Fabrication of a Bio-Based Superhydrophobic and Flame-Retardant Cotton Fabric for Oil–Water Separation

It is an urgent task to develop environmentally friendly and flame retardant durable oil–water separation materials. A green TA/B@PDA coating derived from bio-based materials such as tannic acid (TA), borax (B), and polydopamine (PDA) is deposited on cotton fabric through facile dip-coating method and step-by-step assembly method. A series of methods are used to characterize the as-prepared cotton fabric. PDA provides a reactive interface, while n-dodecyl mercaptan enhances the hydrophobicity of the surface with a water contact angle (WCA) and shedding angle (SA) of 153.3° ± 1.2° and 9° ± 0.8°, respectively. The as-prepared fabric exhibits outstanding oil/water separation efficiency (>98.5%) for various types of oil, and wear resistivity, washability, and reusability. Meanwhile, combustion test and limit oxygen index (LOI) test show that the modified fabric has excellent flame retardant performance. The cone calorimeter test (CCT) indicates that compared with the pristine cotton fabric, the peak heat release rate (PHRR) and total heat release (THR) of the TA/B@PDA cotton is decreased by 50% and 32%, respectively. Through the analysis of char residues, the flame retardant mechanism is studied. This method provides a general green way for the construction of superhydrophobic surfaces, and can be further applied to the broad fields of durable oil–water separation.     

Superhydrophobic and Superlipophilic Low Density Polyethylene/Styrene–Butadiene Rubber Thermoplastic Vulcanizate Film for Pressure-Responsive Continuous Oil–Water Separation

In recent years, with the continuous discharge of wastewater, which has caused serious environmental pollution, it is a task to separate oil or water from wastewater. Therefore, an efficient and low-cost oil–water separation method is needed to separate the oil–water mixture. Here, a superhydrophobic/superoleophilic low density polyethylene/styrene-butadiene rubber (LDPE/SBR) thermoplastic vulcanizate (TPV) film (oil contact angle of 0° and water contact angle of 161.1° ± 1.7°) is prepared using an etched aluminum foil as a template and applied to a laboratory-assembled oil–water separation device, which is a new method for oil–water separation via a pressure response valve. The LDPE/SBR TPV film is rolled up and stuffed into the through-valve, and the gap between the films is used as the pressure response channel for oil and water separation, thus achieving oil and water separation. When the film gap is 25 or 50 µm, the separation efficiency of TPV film is greater than 99% with the variation of external pumping force, indicating that this method can achieve complete oil–water separation under a suitable external pumping force. This functional TPV film has good recyclability, environmental stability, chemical stability, mechanical durability, as well as thermal stability, which makes it have great application potential.     

Measuring and Modeling Liquid–Liquid Equilibria for a Soybean Oil, Oleic Acid, Ethanol, and Water System

Vegetable oils can be deacidified by liquid–liquid extraction based on differences in polarity between triglycerides and fatty acids and differences in solubility. Information on the equilibrium between the phases of such systems is important for designing separation processes. The present paper reports experimental data for the extraction of fatty acid from soybean oil by (ethanol + water) as a mixed-solvent for system of soybean oil + oleic acid + ethanol + water at 30 °C at different water contents. The liquid–liquid equilibrium data of the systems were used to obtain interaction parameters in the universal quasi-chemical theory (UNIQUAC) activity coefficient model. These parameters can be used to predict equilibrium data of ternary and quaternary systems. The deviations between experimental and calculated compositions in both phases for each system using this model were calculated. The distribution coefficients and the selectivity factors of solvents for extraction of fatty acid from oil at 30 °C were calculated. Increasing of the water content as the co-solvent decreased the distribution coefficients and increased the selectivity factors of mixed-solvents, therefore considering the economical and practical aspects the optimum water content may be used for extracting oleic acid from soybean oil. We concluded that (ethanol + water) as a mixed-solvent can be used for extracting fatty acids from edible oils in a normal temperature.     

Degradable Superhydrophilic Iron-Pillared Bentonite Doped with Polybutylene Adipate/Terephthalate Open-Cell Foam: Its Application in Dye Degradation,Removal of Heavy Metal Ions,and Oil–Water Separation

Development of industrialization has brought convenience to people's lives; however, it has also brought serious harm to the environment, where, water pollution is the most obvious. Here, a polybutylene adipate terephthalate (PBAT) open-cell foam doped with iron-pillared bentonite (IPB) is prepared by using sugar as a pore-forming agent and solution phase separation, and then combined with a solution dipping method to coat the foam surface with a polyacrylamide/SiO₂, which makes the PBAT foam superhydrophilic. The static adsorption effect of superhydrophilic IPB-doped PBAT open-cell foam on methylene blue (MB) and Cu²⁺ is studied. The adsorption isotherm fitting shows that the adsorption conforms to the Langmuir model and it has biased toward monolayer adsorption. The adsorption kinetics fitting confirms that the adsorption process is in line with the pseudo-second-order adsorption model, which is dominated by chemical adsorption. The modified PBAT open-cell foam has an adsorption effect on Cu²⁺; however, it has weak cyclic adsorption capacity. It shows a good cyclic adsorption ability for the cationic dye MB and it has >95% photodegradation efficiency of the MB after five time's cyclic adsorption. The superhydrophilicity makes the foam to have better applications in oil–water separation.     

Novel Core–Shell of Polymethyl Methacrylate/butyl Acrylate/vinyl Silica Nanocomposite Particles through Seed Emulsion Polymerization

A new core–shell structure of polymethyl methacrylate/butyl acrylate copolymer/vinyl silica nanocomposite was successfully prepared in aqueous solution through seed emulsion polymerization. Vinyl-functionalized silica nanoparticles were synthesized using sol–gel technique of triethoxyvinylsilane in aqueous solution. New established covalent bond between the vinyl groups located on the surface of vinyl-functionalized silica nanoparticles and vinyl group of monomers and the encapsulation into methyl methacrylate/butyl acrylate copolymer through seed emulsion polymerization process. The prepared core–shell latex polymers were characterized by Fourier transform infrared, UV–vis, thermal analyses, tensile strength, elongation at break, field emission scanning electron microscope, transmission electron microscope, and zeta potential. The tensile strength improved by introducing vinyl silica into the matrix up to 5%, which proved the reinforcing role of vinyl silica in the matrix of polymer.     

Plasma and Silane Surface Modification of SiC/Si: Adhesion and Durability for the Epoxy–SiC System

Gaseous plasma pretreatments and surface derivatization using silane coupling agents (SCA) have been used to enhance the adhesive bonding of an epoxy to SiC-coated Si wafers (SiC/Si). The surface modification approaches included 1) an SCA treatment using 3-aminopropyltriethoxysilane (APS) or 3-glycidoxypropyltrimethoxysilane (GPS) and 2) an oxygen plasma pretreatment followed by a silane treatment. Durability was evaluated by immersing epoxy-coated SiC/Si samples in aqueous solutions at various pHs at 60°C for selected times. Adhesion durability for the epoxy-coated SiC/Si systems was qualitatively evaluated by visual inspection to identify debonding and quantitatively evaluated with a probe test to determine the critical strain energy release rate, G _c . Durability via either test approach varied as a function of surface treatment in this manner: oxygen plasma treatment plus silane modification > silane treated > no treatment. X-ray photoelectron spectroscopic characterization of surfaces was carried out following the surface treatments and after complete adhesion failure in the durability tests. The XPS results suggested that improved performance was due to plasma cleaning and modification of the substrate surface, promotion of silane surface interaction, and the formation of a thicker oxide layer.     

Thiol–ene networks and reactive surfaces via photoinduced polymerization of allyl ether functional hyperbranched polymers

A series of allyl ether functionalized hyperbranched (HB) polyester of three generations was synthesized from commercially available Boltorn^®. These modified HB polymers were homopolymerized to form films with a large number of residual allyl ether groups available for post film formation reactions. Additionally, the polyester multifunctional molecules were cured with a di and tetrathiol monomer in a one to one molar ratio to determine the effect of conversion on the resulting network thermal and physical properties. The same UV-cure chemistries were carried out with a similar second generation polyester dendrimer for comparison. This was in an effort to determine if there is any significant difference in the film chemical conversion and properties with dendrimers in comparison to HB molecules. The highly crosslinked films were obtained and characterized with respect to physical (DMTA) and thermal (DSC and TGA) properties.     

Biofunctionalization of Metal–Organic Framework Nanoparticles via Combined Nitroxide-Mediated Polymerization and Nitroxide Exchange Reaction

Surface engineering of metal–organic framework nanoparticles (MOF NPs), and enabling their post-synthetic modulation that facilitates the formation of bio-interfaces has tremendous potential for diverse applications including therapeutics, imaging, biosensing, and drug-delivery systems. Despite the progress in MOF NPs synthesis, colloidal stability and homogeneous dispersity—a desirable property for biotechnological applications, stands as a critical obstacle and remains a challenging task. In this report, dynamic surfaces modification of MOF NPs with polyethylene glycol (PEG) polymer is described using grafting-from PEGylation by employing nitroxide-mediated polymerization (NMP) and inserting arginylglycylaspartic acid (RGD) peptides on the surface via a nitroxide exchange reaction (NER). The dynamic modification strategy enables tailoring PEG-grafted MOF NPs of the type UiO-66-NH₂ with improved colloidal stability, and high dispersity, while the morphology and lattice crystallinity are strictly preserved. The interaction of PEG-grafted MOF NPs with human serum albumin (HSA) protein under physiological conditions is studied. The PEG-grafted colloidal MOF NPs adsorb less HSA protein than the uncoated ones. Therefore, the described approach increases the scope of bio-relevant applications of colloidal MOF NPs by reducing nonspecific interactions using NMP based PEGylation, while preserving the possibility to introduce targeting moieties via NER for specific interactions.     

Liquid–Liquid Equilibrium for Systems Containing Epoxidized Oils,Formic Acid,and Water: Experimental and Modeling

Epoxidized oils are eco-friendly plasticizers, which are industrially produced through the epoxidation reaction in a formic acid-hydrogen peroxide autocatalyzed system. The fundamental knowledge to describe the phase equilibrium of systems after epoxidation reaction is lacking, which is crucial for the design of the purification facilities. This work reported experimental data for the liquid–liquid equilibrium of three systems, i.e., epoxidized fatty acid methyl esters + formic acid + water, epoxidized fatty acid 2-ethylhexyl esters + formic acid + water, and epoxidized soybean oil + formic acid + water, in the temperature range (303.15–348.15) K under atmospheric pressure. The results indicated that the liquid–liquid equilibrium constant of formic acid in the systems followed the order of epoxidized fatty acid 2-ethylhexyl esters > epoxidized fatty acid methyl esters > epoxidized soybean oil. Moreover, the obtained experimental data were correlated using nonrandom two liquid (NRTL) and universal quasi chemical (UNIQUAC) models. The maximum root mean square deviation (RMSD) values as low as 0.0052 and 0.0263 were estimated using the NRTL and UNIQUAC model, respectively. The NRTL model is more suitable than the UNIQUAC model to describe the liquid–liquid equilibrium behavior of these ternary systems.     

How to Attain Ultralow Interfacial Tension and Three-Phase Behavior with Surfactant Formulation for Enhanced Oil Recovery: A Review. Part 1. Optimum Formulation for Simple Surfactant–Oil–Water Ternary Systems

Enhanced recovery of crude oil by surfactant flooding requires the attainment of an ultralow interfacial tension. Since Winsor’s work in the 1950s it has been known that a minimum interfacial tension and a concomitant three-phase behavior of a surfactant–oil–water system occurs when the interactions of the surfactant and the oil and water phases are exactly equal. It has been known since the 1970s that these conditions are attained when a linear correlation is satisfied between the formulation variables, which are characteristic parameters of the substances as well as the temperature. This first part of our review on how to attain ultralow interfacial tension for enhanced oil recovery shows how formulation scan techniques using these correlations are used to determine an optimum formulation and to characterize unknown surfactants and oils. The physicochemical significance of the original empirical correlation is reported as the surfactant affinity difference or hydrophilic–lipophilic deviation model. We report the range of accurate validity of, and how to test, this simple model with four variables.     

Editorial board page for “Separation Science and Technology”, Volume 17, Number 13–14

Abstract

This is a scanned image of the original Editorial Board page(s) for this issue     

A Star-Shaped Anionic Surfactant: Synthesis,Alkalinity Resistance,Interfacial Tension and Emulsification Properties at the Crude Oil–Water Interface

In this research, a star‐shaped surfactant was synthesized through the chlorination reaction, alkylation reaction and sulfonation reaction of triethanolamine, which is composed of three hydrophobic chains and three sulfonate hydrophilic groups. The critical micelle concentration (CMC) of the surfactant was measured by the surface tension method, and the results showed that it had high surface activity with CMC of 5.53 × 10^?5 mol/L. The surfactant was superior in surface active properties to the reference surfactants SDBS and DADS‐C₁₂. The interfacial tension (IFT) of the studied crude oil–water system (surfactant concentration 0.1 g/L, NaOH concentration 0.5 g/L, and experimental temperature 50 °C) dropped to 1.1 × 10^?4 mN/m, which can fulfil the requirement of surfactants for oil displacement. An aqueous solution of the surfactant and crude oil was emulsified by shaking, which formed a highly stable oil‐in‐water (O/W) emulsion with particle size of 5–20 μm. The oil displacement effect was almost 12%.     

Soy Protein–Gum Karaya Conjugate: Emulsifying Activity and Rheological Behavior in Aqueous System and Oil in Water Emulsion

The main objective of this study is to investigate the effects of mixing and conjugation of soy protein isolate (SPI) with gum karaya on the characteristics of the hybrid polymer (protein–gum) in both aqueous systems and oil‐in‐water (O/W) emulsions. It was hypothesized that the covalent linkage of gum karaya with SPI would improve the emulsifying activity and rheological properties of both polymers. Conjugation occurred under controlled conditions (i.e., 60 °C and 75 % relative humidity, 3 days). The conjugated hybrid polymer produced smaller droplet with better uniformity, higher viscosity and stronger emulsifying activity than native gum karaya, suggesting the conjugated polymer provided a bulkier secondary layer with more efficient coverage around oil droplets, thereby inducing stronger resistance against droplet aggregation and flocculation. Emulsions containing the native gum karaya produced the largest droplet size among all prepared emulsions (D_3,2 = 8.6 μm; D_4,3 = 22.4 μm); while the emulsion containing protein–gum conjugate (1:1 g/g) had the smallest droplet size (D_3,2 = 0.2 μm; D_4,3 = 0.7 μm) with lower polydispersity. The protein–gum conjugate (1:1 g/g) also showed the highest elastic and viscous modulus, the lowest polydispersity (span) and the highest emulsifying activity among all native, mixed and conjugated polymers. Therefore, the percentage of gum karaya used for production of O/W emulsion can be decreased by partially replacing it with the conjugated gum.     

The Content and Composition of Total,Free, and Esterified Sterols of Lotus Plumule Oil by GC–MS/FID

This study investigated the content and composition of total, free, and esterified sterols of three varieties of lotus plumule oil (Hunan lotus, Jiangxi lotus, and Fujian lotus) using GC–MS/FID. The fatty acid composition of sterol fatty acid esters (SFAE) was also analyzed and compared with that of triglycerides. Results showed that total sterol of lotus plumule oil (12.10–14.21 g/100 g) was higher than that of other plant oils (corn germ oil, 1.11 g/100 g; rapeseed oil, 0.78 g/100 g). No significant difference was found among the total sterol contents of the three types of lotus plumule oils (p > 0.05). Most sterol existed in ester forms (81.8–89.1%) rather than in free forms (8.4–10.1%). β‐Sitosterol (71.4–73.4%), and campesterol (6.2–7.5%) were the predominant fractions of free sterols. β‐Sitosterol (41.3–53.7%) and ?5‐avenasterol (27.1–31.1%) were the predominant fractions of esterified sterols, followed by campesterol (12.1–13.0%) and ?7‐avenasterol (3.4–3.7%). Linoleic acid (63.6–65.8%), oleic acid (8.3–10.4%), and behenic acid (9.0–9.9%) were the main fatty acids of SFAE, which were different from those of triglycerides. The results from this study suggest that lotus plumule oil may be a good resource of SFAE and can be used as a supplemental ingredient in functional foods.     

Experimental Investigation of Noble Viscoelastic Surfactant and Chelating Agent for Heavy Oil Enhanced Oil Recovery in High-Pressure–High-Temperature Carbonate Reservoirs

The success of chemical enhanced oil recovery (cEOR) is significantly dependent on the type of reservoir and its pressure and temperature conditions. The recovery of heavy oil from carbonate reservoir using cEOR method is still challenging because of its highly complex internal structures and high pressure–high temperature (HPHT) conditions. This research work is the first account of the use of AGA-97 (viscoelastic surfactant [VES)) along with a chelating agent diethylene triamine penta acetic acid (DTPA) for their application in cEOR method in heavy-oil-carbonate reservoirs. Several core flooding experiments were carried out to ascertain the effectiveness of the VES AGA-97 and chelating agent for cEOR method. The effect of VES on viscosity and interfacial tension was also studied with varying concentration, temperature, and time. The thermal stability of VES was analyzed with the help of thermogravimetric analysis, nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy. VES AGA-97 was found to have high thermal stability in short-term aging. The static adsorption and dynamic adsorption of VES AGA-97 was studied with the help of total organic carbon analysis. After all the analysis, it was found that VES AGA-97 and DTPA can be effectively used for cEOR method in carbonate reservoir at HPHT conditions, and the total additional oil recovery of 5.82–9.64% may be achieved.     

Robust,fluorine-free and superhydrophobic composite melamine sponge modified with dual silanized SiO_2 microspheres for oil–water separation

Massive oily wastewater discharged from industrial production and human daily life have been an urgent environmental and ecological challenge. Superhydrophobic materials have attracted tremendous attention due to their unique properties and potential applications in the treatment of wastewater. In this study, a novel superhydrophobic/superoleophilic composite melamine sponge modified with dual silanized Si O_2 microspheres was fabricated simply by a two-step sol–gel method using vinyltriethoxysilane and hexadecyltrimethoxysilane as functional agent, which exhibited a water contact angle of 153.2° and a water sliding contact angle of 4.8°. Furthermore, the composite sponge showed the excellent oil adsorption performance and the compressive elasticity reaching up to 130 g·g~(-1) of dichloromethane and 33.1 k Pa of compressive stress. It was worth noting that the composite sponge presented the excellent separation efficiency(up to 99.5%) in the processes of continuous oil/water separation. The robust superhydrophobic composite melamine sponge provided the possibility with the practical application for oil–water separation.     

Preparation and characterization of TiO2, ZnO,and TiO2/ZnO nanofilms via sol–gel process

The preparation of the TiO₂, ZnO, and TiO₂/ZnO nanofilms was conducted on glass via sol–gel process. The prepared film was detailedly characterized by means of OM, SEM, XRD, and EDS. The results showed that the obtained pure TiO₂ was composed of nanoparticles. For pure ZnO it consisted of nanoparticles and large agglomerates. Both the microstructural morphology and the crystallization of the prepared TiO₂/ZnO composite film were strongly related to the Ti/Zn ratio in the film. With a Ti/Zn ratio less than 1/1, the composite film was absence of cracks. Poor crystallization was definitely observed for the composite film with Ti/Zn ratio of 3/1 and 1/1. The EDS analysis revealed homogeneous distribution of Ti and Zn elements in the film.     

Editorial board page for “Separation Science and Technology”, Volume 16, Number 1

Abstract

This is a scanned image of the original Editorial Board page(s) for this issue.     

Editorial board page for “Separation Science and Technology”, Volume 16, Number 7

Abstract

This is a scanned image of the original Editorial Board page(s) for this issue.