SO3H Groups Research Articles

Asymmetric synthesis of a novel “dual-matrix” mixed matrix membrane (MMM) and its food applications

The purpose of this study is to develop a ternary mixed matrix membrane (MMM) for food packaging using activation-graft-polymerization method. In this work, poly ether sulfone (PES) was activated by introducing -SO3H groups to establish a supported layer. Ag0 nanoparticles (AgNPs) were introduced on the activated surface of PES as functional fillers. Polyamide (PA) layer was formed as surface protective layer through interfacial polymerization of m-phenylenediamine and trimesoyl chloride. A series of physical and chemical assays were preformed to characterize the physical and chemical properties of the MMM. Results revealed that the antimicrobial rate of MMM for suspensions exceeded 86 %, while the silver release from the packaging was within the safety limit (below 100 µg/L). The prepared MMM was used as fresh-keeping packaging to preserve frozen salmon samples. It significantly slowed down the decline process of samples’ quality indexes, greatly extending the shelf life of preserved fish (26 % ∼ 47 %). The overall research results revealed the significant potential of the prepared MMM in food applications.

Synthesis of 5-hydroxymethylfurfural from cellulose using silica-amorphous carbon and choline chloride:CrCl3

The silica-amorphous carbon bearing SO3H group was synthesised by incomplete carbonisation of glucose and sulfonation with concentrated H2SO4 and the structure was determined by FTIR, XRD, and EDX. In this study, their catalytic activities were investigated in the synthesis of 5-hydroxymethylfurfural (HMF) from cellulose with choline chloride:CrCl3 deep eutectic solvent (DES). The results showed the highest yield of HMF at a reaction temperature of 140ºC for 1 h with 162 mg cellulose, 6 mmol [EMIM]Cl, 10 mg silica-amorphous carbon and 50% mol DES ChCl:CrCl3. In particular, the catalyst was able to recover and reuse three times with a small decrease in yield for the conversion of cellulose to HMF.

Effects of microstructure on the retention of proton conductivity of Nafion/SiO2 composite membranes at elevated temperatures:An in situ SAXS study

The operating temperature of modified Nafion membranes remains too low to satisfy the requirements for high-temperature proton exchange membrane fuel cells (HT-PEMFCs) because most can only operate well below 120 °C. In this article, we prepare a series of Nafion/SiO2 composite membranes with different contents of doped silica nanoparticles by in situ growth of SiO2 nanoparticles near the –SO3H group. The water dynamic change process and the functional properties of Nafion/SiO2 composite membranes are studied and found to correlate well with structural parameters, such as crystallinity and average chain spacing. Also, microstructure information including the phase separation structure changes, structural complexity, and ion cluster fraction of Nafion/SiO2 composite membranes at different temperatures are investigated using synchrotron-based in situ small angle X-ray scattering (SAXS). Differing from expectations, the amount of water in the Nafion/SiO2 composite membranes may not be the decisive factor to maintain proton conductivity at relatively high temperatures. Instead, the complexity or connectivity of the proton transport channel may play a more important role in the effective proton transfer inside the composite membranes, which also provides valuable guidance and insight for the development of novel HT-PEM materials with well-designed ion transport pathways in the future.

Synthesis and property comparison of mono-, di-, and trisulfonated poly(arylene ether phosphine oxide)s with fluorenyl moieties as proton exchange membranes

The microstructure of proton exchange membranes (PEMs) is seldom to be adjusted by the distribution modes of the sulfonic-acid groups to enhance their overall properties. Herein, monosulfonated poly(arylene ether phosphine oxide)s (msPAEPO), disulfonated poly(arylene ether phosphine oxide)s (dsPAEPO), and trisulfonated poly(arylene ether phosphine oxide)s (tsPAEPO) with fluorenyl moieties are synthesized. The distribution modes of the –SO3H groups and the structural unit of diphenol monomer markedly affect the properties of the resulting PEMs. From msPAEPO to dsPAEPO, and then to tsPAEPO, the size of the hydrophilic ionic channels enhances but their connectivity reduces, thus forming distinct microstructures. The resulting PEMs achieve superior comprehensive properties by further adjusting sulfonation degree. As a result, the approach of the distribution adjustment of the sulfonic acid groups is equally effective to tune the microstructure and properties of the sPAEPO membranes with different structural units of diphenols and can be extended to fabricate various high-performance PEMs.

Sulfonic Acid Functionalized Precipitated Silica as Efficient Solid Acid Catalyst for Acetylation Reactions

Introduction: Precipitated Silica has very high commercial significance in terms of ease of preparation, market volume, cost benefits and a wide range of industrial applications. The surface silanol groups of Precipitated Silica can be modified with reactive organic functional groups to achieve desired properties for specific applications, including catalysis. Objective:: The objective of this study is to demonstrate sulfonic acid functionalized Precipitated Silica as a true heterogeneous catalyst in acetylation reaction, where the catalytic activity and desired product selectivity is a magnitude higher than industrial solid acid zeolite catalysts as well as similar catalysts reported in literature. Methods: A novel and cost-effective method for the functionalization of Precipitated Silica with sulfonic acid (–SO3H) is reported, where the silica nanoparticles are first functionalized in situ with a tetrasulfide organosilane, followed by oxidation of the tetrasulfide moiety to –SO3H groups, which are grafted to the surface silanol groups through covalent linkage. Results: CHNS analyses and XPS prove successful functionalization of –SO3H group onto the nano silica surface. The resultant material acts as a solid acid catalyst and shows exceptional activity in the acetylation of benzyl alcohol and >99% selectivity towards the desired product benzyl acetate. The resultant material can also be recycled and reused several times. Conclusion: The following factors make sulfonic acid functionalized Precipitated Silica a new generation of solid acid catalyst; (i) higher atom economy, (ii) recyclability and reusability, and (iii) significant cost benefits with respect to industrial catalysts.

KIT-5 Structural and Textural Changes in Response to Different Methods of Functionalization with Sulfonic Groups.

In this project, KIT-5 materials were effectively functionalized with sulfonic groups introduced by grafting or the co-condensation method and tested as heterogeneous solid acid catalyst. A co-condensation procedure leading to the stable, -SO3H functionalized KIT-5 materials was successfully established. Moreover, the influence of both synthesis methods on the structural and textural parameters, as well as surface chemistry, morphology, and catalytic activity of -SO3H/KIT-5 materials was thoroughly investigated. The syntheses with 3-mepkaptopropyltrimethoxysilane (MPTMS) acting as a modifying agent resulted in samples in which functional groups were introduced into the structure and/or onto the mesoporous silica surface. The oxidation stage of -SH to -SO3H groups was carried out under mild conditions, using a "green" oxidant (H2O2). The application of different functionalization techniques and the introduction of different amounts of modifying agent allowed for an evaluation of the influence of these parameters on the ordering of the mesoporous structure of KIT-5 materials. The applied methods of assessment of the physicochemical parameters (XRD, low-temperature N2 sorption, TEM) showed that, especially when the co-condensation method was applied, as the number of functional groups increased, the ordering of structure characteristic of KIT-5 decreased. On the other hand, the samples modified by grafting had a stable structure, regardless of the amount of introduced MPTMS. Test reactions carried out on the basis of Friedel-Crafts alkylation process showed that the synthesized materials can be considered promising acid catalysts in heterogeneous catalysis reactions.

SO3H-functionalized carbon fibers for the catalytic transformation of glycerol to glycerol tert-butyl ethers

Carbon fibers (CFs) of high quality were produced from hydrocarbons such as isobutane or ethylene using the catalytic chemical vapor deposition method (CCVD) and Ni catalyst. The as-prepared samples were functionalized with acidic groups using concentrated sulfuric acid or 4-benzenediazonium sulfonate (BDS) generated in situ from sulfanilic acid and sodium nitrite. The morphological features of the materials were confirmed by transmission electron microscopy, whereas their physicochemical properties were characterized by means of elemental and textural analyses, thermogravimetric (TG) method, Raman spectroscopy, potentiometric back titration, and X-ray diffraction analysis. The obtained CFs were used as catalysts in glycerol etherification with tert-butyl alcohol at 110 °C under autogenous pressure. The BDS-modified CFs were particularly effective in the reaction, showing high glycerol conversions (of about 45–55% after 6 h) and substantial yields of mono- and di-glycerol ethers. It was found that the chemistry of the sample surface was crucial for the process. The high concentration of -SO3H groups decorating CFs boosted the formation of di- and tri-tert-butyl glycerol ethers. Surface oxygen functionalities also had a positive effect on the reaction, however, their impact on the catalytic performances of CFs was significantly weaker compared to that shown by -SO3H groups and it was probably due to the adsorption of reagents on the catalyst surface.

Effects of direct sulfonation on the catalytic activity and recyclability of novel lignin-based solid acid catalysts from agri-food waste

Catalytic systems derived from lignin are emerging as quite efficient and profitable materials in many catalyzed transformations. However, these catalysts have been predominantly synthesized by carbonization. Alternatively, we prepared direct sulfonation lignin (DSL) and compared it to the carbonized-sulfonated lignin (CSL) catalyst, aiming to reveal the effects of direct functionalization of lignin on its catalytic performance and to simplify its preparation. Both catalysts were well characterized by several physicochemical techniques, and their catalytic activities were assessed by catalyzed esterification. Using CSL, the yield reached 94.11 % under the optimal conditions (60 °C, 4 h and 50 mg loading), while DSL yielded 93.97 % with only 2 h under the same conditions, which is attributed to the abundant catalytic active sites in DSL (0.62 mmol/g of SO3H against 0.39 mmol/g for CSL). Furthermore, the activation energies were found to be 21 and 16 kJ mol−1 for CSL and DSL, respectively, suggesting that esterification can occur with less energy input using DSL. Reusability showed that leaching of SO3H groups and mass loss are inherently responsible for deactivation. However, both lignin-based catalysts show good stability and can be reused for 4 successive cycles. Direct lignin functionalization can be an alternative to conventional catalyst processing.

Sulfonic Acid-Grafted Hybrid Porous Polymer Based on Double-Decker Silsesquioxane as Highly Efficient Acidic Heterogeneous Catalysts for the Alcoholysis of Styrene Oxide.

β-Alkoxyalcohols generated from epoxide ring-opening reactions are significant due to their enormous value as pharmaceutical intermediates and fine chemicals. Using a phenyl-substituted double-decker-type silsesquioxane as the precursor, a hybrid porous material (PCS-DDSQ) was synthesized through a Scholl coupling reaction with an AlCl3 catalyst. Then, novel excellent Brønsted acid-derived silsesquioxane solid catalysts (PCS-DDSQ-SO3H-x) were successfully obtained through an electrophilic aromatic substitution reaction of chlorosulfonic acid on phenyl rings of PCS-DDSQ, fully characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, temperature-programmed desorption, water contact angle, Brunauer-Emmett-Teller model, thermogravimetric analysis, and solid-state 13C and 29Si nuclear magnetic resonance techniques. The catalytic behavior of the PCS-DDSQ-SO3H-x with different SO3H loadings for the methanolysis of styrene oxide was compared and evaluated. The presence of SO3H groups endows them with excellent catalytic abilities, achieving the highest values from PCS-DDSQ-SO3H-1 (the acid site of its catalyst is 1.84 mmol/g) as 99% conversion and 100% selectivity for the methanolysis of styrene oxide in 30 min, which shows superior catalytic properties of low dosage and high efficiency. Furthermore, the PCS-DDSQ-SO3H-1 catalyst can maintain high activity and selectivity after three cycles. This study provides a feasible method for the preparation of Brønsted solid acid catalysts with different acid loadings by introducing the sulfonic group into PCS-DDSQ.

Highly effective synthesis of biomass-derived furanic diethers over a sulfonated zirconium–carbon coordination catalyst in alcohol systems

A sulfonated zirconium–carbon coordination catalyst (Zr-GC-SO3H-1.0), containing Zr4+–O2−pairs and –SO3H groups, showed excellent catalytic activity, stability and universality for the synthesis of various biomass-derived furanic diethers.

Continuous conversion of furfural to furfuryl alcohol by transfer hydrogenation catalyzed by copper deposited in a monolith reactor

A polymer monolith catalytic reactor, which is fabricated by anchoring –SO3H groups on the surface of the fibers and by depositing Cu species, exhibits outstanding performance and high stability in continuous transfer hydrogenation of furfural.

One-pot reductive etherification of biomass-derived 5-hydroxymethylfurfural to 2,5-bis(isopropoxymethyl)furan over a sulfonic acid-functionalized zirconium-based coordination catalyst

A sulfonic acid-functionalized zirconium-based coordination catalyst (Zr-BDC-S60) containing Zr4+–O2−pairs and –SO3H groups showed satisfactory catalytic activity and stability for the one-pot reductive etherification of HMF to BIPMF.

Advances in production & activation of marine macroalgae-derived biochar catalyst for sustainable biodiesel production

Biodiesel is considered as a promising sustainable biofuel from renewable resources with lower pollutant emissions. However, high production cost, difficulty in recovering catalyst, and an expensive separation process associated with the use of homogeneous catalysts are still critical challenges. Heterogeneous catalysts derived from biomass are considered as viable options. Marine macroalgae-derived biochar owing to its vast surface area, diverse functional groups, presence of inorganics, and high porosity, could be considered as a suitable heterogeneous catalyst or as a supported catalyst for biodiesel synthesis. Thermochemical conversion processes, such as hydrothermal carbonization and pyrolysis, convert marine macroalgae biomass into biochar, which primarily composed of carbon, oxygen, and inorganics (Ca, K, Mg, Fe, etc.). The activation of macroalgae-derived biochar either physically or chemically played a vital role towards biofuel production. The catalytic activity and the performance of the macroalgae-derived biochar catalyst are influenced by its physicochemical properties (–SO3H group density, porosity, overall surface area, functional groups, and so on). Biodiesel production over marine macroalgae-derived biochar catalyst represents a more sustainable solution to current energy demands and develops economically beneficial biodiesel technology. This article provides a critical assessment of the marine macroalgae-derived biochar catalysts for the production of biodiesel. Initially, macroalgal biochar is produced through different thermochemical conversion technologies, including hydrothermal carbonization and pyrolysis, and its yield and physicochemical characteristics are discussed. After that, various techniques for the activation of macroalgae-derived biochar are discussed.

Sulfonic-functionalized MIL-100-Fe MOF for the removal of diclofenac from water

In this work, a novel adsorbent (MIL-100-Fe-AMSA), for the removal of the nonsteroidal anti-inflammatory drug sodium diclofenac (DCF), was prepared by grafting aminomethanesulfonic acid to the open iron sites in a porous MIL-100-Fe MOF obtained by a green microwave-assisted synthesis. The obtained materials were characterized by XRD, N2 adsorption-desorption, FTIR spectroscopy of adsorbed CO, electron microscopy and EDS spectroscopy. MIL-100-Fe-AMSA showed fast adsorption kinetics and an excellent maximum adsorption capacity of 476 mg/g. Synergistic effect of H-bonding, between the electronegative ionized –SO3H groups of MIL-100-Fe-AMSA and –NH group of DCF, and π−π interactions between the aromatic rings that are present in both MOF and pollutant, is probably the main mechanism of adsorption. In addition, the developed functionalized-MOF showed excellent reusability for at least five consecutive adsorption-desorption cycles, demonstrating its stability and potential for the removal of DCF. For practical applications, the prepared MIL-100-Fe-AMSA was incorporated into a 3D printed column for flow-through solid-phase extraction of pharmaceuticals pollutants before HPLC determination. The functional device showed excellent performance for the preconcentration and further detection and quantification of ketoprofen and DCF pollutants.

Silica modified sulphonated Poly(ether ether ketone) proton exchange membranes for DMFC application

Herein, we report sol-gel modified sulfonated poly(ether ether ketone) (SPEEK) organo-silane based composite proton exchange membranes for their suitability in direct methanol fuel cells (DMFCs). Different concentrations (0.2–1.5 wt%) of aminopropyl trimethoxysilane (APTES) are incorporated in SPEEK matrix by in-situ sol-gel method. Physico and electrochemical performances of composite membranes are enhanced by induced H-bonding interactions between free –NH2 and –SO3H groups. With increase in APTES concentration to 0.8 wt%, the ionic conductivity illustrates improvement by ⁓80% while IEC and Proton conductivity (Pc) enhances by ∼21% and ∼70%, respectively than SPEEK. To further explore the feasibility of the membranes in DMFC. Methanol crossover resistance is calculated to as low as 5.30 × 10−7 cm2 s−1 and offers highest selectivity of 4.43 S s cm−3 in contrast to 12.55 × 10−7 cm2 s−1 and 0.31 S s cm−3 for SPEEK, respectively. This study reveals that the Si-SPEEK membrane is a potential alternate for DMFC.

Functional molecular cross‐linked zeolite nanosheets heighten ion selectivity and conductivity of flow battery membrane

AbstractMembranes with high ion selectivity and conductivity are critical for the wide application of electrochemical energy conversion and storage devices. Herein, functional molecular cross‐linked two‐dimensional zeolite nanosheets (ZN) with ‐NH2 and ‐SO3H groups are prepared and incorporated into sulfonated poly (ether ether ketone) (SPEEK) polymer matrix. These embedded nanosheets act as strong barrier to vanadium ions, while their internal pores provide transport channels for protons. In addition, the side functional groups grafted on ZN not only effectively enhance the surface affinity, but also bind and arrange the sulfonic acid groups of the polymer matrix to construct a continuous fast proton transfer pathway along the interface between SPEEK and ZN. Consequently, the hybrid membranes exhibit synchronously enhanced conductive‐ion selectivity and impressive performance with coulombic efficiency (CE) of ~99.0% and energy efficiency (EE) of ~85.0% at 120 mA cm−2, which is much higher than these of pure SPEEK (CE: ~97.8%, EE: ~78.4%) and Nafion 212 membranes (CE: ~96.3%, EE: ~80.1%). This functional‐designed hybrid approach provides a general strategy to develop high‐performance proton conductive membranes for energy‐related applications.

Introduction of cellulose-binding site B–OH group onto carbon-based solid acid and its promoting effect on hydrolysis of cellulose

B–OH group was introduced into carbon-based solid acids by the method of low-temperature co‑carbonization. This method also ensures that the solid acid has a high density of –SO3H group. Adsorption kinetics and adsorption thermodynamics of cellobiose on the solid acid were discussed to analyze the adsorption mechanism. And further proved that B–OH group on the solid acid was a strong adsorption site of cellobiose. Therefore, the introduction of B–OH group greatly improved the affinity of the solid acid to cellulose. In addition, boron doping brought a series of positive changes to the structure of solid acid, which all contributed to improving the catalytic activity of solid acid. The hydrolysis activity of the solid acid was increased by 70.34% in comparison with the cellulose-based solid acid.

Brønsted acid catalyzed Prins-Ritter reaction for selective synthesis of terpenoid-derived 4-amidotetrahydropyran compounds

A number of SO3H-functionalized solids (biochar, montmorillonites, carbon and halloysite nanotubes) has been studied as catalysts in the cascade Prins-Ritter reaction of (-)-isopulegol with benzaldehyde and acetonitrile for synthesis of octahydro-2H-chromene amides (as 4R- and 4S-isomers). A high selectivity to these products at 30 °C in the presence of H2O was observed on catalysts modified with chlorosulfonic acid (CSA) reaching 84% (4R/4S of 5.7) in the case of biochar, while a relatively large amount of octahydro-2H-chromenols (up to 31%), products of Prins condensation, was formed on the materials functionalized by 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CSP). Although Prins condensation proceeds efficiently on weak acid sites, the Prins-Ritter reaction requires sulfated materials with strong (0.33 – 5.8 mmol/g) Brønsted acidity. Catalysts functionalized by CSP were stable, while for the materials modified with chlorosulfonic acid, leaching of -SO3H groups was observed. Nonetheless, on resistant Bioсhar-CSP, selectivity to the amides at 30 °C (67%) was higher than that with the commercial Amberlyst-15 (47%), and triflic acid at − 25 °C (62%). Similar selectivity to the desired products on Biochar-CSA (-SO3H groups) and H2SO4 (81–84%) as well as on Biochar-CSP (-PhSO3H) and with p-toluenesulfonic acid (67–70%) was observed. DFT calculations and experimental results showed that at 30 °C formation of 4S-amide thermodynamically is more beneficial than of alcohols and dehydration products. However, addition of water results in a sharp increase in the reaction rate and 4R-amide selectivity due to a change to the kinetic control, leading eventually to both high yields and stereoselectivity. The proposed reaction pathways also were confirmed by kinetic modelling.

Kinetic Parameters Investigation for The Esterification of Free Fatty Acid from Coconut Oil Mill Waste using Montmorillonite-Sulfonated Carbon from Glucose Composite Catalyst

Coconut oil mill waste (CMW) contained high free fatty acid (FFA) content which potentially could be converted into a value-added product such as fatty acid methyl ester (FAME). In this study, a montmorillonite-sulfonated carbon catalyst was used to evaluate the kinetic parameter of FFA conversion from CMW into FAME. The characterization of FTIR and SEM-EDX confirmed that the -SO3H groups were successfully incorporated into montmorillonite- carbon catalyst. The highest catalyst acidity (9.4 mmol/g) was achieved by a ratio of montmorillonite to sulfonated carbon of 1:3 % w/w. The kinetic study using montmorillonite-sulfonated carbon 1:3 % w/w showed that the reaction temperature and molar ratio of methanol to FFA (% v/v) were positively correlated to the reaction rate. The highest rate constant of esterification towards the product (k1), reactant (k2), and equilibrium were 0.1187, 0.0595, and 1.995, achieved by a temperature of 80 ˚C, respectively. The Arrhenius constant and activation energy towards the product were 3.3085×106 and 50.3 J/mole, respectively. The reaction temperature was positively correlated to the equilibrium constant, which indicated that the reaction was endothermic. The kinetic model validation revealed that the predicted value from the model was adequately in accordance with the experimental value, as indicated by a high coefficient of determination.

High performance proton exchange membranes with double proton conduction pathways by introducing MOF impregnated with protic ionic liquid into SPEEK

Metal-organic frameworks (MOFs) have great advantages in proton conduction due to their unique structures. Both the pores in the MOFs and the outer surface of the MOFs can be modified to conduct protons. In this paper, MIL-125-NH2 was used to support protic ionic liquid ([DBUH][BO2]) and introduced into sulfonated poly (ether ether ketone) (SPEEK) substrate to prepare novel proton exchange membranes. Inside the MOF, the cation of the ionic liquids and water molecules can form hydrogen bonds to achieve proton conduction. Meanwhile, the –NH2 groups on MIL-125-NH2 can form hydrogen bonds with the –SO3H groups on SPEEK to facilitate proton conduction outside the MOF. Due to the double proton conduction paths within the hybrid membranes, the highest proton conductivity of IL@MIL-125-NH2/SPEEK-5 is up to 0.32 S cm−1, which is much higher than that of many reported proton exchange membranes. In addition, IL@MIL-125-NH2/SPEEK-5 has good oxidation stability and proton conduction stability by the addition of MIL-125-NH2. This study provides novel insight into the preparation of stable proton exchange membranes with high proton conductivity.