Organic Surfactants Research Articles

Spontaneous Imbibition Oil Recovery by Natural Surfactant/Nanofluid: An Experimental and Theoretical Study.

Organic surfactants have been utilized with different nanoparticles in enhanced oil recovery (EOR) operations due to the synergic mechanisms of nanofluid stabilization, wettability alteration, and oil-water interfacial tension reduction. However, investment and environmental issues are the main concerns to make the operation more practical. The present study introduces a natural and cost-effective surfactant named Azarboo for modifying the surface traits of silica nanoparticles for more efficient EOR. Surface-modified nanoparticles were synthesized by conjugating negatively charged Azarboo surfactant on positively charged amino-treated silica nanoparticles. The effect of the hybrid application of the natural surfactant and amine-modified silica nanoparticles was investigated by analysis of wettability alteration. Amine-surfactant-functionalized silica nanoparticles were found to be more effective than typical nanoparticles. Amott cell experiments showed maximum imbibition oil recovery after nine days of treatment with amine-surfactant-modified nanoparticles and fifteen days of treatment with amine-modified nanoparticles. This finding confirmed the superior potential of amine-surfactant-modified silica nanoparticles compared to amine-modified silica nanoparticles. Modeling showed that amine surfactant-treated SiO2 could change wettability from strongly oil-wet to almost strongly water-wet. In the case of amine-treated silica nanoparticles, a strongly water-wet condition was not achieved. Oil displacement experiments confirmed the better performance of amine-surfactant-treated SiO2 nanoparticles compared to amine-treated SiO2 by improving oil recovery by 15%. Overall, a synergistic effect between Azarboo surfactant and amine-modified silica nanoparticles led to wettability alteration and higher oil recovery.

(Digital Presentation) Investigation of Microstructure Dependent Inhibitor Adsorption Mechanism on Carbon Steel By in Situ Atomic Force Microscopy

In the petroleum industry, organic surfactant type inhibitors have been widely applied in the oil and gas industry considering their high efficiency. Carbon steels with various carbide contents have also been used extensively as pipeline materials during the transport and storage of crude oil due to their excellent mechanical properties and low cost. The previous investigation of inhibition mechanism on carbon steel is limited by lack of surface characterization techniques at a molecular level. Atomic force microscopy (AFM) can not only provide localized visual observation, but can also achieve the detection of mechanical properties of an inhibitor film. In this study, in situ AFM contact mode friction imaging and in situ AFM tapping mode phase imaging techniques have been applied to investigate the influence of the ferritic-pearlitic microstructure of carbon steel on inhibitor adsorption mechanisms during CO2 corrosion under different inhibitor concentrations. At concentration above surface saturation, AFM contact mode friction images show a large friction contrast between inhibitor covered cementite structures and ferrite structures, while in the absence of inhibitor, this friction contrast almost disappears, indicating the inhibitor adsorption induced this difference. AFM tapping mode phase images indicate uniform adsorption of inhibitor on both cementite and ferrite structures.The differences observed in these AFM analyses indicate that the adhesion force of inhibitor molecules on cementite could be smaller than on ferrite, or the molecular orientations of inhibitor molecules adsorbed on cementite and ferrite structures could be different. The special adsorption behavior of inhibitor molecules on cementite means the carbide component of the microstructure could directly influence inhibitor adsorption and may decrease inhibitor efficiency. Simultaneous linear polarization resistance tests in electrochemical AFM (EC-AFM) cell indicates a maximum inhibition efficiency at concentration above saturation.Keywords : Contact mode AFM, friction contrast, tapping mode AFM, phase contrast, cementite, ferrite, organic inhibitor, adhesion force.Statement of importance:Studies related to inhibitor adsorption mechanisms on ferritc-pearlitic carbon steels can be connected with the practical issues that iron carbide can impair the corrosion inhibitor performance on carbon steels. This AFM work connects the corrosion inhibition effect with the carbon steel components at a molecular level for the first time. Physical explanations regarding the interactions between inhibitor molecules and carbon steel microstructures can also be provided with the assistance of molecular simulations.Figure caption: Contact and tapping mode AFM images of inhibitor film formed on UNS G1018 steel at 2 CMC (100ppm) tetradecyldimethylbenzylammonium inhibitor + 1 wt% NaCl. The contact mode friction image indicates a large friction contrast between inhibitor covered cementite and ferrite structure, while the tapping mode phase image indicates a negligible softness contrast between cementite and ferrite structure. Figure 1

Surfactant−free synthesis of flower−like Au NPs/Au island hybrid substrate for quantitative SERS detection of pesticide residues on fruit

Surface enhanced Raman scattering (SERS) has been extensively applied in the field of biochemical detection ascribed to its high sensitivity and nondestructive pattern. Nevertheless, the further improvement of such attractive protocol is severely hindered by the absence of enough surface roughness as well as the presence of organic surfactant. Herein, we demonstrated a highly sensitive and robust SERS hybrid substrate composed of plasmonic flower−like Au nanoparticles (FANPs)/Au island with clean surface. The development of this novel FANPs architecture could be attributed to the drastic reduction of Au 3+ ions, which triggered the overgrowth of Au atoms in the absence of surfactant. Meanwhile, the pre-existent Au monolayer on the silicon matrix were found to synchronously grew to Au islands, resulting in the formation of hybrid substrates. The FANPs/Au island hybrid substrate performed satisfactorily while monitoring 4 −mercaptobenzoic acid and gave out an excellent enhancement factor of 6.74 × 10 6 . Particularly, the high sensitivity makes the hybrid substrate a fascinating platform for practical monitoring. In this regard, the in−situ detection of thiabendazole on apple was conducted and a limit of detection low to 8.3 ng/mL was achieved. This high−performance SERS substrate provides more opportunities for appreciable in−situ assay in some practical fields. • A plasmonic flower−like Au NPs (FANPs)/Au island with clean surface was constructed without any surfactant. • An excellent enhancement factor as high as 6.74 × 10 6 was achieved by the FANPs/Au island hybrid substrate. • The in−situ detection of thiabendazole on apple was conducted and the limit of detection was achieved as low as 8.3 ng/mL.

Exploring the Nanostructures Accessible to an Organic Surfactant Atmospheric Aerosol Proxy.

The composition of atmospheric aerosols varies with time, season, location, and environment. This affects key aerosol properties such as hygroscopicity and reactivity, influencing the aerosol’s impact on the climate and air quality. The organic fraction of atmospheric aerosol emissions often contains surfactant material, such as fatty acids. These molecules are known to form three-dimensional nanostructures in contact with water. Different nanostructures have marked differences in viscosity and diffusivity that are properties whose understanding is essential when considering an aerosol’s atmospheric impact. We have explored a range of nanostructures accessible to the organic surfactant oleic acid (commonly found in cooking emissions), simulating variation that is likely to happen in the atmosphere. This was achieved by changing the amount of water, aqueous phase salinity and by addition of other commonly coemitted compounds: sugars and stearic acid (the saturated analogue of oleic acid). The nanostructure was observed by both synchrotron and laboratory small/wide angle X-ray scattering (SAXS/WAXS) and found to be sensitive to the proxy composition. Additionally, the spacing between repeat units in these nanostructures was water content dependent (i.e., an increase from 41 to 54 Å in inverse hexagonal phase d-spacing when increasing the water content from 30 to 50 wt %), suggesting incorporation of water within the nanostructure. A significant decrease in mixture viscosity was also observed with increasing water content from ∼104 to ∼102 Pa s when increasing the water content from 30 to 60 wt %. Time-resolved SAXS experiments on levitated droplets of this proxy confirm the phase changes observed in bulk phase mixtures and demonstrate that coexistent nanostructures can form in droplets. Aerosol compositional and subsequent nanostructural changes could affect aerosol processes, leading to an impact on the climate and urban air pollution.

Bifunctional Activity of PVP K‐30 Assisted Cobalt Molybdate for Electrocatalytic Water Splitting**

AbstractHydrogen fuel has emerged as pollution free renewable energy source and is a better substitute for carbon‐based fossil fuels. Now it is a big challenge for research community to produce green efficient hydrogen fuel in order to fulfil the demand of our daily need. Water splitting process is a highly recognized way of hydrogen production and storage. The fabrication of efficient electrocatalyst is highly desirable for water splitting application. Structure directing groups play an unique role in controlling the size, and morphology of nanoparticles which ultimately affects the efficiency. Here we report a cost‐effective CoMoO4 electrocatalyst, which was synthesized by an easy chemical co‐precipitation method in presence of organic polymeric surfactant K‐30. It has a rod shape morphology. CoMoO4 electrocatalyst exhibits high OER activity with low overpotential of 240 mV at 10 mA cm−2 and low Tafel slope value, 75 mV/dec and stability of 10 h. The electrocatalyst also exhibits better HER activity with over potential of 224 mV at 10 mA cm−2 and Tafel slope value of 104 mV/dec and stability of 8 h.

Self-Assembly of Matchstick-Shaped Inorganic Nano-Surfactants with Controlled Surface Amphiphilicity.

Molecular and nanoscale amphiphiles have been extensively studied as building blocks for organizing macroscopic matter through specific and local interactions. Among various amphiphiles, inorganic Janus nanoparticles have attracted a lot of attention owing to their ability to impart multifunctionalities, although the programmability to achieve complicated self-assembly remains a challenge. Here, we synthesized matchstick-shaped Janus nano-surfactants that mimic organic surfactant molecules and studied their programmable self-assembly. High amphiphilicity was achieved through the hard–soft acid–base-based ligand-exchange reaction with strong selectivity on the surface of nano-matchsticks consisting of Ag2S heads and CdS stems. The obtained nano-surfactants spontaneously assembled into diverse ordered structures such as lamellar, curved, wrinkled, cylindrical, and micellar structures depending on the vertical asymmetry and the interfacial tension controlled by their geometry and surface ligands. The correlation between the phase selectivity of suprastructures and the characteristics of nano-surfactants is discussed. This study realized the molecular amphiphile-like programmability of inorganic Janus nanostructures in self-assembly with the precise control on the surface chemistry.

WASTEWATER TREATMENT BAKERY USING ACTIVE CARBON OF WATER HYACINT AND BOILER WASTE

Bakery industry wastewater usually comes from the washing process of production equipment and generally contains organic compounds, oils, fats, and surfactants. Efforts are needed to overcome these problems so that contamination due to bakery waste can be handled. This study aims to determine the ability of water hyacinth activated carbon and boiler waste activated carbon in improving the quality of wastewater through the adsorption process so that it is expected to be in accordance with the wastewater quality standards set by the Central Java Regional Government. The variables used are activated carbon mass, time, and temperature of the adsorption process. The results showed a change in color and odor, from greenish to clear, and a reduction in fishy odor in the wastewater. A decrease in COD value and an increase in pH also occurred, with the best results being obtained using activated carbon from boiler waste at a mass weight of 20 g, a time of 90 minutes, and a temperature of 45 °C. The best results are obtained by combining activated carbon from water hyacinth and boiler waste at a mass ratio of 1:19 g, a time of 120 minutes, and a temperature of 35 °C.Keywords: Bakery Industry Wastewater, Adsorption, Activated Carbon, Color, COD, pH

Insight into the role of ultrasound, morphology and crystal structure for enhancing the recycling and catalytic performance of Au-MoS2 nanocomposite catalyst in reduction of nitro-compounds

The chemical intercalation exfoliation of commercial MoS2 and the hydrothermal synthesis within their multi-step procedures and high cost have been reported as the prevalent approaches to produce 2D-MoS2 nanosheet, so far. In this study, the high-intensity ultrasound, as a novel straightforward sonochemical approach was utilized for the synthesis of 1 T-MoS2 nanosheets which were then decorated with small sizes of Au nanoparticles (~10 nm) giving rise to the uniform dispersion. When reference materials of the same composition were synthesized in a classic hydrothermal medium, flower-like morphology with a 2-H structure was obtained with a broad and big size distribution of Au nanoparticles (≥50 nm). The prepared materials were thoroughly characterized using XRD, SEM/TEM/EDS mapping, N2-BET adsorption-desorption, and XPS. The nanocomposite morphology and structure were found to have a great effect on the catalytic reduction of hazardous chemicals (nitrobenzene and 3-nitroacetophenone), revealing the benefits of the sonochemically produced catalysts. Notably, the obtained catalytic results revealed that among the produced catalysts, the sonochemically synthesized Au/MoS2 NSs exhibited the highest aniline selectivity of 99 % at conversion ratio of 95 %, and 3-aminoacetophenone selectivity of 99 % at conversion ratio of 98 %. Moreover, the as-prepared sonochemically catalyst displayed high stability for at least 8 cycles of reaction while maintaining high reducing efficiency. The superior activity is discussed in terms of higher surface area and pore diameter, the sulfur deficient surface and the synergistic effect between Au0 and Au+ species. The developed new sonochemical route opens up new opportunities for the facile production of the versatile MoS2 NSs-based core/satellite nanostructures with high catalytic activity. The fulfillment of the green chemistry principle of the ultrasonic technique (eliminating any toxic reducing agents, stabilizers, or organic surfactants) is emphasized.

Decomposition of organic additives in the oxidative chalcopyrite leaching with hydrogen peroxide

Recent investigations have shown that the addition of short-chain organic additives (methanol, ethanol, ethylene glycol, acetone, isopropanol, formic and acetic acids), surfactants (Tween 20 and 80) and organic ligands (EDTA, oxalic and citric acids) in acidic leaching solutions with hydrogen peroxide, significantly promote chalcopyrite dissolution. However, despite these positive findings, until now, the relation between the percentage of dissolution of chalcopyrite, hydrogen peroxide decomposition by Fenton and Fenton type reactions, and the level of decomposition (partial or complete oxidation to CO2 and H2O) of organic additives due to electrophilic attack by the OH* radical, has not been reported. For that reason, a systematic study was undertaken to explore those aspects. The results demonstrated that all the organic additives slowed, but did not prevent the decomposition of hydrogen peroxide, which favored the production of OH*, a radical with elevated oxidizing power capable of promoting the oxidation of organic additives. The degree of organic compound (RH) mineralization (complete oxidation to CO2 and H2O) was structure-dependent, as well as the R* reactivity with H2O2, dissolved copper and iron, although it was not proportional to H2O2 decomposition. Finally, it was found that cyclohexanol is the most promising organic additive because it greatly slows the decomposition of hydrogen peroxide, but it is not mineralized by the OH* radical, and substantially improves chalcopyrite dissolution.

Nanocellulose-based nanogels for sustained drug delivery: Preparation, characterization and in vitro evaluation

Polysaccharide-based nanocarriers such as nanogels have recently received considerable attention in modified drug delivery due to their biocompatibility and biodegradability. However, the application of the nanocarriers was limited due to longer preparation time, usage of large amounts of organic solvents and surfactants as well as lower drug loading capacity (LC) and encapsulation efficiency (EE). In this study, nanogels were prepared from carboxymethyl nanocellulose (CMNC)-lysozyme blends in aqueous phase via electrostatic interaction, a simple and surfactant-free approach, for sustaining drug release with better LC and EE. The nanogels were investigated in terms of size, polydispersity index (PDI), turbidity, colloidal and thermal stabilities, chemical functionality, morphology, crystallinity, LC, EE, and in vitro release patterns of different Biopharmaceutics Classification System (BCS) class drugs (acyclovir, carbamazepine, and furosemide). At pH 7.4 and above, nanogels remained in collapse state through strong electrostatic interaction between the polyelectrolytes, followed by the intramolecular H-bonding for further reduction of the size of the nanogels. Spherical nanogels in the size of <110 nm with PDI <0.2, and large zeta potential ranging from −38 to −55 mV were prepared at optimal condition (at 1:1 wt ratio of CMNC:lysozyme, heating temperature and time: 75 °C and 30 min, pH 7.4). The size and PDI of the nanogels were significantly affected by the weight ratios of CMNC-lysozyme, pH, sonication and heating times (p < 0.01), but not much affected by drug loading and storage conditions. The nanogels demonstrated high EE (62–94%) and LC (18–27%), and sustained release (48–80%) profiles of the model drugs over 12 h. These results suggest that the synthesized nanocellulose-based nanogels following easy and green preparation approach exhibited attractive properties with respect to the size, PDI, zeta potential, shape, thermal stability, EE, LC, and versatility for encapsulating and sustaining different BCS class drugs.

Electrochemical Oxidation in Aqueous Solutions of Organic Complexing Agents and Surfactants

Electrochemical Oxidation in Aqueous Solutions of Organic Complexing Agents and Surfactants

The Effect of Capping Agents on Gold Nanostar Stability, Functionalization, and Colorimetric Biosensing Capability.

Capping agents (organic ligands, polymers, and surfactants) are pivotal for stabilizing nanoparticles; however, they may influence the surface chemistry, as well as the physico-chemical and biological characteristics, of gold nanostar (AuNS)-based biosensors. In this study, we proved that various capping agents affected capped and bioconjugated AuNS stability, functionality, biocatalysis, and colorimetric readouts. Capped and bioconjugated AuNSs were applied as localized surface plasmon resonance (LSPR)-based H2O2 sensors using glucose oxidase (GOx) as a model enzyme. Furthermore, our analyses revealed that the choice of capping agent influenced the properties of the AuNSs, their stability, and their downstream applications. Our analyses provide new insights into factors governing the choice of capping agents for gold nanostars and their influences on downstream applications with conjugated enzymes in confined environments.

Hyaluronic Acid: Its Versatile Use in Ocular Drug Delivery with a Specific Focus on Hyaluronic Acid-Based Polyelectrolyte Complexes.

Extensive research is currently being conducted into novel ocular drug delivery systems (ODDS) that are capable of surpassing the limitations associated with conventional intraocular anterior and posterior segment treatments. Nanoformulations, including those synthesised from the natural, hydrophilic glycosaminoglycan, hyaluronic acid (HA), have gained significant traction due to their enhanced intraocular permeation, longer retention times, high physiological stability, inherent biocompatibility, and biodegradability. However, conventional nanoformulation preparation methods often require large volumes of organic solvent, chemical cross-linkers, and surfactants, which can pose significant toxicity risks. We present a comprehensive, critical review of the use of HA in the field of ophthalmology and ocular drug delivery, with a discussion of the physicochemical and biological properties of HA that render it a suitable excipient for drug delivery to both the anterior and posterior segments of the eye. The pivotal focus of this review is a discussion of the formation of HA-based nanoparticles via polyelectrolyte complexation, a mild method of preparation driven primarily by electrostatic interaction between opposing polyelectrolytes. To the best of our knowledge, despite the growing number of publications centred around the development of HA-based polyelectrolyte complexes (HA-PECs) for ocular drug delivery, no review articles have been published in this area. This review aims to bridge the identified gap in the literature by (1) reviewing recent advances in the area of HA-PECs for anterior and posterior ODD, (2) describing the mechanism and thermodynamics of polyelectrolyte complexation, and (3) critically evaluating the intrinsic and extrinsic formulation parameters that must be considered when designing HA-PECs for ocular application.

Hydrophilicity and hydrophobicity consideration of organic surfactant compounds: Effect of alkyl chain length on corrosion protection

Hydrophilicity and hydrophobicity consideration of organic surfactant compounds: Effect of alkyl chain length on corrosion protection

High‐Conductivity Crack‐Free 3D Electrical Interconnects Directly Printed on Soft PDMS Substrates

AbstractNanoparticle 3D printing and sintering is a promising method to achieve freeform interconnects on compliant substrates for applications such as soft robotics and wearable healthcare devices. However, previous strategies to sinter metallic nanoparticles while preserving the soft polymer substrate are rife with problems such as cracking and low conductivity of the metallic features. In this paper, the mechanisms of cracking in nanoparticle‐based 3D printed and sintered stretchable interconnects are identified and architecture and processing strategies are demonstrated to achieve crack‐free interconnects fully embedded in thin (&lt;100 μm in thickness) stretchable polydimethylsiloxane (PDMS) with external connectivity. Capillary forces between nanoparticles developed through rapid solvent evaporation in the colloidal ink is hypothesized to initiate cracking during drying. Additionally, the presence of oxygen promotes the removal of organic surfactants and binders in the nanoparticle ink which increases nanoparticle agglomeration, grain growth, and subsequently conductivity. An experimental step‐wise variation of the thermal/atmospheric process conditions supports this hypothesis and shows that the presence of air during a low temperature drying step reduces the capillary stress to produce crack‐free interconnects with high conductivities (up to 56% of bulk metal) while having an excellent compatibility with the underlying polymer materials. Finally, stretchable interconnects fully‐encapsulated in PDMS polymer, with 3D pillar architectures for external connectivity are demonstrated, thus also solving an important “last‐mile” problem in the packaging of stretchable electronics.

Aerosol Impacts on Water Relations of Camphor (Cinnamomum camphora).

Major parts of anthropogenic and natural aerosols are hygroscopic and deliquesce at high humidity, particularly when depositing to leaf surfaces close to transpiring stomata. Deliquescence and subsequent salt creep may establish thin, extraordinary pathways into the stomata, which foster stomatal uptake of nutrients and water but may also cause stomatal liquid water loss by wicking. Such additional water loss is not accompanied by a wider stomatal aperture with a larger CO2 influx and hypothetically reduces water use efficiency (WUE). Here, the possible direct impacts of aerosols on physical and physiological parameters of camphor (Cinnamomum camphora) were studied (i) in a greenhouse experiment using aerosol exclusion and (ii) in a field study in Taiwan, comparing trees at two sites with different aerosol regimes. Scanning electron microscopy (SEM) images showed that leaves grown under aerosol exclusion in filtered air (FA) were lacking the amorphous, flat areas that were abundant on leaves grown in ambient air (AA), suggesting salt crusts formed from deliquescent aerosols. Increasing vapor pressure deficit (VPD) resulted in half the Ball-Berry slope and double WUE for AA compared to FA leaves. This apparent contradiction to the wicking hypothesis may be due to the independent, overcompensating effect of stomatal closure in response to VPD, which affects AA more than FA stomata. Compared to leaves in a more polluted region in the Taiwanese Southwest, NaCl aerosols dominated the leaf surface conditions on mature camphor trees in Eastern Taiwan, while the considerably lower contact angles and the 2.5 times higher minimum epidermal conductances might have come from organic surfactants. Interpretations of SEM images from leaf surface microstructures should consider amorphous areas as possible indicators of aerosol deposition and other hygroscopic material. The amount and type of the material determine the resulting impacts on plant water relations, together with the surrounding atmosphere and ecophysiological traits.

Hyaluronic Acid – from Production to Application: A Review

Hyaluronic acid (HA) was traditionally obtained by extraction from animal sources, specifically from rooster combs. However, this method of obtaining it has several disadvantages. Therefore, the number of researches has increased, and several microbial strains have been studied to synthesize HA. In this review, the characteristics of hearing aids were addressed; the microorganisms involved in the production of HA, operations for HA recovery and purification, and HA applications. Several species of microorganisms are capable of producing HA, mainly Streptococcus zooepidemicus, which can produce up to 7 g/L under ideal growing conditions. The culture medium, as well as the environmental conditions (pH, temperature, aeration, agitation), are factors that directly influence the production of HA, which can reduce or maximize it. Regarding recovery and purification methods, several techniques in sequence are used involving the precipitation of HA from the fermentation broth, usually using repeatedly organic solvents, surfactants, centrifugation, and membrane separation, among others. The functions of the HA cover several areas such as pharmaceutical, medical, and aesthetics, among others, causing the commercial demand for this biopolymer to increase every year, justifying research involving its bioproduction.

Effect of Tetrabutylammonium on Methylene Blue Adsorption

Artificial dyes such as methylene blue are commonly detected in textile industry wastewater. Clay is commonly used as an economical and effective adsorbent for methylene blue in textile waste treatment. The addition of surfactants into the system is usually done to increase the adsorption capacity of the clay. In this study, we used a molecular dynamics simulation method to study the effect of tetrabutylammonium organic surfactant on the adsorption process of methylene blue on the clay surface. The modelled clays are pyrophyllite and montmorillonite which are hydrophobic and negatively charged, respectively. The simulation results show that the addition of tetrabutylammonium surfactant causes a 12 % and 40% decrease in the binding of methylene blue to the surfaces of pyrophyllite and montmorillonite, respectively. This is due to the occurrence of competitive adsorption in both systems. Therefore, the addition of tetrabutylammonium surfactant was considered ineffective in increasing the adsorption capacity of pyrophyllite and montmorillonite.

Biopolymer-Based Mixed Matrix Membranes (MMMs) for CO2/CH4 Separation: Experimental and Modeling Evaluation.

Alternative materials are needed to tackle the sustainability of membrane fabrication in light of the circular economy, so that membrane technology keeps playing a role as sustainable technology in CO2 separation processes. In this work, chitosan (CS)-based mixed matrix thin layers have been coated onto commercial polyethersulfone (PES) supports. The CS matrix was loaded by non-toxic 1-Ethyl-3-methylimidazolium acetate ionic liquid (IL) and/or laminar nanoporous AM-4 and UZAR-S3 silicates prepared without costly organic surfactants to improve CO2 permselectivity and mechanical robustness. The CO2/CH4 separation behavior of these membranes was evaluated experimentally at different feed gas composition (CO2/CH4 feed mixture from 20:80 to 70:30%), covering different separation applications associated with this separation. A cross-flow membrane cell model built using Aspen Custom Modeler was used to validate the process performance and relate the membrane properties with the target objectives of CO2 and CH4 recovery and purity in the permeate and retentate streams, respectively. The purely organic IL-CS and mixed matrix AM-4:IL-CS composite membranes showed the most promising results in terms of CO2 and CH4 purity and recovery. This is correlated with their higher hydrophilicity and CO2 adsorption and lower swelling degree, i.e., mechanical robustness, than UZAR-S3 loaded composite membranes. The purity and recovery of the 10 wt.% AM-4:IL-CS/PES composite membrane were close or even surpassed those of the hydrophobic commercial membrane used as reference. This work provides scope for membranes fabricated from renewable or biodegradable polymers and non-toxic fillers that show at least comparable CO2/CH4 separation as existing membranes, as well as the simultaneous feedback on membrane development by the simultaneous correlation of the process requirements with the membrane properties to achieve those process targets.

Enhanced removal of Sb(V) from aqueous solutions using layered double hydroxide modified with sodium dodecyl sulfate

In this study, surfactant-modified layered double hydroxides (LDHs) were prepared via a hydrothermal method using sodium dodecyl sulfate (SDS). The synthesized sorbent (DS-LDH) was utilized for the removal of Sb(V) from aqueous solutions. The results demonstrated that DS4-LDH with a SDS/(Mg2++Al3+) molar ratio of 0.35 exhibited excellent Sb(V) sorption ability (136 mg g−1), which was 11 times that of pure LDH (12 mg g−1), for an initial Sb(V) concentration of 40 mg L−1. Acidic and alkalescent aqueous solutions and ionic strength hardly affected Sb(V) sorption by DS4-LDH, whereas strong alkalinity inhibited Sb(V) sorption. Under neutral conditions, coexisting anions, including sulfate and phosphate, exhibited a significant influence on Sb(V) removal, whereas chloride, acetate, and carbonate had negligible effects. Ion exchange and the formation of brandholzite-like structures primarily contributed to the Sb(V) sorption by DS4-LDH. The intercalation of dodecyl sulfate ions in LDH increased the interlayer spacing, which enhanced anion exchange between the original interlayer ions of LDH and Sb(OH)6-, and facilitated contact between the interlayer functional sites and Sb(OH)6-, leading to an improved removal of Sb(V). This study proposes a new concept for the development of high-performance LDH sorbents modified by organic surfactants, which could be promising remediating substances for the efficient removal of Sb(V).