Narrow Pore Size Distribution Research Articles

Waste cigarette filters-based polymer blends membrane for filtration of high loaded natural organic matter river water

Waste cigarette filter (WCF) is one of the most common wastes found in the environment. Cigarette filters contain up to 96% cellulose acetate (CA), which can be used as a material for membrane fabrication. However, the CA-based membrane from WCF posed a weak mechanical property (brittle). Therefore, the objective of this work is to improve mechanical property of CA-based membrane from WCF by preparing blend membranes with polyvinylidene fluoride (PVDF) polymer and evaluate their performance for filtration of real river water containing high natural organic matter (NOM) concentrations. The variations of WCF and PVDF used were 100:0, 75:25, 50:50, 25:75, and 0:100. The membranes were then characterized to determine the morphology, pore size and pore size distribution, hydrophilicity, mechanical properties, and filtration performance of the membrane using clean water and river water. The SEM test results showed the presence of spherulites on the surface of the blend membrane, indicating that crystallization occurred during membrane formation. The spherulites resulted in smaller pore size, narrower pore size distribution, higher hydrophilicity, and mechanical properties. Meanwhile, the filtration test results showed that blend membranes produced higher permeability compared to pristine WCF, PVDF, and commercial-based CA membranes, where the result of river water permeability was in the range of 875–1062.5 L/m2.h.bar. The membrane fouling formation was aligned well with the result of permeability and is dominated by irreversible fouling formation from the dynamic cake layer built on the membrane surface, with NOM rejections of 26.6–33.8%, suggesting the need for further developments.

Pore-scale study of coupled heat and mass transfer during primary freeze-drying using an irregular pore network model

This study presents a pore network (PN) model with transient heat transfer and quasi-steady transitional vapor transport that is for the first time applied to irregular porous structures that are obtained by reconstruction of X-ray tomography image data. In contrast to previous studies, the irregular pores are not approximated by spheres but implemented in their original shape. Secondly, instead of assuming cylindrical throats as pore connections, the actual distance between pore centers as well as the pore cross sections are used for the computation of the vapor transport coefficient. The control volume elements of the computational model are matched with the cells obtained by Voronoi tessellation. The improvements have clear advantages over former approaches where the reconstructed void space is usually strongly simplified by balls and sticks confined in a regular lattice structure. A freeze-dried sample of maltodextrin DE12 with 20% (w/w) solid content is used for benchmarking the new methodology. Its morphological and thermal properties are determined by the novel PN model. The simulation results of primary freeze-drying (FD) are compared to reference cases in two ways. First, the differences in heat and mass transfer kinetics as compared to regular PNs are emphasized. Secondly, the PN simulation results are confronted with a simple literature model that neglects pore size distribution (PSD) and transient heat transfer. It is shown that already in small domains with relatively narrow PSD, the variation of the mass transfer coefficient affects the computed sublimation fluxes and yields a significant deviation from the simpler literature model. Moreover, it is revealed in this study that the structure has a significant impact on the sublimation front temperature. This is demonstrated by the comparison of FD in the irregular PN to a regular PN with almost identical PSD but different porosity. The development, verification, and benchmarking of the new PN model can be seen as an important step for studies of the structure dependence of FD.

Magnesium nitrate-tricine nanoparticles: Temperature impact to enhancing third order optical nonlinearity

Nano-hybrid promoted as materials with improved optical properties. The aim of this study was to analyze differences in optical properties at micro-scale. This research focuses on the impact of reaction temperature during the creation of magnesium nitrate-tricine nanoparticles through chemical vapor deposition. The study investigates how temperatures of 200°C and 300°C affect the particle size, crystallinity, and morphology of the nanoparticles. Optimizing these properties is essential for achieving the desired third-order NLO effect. By understanding the influence of temperature on nanoparticle characteristics, researchers can develop more effective NLO materials for future photonic devices. This study explores the chemical and structural differences between MNT 300 and MNT 400 materials using various techniques. Spectroscopic analysis reveals similarities in both materials with a shared peak at 1400 cm−1. However, MNT 400 exhibits additional peaks suggesting the presence of aromatic rings, nitro compounds, or variations in N–H bonds. Both MNT 300 and MNT 400 exhibit micro porous behaviour with a narrow pore size distribution around 14 nm to 15 nm, indicating tightly packed structures. Transmission Electron Microscopy analysis shows a wide particle size range (2 nm to 200 nm) in both materials, suggesting the presence of atomic clusters, individual molecules, and potentially agglomerated structures. FT-Raman spectroscopy reveals higher intensity peaks in MNT 400, which could be due to a higher concentration of specific bonds, a more ordered structure, or enhanced Raman scattering. This suggests greater crystallinity or molecular uniformity in MNT 400 compared to MNT 300.

An Engineering Porous Spherical Carbon Cathode for High-Energy Sodium-Ion Capacitor.

Sodium-ion hybrid capacitors (SICs) are emerging as promising devices that can balance energy and power output. However, the lack of a high-capacity cathode that can match the anode has limited its further application. In this work, we develop an efficient method to prepare spherical porous carbons (SPCs) with great specific surface area and narrow pore size distribution from coal-based humic acid via spray drying and a subsequent chemical activation process. Thanks to this unique porous structure, the SPC cathode has a superb capacity of 223 F g-1 at 0.05 A g-1, as well as splendid rate performance and cycling stability. SICs constructed by an SPC cathode and hard carbon anode can exhibit a high energy density of 179.8 Wh kg-1 at 155 W kg-1 and achieved 89.4% capacity retention after 10 000 cycles at 0.5 A g-1. This outcome presents a viable approach to attaining high-capacity cathodes for constructing outstanding performance hybrid capacitors.

Porous organic cage induced high CO2/CH4 separation efficiency of carbon molecular sieve membranes

Porous fillers have been incorporated into precursor membranes to fabricate carbon molecular sieve (CMS) membranes, where the interfacial compatibility between fillers and matrix significantly influences the separation performance of converted CMS membranes. To address this issue, we introduce molecular fillers of porous organic cages (POCs) into precursor membranes, the organic composition and discrete molecular characteristics of which can enhance the compatibility with the polymer matrix (PIM-1), bringing enhanced porosity and narrowed pore size distribution, especially in the ultra-micropore region, to the CMS membranes. The obtained CMS membrane shows simultaneously improved gas permeability and selectivity wherein the optimized CMS membrane pyrolyzed at 600 °C with 10 wt% POCs loading (CMS-10%-600) exhibits a CO2 permeability of 2002 Barrer and a CO2/CH4 selectivity of 221.6, surpassing the 2019 CO2/CH4 upper bound and superior to most of reported CMS membranes. Due to the incorporation of POC, the CMS-10%-600 membrane demonstrates a 147.5 % increase in CO2 permeability and a 297.1 % increase in CO2/CH4 selectivity compared to pristine PIM-1-based CMS membrane, along with the excellent aging resistance for over 30 days. This study provides new insights into the design of high-performance CMS membranes for gas separation.

Ultrasound-assisted freezing for the preparation of aerogel-based intelligent packaging

Due to their highly porous and high specific surface area, aerogels are promising materials for intelligent food packaging. However, aerogel-based intelligent packaging prepared by traditional freeze-drying methods severely limits the preparation efficiency and the packaging performance of the aerogels due to the low freezing efficiency and the large and uncontrollable pore size caused by the uncontrolled growth of the crystals during freezing; this leads to the destruction of the aerogel structure. In this study, an aerogel-based food intelligent packaging was prepared using gelatin and gum Arabic (GG) as the substrate materials for real-time shrimp freshness detection. An ultrasound-assisted freeze-drying (UAFD) strategy was applied to improve the freezing efficiency of the cavitation-induced nucleation of aerogel. By affecting secondary nucleation, the UAFD-160 W strategy produced aerogels (GG-160) with smaller pore sizes (14.76 μm) and narrower pore size distributions than those using intelligent packaging prepared by the traditional freeze-drying method (GG-0, pore size = 254.14 μm). Due to the advantages of the above structure, the GG-160 aerogel has a significantly improved hardness (28956.5 ± 101.6 N), excellent water resistance and hydrophobicity (93.6 ± 0.99°), sensitive ammonia responsiveness, and stable properties under high humidity. Consequently, compared with that in the GG-0 treatment, the color of the shrimp in the GG-160 treatment was more sensitive to spoilage. The proposed UAFD strategy provides a new way to improve the properties of aerogels by structural modulation such that the prepared aerogels have better food packaging applications.

A novel 3D hierarchical NiFe-LDH/graphitic porous carbon composite as multifunctional adsorbent for efficient removal of cationic/anionic dyes and heavy metal ions

Developing effective adsorbents for wastewater purification is crucial, as excessive emissions of toxic dyes and heavy metal ions have been proven harmful to ecosystems and human health. A NiFe-layered double hydroxide/graphitic porous carbon (NiFe-LDH/GPC) composite was fabricated by introducing NiFe-LDH nanosheets into GPC via a simple hydrothermal method to utilize the advantages of both materials fully, and thus ultimately obtain a composite adsorbent with improved adsorption properties. The samples obtained were comprehensively characterized by various characterization means, and the effects of several critical influential factors on the pollutant uptake capability of the NiFe-LDH/GPC were also studied through batch experiments. The results show that the as-synthesized NiFe-LDH/GPC exhibits a three-dimensional (3D) fluffy ultrathin-wall hierarchical porous structure, which possesses a high specific surface area and pore volume separately up to 506.74 m2/g and 0.22 cm3 g−1 as well as a relatively narrow pore size distribution. These characteristics bring advantages to enhance the adsorption ability of the NiFe-LDH/GPC for cationic/anionic dyes and heavy metal ions such as congo red (CR), malachite green (MG) and hexavalent chrome (Cr(VI), which reached the maximum adsorption capacity of 1726.51 mg/g, 1157.11 mg/g and 155.72 mg/g under the optimum conditions, respectively. Meanwhile, the adsorption behavior can be well described by the pseudo-second-order kinetic model and Langmuir isotherm model, reflecting that the sorption process mainly occurred chemically in the adsorbent monolayer. Furthermore, the NiFe-LDH/GPC maintained relatively high adsorption performance after multicycle testing, manifesting its good recyclability and stability.

Petroleum residue-based ultrathin-wall graphitized mesoporous carbon and its high-efficiency adsorption mechanism

Creating petroleum residue-based new functional materials are vital for the sustainable development of petroleum residues. This study developed a method to prepare a petroleum residue-based ultrathin-wall graphitized mesoporous carbon (PGMC) with high specific surface area by the carbonization of a composite of the petroleum residue uniformly mixed with aluminium isopropoxide. Results show that the PGMC possesses a highly fluffy ultrathin-wall mesoporous structure with a high degree of graphitization. It had a high specific surface area of 1174 m2 g−1 with a high pore volume of 4.57 cm3 g−1 and a narrow pore size distribution at 8.09 nm. These unique features endow the PGMC with excellent adsorption properties for Congo red, Malachite green, and Methylene blue removal. The experimental data were better described with Freundlich isotherm and Quasi-second-order kinetic models. Thermodynamic analysis indicated a spontaneous and endothermic adsorption process. The adsorption mechanisms proposed that pore-filling effect, π-π conjugation, and electrostatic interaction were the main interactions between the PGMC and dyestuff, followed by functional groups and hydrogen bonding. Moreover, the PGMC could maintain good adsorption rates after five cycles, proving that it is an effective adsorbent with good adsorption ability and cycling stability.

Structural Diversity Enables Dramatic Changes in Photocatalytic Efficiency of Porphyrinosilica Particles in Chem-Bio Binary Applications

Because of their potential applications in catalysis, separation, and gas storage, porous materials such as metal–organic frameworks (MOFs), porous coordination polymers (PCPs), porous organic polymers (POPs), and polymers with intrinsic microporosity (PIMs) have received much attention. Various building blocks have been introduced with various functional groups. Among the various organic building blocks, porphyrin has become one of the most important building blocks for the construction of such materials witnessed by a wide range of molecular architectures using porphyrin derivatives with various applications. In addition, they are often used to modify the surface of porous silica materials such as SBA-15, MCM-41 and MCM-48, because these porous silica materials exhibit narrow pore size distributions, high thermal stability and easy accessibility.In this presentation, a series of highly ordered mesoporous porphyrinosilicas akin to MCM-41 will be discussed, as novel recyclable heterogeneous photocatalysts, demonstrating their efficacy in the selective oxidation. Porphyrins are recognized as efficient photocatalysts for oxidation reactions, attributed to their capacity to generate reactive oxygen species (ROS). Integrating them into a mesoporous silica framework can mitigate self-degradation, thereby yielding an efficient catalytic system with an extended operational lifetime.

Enhanced CO2 Methanation over Nickel‐Based Unsupported Catalyst Synthesized by Chemical Precipitation Method

AbstractThis study investigated the catalytic CO2 methanation using nickel oxide (NiO) nanoparticles and nickel oxalate (NiC2O4) as catalysts. The NiC2O4 precursor was synthesized through a chemical precipitation reaction between nickel (II) nitrate hexahydrate (Ni(NO3)2.6H2O) and oxalic acid (H2C2O4.2H2O). Nickel oxide (NiO) nanoparticles were synthesized through thermal decomposition of NiC2O4 precursor at 450 °C in air. The samples were characterized by XRD, FTIR, BET, SEM, and EDX. The XRD and FTIR analyses revealed that the NiO nanoparticles were well‐crystallized having size 17.30 nm. The BET analysis of the NiO sample revealed mesoporous NiO nanoparticles with a specific surface area (SBET) of 29.08 m2/g and a narrow distribution of pore sizes. The catalytic performance of NiO and NiC2O4 catalysts studied for the CO2 methanation in tubular packed bed reactor at 150–550 °C and 1 atm. The reduced NiO nanoparticles exhibited more catalytic activity than the decomposed NiC2O4 catalyst. At 380 °C, 1 atm, and gas hourly space velocity (GHSV) of 9000 mL g−1 h−1, the reduced NiO nanoparticle catalyst showed high catalytic activity, with a maximum CO2 conversion of 85.54 %, 99 % CH4 selectivity, and 84.69 % CH4 yield. Furthermore, the NiO nanoparticle catalyst demonstrated excellent stability after 12 h of streaming at 380 °C.

Preparation of novel highly stable fluorinated microporous polyketone networks through direct C–H arylation polycondensation for efficient natural gas separation

Two novel hyper-cross-linked fluorinated microporous polyketone networks (FMPN-1 and FMPN-2) with permanent porosity and narrow pore size distribution were synthesized via a facile “one-step” polycondensation between the trifluoroacetophenone-based monomers and 1,3,5-triphenylbenzene. The result polymers were investigated by FTIR, solid state NMR, EDX, XRD, TGA, SEM, and TEM et al. The geometry configurations difference of building blocks resulted in the polyketone networks exhibiting the BET special surface areas from 622 to 706 m2 g−1 and total volume from 0.58 to 0.66 cm3 g−1. What's more, ideal adsorbed solution theory (IAST) analysis showed that the two polymers possessed good C3H8/CH4, C2H6/CH4 selectivities at 298K/1 bar. Together with the excellent thermal and physicochemical stabilities, the microporous fluorinated polyketone networks obtained in this work showed promising applications in adsorption/separation for C1–C3 hydrocarbons.

Modification of Silica with Sucrose and Ammonium Fluoride Agents: A Facile Route to Prepare Supports of Iridium Catalysts for Hydrogenation Reaction.

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous silica. The influence of synthesis conditions (pH, temperature, time) on the textural properties of the final materials was determined. Samples obtained in an acidic medium, at pH = 1, and treated at room temperature, yielded products with a large surface area and a narrow pore size distribution in the range of 2-5 nm, while the synthesis at pH = 8 allowed for the formation of mesoporous systems with pores in the range of 14-20 nm. To generate acidity, the silicas were modified with an ammonium fluoride solution and then used as supports for iridium catalysts in a hydrogenation reaction, with toluene as a model hydrocarbon. The influence of parameters such as specific surface area, support acidity, and iridium dispersion on catalytic activity was determined. It was shown that modification with sucrose improved the porous structure, and NH4F modification generated acidity. These parameters favored better reducibility and dispersion of the active phase, resulting in higher activity of the catalysts in the studied hydrogenation reaction.

Polyethersulfone mixed matrix membrane with abundant sponge pores for high‐separation performance with high flux retention and cycling stability

AbstractIn recent years, a series of high‐performance ultrafiltration membranes have been developed, but maintaining high flux and high pollutant retention rate without sacrificing service life remains a long‐standing challenge. In this study, a porous polyethersulfone ultrafiltration membrane enriched with ZIF‐8 and TiO2 additives is prepared based on a non‐solvent induced phase separation method. During the phase transition process, the addition of organic nanocrystals ZIF‐8 and inorganic nanocrystals TiO2 delayed the phase transition rate, resulting in the transformation of the polyethersulfone modified membrane from a finger‐like pore structure to a sponge‐like pore structure. Compared to other structures, the sponge‐like modified membrane has a uniform and narrow pore size distribution, fewer surface defects, stable retention performance, and can simultaneously improve membrane permeability and mechanical strength. Therefore, the polyethersulfone modified membrane with a sponge‐like pore structure prepared in this research exhibits high flux for small molecules and good retention rate for large molecules. Long‐term cycling stability tests of the modified membrane shows high retention rate (over 98%), high flux, long service life, and good cycling stability for solute molecules. The study indicates that the prepared polyethersulfone modified membrane has high potential for application in relevant environmental separation processes.

Advancing Ion Separation: Covalent-Organic-Framework Membranes for Sustainable Energy and Water Applications.

ConspectusMembranes are pivotal in a myriad of energy production processes and modern separation techniques. They are essential in devices for energy generation, facilities for extracting energy elements, and plants for wastewater treatment, each of which hinges on effective ion separation. While biological ion channels show exceptional permeability and selectivity, designing synthetic membranes with defined pore architecture and chemistry on the (sub)nanometer scale has been challenging. Consequently, a typical trade-off emerges: highly permeable membranes often sacrifice selectivity and vice versa. To tackle this dilemma, a comprehensive understanding and modeling of synthetic membranes across various scales is imperative. This lays the foundation for establishing design criteria for advanced membrane materials. Key attributes for such materials encompass appropriately sized pores, a narrow pore size distribution, and finely tuned interactions between desired permeants and the membrane. The advent of covalent-organic-framework (COF) membranes offers promising solutions to the challenges faced by conventional membranes in selective ion separation within the water-energy nexus. COFs are molecular Legos, facilitating the precise integration of small organic structs into extended, porous, crystalline architectures through covalent linkage. This unique molecular architecture allows for precise control over pore sizes, shapes, and distributions within the membrane. Additionally, COFs offer the flexibility to modify their pore spaces with distinct functionalities. This adaptability not only enhances their permeability but also facilitates tailored interactions with specific ions. As a result, COF membranes are positioned as prime candidates to achieve both superior permeability and selectivity in ion separation processes.In this Account, we delineate our endeavors aimed at leveraging the distinctive attributes of COFs to augment ion separation processes, tackling fundamental inquiries while identifying avenues for further exploration. Our strategies for fabricating COF membranes with enhanced ion selectivity encompass the following: (1) crafting (sub)nanoscale ion channels to enhance permselectivity, thereby amplifying energy production; (2) implementing a multivariate (MTV) synthesis method to control charge density within nanochannels, optimizing ion transport efficiency; (3) modifying the pore environment within confined mass transfer channels to establish distinct pathways for ion transport. For each strategy, we expound on its chemical foundations and offer illustrative examples that underscore fundamental principles. Our efforts have culminated in the creation of groundbreaking membrane materials that surpass traditional counterparts, propelling advancements in sustainable energy conversion, waste heat utilization, energy element extraction, and pollutant removal. These innovations are poised to redefine energy systems and industrial wastewater management practices. In conclusion, we outline future research directions and highlight key challenges that need addressing to enhance the ion/molecular recognition capabilities and practical applications of COF membranes. Looking forward, we anticipate ongoing advancements in functionalization and fabrication techniques, leading to enhanced selectivity and permeability, ultimately rivaling the capabilities of biological membranes.

Improving green hydrogen production: Microwave-assisted synthesis of diverse Ni-based nanocatalysts on Al2O3 for thermochemical water splitting

This study investigated the role of microwave-assisted synthesis in enhancing green hydrogen (H2) production via thermochemical water splitting (TWS) using Ni-based nanocatalysts on an Al2O3 support. H2-TPR analysis showed that the microwave-assisted synthesized (MW) catalysts exhibited stronger peaks at lower temperatures, indicating improved Ni dispersion on the Al2O3 support. Moreover, higher H2-uptake values were observed with increasing Ni concentration for both synthesis methods, indicating the presence of more accessible reducible sites crucial for catalytic activity. The MW-prepared catalysts displayed smaller particle sizes, narrower pore size distributions, and higher hydrogen adsorption capacities than those synthesized via impregnation. Additionally, they demonstrated superior catalytic activity and efficiency for hydrogen generation, with yields (∼55.42 %). Overall, our research underscores the potential of microwave-assisted synthesis as a promising method to develop efficient catalysts for hydrogen production applications.

Mesoporous N‐Doped Carbon Nanospheres as Anode Material for Sodium Ion Batteries with High Rate Capability and Superior Power Densities

AbstractOptimized sodium ion battery (SIB) carbon anodes with high stability supporting high power densities are a much‐needed material class and therefore intensively researched. The optimum graphitization degree to accommodate sodium ions, while providing high conductivity, as well as the influence of particle size distribution or pore sizes on the performance of carbon anodes, is one of the most discussed topics in this field. While a lot of studies have been published discussing these questions, the convoluted nature of these parameters, originating from material synthesis constraints, usually prevents their independent optimization. Based on Mesoporous N‐doped Carbon Nanospheres (MPNC) as model carbon material systems, the graphitization temperaturefor spherical particles with a monomodal particle size distribution (≈280 nm) and a narrow pore size distribution (≈30 nm) is optimized for faradaic sodium ion storage (plateau capacity) and electrodes with a very high power density of 2680 W kg−1 at 1000 mA g−1 and a remarkable capacity retention over 2000 cycles of 86 %, only losing 0.04 % of its specific capacity per cycle, are demonstrated.

Preparation of Monodisperse Silica Mesoporous Microspheres with Narrow Pore Size Distribution.

The purpose of this study is to prepare monodisperse silica mesoporous microspheres with narrow pore size distribution to promote their application in the field of liquid chromatography. An improved emulsion method was used to prepare silica mesoporous microspheres, and the rotary evaporation temperature, emulsification speed, dosage of porogen DMF, and dosage of the catalyst NH3·H2O were optimized. Subsequently, these microspheres were respectively treated by alkali-heating, calcination, and sieving. The D50 (particle size at the cumulative particle size distribution percentage of 50%) of as-prepared silica mesoporous microspheres is 26.3 μm, and the D90/D10 (the ratio of particle size at a cumulative particle size distribution percentage of 90% to a cumulative particle size distribution percentage of 10%) is 1.94. The resultant silica mesoporous microspheres have distinctive pore structures, with a pore volume of more than 1.0 cm3/g, an average pore size of 11.35 nm, and a median pore size of 13.4 nm. The silica mesoporous microspheres with a large particle size, uniform particle size distribution, large average pore size and pore volume, and narrow mesopore size distribution can basically meet the requirements of preparative liquid chromatographic columns.

Should we still be using HCl in the synthesis of SBA-15 and Al-SBA-15?

HCl is not always the best option for synthesizing SBA-15 and Al-SBA-15, and using different acids can bring beneficial structural and surface properties. While SBA-15-HCl and SBA-15-H2SO4 exhibited similar structural and textural characteristics, SBA-15-H2SO4 showed significantly lower contamination of the acid counterion in the final material, making it advantageous in catalytic applications where Cl− poisoning is a concern. On the other hand, SBA-15-HBr demonstrated a narrower pore size distribution. Notably, no residual Br− was detected in the final material for SBA-15-HBr. SBA-15-HNO3 and SBA-15-HBr displayed the highest concentration of 29Si MAS-NMR Q2 species, which can benefit grafting applications. The high degree of silica condensation in SBA-15-HCl and SBA-15-H2SO4 provides superior hydrothermal stability for these samples. From a fundamental perspective, a linear correlation was also identified between the Gibbs Free Energy of Hydration (ΔGhyd) of the anions and the SBA-15 mesopore sizes. Additionally, the study extended to preparing Al-SBA-15, and a facile methodology based on the pH-adjusting method was proposed. The samples displayed a Brønsted/Lewis ratio higher than typically reported, suggesting an efficient incorporation of Al as Brønsted acid sites.

Piezoelectric PMS activation by ZnO embedded polytetrafluoroethylene membrane for efficient degradation of carbamazepine

The wide-spread micropollutants in water have posed severe risks to human health and eco-environment. However, the current treatment techniques generally suffer from low efficiency, high cost and unpractical application feasibility. In this study, a piezoelectric membrane was fabricated by embedding zinc oxide (ZnO) nanorods with several micrometer length into polytetrafluoroethylene nanofiber membrane and applied for the removal of carbamazepine (CBZ) from water. After the sintering, the prepared membrane showed a narrower pore size distribution with the average pore size of ∼1.7 µm. The addition of ZnO nanorods could significantly improve the piezoelectric property of the membrane. During the membrane filtration, the peroxymonosulfate could be effectively activated by the prepared piezoelectric membrane with 2 % ZnO dosage to generate free radicals, achieving about 83.1 % of CBZ from water. According to the radical quenching tests and electron spin-resonance analysis, the hydroxyl radical, sulfate radical, singlet oxygen and superoxide radical greatly participated in the CBZ removal. The CBZ removal efficiency in the US/PMS/PTFE@ZnO-2 system was decreased by 18.2 % after continuous 5-cycle operation, but the performance could be easily renewed by methanol rinsing, demonstrating its attractive reusability and application potential on the efficient removal of micropollutants from water.

Solvent-resistant isoporous membranes with tailored pore characteristics and on-demand sieving by site-selective hyper-crosslinking

Isoporous block copolymer membranes with high porosity and narrow pore size distribution have been viewed as ideal membrane platforms for precise separation of similarly sized particles or solutes. However, tailored made fabrication of solvent-resistant isoporous membranes with switchable pores and rigid pores for customizable sieving have been rarely reported. Herein, we show that site-selective hyper-crosslinking is effective and robust to prepare such membranes from polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP). The selective crosslinking in PS domains endows the membrane with excellent solvent resistance and structural stability. Since not participated in the crosslinking reaction, the P4VP brushes located in pore walls endow the crosslinked membranes with adaptive pore size, switchable permeance and tunable rejections that vary with Hansen solubility parameter of solvents. Moreover, by a facile while complete etching the P4VP from pores, the switchable performance is removed and resultant membranes show rigid pore characteristics and constant rejections. Crosslinked membranes with either switchable pores or rigid-likes pores exhibit superior long-term stability (30 days) in harsh solvents. This work presents a top-down method to construct highly stable isoporous membranes with both switchable and rigid pore characteristics from the same block copolymer, which will shed the light on precisely tailoring the pore size and pore rigidity for crosslinked isoporous membranes that will not only enable the tailored sieving but also the modelling of solvent flowing behaviours in nanopores.