Study on Spinnability of Arabinoxylan Extracted From Barley Husks

Valorisation of bio-based materials derived from agricultural and industrial side-streams or waste-streams is a basis of circular economy. However, the success of it depends on the full understanding of materials and finding their optimal way of processing. Barley husk is a side-stream waste material derived from the starch and ethanol production. This study is focused on the processability of the arabinoxylan extracted from barley husk using the electrospinning technique to produce thin xylan-poly(vinyl alcohol) fibers. As a comparison, lignin-free xylan of beech wood was used. The properties of spinning solutions and resulting nanofibrous mats were assessed by using rheological measurements, FTIR spectroscopy, scanning electron microscopy and contact angle measurements. It was found that solubility plays a crucial role in the spinnability of xylan extracts. Decrease in viscosity of arabinoxylan achieved by decreasing its concentration was found to improve the jet stability but at the same time, to reduce the diameter of spun fibre. Hydrophilicity of nanofibrous mats were strongly affected by the type of xylan and solvent used.

Synthesis, Hydrophilicity and Micellization of Coil–Brush Polystyrene-b-(polyglycidol-g-polyglycidol) Copolymer—Comparison with Linear Polystyrene-b-Polyglycidol

In this paper, an original method of synthesis of coil–brush amphiphilic polystyrene-b-(polyglycidol-g-polyglycidol) (PS-b-(PGL-g-PGL)) block copolymers was developed. The hypothesis that their hydrophilicity and micellization can be controlled by polyglycidol blocks architecture was verified. The research enabled comparison of behavior in water of PS-b-PGL copolymers and block–brush copolymers PS-b-(PGL-g-PGL) with similar composition. The coil–brush copolymers were composed of PS-b-PGL linear core with average DPn of polystyrene 29 and 13 of polyglycidol blocks. The DPn of polyglycidol side blocks of coil–b–brush copolymers were 2, 7, and 11, respectively. The copolymers were characterized by 1H and 13C NMR, GPC, and FTIR methods. The hydrophilicity of films from the linear and coil–brush copolymers was determined by water contact angle measurements in static conditions. The behavior of coil–brush copolymers in water and their critical micellization concentration (CMC) were determined by UV-VIS using 1,6-diphenylhexa-1,3,5-trien (DPH) as marker and by DLS. The CMC values for brush copolymers were much higher than for linear species with similar PGL content. The results of the copolymer film wettability and the copolymer self-assembly studies were related to fraction of hydrophilic polyglycidol. The CMC for both types of polymers increased exponentially with increasing content of polyglycidol.

Ionomer Films Impact on The Structure, Flow Regime, and The Wettability of The Catalyst Layer of PEMFC

Percolation testing and contact angle measurements have been used to investigate the role of relative humidity on structure, mass transport, and wettability of a PEM fuel cell catalyst layer and membrane. Four samples were tested, two catalyst layers and two membranes. Structure and mass transport changes in the catalyst layers resulting from RH changes were studied in terms of percolation pressure. A clear change in the structure between low and high RH conditioning was observed. Relative humidity (RH) cycling also impacted percolation pressures with an indication of catalyst layer cracking. In addition, RH effect on wettability of both catalyst layers and membranes was studied by measuring contact angles of sessile drops.

Influence of Terpenic Oil on Flotation Behavior of Sphalerite and Implication for the Selective Separation

Terpenic oil (TO) is commonly used as a flotation frother for the selective separation of sulfide minerals. As a frother, most reports have mainly focused on its effect on froth stability and froth entrainment, whereas its influence on the floatability of sulfide minerals has received little attention. In this work, the influence of TO on the flotation behavior of sphalerite was investigated by using microflotation tests, contact angle and zeta potential measurements, and FT-IR and SEM-EDS analyses. Microflotation tests conducted in a modified Hallimond tube indicated that compared with the collector potassium butyl xanthate (KBX), the flotation recovery of sphalerite was significantly increased when TO was added to the pulp, but the recovery of Cu-activated sphalerite with the addition of TO was lower than that with the addition of KBX. Contact angle measurements demonstrated that the contact angle of sphalerite was distinctly increased by the addition of TO, but the contact angle of sphalerite treated with TO was lower than that treated with KBX after Cu activation. Zeta potential measurements demonstrated that the zeta potential of sphalerite particles was slightly decreased when treated with TO, and the isoelectric point (IEP) was decreased from 3.3 to 3.1 due to the interaction of TO with sphalerite particles. FT-IR and SEM-EDS confirmed that TO could be adsorbed on the sphalerite surface on the formation of the oil film due to its low solubility, thereby increasing the surface hydrophobicity of the sphalerite. In addition, the TO absorbed on the surface acts as a bridging role and promotes the hydrophobic agglomeration of sphalerite particles. These results suggest that except for froth entrainment, the influence of TO on the flotation behavior of sphalerite may be another reason for the misreporting of sphalerite in concentrates.

Effects of imidazolium- and ammonium-based ionic liquids on clay swelling: experimental and simulation approach

Water-based fracturing fluids without an inhibitor promote clay swelling, which eventually creates wellbore instability. Several ionic liquids (ILs) have been studied as swelling inhibitors in recent years. The cations of the ILs are crucial to the inhibitory mechanisms that take place during hydraulic fracturing. Individual studies were carried out on several ILs with various cations, with the most frequently found being ammonium and imidazolium cations. As a result, the goal of this study is to compare these two cations to find an effective swelling inhibitor. A comparison and evaluation of the clay swelling inhibitory properties of tetramethylammonium chloride (TMACl) and 1-ethyl-3-methylimidazolium chloride (EMIMCl) were conducted in this work. Their results were also compared to a conventional inhibitor, potassium chloride (KCl), to see which performed better. The linear swelling test and the rheology test were used to determine the inhibitory performance of these compounds. Zeta potential measurements, Fourier-transform infrared spectroscopy, and contact angle measurements were carried out to experimentally explain the inhibitory mechanisms. In addition, the COSMO-RS simulation was conducted to explain the inhibitory processes and provide support for the experimental findings. The findings of the linear swelling test revealed that the swelling was reduced by 23.40% and 15.66%, respectively, after the application of TMACl and EMIMCl. The adsorption of ILs on the negatively charged clay surfaces, neutralizing the charges, as well as the lowering of the surface hydrophilicity, aided in the improvement of the swelling inhibition performance.

Novel Thermosensitive-co-Zwitterionic Sulfobetaine Gels for Metal Ion Removal: Synthesis and Characterization

Zwitterionic betaine polymers are promising adsorbents for the removal of heavy metal ions from industrial effluents. Although the presence of both negative and positively charged groups imparts them the ability to simultaneously remove cations and anions, intra- and/or inter-chain interactions can significantly reduce their adsorption efficiencies. Therefore, in this study, novel gels based on crosslinked co-polymers of thermosensitive N-isopropylacrylamide (NIPAAM) and zwitterionic sulfobetaine N,N-dimethylacrylamido propyl ammonium propane sulfonate (DMAAPS) were synthesized, characterized, and evaluated for ion removal. Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) analyses confirmed the success of the co-polymerization of NIPAAM and DMAAPS to form poly(NIPAAM-co-DMAAPS). The phase transition temperature of the co-polymer increased with increasing DMAAPS content in the co-polymer, indicating temperature-dependent amphiphilic behavior, as evidenced by contact angle measurements. The ion adsorption analyses of the poly(NIPAAM-co-DMAAPS) gels indicated that co-polymerization increased the molecular distance and weakened the interaction between the DMAAPS-charged groups (SO3− and N+), thereby increasing the ion adsorption. The results confirmed that, with a low concentration of DMAAPS in the co-polymer gels (~10%), the maximum amount of Cr3+ ions adsorbed onto the gel was ~58.49% of the sulfonate content in the gel.

Peptide-Based Capture of Chikungunya Virus E2 Protein Using Porous Silicon Biosensor

The detection of pathogens presents specific challenges in ensuring that biosensors remain operable despite exposure to elevated temperatures or other extreme conditions. The most vulnerable component of a biosensor is typically the bioreceptor. Accordingly, the robustness of peptides as bioreceptors offers improved stability and reliability toward harsh environments compared to monoclonal antibodies that may lose their ability to bind target molecules after such exposures. Here, we demonstrate peptide-based capture of the Chikungunya virus E2 protein in a porous silicon microcavity biosensor at room temperature and after exposure of the peptide-functionalized biosensor to high temperature. Contact angle measurements, attenuated total reflectance—Fourier transform infrared spectra, and optical reflectance measurements confirm peptide functionalization and selective E2 protein capture. This work opens the door for other pathogenic biomarker detection using peptide-based capture agents on porous silicon and other surface-based sensor platforms.

Bioinspired Repellent Pipette Tips with Low Retention Properties Prevent Contamination in Handling Biological Samples

Cross-contamination of biological samples during handling and preparation, is a major issue in laboratory setups, leading to false-positives or false-negatives. Sample carryover residue in pipette tips contributes greatly to this issue. Most pipette tips on the market are manufactured with hydrophobic polymers that are able to repel high surface tension liquids, yet they lack in performance when low surface tension liquids are involved. This presents an obstacle for pipette tips as inaccuracies and loss in precision arise when low surface tension liquids such as viscous oils are pipetted. Here we propose the use of lubricant-infused surface (LIS) technology to achieve omniphobic properties in pipette tips. Using a versatile and simple design, the inner lumen of commercially available pipette tips was coated with a fluorosilane (FS) layer using chemical vapor deposition (CVD). We show that after lubricating the tips through simply pipetting up and down a fluorinated lubricant, the surface free energy of the tips drastically decreased enabling them to attain low retention properties. Contact angle measurements reveals that the treated pipette tips have enhanced omniphobic properties. The repellent behavior of the lubricant-infused pipette tips against physical adsorption is investigated through pipetting a food coloring dye as well as human blood samples and are compared to the untreated tips. The results show significantly less amount carryover residue when the lubricant-infused tips are utilized compared to commercially available ones.

Toward the Rational Design of Chemical Formulations for EOR from Carbonates: Molecular–Level Understanding of Carbonate Wettability and its Reversal by Surfactants and Ions

Wettability is a key factor influencing oil production, particularly from the oil-wet carbonate reservoirs where the recoveries are often low. This is a serious problem for the oil industry as significant portion of the world's hydrocarbon reserves resides in carbonate formations. Since the wettability has its roots in the inter-molecular interactions between the oil and the mineral, our objectives are, first, to provide the molecular-level understanding of the carbonate wettability and, second, to apply this understanding to devise effective approaches for wettability alteration. Specifically, we focused on chemical additives such as surfactants and ions, which have demonstrated potential as wettability reversal agents. Molecular dynamics (MD) simulations were used as the primary method to study the wettability properties on newly-developed model calcite and dolomite surfaces that mimic experimentally-known mineral properties. Wettability reversal by cationic, anionic, and non-ionic surfactants, as well as by divalent ions (Ca2+, Mg2+, and SO42-) were investigated. A systematic approach for maximizing the surfactant efficiency by tuning the cationic surfactant head-group chemistry was proposed. To validate the MD simulation results, experimental contact angle measurements on dolomite chips were conducted. The MD simulation results demonstrated that, in the absence of asphaltenes, the oil-wetness of the carbonate minerals arises from the electrostatic attraction between the (negatively charged) oil carboxylates and the (positive) surfaces. Due to this electrostatic nature, the wettability could be reversed only by the cationic (positive) surfactants, which screen the oil-surface attraction. Other surfactant types had negligible effect, in agreement with the experimental contact angle measurements. Moreover, the wettability alteration efficiency of the cationic surfactants was directly related to their molecular charge distributions, offering guidelines for the practical design of the most potent wettability-reversing molecules. The simulations of the wettability alteration by Mg2+, Ca2+, and SO42- ions were likewise consistent with the contact angle measurements. The roles of individual ions in the multiple ion exchange (MIE) mechanism were deduced, and the known strong temperature dependence of their wettability alteration effect explained by the stability of the ion hydration shells. Finally, the simulations also exposed differences between the wettability reversal mechanisms on calcite and dolomite minerals, which may have important practical impact. Our results offer a novel perspective on the carbonate wettability and its reversal from the standpoint of atomic-level interactions and molecular mechanisms. New models for the carbonate surfaces were developed for reliable simulations of the wetting properties, which led to new insights into the origins of carbonate oil-wetness and the mechanisms of its reversal in two types of minerals. Lastly, the MD simulations demonstrated their utility as a powerful tool for the practical design and evaluation of potential chemical agents for EOR from carbonate reservoirs.