Organic Surfactants Research Articles

Rigid palm oil-based polyurethane foam reinforced with diamine-modified montmorillonite nanoclay

This paper presents work on organically-modified montmorillonite (MMT) nanoclay embedded in rigid palm oil-based polyurethane (PU) foam. MMT was modified with organic surfactant diamino propane (DAP). PU foam was fabricated in closed mold, and the amount of DAP-MMT was varied in each foam formulation. The obtained foam was tested for its microstructure and morphology. Appearance of peaks from infra-red spectra corresponding to N-H, C=O, and C-N confirms the formation of PU networks. Scanning electron microscopy (SEM) revealed fine, closed-cellular structure at low clay loading; increasing DAP-MMT content induced larger cell sizes with blowholes. X-ray diffraction (XRD) indicates fully-exfoliated clays at 1 wt. % and partial-exfoliation at 3 wt. % clay loading, suggesting clumping of clays as DAP-MMT content increased.

The synthesis of hydrophilic molecularly imprinted polymer microspheres and their application for selective removal of bisphenol A from water

The adsorptive materials which have the function of molecular recognition are becoming important as the fast emerging environmental requirements for the analysis and repair of target contaminants present at low concentrations in aqueous matrices. Here, we demonstrate a Pickering emulsion polymerization strategy to build bisphenol A (BPA) imprinted poly(methacrylic acid) microspheres without the traditional organic surfactant. In the synthesis, the only stabilizer is silica particles derived from Stöber process. The molecularly imprinted polymer microspheres were prepared by radical polymerization in the Pickering oil/water emulsion. Both the solid stabilizers and the molecular templates were conveniently removed from the microspheres. The obtained microspheres are of regularly spherical structures and hydrophilic surfaces. The formation of molecularly imprinted sites on the microspheres was validated by the excellent recognition capability toward BPA in the rebinding and competitive binding experiments.

Facile synthesis of magnetic hybrid metal–organic frameworks with high adsorption capacity for methylene blue

A magnetic hybrid material (Fe3O4‐COOH/HKUST‐1) was easily synthesized via a two‐step simple solvothermal method. Through adding sodium acrylate directly into the synthesis of Fe3O4 spheres, the surface has more carboxyl groups. It is notable that the reactions proceed without use of organic surfactants. The magnetic hybrid material was characterized using various techniques. The magnetic hybrid material has a high specific surface area (430.15 m2 g−1) and excellent magnetism (23.65 emu g−1). It is an efficient adsorbent for removing organic dyes like methylene blue (MB) from aqueous solution. It also can be easily recovered from liquid media using an external magnetic field. Adsorption experiment shows the magnetic hybrid material possesses a high adsorption capacity (118.6 mg g−1), and has high adsorption efficiency (94.3%) after five adsorption cycles with ethanol (0.2% HCl) as eluent. The sorption kinetics and isotherm analysis indicate these sorption processes are better fitted to the pseudo‐second‐order and Langmuir equations. Thermodynamic study shows the sorption processes are spontaneous and endothermic.

Effect of organo-montmorillonite nanoclay on VOCs inhibition of bitumen

The volatile organic compounds (VOCs) emission from bituminous materials can lead to serious environmental and health issues during their applications. In this study, organo-montmorillonite nanoclays were used to modify the base bitumen, and their effect on inhibiting the VOCs emission of bitumen was evaluated by pyrolysis gas chromatograph interfaced with mass spectrometer (Py-GC/MS). Laboratory ageing study was designed and tested to evaluate the effects of the nanoclay on the ageing resistance of base binder. The results indicated that the nanoclay can effectively inhibit the VOCs emission of bitumen. The reason can be that the light components of bitumen were intercalated into the interlayer space of nanoclay which limited their emission. The organic surfactant on the surface of the nanoclay played an important role to determine the compatibility between the nanoclay and the bitumen, and it finally determined this inhibition effect. The ageing resistance of modified bitumen improved not only due to the block effect of nanoclay to the oxygen invasion, but also due to its inhibition to VOCs emission at high production temperatures. Therefore, the organo-montmorillonite can function as an inhibitor of VOCs emission and at the same time improve the ageing resistance.

Organics- and Surfactant-Free Molten Salt Medium Controlled Synthesis of Pt-M (M = Cu and Pd) Bi- and Trimetallic Nanocubes and Nanosheets

We present a novel synthetic strategy for the shape-controlled synthesis of Pt-based alloy nanoparticles (NPs) in inorganic molten salt without using any organic surfactants or capping agents. Graphene oxide (GO) was chosen as the stabilizer in the inorganic molten salt synthetic strategy, due to the existence of various oxygen-containing functional groups on its surface, which adsorb, anchor, and stabilize the metal ions or NPs. After GO was added in molten salt, the PtPd nanosheets were formed on its surface in H2 atmosphere. In addition, when KI was chosen as the shape-inducing agent to selectively adsorb on and fully protect the (100) facets of alloys, PtPd nanocubes with core–shell structure, PtCu nanohemicubes, and PtPdCu nanocubes were prepared successfully on the surface of GO in molten salt. Introduction of GO as the stabilizer in molten salt proves a new approach in synthesis of Pt-based nanocrystals with controlled morphologies.

The influence of a novel two dimensional graphene-like nanomaterial on thermal stability and flammability of polystyrene

Significant improvements in thermal stability and fire resistance properties of polymer materials with nanofillers at low loadings hold tremendous promise for fire safety materials. In this study, a novel two dimensional (2D) graphene-like nanomaterial (VOP) was synthesized by a simple refluxing method and then modified with typical organic surfactants. Subsequently, the novel graphene-like nanomaterials were incorporated into polystyrene (PS) matrix for reducing fire hazards. The SEM and TEM images indicated that the VOP nanosheets were well dispersed throughout the matrix without obvious aggregates, leading to remarkable improvements of thermal stability and fire safety properties. With the loading of 1wt% modified VOP, the T5%, T10%, T50% and Tmax values were increased by 15, 22, 29 and 33°C, respectively. In addition, the presence of VOP nanosheets decreased the decomposition rate of PS and increased the amount of char residues. Furthermore, the peak heat release rate and total heat release of PS composites was decreased by 48.3% and 43.6%, respectively, compared to that of neat PS. The well dispersion, physical barrier effect and catalytic carbonization effect of VOP nanosheets were the main causations for the reduction of fire hazards.

Self-Functionalization Behind a Solution-Processed NiOx Film Used As Hole Transporting Layer for Efficient Perovskite Solar Cells.

Fabrication of solution-processed perovskite solar cells (PSCs) requires the deposition of high quality films from precursor inks. Frequently, buffer layers of PSCs are formed from dispersions of metal oxide nanoparticles (NPs). Therefore, the development of trustable methods for the preparation of stable colloidal NPs dispersions is crucial. In this work, a novel approach to form very compact semiconducting buffer layers with suitable optoelectronic properties is presented through a self-functionalization process of the nanocrystalline particles by their own amorphous phase and without adding any other inorganic or organic functionalization component or surfactant. Such interconnecting amorphous phase composed by residual nitrate, hydroxide, and sodium ions, proved to be fundamental to reach stable colloidal dispersions and contribute to assemble the separate crystalline nickel oxide NPs in the final film, resulting in a very homogeneous and compact layer. A proposed mechanism behind the great stabilization of the nanoparticles is exposed. At the end, the self-functionalized nickel oxide layer exhibited high optoelectronic properties enabling perovskite p-i-n solar cells as efficient as 16.6% demonstrating the pertinence of the presented strategy to obtain high quality buffer layers processed in solution at room temperature.

Bio-activity of superparamagnetic maghemite nanorods capped with dl-alanine

The present research work explores an economic way of synthesizing maghemite (ᵞ-Fe2O3) nanorods through chemical coprecipitation method in which, ferric chloride was used, as one of the precursors and Sodium hydroxide as fuel with the assistance of dl-alanine, an organic surfactant. The obtained ᵞ-Fe2O3 nanorods have been characterized by X-ray diffraction, Fourier Transform Infrared Spectroscopy, Scanning electron microscopy, Transmission Electron Microscopy and Vibrating sample magnetometer techniques. X-ray diffraction results show that the synthesized ᵞ-Fe2O3 nanorods are in cubic spinel phase with improved crystalanity. The morphology and the size of the nanoparticles were confirmed by SEM as well as TEM. High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) of the sample have been performed. The FTIR spectra indicate the incorporation of dl-alanine on ᵞ-Fe2O3 nanorods. The saturation magnetization value of maghemite, measured by vibrating sample magnetometer corresponds to the typical superparamagnetic behavior. On examining the magnetic saturation (Ms) was found out to be 142emu/g, 57.7% higher than the bulk value, which is highly recommended for biomedical application. The antibacterial activity of ᵞ-Fe2O3 sample against gram-positive Streptococcus mutans, Staphylococus aures and gram-negative E.coli, Klebsiella pneumonia was investigated using Well diffusion method. The antifungal activity was tested by the same method against Aspergillus niger and Candida albicans. The MTT assay was employed to test the anticancerous activity of ᵞ-Fe2O3 against HT29 (coloncarcinoma) cell line. The sample shows positive control over antimicrobial species. The Lethal Dosage of the sample calculated to be 45.3149μg/ml, establishes its strong activity over HT29 cell line.

Development of efavirenz loaded solid lipid nanoparticles: Risk assessment, quality-by-design (QbD) based optimisation and physicochemical characterisation

The purpose of this study was development and characterisation of efavirenz (EFZ) loaded solid lipid nanoparticles (SLN) using QbD approach. Quality target product profile of EFZ loaded SLN were defined and critical quality attributes were identified. SLN were prepared by nanoprecipitation method. Initially, feasibility of SLN formation was studied by using different lipids including glyceryl monostearate, stearic acid and surfactants such as poloxamer 188, tween 80, docusate sodium and sodium lauryl sulphate. A 32 factorial design was employed to optimize EFZ loaded SLN wherein acetone/methanol ratio in organic phase and surfactant concentration were selected as independent variables whereas particle size (PS) and %entrapment efficiency (EE) were selected as responses. PS of SLN was found to be varied from 167.77 to 1166 nm and %EE was in the range of 23.07–88%. DSC thermograms indicated the amorphous state of EFZ in the SLN. The FTIR studies confirmed no interaction among materials used in fabrication of SLN while NMR studies confirmed their incorporation in the SLN. Spherical shape of SLN was confirmed by TEM. This study suggests the importance of implementation of QbD approach for identifying critical process and formulation parameter in order to develop nano based pharmaceutical product.

Influences of surfactants on the structures and properties of organo-palygorskite in oil-based drilling fluids

Organo-palygorskite (OPal) is a potential rheological additive in oil-based drilling fluids. This work aims to reveal the influences of surfactants on the structures and properties of OPal in oil-based drilling fluids. Firstly, palygorskite was organically modified by three quaternary ammonium salts with different lipophilicity. The crystal structures and morphologies of OPal samples were characterized by X-ray diffraction and scanning electron microscope. Organic surfactants coated on the surface of palygorskite. Gel volume tests were used to indicate the compatibility between OPal and oil. Viscosity tests were applied to characterize the gel strength and ability of gel formation. The contents of different components of OPal/oil fluids and OPal/oil gels were obtained by mass analysis. Optical microscopy testified the dispersity of OPal/oil fluids. X-Ray diffraction was also applied to characterize the gel structure of OPal/oil. Better lipophilicity of surfactants lead to better dispersity of OPal in oil. However, excellent dispersity of can't automatically contribute to high viscosity and gel strength. A little polarity is beneficial for promoting the rheological properties of oil-based drilling fluids. Temperature rising facilitates the disaggregation of OPal in oil, but high temperature may result in thermal decomposition of surfactants on the surface of palygorskite.

Novel ‘Pickering’ modified TiO2 photocatalysts with high De-NOx efficiency

Modified TiO2 nanoparticles were prepared by a Pickering emulsions route with the use of hydrophobic (oleylamine) and hydrophilic (polyethylene glycol) organic surfactants and their combination, as well. The attachment of modifiers to the TiO2 nanoparticles was proved via FT-IR and thermal analysis. Thicker modifier layer was formed on the TiO2 surface but lower average particle size was attained when amphiphilic modification was applied that was revealed by TEM analysis and dynamic light scattering, correspondingly. The amphiphilic modification permitted control of the hydrophobic properties of the TiO2 nanoparticles so that their incorporation in cement matrix led to preparation photocatalytic cement materials with superior De-NOx efficiency.

Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr3 NCs at 160°C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr3 NCs obtained at relatively low temperatures (120 and 140°C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120°C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr3 NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens the fabrication of different nanostructures via self-assembly methods for further optoelectronic applications.

Hydrophobic/lipophobic barrier capable of confining aggressive liquids for paper-based assay

As traditional barriers are vulnerable to organic solvents or surfactants, a new fluoroalkyl-silica barrier with superior confining ability was developed for paper-based analytical devices (PADs). The as-prepared fluoroalkyl-silica barrier is able to contain surfactant solutions and pure organic solvents even alcohols. Based on the fluoroalkyl-silica barrier, PADs associated with condensing-enrichment effect were explored for Ni(II) assays involving ethanol and bacteria assays including sodium dodecyl sulfate (SDS) and chloroform. The exhibited work has the potential to significantly expand the applications of paper-based microfluidics or assays to include process/analysis involving organic solvents or surfactant solutions.

Change of organobentonite interlayer microstructure induced by sorption of aromatic and petroleum hydrocarbons—A combined study of laboratory characterization and molecular dynamics simulations

In this study, the impact of secondary sorption of hydrocarbons on the interlayer morphology of organic surfactant modified montmorillonites was studied. Montmorillonites intercalated with two quaternary ammonium surfactants, hexadecyltrimethylammonium (HDTMA+) and bis (hydrogenated tallow alkyl) dimethyl ammonium were chosen as the soil sorbents to uptake naphthalene and gasoline. Laboratory characterization using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) were carried out, and molecular dynamics (MD) simulations were performed. The successive interlayer expansion of montmorillonites due to the intercalation of surfactants and hydrocarbons were measured by XRD and TEM. FT-IR was employed to verify the intercalation of organic surfactants and sorbates. Additionally, the MD modeling was conducted to demonstrate the interlayer microstructure of organoclays and to quantify interactions between minerals, surfactants, and sorbates. The experimental and simulation results validated the transitions of montmorillonite interlayer expansion due to the successive intercalation of organic surfactants and sorbates, yielding insights into the understanding of the microstructures of sorbate/surfactant/clay hybrids and their physical-chemical and mechanical behaviors.

Isolation, one-step affinity purification, and characterization of a polyextremotolerant laccase from the halophilic bacterium Aquisalibacillus elongatus and its application in the delignification of sugar beet pulp

The aim of the present work was to study the ability of a halophilic bacterial laccase to efficient delignification in extreme conditions. Here, a highly stable extracellular laccase showing ligninolytic activity from halophilic Aquisalibacillus elongatus is described. The laccase production was strongly influenced by NaCl and CuSO4 and under optimal conditions reached 4.8UmL−1. The monomeric enzyme of 75kDa was purified by a synthetic affinity column with 68.2% yield and 99.8-fold purification. The enzyme showed some valuable features viz. stability against a wide range of organic solvents, salts, metals, inhibitors, and surfactants and specificity to a wide spectrum of substrates diverse in structure and redox potential. It retained more than 50% of the original activity at 25–75°C and pH 5.0–10.0. Furthermore, the enzyme was found to be effective in the delignification of sugar beet pulp in an ionic liquid that makes it useful for industrial applications.

Host composition dependent tuneable morphology and luminescent property of the CaXSrYBa1−X−YWO4:RE3+ (RE=Pr, Ho, and Er) phosphors

Novel Pr3+, Ho3+, and Er3+ single-doped CaXSrYBa1−X−YWO4 phosphors were successfully prepared via a facile hydrothermal method. The hydrothermal process was conducted in aqueous condition without the use of any organic solvent, surfactant, or catalyst. The effects of doping-host composition and RE3+ doping concentration on the emission intensity were investigated to optimize the luminescent properties of CaXSrYBa1−X−YWO4:RE3+ phosphors. Experimental results demonstrate that the morphologies of the products vary gradually and regularly with the change of the host composition, in which the anisotropic growth played a key role. Moreover, the down-conversion emissions of Pr3+, Ho3+, and Er3+ in CaXSrYBa1−X−YWO4 host were successfully realized. After optimizing the luminescent properties, Ca0.4Sr0.6WO4:0.01Pr3+, Ca0.8Sr0.2WO4:0.01Ho3+, and Ca0.6Sr0.4WO4:0.005Er3+ exhibited optimal luminescent property, with orange, yellowish-green, and green emissions, respectively.

Organic Solvent and Surfactant Resistant Paper-Fluidic Devices Fabricated by One-Step Embossing of Nonwoven Polypropylene Sheet

In this communication, we report a physical method for the fabrication of organic solvent and surfactant-resistant barriers on paper-based fluidic devices. When nonwoven polypropylene sheet is embossed with a steel mold, the embossed region acts as a physical barrier that can prevent the flow of liquids. Embossed polypropylene barriers not only block water, but also block organic solvents and surfactants, which are known to be difficult to handle on previous paper-based devices. Various amounts of embossing pressures were tested to determine the minimum embossing pressure required for leakproof barrier formation. The compatibility of the barrier was also investigated with several surfactants and organic solvents. As a demonstration, a lysis buffer, which was known to leak through wax-printed barriers, was used to detect Escherichia coli (E. coli) O157:H7. To the best of our knowledge, this paper is the first to report a one-step fabrication method of paper-fluidic devices capable of handling surfactants and organic solvents, including alcohols.

Nano-scale synthesis of the complex silicate minerals forsterite and enstatite

Olivine is a relatively common family of silicate minerals in many terrestrial and extraterrestrial environments, and is also useful as a refractory ceramic. A capability to synthesize fine particles of olivine will enable additional studies on surface reactivity under geologically relevant conditions. This paper presents a method for the synthesis of nanocrystalline samples of the magnesium end-member, forsterite (Mg2SiO4) in relatively large batches (15–20g) using a sol-gel/surfactant approach. Magnesium methoxide and tetraethylorthosilicate (TEOS) are refluxed in a toluene/methanol mixture using dodecylamine as a surfactant and tert-butyl amine and water as hydrolysis agents. This material is then cleaned and dried, and fired at 800°C. Post-firing reaction in hydrogen peroxide was used to remove residual organic surfactant. X-ray diffraction showed that a pure material resulted, with a BET surface area of up to 76.6m2/g. The results of a preliminary attempt to use this approach to synthesize nano-scale orthopyroxene (MgSiO3) are also reported.

Synthesis and electrochemical characterization of polypyrrole films doped with organic surfactants

Synthesis and electrochemical characterization of polypyrrole films doped with organic surfactants

Activation of persulfate by MMIOC for highly efficient degradation of rhodamine B

Mesoporous magnetic iron oxide composites (MMIOCs) were successfully prepared by one-step evaporation induced self-assembly using an organic ferrocene surfactant, and innovatively studied as a potential alternative to Co3O4 for persulfate activation to generate radicals.