Sulfonate Ions Research Articles

Direct observation of the complex S(IV) equilibria at the liquid-vapor interface

The multi-phase oxidation of S(IV) plays a crucial role in the atmosphere, leading to the formation of haze and severe pollution episodes. We here contribute to its understanding on a molecular level by reporting experimentally determined pKa values of the various S(IV) tautomers and reaction barriers for SO2 formation pathways. Complementary state-of-the-art molecular-dynamics simulations reveal a depletion of bisulfite at low pH at the liquid-vapor interface, resulting in a different tautomer ratio at the interface compared to the bulk. On a molecular-scale level, we explain this with the formation of a stable contact ion pair between sulfonate and hydronium ions, and with the higher energetic barrier for the dehydration of sulfonic acid at the liquid-vapor interface. Our findings highlight the contrasting physicochemical behavior of interfacial versus bulk environments, where the pH dependence of the tautomer ratio reported here has a significant impact on both SO2 uptake kinetics and reactions involving NOx and H2O2 at aqueous aerosol interfaces.

Catalytic synthesis of DHHB using solid acids

Abstract DHHB (Diethylamino hydroxybenzoyl hexyl benzoate) is a widely regarded UV absorber with a high degree of safety, excellent efficiency and good solubility characteristics. In the conventional method of DHHB synthesis, H2SO4 is not effective as a catalyst. To address this drawback, we synthesized solid acid (sulfonic acid group-modified ion exchange resin) catalysts to replace H2SO4 by suspension polymerization modification and optimized the process. The experimental results showed that the yield of DHHB could reach 85% at 110 °C for 10 h, and the conversion of DHHB could be maintained above 90% after 10 cycles of the catalyst. SEM, FT-IR characterization and analysis of the solid acid catalysts before and after use revealed that the catalysts did not show any significant changes. The use of solid acid not only improves the yield of DHHB and reduces the energy consumption in the experimental process, but also the solid acid is simple to recover, recycled and has less waste acid. This experiment successfully explored a green and economic synthesis method for synthesizing DHHB.

A cucurbit[6]uril-based fluorescence supramolecular assembly for information encryption and visualization detection of nitro compounds and antibiotics

A novel CB[6]-based supramolecular assembly [K(ANS)(CB[6])2(DMF)2(H2O)0.5] (1) (CB[6] = cucurbit[6]uril, ANS- = 8-amino-1-naphthalene sulfonic acid ion) was successfully synthesized under solvothermal condition. Performance studies have shown that 1 exhibited excellent chemical stability and recycling performance. Meanwhile, 1 exhibited remarkable potential as a fluorescence sensor for the detection of 2,4,6-trinitrophenol (TNP), 4-nitrophenol (4-NP), and rifampicin (RFP) in both aqueous environments and practical samples. This sensing capability is achieved through fluorescence quenching, which offers fast response times and exceptional sensitivity, with detection limits of 0.19 μM for both TNP and 4-NP, and 0.21 μM for RFP. Even more remarkably, an anti-counterfeiting ink based on 1 and a portable test hydrogel were devised for encrypting information and visually detecting using a smartphone application. This work has the potential to expand the utilization of CB[6]-based materials in optical applications.

Dendrite-free, long cycle life Zn–MnO2 battery based on a polyanionic hydrogel electrolyte by constructing transfer channels and regulating solvation structure

Aqueous zinc ion batteries (AZIBs) are highly regarded as new generation of energy storage devices because of low cost and environmental friendliness. Particularly, flexible AZIBs with hydrogel electrolytes are suitable candidates for wearable electronics. However, continuous water-induced side reactions, uncontrolled dendrites and trade-off of electrochemical performances with mechanical strength are still obstacles for high-performance AZIBs. To address these issues, we designed a polyanionic hydrogel electrolyte (PAPHE) with sulfonate monomers and polyethylene glycol diacrylate (PEGDA) as crosslinker. Due to the electrostatic interactions between Zn2+ and sulfonate ions, Zn2+ can migrate along polyanionic chains. Meanwhile, electronegative oxygen atoms in PEGDA also interact with Zn2+ and weaken electrostatic interactions. The transfer channels are formed with “wall” of polyanion chains and PEGDA. Moreover, both sulfonate ions and ether bonds on the “wall” can regulate the solvation structure to reduce the activity of water, inhibiting side reactions, corrosion or by-products. Therefore, the PAPHE shows satisfying conductivity of 16.38 mS cm−1, stable Zn plating/stripping over 1600 h, flexibility and high compressive resistance (0.501 MPa at strain of 50 %). The Zn||PAPHE||MnO2 cells deliver good specific capacity of 274.5 mAh g−1 and can cycle over 1800 times. The pouch-cell can also work stably under various deformations.

Enhanced performance of high-temperature proton exchange membranes via polyfluorene cross-linked zwitterionic liquid

A satisfactory trade-off between physical/chemical stability and conductivity is crucial for high-temperature proton exchange membrane (HT-PEM) applications. Herein, a series of ether-free polyfluorenes cross-linked with zwitterionic liquids possessing both quaternary ammonium (QA+) and sulfonate ion (–SO3−) were prepared as crosslinked cHFTP–VIPSx via UV irradiation. Compared with non-crosslinked HFTP–TMA, crosslinked cHFTP–VIPSx exhibited enhanced conductivity, dimensional stability, oxidation stability, and phosphoric acid retention, which are attributed to the well-developed crosslinked structure and incorporated –SO3- groups. The as-fabricated H2/air single cell with a cross-linked cHFTP–VIPS30 achieved a higher peak power density (728 mW cm−2) than that of uncross-linked HFTP–TMA (287 mW cm−2) at 120 °C. Considering their enhanced performance, these cHFTP–VIPSx membranes cross-linked with zwitterionic liquid are promising HT-PEM materials for fuel cells.

Solvent-free mechanochemical synthesis of a sodium disulfonate covalent organic framework for simultaneous highly efficient selective capture and sensitive fluorescence detection of fluoroquinolones

Covalent organic frameworks (COFs) have great adsorption potential due to their tunable pore size and pore architecture as well as tailorable functionalities. However, the green and rapid synthesis of COFs with excellent adsorption properties remains a great challenge. Here, we presented a solvent-free and facile mechanochemical approach for the synthesis of COFs. The as-prepared COF TpBD-(SO3Na)2 containing sulfonate ions exhibited good thermal and chemical stability and can serve as an effective adsorbent for selective capture of fluoroquinolone antibiotics (FQs) benefiting from the ionic interface and abundant negatively charged sites. The maximum adsorption capacities of norfloxacin, enoxacin, and ciprofloxacin were 1709.6, 1661.5, and 1362.8 mg g−1, respectively, which outperformed those of other reported adsorbents. The adsorption mechanism was deeply explored through characterizations combined with density functional theory calculations, proving the synergistic adsorption effects of TpBD-(SO3Na)2 and FQs, including π-π* interactions, electrostatic interactions, and hydrogen bonding. Moreover, a fluorescence detection platform for FQs was developed based on the fluorescence signal of sodium disulfonate TpBD-(SO3Na)2. The limit of detection of norfloxacin was 8 nmol/L with a linear range from 0.03 to 6 μmol/L. This research provides a new strategy for the green synthesis of COFs and expands their application in the synchronous detection and removal of FQs in aquatic environments.

Species Transport in Hydrophilic Nafion-Coated Cu Catalysts for CO2 Electroreduction

Ionomer coated catalysts have increasingly been utilized in the electrocatalytic reaction of CO2 to multi-carbon products on Cu-based GDEs1,2. Their proton conductivity coupled with the Donnan exclusion due to the charged immobilized ions have served as a means of tailoring the microenvironment of the catalyst to desired products. Whilst there are experimental efforts geared towards the tuning of the local environment to desired products, there is a lack of supporting computational models that elucidate ionic species profile within the Nafion coated catalyst in the presence of fixed negative sulfonate ion charges from Nafion and the negative charges from the electrocatalysts.On the other hand, hydrated Nafion ionomer in the presence of a supporting electrolyte forms a biphasic polymer matrix which allows the transport of CO2 in both the hydrophilic and hydrophobic regions of Nafion ionomer3. Recent literature has highlighted the transport of CO2 in hydrophobic domains but in not in hydrophilic domains4. In this work, we look a closer look at CO2 transport in hydrophilic domains. We combine mass transport generalized modified Poisson-Nernst-Planck (GMPNP) equations and molecular dynamics to elucidate the transport of reactant/product species in the local environment of Nafion coating on planar Cu catalysts.We find that the thickness of the Nafion coating, the presence of immobilized sulfonic charges, ionic concentration of electrolyte impacts the availability of CO2, pH and the concentration of cations which are important parameters for CO2 reduction reaction. We also provide a relationship between the pKa of Nafion and the local dielectric constant of the reaction’s microenvironment using molecular modelling and the corresponding impact of Nafion’s ability to effectively minimize carbonate reactions. Our results underscore the need to manage the catalyst-ionomer microenvironments for CO2 reduction on copper electrodes. This model in conjunction with further experimental endeavours can serve as a benchmark for other intricate porous catalyst models that are significant for optimizing catalyst performance for large scale CO2 reduction operations. Bibliography Bui, J. C. et al. Engineering Catalyst–Electrolyte Microenvironments to Optimize the Activity and Selectivity for the Electrochemical Reduction of CO2 on Cu and Ag. Acc. Chem. Res. 17, acs.accounts.1c00650 (2022).Kim, C. et al. Properties of the ionomer under CO 2 R-related environments Tailored catalyst microenvironments for CO 2 electroreduction to multicarbon products on copper using bilayer ionomer coatings. doi:10.1038/s41560-021-00920-8 (2022).Ren, X., Myles, T. D., Grew, K. N. & Chiu, W. K. S. Carbon Dioxide Transport in Nafion 1100 EW Membrane and in a Direct Methanol Fuel Cell. J. Electrochem. Soc. 162, F1221–F1230 (2015).García de Arquer, F. P. et al. CO2 electrolysis to multicarbon products at activities greater than 1 A cm−2. Science (80-. ). 367, 661–666 (2020). Figure 1

Mechanistic Study of Reaction between 5-Sulfosalicylic Acid and Colloidal MnO2

The reaction between 5-sulfosalicylic acid (5-SSA) and colloidal MnO2 has been studied kinetically in acidic medium. During the reaction the concentration of 5-SSA was kept highly excess than the concentration of colloidal MnO2 to maintain the pseudo-first-order condition. The reaction was studied by following decrease in absorbance of colloidal MnO2 at 390 nm and the first order rate constants were determined from linear log (Abs.) against time plots. The linearity of the first-order plots did not involve any autocatalytic part. The oxidation of 5-sulfosalicylic acid (5-SSA) by colloidal MnO2 involves intervention of free radicals and Mn(III). The product of reaction in colloidal MnO2 was p-hydroxy benzene sulfonate ion as confirmed by LCMS-MS analysis. The oxidation by colloidal MnO2 consists of acid dependent and independent mechanisms. The results of added Mn(II), Na4P2O7 and acrylonitrile indicate involvement of Mn(III) and free radical during oxidation by colloidal MnO2. The probable mechanisms for acid dependent and independent paths were predicted and the rate expressions were also obtained. The activation parameters also support the proposed mechanisms.

Mobile hydrogen-bonding donor in covalent organic framework for efficient iodine capture

Covalent organic frameworks (COFs) show promise for applications in molecule capture such as radioactive iodine (I2) capture, which is important in the development for nuclear energy and radiation medicine. However, fast and efficient I2 capture and release have remained insufficient for practical applications. Here, we demonstrated that mobile cationic hydrogen-bonding donor in nanochannel of anionic covalent organic framework (COFs) can promote the absorption and desorption of I2. The adsorption rate of COF Bmim-TpPaSO3 affording unfixed hydrogen-bonding donor 1-butyl-3-methylimidazolium ([Bmim]+) in the nanochannel reaches 2.86 g h−1, which is higher those of COF TpPa-SO3H (0.57 g h−1) with fixed hydrogen-bonding donor and COF TpPa-SO3K without hydrogen-bonding donor. The adsorption capacity was also increased from 1.50 g g−1 to 5.25 g g−1. Experiments and quantum chemistry calculations show that introducing the hydrogen bond donor enhances the interaction of Bmim-TpPaSO3 with iodine and induces sulfonate ion of Bmim-TpPaSO3 to convert iodine molecules into polyiodide via charge-transfer mechanism. In addition, Bmim-TpPaSO3 has good recyclability and storage performance. This strategy has unlimited potential to significantly improve the performance of covalent organic framework materials in the field of gas adsorption.

Sulfonato Complex Formation Rather than Sulfonate Binding in the Extraction of Base Metals with 2,2′-Biimidazole: Extraction and Complexation Studies

The application of a bidentate aromatic N,N’-donor ligand, 2,2′-biimidazole (BIIMH2), as an extractant in the form of 1-octyl-2,2′-biimidazole (OBIIMH) and related derivatives in the solvent extraction of base metal ions (Mg2+, Mn2+, Fe3+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) from an acidic sulfonate medium using dinonylnaphthalene disulfonic acid (DNNDSA) as a synergist was investigated. OBIIMH with DNNDSA as a co-extractant showed a lack of selectivity for base metals ions (Mg2+, Mn2+, Fe3+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) despite its similarity with a related bidentate aromatic ligand, 2,2′-pyridylimidazole, which showed preference for Ni(II) ions. The nickel(II) specificity, through stereochemical “tailor-making”, was not achieved as expected and the extracted species were isolated to study the underlying chemistry. The homemade metal sulfonate salts, M(RSO3)2·6H2O (R = Toluene and M2+ = Co2+, Ni2+, Cu2+ and Zn2+), were used as precursors of the metal complexes of BIIMH2 using toluene-4-sulfonic acid as the representative sulfonate. Spectroscopic analysis and single-crystal X-ray analysis supported the formation of similar neutral distorted octahedral sulfonato complexes through the bis coordination of BIIMH2 and two sulfonate ions rather than the formation of cationic complex species with anion coordination of sulfonates. We attributed the observation of similar complex species and the similar stability constants of the bis-complexes in solution as the cause for the lack of pH-metric separation of the later 3d metal ions.

Molecular Dynamic Simulations of Proton and Water Transport Mechanism in a Nafion Pore

Herein, nonequilibrium molecular dynamics simulations are conducted to study the hydraulic permeation and vehicle transport of protons in proton exchange membranes (PEMs) with different structures. The results indicate that water molecules and hydronium ions are transported in porous PEMs in the form of clusters. Water molecules are more concentrated in the bulk areas of pores, whereas hydronium ions had a high‐density profile near the pore surface areas since sulfonate ions of the side chain exhibit a stronger adsorption effect on hydronium ions. Due to the confined pore size, the slip flow of water molecules and hydronium ions occurs near the pore surfaces and it becomes more significant as side chain separation or pore size increases. As pore size decreases, the reduction of movement region and the deep attractive potential near the pore wall lower the specific enthalpy due to enhanced molecule‐wall collisions. In addition, the transport diffusivity coefficients of positively charged hydronium ions are smaller than that of water molecules due to the stronger Coulomb interactions and hydrogen bonding with negatively charged side chains. Transport diffusivity coefficients of water molecules and hydronium ions increase as pore size and side chain separation increase.

The characterization study of inhibited silica/silicate scale using vinyl sulfonated copolymer (VS-Co)

Silica/silicate scale is a significant problem, especially in oilfield production during Alkaline Surfactant Polymer (ASP) flooding, where chemical inhibitors are the preferred method to prevent them. In this study, the effect of inhibitor vinyl sulfonated copolymer (VS-Co) on silica/silicate scale formation was analysed using X-Ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR).The functional group type of VS-Co are sulfonate ions, SO3-, and these interact in the scaling process. Bulk-inhibited scaling brine tests were conducted at 60C and pH 8.5. During these tests, the silicon brine (with VS-Co) representing the inhibited ASP leachate was mixed with a magnesium brine representing the connate water to replicate reservoir conditions during ASP flooding. The samples tested in this study were non-inhibited Si/Mg mixed brine of 60 ppm Mg2+ and 940 ppm Si4+ (60Mg:940Si) as a blank, and inhibited 60Mg:940Si mixture with various VS-Co concentrations of 20 ppm, 50 ppm, and 100 ppm. The inhibition efficiency of the VS-Co was determined, followed by the characterisation study of the silica/silicate scale deposited from both test conditions.The IR spectra of all 60Mg:940Si samples show a similar peak at 1050 cm-1 to 1080 cm-1, attributed to a Si-O covalent bond and a band at 790 cm-1 to 800 cm-1 showing the presence of Si-O-Si stretching. XRD patterns produced a broad scattering peak for all samples at 2 of 24 showing that the samples are amorphous silica. For tests of high Mg2+ in the brine mix, 900Mg:940Si, a mix of crystalline silica and crystalline magnesium silicate was produced. Based on these results, it can be concluded that the scale formed even with 100 ppm of VS-Co present. Further studies are required to address how to mitigate scale formation effectively in the future.Based on the research conducted, we can conclude that the VS-Co alone could not significantly inhibit the formation of silica/silicate scale even at the highest concentration (100 ppm) of VS-Co. However, having VS-Co present caused an alteration in IR spectra frequency which requires further investigation to assess how best to develop the inhibiting properties of the VS-Co product. The application of nanoparticles and their successful stories spark the interest of authors in searching for an efficient method of managing the silica/silicate scale where the modification of potential scale inhibitor (SI) with nanoparticles may be able to improve the inhibition efficiency towards the silicate/silicate scale.The presence of VS-Co in the scaling brine only slightly inhibits the Mg2+ ion (initially comes from connate water) from reacting. It is worth further investigation on how this VS-Co can make it happen. Hence, the functional groups responsible for this may be altered by adding other functional groups to provide a synergistic effect in preventing this silica/silicate scale; or by modifying the VS-Co with nanoparticles to improve their adsorption/desorption capacity.The newly developed technique in analysing the inhibition mechanism of a chemical inhibitor using various spectroscopic analysis is promising where an alteration in the spectra may provide proof of the chemicals inhibition efficiency.

Zwitterion-Functionalized Cuprous Oxide Nanoparticles for Highly Specific and Enzymeless Electrochemical Creatinine Biosensing in Human Serum

Herein, we report the development of a novel enzymeless electrochemical biosensor for highly specific detection of creatinine utilizing zwitterion-functionalized cuprous oxide nanoparticles (Cu2O NPs). We utilized a simple yet effective alternative to traditionally used cover layers based on the surface engineering of Cu2O NPs with N-hexadecyl-N,N dimethyl-3-ammonio-1-propanesulfonate zwitterion. This surface modification generates a pseudo-proton-exchange membrane which electrostatically hinders interfering agents from reaching the electrode surface, thus resulting in highly specific creatinine detection without loss in sensitivity. To fabricate the enzymeless biosensor, single-crystalline Cu2O NPs were synthesized via a sulfonate ion-directed seed aging protocol and were simply drop-cast onto screen-printed carbon electrodes. The shape directional effect of sulfonate ions to induce truncation in the final morphologies of the synthesized Cu2O NPs is also reported for the first time. The creatinine biosensor demonstrated fast response time (<50 s), good reproducibility (RSD = 2.8%, n = 10), and high specificity against interferents like ascorbic acid, acetic acid, glucose, urea, and uric acid. A linear response to creatinine concentration from 10 to 200 μM (R2 = 0.9876 and LOD = 5.0 μM) was observed, which covers the entire range of physiological creatinine in human serum. Moreover, robust storage stability with a negligible decrease in signal strength over an extended storage period of 6 months was achieved, thus highlighting the practical feasibility for point-of-care testing of creatinine.

Removal of Cr(VI) by ultrafiltration enhanced by a cellulose-based soluble polymer

In this study, polymer-enhanced ultrafiltration (PEUF) was used to remove chromium ions (Cr(VI)) from water using quaternized hydroxyethyl cellulose ethoxylate (QHECE) as the extracting agent. The polymer was structurally and thermally characterized before and after loading, where Fourier transform spectra were used to corroborate the Cr(VI) binding sites. Thermogravimetric analysis showed an increase in the residual mass due to the formation of macromolecular aggregates from the water-soluble polymer (WSP) and Cr(VI). SEM/EDX was used to corroborate the presence of Cr(VI) on the WSP surface. The washing method was used to study Cr(VI) retention as a function of the solution pH, WSP quantity, pressure, Cr(VI) concentration, membrane type and presence of interfering ions (NaCl, Na2SO4 and NaHPO4) at three Cr(VI):interferent molar ratios (1:1, 1:2 and 1:4). In addition, the polymer reusability was studied over six sorption-desorption cycles. Next, the enrichment method was used to determine the maximum retention capacity of the polymer. Finally, PEUF was used to test Cr(VI) removal in simulated industrial electroplating wastewater.By varying different parameters, 92 % retention efficiency was achieved at pH 9.0 using a polymer mass of 50 mg, a pressure of 2.0 bar, an initial Cr(VI) concentration of 30 mg L−1 and a 10-kDa regenerated cellulose membrane. Increasing the Cr(VI):interferent molar ratio was found to decrease the retention efficiency, and significant decrease was obtained for the highest ratio of sulfonate ions to Cr(VI) used. Finally, the maximum retention capacity was determined to be 299.46 mg g−1 using the enrichment method, and it was demonstrated that the polymer could be reused for up to four consecutive sorption-desorption cycles.

A novel core–shell structure of CuNW@PSS accelerates the process of methane hydrate formation

Considering the high thermal conductivity of copper material and the promoting effect of sulfonate ions on methane hydrate formation, in this study, copper nanowires coated with sulfonate polymer (CuNW@PSS) were used in methane hydrate experiments. The morphology of synthesized CuNW@PSS was confirmed by SEM and TEM, and the composition was analyzed by elemental analysis, it has clearly core–shell structure. The surface wettability of the material changed from hydrophilic to hydrophobic after sulfonate modification. In methane hydrate formation experiments, compared with PSS, CuNW@PSS can shorten the induction time by 78.5 %, from 61.87 ± 21.71 min to 13.28 ± 5.47 min, the growth rate increased by 130 %, from 0.6 ± 0.13 mmol/min to 1.38 ± 0.34 mmol/min. In addition, CuNW@PSS has good cycling and defoaming performance in the multi-cycle methane hydrate formation and dissociation experiments, which would have potential application for natural gas storage and transportation.

A Polyethylenimine‐Functionalized Protic Ionic Liquid (PolyE‐IL) Catalyst for Conversion of Aqueous 2,3‐Butanediol into Methyl Ethyl Ketone (MEK)

AbstractThe dehydration of C6 sugars derived 2, 3‐butane diol (2, 3‐BDO) into Methyl Ethyl Ketone (MEK) is an emerging, and green alternative for production of green platform chemicals. In the present manuscript polyethyleneimine (PEI) functionalized protic ionic liquid (PolyE‐IL) has been integrated as a selective, recyclable, robust and efficient catalyst for dehydration of aqueous 2, 3‐BDO into MEK. The exploration of PolyE‐IL catalyst provides selective dehydration of aqueous 2,3‐BDO with significantly higher yield (&gt;70 %) of MEK and conversion (&gt;80 %) of 2,3‐BDO. PolyE‐ILs with different counter ions were synthesized and tested for 2,3‐BDO dehydration. Of the tested catalyst, PolyE‐IL‐1 with sulfonic acid counter ion ([PEI]+[HSO4]−) showed excellent performance for obtaining high MEK yield (77 %) and 2,3‐BDO conversion (85 %) at 220 °C. Moreover, the [PEI]+[HSO4]− catalyst showed excellent performance in term of TON (4.16) and TOF (0.14) with E‐Factor (0.33) and PMI (28.3). The recyclability study for five consecutive runs showed the consistency in yield (&gt;70 %) and conversion (&gt;80 %). Thus, PolyE‐IL catalyst found to be robust and stable under optimized reaction conditions. The present process provides several environmental and process economical benefits of low operating temperature, pressure, reaction time, and catalyst recycle. The use of PolyE‐IL shall contribute to development of economically and industrially feasible process.

Experimental investigation of the controversial effects of a cationic surfactant with brine on spontaneous imbibition of an asphaltenic crude oil

Carbonate formations, which are often naturally fractured and oil-wet, include a significant portion of the discovered oil reserves. Due to their tendency to retain oil at the rock surface, enhanced oil recovery (EOR) from these reservoirs is difficult. It has been suggested that low salinity (LS) water injection be used to recover more oil from these types of oil reservoirs. A surfactant is one of the chemicals that is broadly applied as an agent to alter wettability towards water-wet conditions. In these reservoirs, if the wettability of the reservoir rock is altered from mostly oil-wet to mostly water-wet, recovery efficiency can be greatly enhanced.In this study, the synergistic effect of a modified brine solution (i.e., increasing the concentration of (SO42-)) and a cationic surfactant, namely cetyltrimethylammonium bromide (CTAB) with two different concentrations (100 ppm and 300 ppm) on the wettability of dolomite rock was considered. The contact angle is used to assess wettability alteration from dolomite rock surface. Also, oil recovery was tested in dolomite core samples via spontaneous imbibition procedures at 60 °C for 30 days. Using the modified brine, the contact angle was reduced from 130° to 27°, and the oil recovery increased from 0% to 33%. While CTAB-surfactant decreased the contact angle from 140° to 32° and 120° to 34°, respectively, for concentrations of 300 ppm and 100 ppm. Moreover, oil recovery was increased to 7.95% and 6.60 % and at concentrations of 300 ppm and 100 ppm, respectively. The oil-wet dolomite rock wettability can be modified by using the sulfonate ion and a cationic surfactant. Indeed, by absorbing SO42- ions on the dolomite slice surface, a repulsive force is formed between SO42- and the carboxylate on its surface and the wettability changes from an oil-wet to a water-wet condition. Furthermore, electrostatic interactions between the surfactant's positively charged head and the negatively charged carboxylate cause the cationic surfactant to adsorb on the oil-wet surface. Indeed, the wettability changes to the water-wet condition when the carboxylate group is removed from the rock surface by forming an ion pair. On the other hand, for low oil recovery in surfactant imbibition, three different scenarios were considered, namely: I) reduction of cationic surfactant concentration in the Amott cell, II) oil snap-off phenomenon, and III) asphaltene deposition and plugging of the pores. The results of the three proposed scenarios are as follows: I) when re-imbibing cationic surfactant into the dolomite core surface, shifting the wettability state from oil-wet to water-wet resulted in higher oil recovery (scenario result (I)), II) after CTAB flooding into the micromodel with varied pore throats, oil could be released from the porous medium throats and the walls of pores. As a result, an increase in oil recovery was seen (scenario result (II)), and III) an oil-in-water emulsion was formed as a result of the interactions between asphaltene and the cationic surfactant, and asphaltene became more unstable. As a result, asphaltene is deposited on the rock surface, plugging pores and reducing permeability, resulting in a decrease in oil recovery (scenario result (III)). The findings of this study can help for better understanding of the impact of modified bine water and cationic surfactant on dolomite rock and the interaction between asphaltene and cationic surfactant and their impact on ultimate oil recovery.

Insight into the relationship between molecular morphology and water/ion diffusion in cation exchange membranes: Case of partially sulfonated polyether sulfone

The molecular design of cation exchange membranes (CEM) is of prime importance due to their significant role in many applications. It has been shown that water and ion transport through CEM depends on the membrane morphology which itself is a function of polymer structure and hydration level. There has been a great deal of experimental research devoted to correlating the polymer structure to water/ion diffusion, with speculations about the relationship between molecular interactions, morphology formation, and water/ion diffusion. In our simulation studies, first, we calculated the water anomalous diffusion coefficients (Da) in sulfonated poly(ether sulfone) (sPES) membranes and compared them with the experimentally ones, confirming an excellent consistency between the results in various conditions. Then we introduced quantitative measures of membrane morphology, namely the pore limiting diameter (PLD), largest cavity diameter (LCD), and pore size distribution (PSD), that strongly correlate with the water/ion anomalous diffusion coefficients. Thus, we show how polymer structure and membrane hydration level change the membrane morphology and that there is a direct correlation between PLD and water/ion anomalous diffusion coefficients. We find a critical PLD value, precisely equal to the size of the diffusing ion (Na+, K+), below which the ion's mobility is extremely limited and above which the ion's anomalous diffusion coefficient increases linearly with PLD. Above the critical PLD, the slope of the D-PLD relation strongly correlates with the ion's residence time near the sulfonate group. Also, our simulations show that a larger hydration level results in a more interconnected and uniform water network, faster water/ion diffusion, less water/ion residence time close to the sulfonate ion and a closer-to-normal water/ion diffusion behavior.

Plasma-assisted preparation of nano-(ZrC, ZrO2)@carbon composites from Zr-loaded sulfonated styrene–divinylbenzene copolymers

We have developed a simple method to prepare nano-(ZrC0.93, ZrO2-polymorphs)@carbon composites with graphite/amorphous carbon content and adjustable Zr/C ratio based on using a multistep tube furnace and plasma-assisted heat treatment of zirconium-loaded sulfonated styrene–divinylbenzene (STY-DVB) copolymers. Pre-pyrolysis of zirconium-loaded sulfonated STY-DVB ion exchangers with 2 and 8 mass % DVB at temperatures between 1000 and 1400 °C for 2 h produced nano-ZrO2@C intermediates with particle sizes of ~ 30–60 nm with no ZrC formation. Plasma processing of nano-ZrO2@C resulted in nano-(ZrC0.93, ZrO2)@C composites with 11% (under a He atmosphere) (C/Zr = 73) or 13% (under a H2 atmosphere) (C/Zr = 58) ZrC0.93 content. Three polymorphs of the zirconium dioxide (tetragonal, monoclinic and cubic, between 18 and 27 nm) were found in the products. The amounts of tetragonal and monoclinic ones are comparable to that of ZrC0.93. The average particle size of ZrC0.93 prepared in this way was found to be 21–23 nm. The BET surface area of the nano-(ZrC0.93, ZrO2)@C(graphite) composites prepared in He and H2 was over 250 and 300 m2/g, respectively. We developed a reproducible and easy method to prepare nano-(ZrC, ZrO2)@C products by setting the DVB content, sulfonation degree, Zr loading and the thermal treatment conditions, which have an influence on the ZrC and graphite/amorphous carbon content of nano-ZrO2@C intermediates. The zirconium-loaded sulfonated styrene–divinylbenzene (STY-DVB) copolymers (2 and 8 mass% DVB) or their thermal decomposition was characterized with vibrational spectroscopy, thermal analysis and DSC or powder XRD, BET, XPS and HRTEM methods, respectively.

Redox Mediator with the Function of Intramolecularly Disproportionating Superoxide Intermediate Enabled High‐Performance Li–O2 Batteries

AbstractThe large charge overpotential and poor cycling stability triggered by sluggish Li2O2 oxidation kinetics and severe superoxide‐related side reactions greatly restrict the development and application of lithium–oxygen batteries. Finding out high‐efficiency catalysts that can effectively facilitate a highly reversible formation/decomposition of lithium peroxide is still a crucial challenge in the field of Li–O2 batteries. Herein, a soluble catalyst of 2,2'‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) that can promote highly reversible formation and decomposition of Li2O2 during discharge and charge processes is reported for the first time. During discharge, it can capture and couple two LiO2 intermediates via its sulfonate and ammonium ions, and induce the intramolecular disproportionation reaction to produce Li2O2 through ionic microenvironment, which not only prompts the solution‐phase growth of Li2O2, but also restricts the reactivity of LiO2 intermediate, thus significantly alleviating the electrode surface passivation issue and suppressing the superoxide‐related side reactions. During charge, it can quickly transport electrons between the electrode and Li2O2 by serving as a new kind of redox mediator (RM), thus greatly facilitating the Li2O2 oxidation kinetics. As a result, the Li–O2 batteries that incorporate ABTS exhibit outstanding electrochemical performance, low charge overpotential, high discharge capacity, and high cycling stability.