SiOH Groups Research Articles

Unraveling the adsorption dynamics of asphaltene molecules on silica surfaces

Understanding the adsorption behavior of heavy oil components on reservoir solids is crucial for improving oil recovery, yet the molecular mechanism remains unclear. This study used molecular dynamics simulations to explore the adsorption kinetics and thermodynamics of asphaltene molecules on silica surfaces. The adsorption process was divided into three stages: free, adsorption, and equilibrium. In the adsorption stage, asphaltenes must pass through two dense hydration layers and adhere to the silica surface in a flat configuration. Carboxyl groups increase asphaltene hydrophilicity, raising interaction energy with water molecules and hindering adsorption. In addition, two distinct hydration layers of water molecules on the silica surface. The first hydration layer, with a peak density of 2000 kg m−3, was located around 0.6 nm from the surface, driven by hydrogen bonding between Si-OH groups and water molecules. The second layer, found at 1.44–1.80 nm, had a lower density of 1200 kg m−3, formed through hydrogen bonding between water molecules. This study aims to enhance the understanding of the physicochemical mechanisms governing oil droplet adsorption on silica surfaces, potentially informing the design of improved oil recovery strategies.

Mechanochemical preparation and performance regulation mechanism of highly durable and multifunctional iron red nanocomposite pigments derived from natural mixed-dimensional palygorskite clay

Iron oxide red pigments are one of the most widely used inorganic red pigments around the world. It is always pursed to improve their physicochemical properties. Herein, a continuous mechanochemical method was employed to fabricate high-performance iron red nanocomposite pigments via anchoring α-Fe2O3 nanoparticles on the surface of natural mixed-dimensional palygorskite clay (MDPal). The mechanical force of twin-screw extrusion promoted the Si-OH groups of MDPal to coordinate with Fe3+ to form the precursor, while MDPal was activated with the residual H+ of the involved nitrate to accelerate the thermal diffusion of Al3+ into α-Fe2O3 crystal lattice, thus the nanocomposite pigments presented a bright yellowish-red color (L∗ ​= ​35.61, a∗ ​= ​33.10, b∗ ​= ​35.86, C∗ ​= ​48.80). Furthermore, the mixed-dimensional nanostructure of MDPal served as a good substrate for chemical bonding of α-Fe2O3 nanoparticles to improve the dispersion and environmental stability of iron red pigments. Due to the synergistic effect of each component and the excellent thermal and chemical stability, the obtained nanocomposite pigments exhibited excellent application prospect as functional inorganic pigments for anti-corrosion coating, overglaze ceramic and coloring and reinforcing of polypropylene, respectively. It provided a facile strategy for preparation of high-performance multifunctional iron red pigments based on MDPal.

Fabrication of transparent silica glass and evaluation of silica particle dispersibility in silica slurries based on the solubility parameters of the slurry components

Silica particles were dispersed in 11 acrylic monomers at various concentrations. The dispersibility of the silica particles was evaluated based on the viscosity of the slurry. Furthermore, the relationship between the viscosity of the slurry and the solubility parameters (SPs) of the silica particles and acrylic monomers was investigated. When the SPs of the silica particles and acrylic monomers were close, the viscosity of the silica slurry decreased and high concentrations of the silica particles could be dispersed in the acrylic monomers. Therefore, SP can be used for predicting the dispersibility of silica particles. The prepared slurry was then used to fabricate sintered silica glass. Silica slurry was cured through photopolymerization to obtain a green body, which was then heat-treated at 850°C in air atmosphere and sintered at 1710°C under vacuum to obtain sintered silica glass. Transparent sintered silica glass with no cracks was obtained using 4-hydroxybutyl acrylate, which has a similar SP to that of silica particles, as a solvent. The obtained sintered silica glass exhibited a transmittance of 92% at a wavelength of 400 nm. In the ultraviolet region, light absorption originated from two-coordinated Si in the glass. The absorption spectrum in the infrared region showed an extremely low peak of the SiOH group, indicating that low-OH silica glass was obtained. Thus, this study provides a new method for fabricating silica glass and provides a method of selecting solvents for the slurries used in powder sintering.

Preparation of superhydrophobic coatings with excellent durability by synergistic reinforcement of cationic starch and tannic acid

The intrinsic hydrophilicity of sustainable and environmentally friendly biobased materials like starch and its derivatives limits their potential as hydrophobic functional materials. This study presents an eco-friendly and non-toxic method to create coatings with exceptionally high hydrophobicity. Octadecyltrimethoxysilane (ODS) reacts with nano silica (SiO2) through a silane coupling reaction to form superhydrophobic SiO2. The Si-OH groups generated from ODS hydrolysis can undergo a condensation reaction with tannic acid (TA), which is rich in phenolic hydroxyl groups. This enables the hydrophobic silane to bind indirectly with cationic starch (CS), resulting in a stable superhydrophobic CS-based coating. The coating demonstrates significant hydrophobicity (contact angle >170°), excellent UV light transmittance (<4.05 %), self-cleaning properties, prolonged shelf life (over eight months), antibacterial activity, and encapsulation capability. It also shows a separation efficiency exceeding 99 % after 25 oil-water separation cycles and is easily recoverable. The study elucidates the mechanism behind the preparation process and the factors enhancing hydrophobic properties. The research findings suggest that the novel, cost-effective CS/TA/ODS/SiO2 coating offers a scalable solution for superhydrophobic applications and broadens the horizon for green starch use in hydrophobic materials.

Preparation and characterization of silica sol-impregnated glass fibers

Abstract Silica sol-impregnated glass fiber products were prepared via the sol-gel method, with tetraethoxysilane (TEOS) as a precursor and hydrochloric acid (HCl) as a catalyst, and characterized by 1H NMR, FT-IR, and solid 29Si NMR analyses. The results indicated that the structure of the impregnating agents was significantly affected by the amount of water added. With a decrease in the molar ratio of added water, the degree of TEOS hydrolysis was reduced, and more ethoxy groups -OCH2CH3 were formed, resulting in the formation of sol products with a linear structure. Furthermore, contact angle and water absorption tests showed that as the molar ratio of water increased, the water contact angle decreased, whereas the water absorption of impregnated glass fiber increased. These results indicate that a higher hydrolysis degree of TEOS with more added water generates more Si-OH groups, facilitating the cross-linking of sol products to form a network structure.

NiO/vermiculite composites prepared for photocatalytic degradation of methanol-water solution and hydrogen generation

A novel eco-friendly NiO/Vm clay based photocatalysts were synthesized from two vermiculites (Vm1 and Vm2) and nickel(II) nitrate hexahydrate (Ni(NO3)2·6H2O salt precursor by the chemical precipitation without and with the sodium hydroxide (NaOH) or ammonium hydroxide (NH4OH, 28% NH3 in H2O) as precipitation agents (Synthesis A) in comparison with the solid-state thermal decomposition (Synthesis B) at 600 °C. Structural properties of all specimens were characterized by X-ray fluorescence, scanning electron microscopy, X-ray diffraction, infrared (IR) and Raman spectroscopy. The photocatalytic performance of NiO/Vm composites was evaluated under UV radiation (λ = 254 nm) for decomposition of methanol-water to hydrogen over 4-h and the stable yield of hydrogen over the 24-h periods. The NaOH and NH4OH affected the NiO crystallite size and therefore the photocatalytic activity during 4 h. Different 2:1 layer charge of Vm1 (0.82 e−) and Vm2 (0.40 e−) and the specific surface area of Vm1 (about 43 m2/g) and Vm2 (about 34 m2/g) supported H2 yield of 628.2 μmol/gcat. and 596.8 μmol/gcat., close to 657.0 μmol/gcat. produced in the presence of commercial photocatalyst TiO2 Evonik P25. Crystalline NiO precipitated and anchored in NiO/Vm composites contained smaller crystallites than those in free NiO. Vermiculite silica surface supports coverage of NiO by hydrogen bonding to Si-OH groups influencing the geometry of the NiO crystal structure (disorder NiO(X)). The heterojunction with Si-O-Ni bonding, at which electrons transfer from Vm to NiO cause enriching electron density in NiO and favoring its photocatalytic activity. Photocatalytic hydrogen generation from methanol–water mixture at the presence of all specimens indicated the main product H2 and minimum by-products CH4 and CO. The stable hydrogen production for 24 h was confirmed only in the presence NiO/Vm1–24 while maintaining the NiO(X) in small crystallites. The thermal solid-state procedure provided the gradual dehydration of vermiculites and Ni(NO3)2·6H2O to the same amount and crystallinity of NiO in NiO/Vm1 and NiO/Vm2 composites. The results of this work confirm that vermiculites mixed layer structures with different negative layer charge play a dominant role as semiconductors for anchored NiO. The photocatalytic activity of NiO/vermiculite composites can be harnessed to treat wastewater containing organic contaminants.

Efficient separation of quartz from hematite for a novel quaternary ammonium collector: Separation performance, comparative study and adsorption mechanism

N-(2-hydroxyethyl)-N, N-dimethyl-3-[(1-oxododecyl)amino]-1-propanaminium (LPDC) was firstly reported in cationic flotation of quartz from hematite. The micro-flotation results demonstrated the superior quartz-collecting properties of LPDC. Under the condition of natural pulp pH, the optimal separation was achieved with LPDC and starch concentrations of 15 mg/L and 3 mg/L, respectively. The iron recovery was above 97 % and iron grade reached 64.75 %. The bench-scale flotation results showed that LPDC had a superior separation effect than dodecylamine (DDA). Moreover, contact angle, atomic force microscopy (AFM), Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations were employed to study the separation mechanism. The adsorption of LPDC on quartz surface was shown to be mainly dependent on electrostatic adsorption of quartz surface with LPDC+ and hydrogen bonding between the Si-OH groups and the hydroxyl groups. LPDC occurred more interaction sites and produced stronger hydrogen bonds on the quartz surface than DDA.

Influence of the steric bulk of a trityl group in the formation of molecular metallosilicates

The molecular silanol (Ph3CO)(iPrO)2Si(OH) was designed to evaluate the degree of steric bulk the trityl moiety imposes on the Si–OH group. The reactivity of the silanol was evaluated by the formation of three metallosilicates with lithium, aluminum, and gallium, and their molecular structures and the degree of association were determined. Hirshfeld atom refinement or DFT calculation, and QTAIM analysis of the electron density in all compounds were used to analyze the bonding situation in the metallosilicate moieties and determine the strength of the intermolecular hydrogen bonds formed by the silanol. Finally, ring-opening polymerization of ε-caprolactone was used as another criterion for the evaluation of the steric bulk imposed by the trityl group.

Hybrid sol-gel silane composite coating reinforced with a hybrid organic/inorganic inhibitive pigment: Synthesis, characterization, and electrochemical properties

This work aims to develop environmentally friendly silane coating reinforced with a hybrid pigment to protect mild steel against corrosion in a saline environment. Fourier-transform infrared (FT-IR) spectroscopy, contact angle (CA) measurement, field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) were used to study the coating structure and its protective mechanisms. The presence of hybrid pigment led to the conversion of more Si–OH groups into Si–O–Si groups during condensation process increasing the cross-linking density of silane; the enhanced cross-linking yields the coating with lower defects and stronger adhesion to substrate and so improved barrier and anti-corrosion properties. The EIS test showed that the charge transfer resistance (Rct) for the sample coated with hybrid sol-gel silane increases up to 40 % for all immersion times after the incorporation of the hybrid pigment into the coating matrix. The polarization test showed that the corrosion current density (icorr) value decreases from 1.40 to 0.56 μA/cm2 after 120 h of exposure to the saline solution when the hybrid pigment is added to the coating matrix. These results demonstrate the inhibitive action of the hybrid pigment enhancing the protective performance of the sol-gel silane coating.

Correlation the microstructure and magnetic properties of Fe-Ni-Mo soft magnetic composites fabricated via polymer-derived ceramics

The coatings play a crucial role in enhancing the performance of soft magnetic composites (SMCs). This study aims to create coatings for Fe-Ni-Mo SMCs using polysilazane (PSZ) as the precursor. The transformation mechanism of the PSZ/resin mixture is studied by analyzing functional groups and chemical bonds at various temperatures. During the self-polymerization process of PSZ at 350 °C, N–H, C = C–H, Si-H bonds, –CH3, and Si-CH3 groups undergo crosslinking reactions to form C–C and Si-N bonds. When the temperature reaches 600 °C, PSZ polymer cleavage, O-Si-C and Si-N-Si bond dominate in the coating. Additionally, PSZ can effectively enhance the heat resistance of silicone resin through its reaction with Si-OH groups, which has a significant effect on increasing the resistivity of SMCs and reducing high frequency core loss. Optimizing the PSZ content to 0.5 wt% enhances the magnetic properties of Fe-Ni-Mo SMCs, resulting in a μe of 74.0 at 100 kHz and a corresponding core loss (Pcv) of 547.7 mW/cm3 at 100 kHz/100 mT. The findings provide valuable insights for optimizing PSZ content to improve magnetic performance in SMCs.

What Determines the Low-Friction Mechanism of the Silicon-Doped Diamond-like Carbon Film in a Water Environment: An Atomic-Level Understanding.

It is widely acknowledged that doping silicon can significantly enhance the friction performance of diamond-like carbon (DLC) films in a water environment. However, the mechanism of low friction caused by doped silicon is still highly controversial. Therefore, this article compares the interface interaction between DLC and Si-DLC films in a water environment through first-principles calculations of physisorption and chemisorption effects. The results indicate that water molecules are predominantly chemically adsorbed rather than physically adsorbed on the Si-DLC surface. Further study reveals that when OH-termination is formed on the Si-DLC surface, water molecules are predominantly physically adsorbed rather than chemically adsorbed on the Si-DLC hydroxylation surface. Consequently, a more stable hydration layer is formed on the surface through the hydrogen bond network formed by Si-OH groups, ultimately leading to lower friction. Moreover, molecular dynamics simulations further suggest that the lower friction coefficient of Si-DLC films in a water environment may be due to more water molecules at the friction interface and fewer interface covalent bonds. In short, the low-friction coefficient of the Si-DLC film in a water environment may be caused not only by the chemisorption of water molecules on its surface but also by the physisorption of water molecules on the Si-DLC film after surface hydroxylation.

Enhanced CO2 conversion with CH4 for greenfuel generation using coke-neutral nickel-loaded fibrous silica titania catalysts

This study reveals a groundbreaking advancement in utilizing carbon dioxide (CO2) for syngas production through methane (CH4) dry reforming using Fibrous Silica Titania (FST) as a support, loaded with different (1%, 3%, and 5%) nickel dosages. FST is distinguished by its fibrous structure, maintains a stable temperature, facilitates the confinement and dispersion of active metal, and is exceptionally effective at preventing carbon deposition. For a thorough examination of the new catalysts, characterization methods including XRD, FESEM, EDX mapping, N2 physisorption, FTIR-KBr, H2-TPR, and CO2-TPD were employed. Importantly, TEM lattice fringes verified the existence of XRD peaks and planes of Ni (111), Ni (200), and TiO2 (101). Aspects such as O-H stretching, Si-O-Si asymmetry, vibrations caused by external Si-OH groups, and Si-O-Si bending were identified using FTIR-KBr analysis. The study ingeniously identified the superior (3Ni/FST) catalyst, which exhibited moderate basicity sites on the CO2-TPD at approximately 350 °C. The catalyst converted nearly 100% CH4 at 750 °C with minimal coke production and 80% CO2 at 850 °C. Surprisingly, the 3Ni/FST catalyst demonstrated remarkable stability during a 72 h TOS stability test at 650 °C, effectively preventing coke-forming side reactions such as CO disproportionation, CO hydrogenation, CO2 and CH4 cracking with syngas ratio around unity and little coke production. The FST support exhibited exceptional attributes for low temperature carbon neutral CH4 reforming.

Silica-supported ionic liquid for efficient gaseous arsenic oxide removal through hydrogen bonding

The emission of highly-toxic gaseous As2O3 (As2O3 (g)) from nonferrous metal smelting poses environmental concerns. In this study, we prepared an adsorbent (SMIL-X) by loading an ionic liquid (IL) ([HOEtMI]NTf2) into MCM-41 through an impregnation–evaporation process and then applied it to adsorb As2O3 (g). SMIL-20% exhibited an As2O3 (g) adsorption capacity of 35.48 mg/g at 400 °C, which was 490% times higher than that of neat MCM-41. Characterization of SMIL-X indicated that the IL was mainly supported on MCM-41 through O–H…O bonds formed between the hydroxyl groups (–OH) and the silanol groups (Si–OH) and the O–H…F bonds formed between the C–F groups and the Si–OH groups. The hydrogen bonds significantly contributed to the adsorption of As2O3 (g), with –NH and –OH groups forming hydrogen bonds with As–O species (i.e., N–H…O and O–H…O). This showed superior performance to traditional adsorbents that rely on van der Waals forces and chemisorption. Moreover, after exposure to high concentrations of SO2, the adsorption capacities remained at 76% of their initial values, demonstrating some sulfur resistance. This study presents an excellent adsorbent for the purification of As2O3 (g) and shows promising application potential for treating flue gas emitted by nonferrous metal smelting processes.

Sensitive quantification of the surface Si–OH group in MQ silicone resins by benzoylation and GPC−UV analysis

The content of the Si–OH group markedly affects the physical and chemical properties of MQ silicone resin (MQ) and its secondary processing products. However, current methods for the determination of the Si–OH group are still unsatisfactory due to their insensitivity and inaccuracy. Herein, an accurate analytical method has been developed for the determination of the active Si–OH group in MQ based on benzoylation and GPC–UV analysis. The UV-insensitive Si–OH group in MQ was converted to a UV-sensitive benzoyl group by the benzoylation with p-methoxy benzoyl chloride, which greatly improved its detection sensitivity. The interference of water was also excluded by the introduction of GPC separation. The effect of several derivatization parameters was investigated and optimized, and complete benzoylation of the Si–OH group in MQ was achieved under the optimized experimental parameters. Good linearity was obtained in a range of 0.425–42.5 μg/g for the content of the Si–OH group in MQ, with a correlation coefficient greater than 0.999. Reasonable reproducibility was also obtained, with the intraday RSD (N = 3) of 1.78 % and the interday RSD (3 days) of 3.98 %, respectively. This method has been successfully applied for the determination of the active Si–OH group in several commercial MQs.

Zeolitic Pickering Emulsifier with Intrinsic Amphiphilicity.

The formation of oil-in-water Pickering emulsions stabilized by lamellar zeolite MWW (International Zeolite Association, three-letters code) emulsifier without surface grafting is investigated. The crucial emulsification factors are the oligolayer morphology and amphiphilicity developed upon acidic treatment (NH4+ exchange/calcination, HNO3 treatment). In contrast with the readily available/abundant hydrophilic ≡Si-OH group in layer MWW, the lipophilicity generated by strong acid sites is another key to the success of emulsification. Hydrocarbon-strong acid site interaction is long known in petrochemistry and superacid research. However, to the best of our knowledge, this interaction was first introduced to gain lipophilicity in emulsion formation. Finally, the Pd-loaded acidic form of the MWW zeolite successfully stabilized the toluene/H2O emulsion system. The biphasic interfacial nitroarene hydrogenation demonstrated excellent catalytic performance. Overall, this work provided not only a new kind of intrinsic solid to emulsify the organic-aqueous biphase system but also a new mechanism to generate lipophilicity. Both are important for the applications and designs of Pickering emulsion materials.

Ordinary hydrophobicity of mesoporous faujasites boosting the catalytic ketalization of glycerol with acetone

A series of faujasite zeolites were used in the glycerol ketalization reaction with acetone. This zeolitic structure is widely explored in cracking reactions and has known mesoporosity and hydrophobicity, resulting from the treatments conducted to remove aluminum atoms from the framework and produce a stabilized structure containing different Si/Al ratios. Such properties, in combination with the typical acidity of zeolites, are extremely suitable for driving the ketalization reaction, a two-phase reaction that involves bulky compounds (compared to the size of the zeolitic pores) and that is reversible with the formation of water as a byproduct. The presence of mesopores in the zeolites was confirmed from the pore size distribution using nitrogen physisorption isotherms. Hydrophobicity was confirmed indirectly by thermogravimetry, measuring the amount of water adsorbed and the water desorption temperature. The contact angle of zeolites with glycerol showed only a slight increase with the increase in the Si/Al ratio due to a rise in SiOH groups, defects that naturally arose from removing aluminum atoms. Despite the high concentration of structural hydrophilic SiOH groups, the accessibility and hydrophobicity of isolated Brønsted acid sites (up to Si/Al = 250) inside the zeolitic pores were important to guarantee an improved performance in the reaction.

Precise Structural and Dynamical Details in Zeolites Revealed by Coupling-Edited 1H-17O Double Resonance NMR Spectroscopy.

Despite the extensive industrial and research interests in zeolites, their intrinsic catalytic nature is not fully understood due to the complexity of the hydroxyl-aluminum moieties. 17O NMR would provide irreplaceable opportunities for much-needed fine structural determination given the ubiquitous presence of oxygen atoms in nearly all species; however, the low sensitivity and quadrupolar nature of oxygen-17 make its NMR spectroscopic elucidation challenging. Here, we show that state-of-the-art double resonance solid-state NMR techniques have been combined with spectral editing methods based on scalar (through-bond) and dipolar (through-space) couplings, which allowed us to address the subtle protonic structures in zeolites. Notably, the often-neglected and undesired second-order quadrupolar-dipolar cross-term interaction ("2nd-QD interaction") can actually be exploited and can help gain invaluable information. Eventually, a comprehensive set of 1H-17O/1H-27Al double resonance NMR with J-/D-coupling spectral editing techniques have been designed in this work and enabled us to reveal atomic-scale precise structural and dynamical details in zeolites including: 1) The jump rate of the bridging acid site (BAS) proton is relatively low, i.e., far less than 100 s-1 at room temperature. 2) The Al-OH groups with 1H chemical shift at 2.6-2.8 ppm, at least for nonseverely dealuminated H-ZSM-5 catalysts, exhibit a rigid bridging environment similar to that of BAS. 3) The Si-OH groups at 2.0 ppm are not hydrogen bonded and undergo fast cone-rotational motion. The results in this study predict the 2nd-QD interaction to be universal for any rigid -17O-H environment, such as those in metal oxide surfaces or biomaterials.

The influence of sodium silicate water glass content on the structure and properties of silicate thermal insulation coating

Thermal insulation slurry was fabricated using sodium silicate water glass (SSWG) as the film-forming material and hollow glass microspheres (HGM) as thermal insulation fillers. The thermal insulation slurry was coated on 316L stainless steel to fabricate a silicate thermal insulation coating. The results show that SiO2 phase is formed by SSWG in the thermal insulation coating after sintering at 680 ℃. Through polymerization and dehydration reactions between Si-OH groups, the Si-O three-dimensional network structure develops at 680 ℃. The optimal value of SSWG to aggregate mass ratios is 2.00. Under this condition, the silicate thermal insulation coating exhibitssmoothsurface, continuous and dense microstructure, high Shore hardness of50.1 HSD,remarkablethermal insulation efficiency of21 %at260 ℃, andexcellentresistance to drop and thermal shock tests without anynoticeablecracks or detachment.

A novel iron-doped mineral/carbon composite electrocatalyst synthesized by reconstituting ash phase of coal gasification fine slag for synergistically improving electrooxidation efficiency

Coal gasification fine slag is typical coal-based solid waste, and the crux to its resource utilization is the co-utilization of carbon and ash. A novel iron-doped mineral and carbon composite electrocatalyst (Fe-FSAPH) was synthesized by depolymerizing and reconstituting the ash phase for the collaborative electrocatalytic degradation of m-cresol wastewater. Exogenous iron participated in and promoted mineral reconstitution, increasing Si(-O)1/Si(-O)3 ratio (0.37→1.18) and promoting the formation of active Si-OH groups. The iron-doped minerals dispersedly developed with a sheet-like on carbon matrix, which improved intimate physical proximity and synergistic behavior of carbon/minerals. The obtained Fe-FSAPH, with a specific surface area of 246.52 m2/g, has a large diffusion rate constant KD2 (2.98 mg·min−0.5/g) in the rate-limiting step of m-cresol adsorption. Its electrochemical performances exhibit excellent, including cyclic voltammetry charge of 8.52 mC/cm3, charge-transfer resistance of 0.59 Ω, and Tafel slope of 159 mV/dec. The m-cresol with a concentration of 194.67 mg/L could be electrooxidized within 18 min due to the abundance of •OH and O2•- in the Fe-FSAPH system, which accelerated the radical attack reaction. Moreover, Si-OH groups catalyzed conversion of •OH to O2•- by generating oxygen vacancies and undergoing dehydroxylation, shortening the rapid reaction time of m-cresol removal to 14 min. The introduction of iron enhanced the synergy of carbon and minerals, with •OH generated via the Fenton-like reaction, offering a convenient environment for mineral catalysis. Hence, the study provided new ideas for the comprehensive utilization of carbon and ash and treatment of waste by waste.

In-situ interfacial polymerization of polyamide TFN membranes by adding a diamino-silane coupling agent: Toward enhanced desalination performance

The primary challenge faced by thin film nanocomposite (TFN) membrane in nanofiltration (NF) process is to effectively resolve the trade-off effect between permeability and selectivity. Herein, a polyamide (PA) TFN membrane with enhanced NF performance was prepared through in-situ interfacial polymerization (in-situ IP) method, using piperazine (PIP) and 3-diamino-methyl-cyclohexyl triethoxysilane (DTES) as co-amine monomers to undergo a reaction with 1,3,5-benzenetricarbonyl trichloride (TMC). This study investigated the effects of DTES on the surface chemical composition, morphologies, hydrophilicity, separation efficiency, and anti-fouling properties of the novel DTES/PIP/TMC TFN membranes. It was found that SiO2 nanoparticles were generated in-situ from the reacted DTES through hydrolysis and self-condensation, resulting in their uniform distribution within the formed PA selective layer with high compatibility and without aggregation. The optimal PA TFN membrane was achieved by adjusting the ration of Si-OH group in formed SiO2 nanoparticles through varying the concentration of DTES concentration. Meanwhile, the induction of SiO2 into the PA layer resulted in an enlargement in membrane pore size and improved surface hydrophilicity. When the concentration of added DTES was 0.333 wt%, the optimal PA TFN membrane (TFN-4) exhibited the highest quantity of formed Si-OH groups, resulting in the excellent performance, including a markedly enhanced water permeability flux of 76.8 L·m−2·h−1 (2-fold larger than that of the pure TFC membrane), a great Na2SO4 rejection of 97.5 %, and a superior Cl−/SO42− permeation selectivity of 46.0. Moreover, the TFN-4 membrane exhibited exceptional stability and superior antifouling properties attributed to its unparalleled hydrophilicity. This work provided a strategy for preparing uniform and high-performance TFN membranes.