelets induce the formation of γ phase when crystallizing from solution, but only α phase forms from melt crystallization. The crystallization kinetics of α phase is promoted due to heterogeneous nucleation ability of GO, which is probably originated from a weak π-dipole interaction between GO and PVDF. Intriguingly, after introduction of strong ion–dipole interactions between GO and PVDF by addition of an ionic surfactant (cetyltrimethylammonium bromide, CTAB), a significant amount of γ crystals are obtained during isothermal melt crystallization. Time-resolved FTIR results further provide a detailed evolution of the γ phase formation, and there are two distinct sta...