High BET Surface Area Research Articles

H2S/Butane Dual Gas Sensing Based on a Hydrothermally Synthesized MXene Ti3C2Tx/NiCo2O4 Nanocomposite.

Real-time sensing of hydrogen sulfide (H2S) at room temperature is important to ensure the safety of humans and the environment. Four kinds of different nanocomposites, such as MXene Ti3C2Tx, Ti3AlC2, WS2, and MoSe2/NiCo2O4, were synthesized using the hydrothermal method in this paper. Initially, the intrinsic properties of the synthesized nanocomposites were studied using different techniques. P-type butane and H2S-sensing behaviors of nanocomposites were performed and analyzed deeply. Four sensor sheets were fabricated using a spin-coating method. The gas sensor was distinctly part of the chemiresistor class. The MXene Ti3C2Tx/NiCo2O4-based gas sensor detected the highest response (16) toward 10 ppm H2S at room temperature. In comparison, the sensor detected the highest response (9.8) toward 4000 ppm butane at 90 °C compared with the other three fabricated sensors (Ti3AlC2, WS2, and MoSe2/NiCo2O4). The MXene Ti3C2Tx/NiCo2O4 sensor showed excellent responses, minimum limits of detection (0.1 ppm H2S and 5 ppm butane), long-term stability, and good reproducibility compared with the other fabricated sensors. The highest sensing properties toward H2S and butane were accredited to p-p heterojunctions, higher BET surface areas, increased oxygen species, etc. These simply synthesized nanocomposites and fabricated sensors present a novel method for tracing H2S and butane at the lowest concentration to prevent different gas-exposure-related diseases.

High efficiency removal of ibuprofen in water using activated carbon derived from Radix Angelica Dahurica residue

AbstractThe exploitation and utilization of Traditional Chinese medicine have annually produced 30 million tons of waste residues including Radix Angelica Dahurica residue (RAR), which raised environmental concerns. Meantime, the non‐steroidal anti‐inflammatory drug of ibuprofen (IBP) is an emerging contaminant in the aquatic environment, annually producing up to 9000 tons in China. After extracting the active substance, RAR is prepared as activated carbon (AC) for the purification of IBP wastewater. Two kinds AC modified without (RAR‐AC) and with phosphoric acid (M‐RAR‐AC) were characterized by FT‐IR, TG, BET and SEM. The phosphoric acid activation contributed to the high BET surface area (564.9914 m2 g−1) and large total pore volume (0.4894 cm3 g−1). M‐RAR‐AC showed 7.7 folds (15 min) and 2.7 folds (30 min) higher extent of IBP removal compared to commercial activated carbon (C‐AC). The enhancement of IBP removal with M‐RAR‐AC was investigated further by varying initial pollutant concentration, absorbent dosage, temperature, pH and rotating speed. Especially, temperature nearly has no effect on IBP removal by M‐RAR‐AC. Isotherm and kinetic studies suggested IBP was adsorbed on the heterogeneous surface in multilayer form and chemisorption played the dominant role in IBP removal. IBP removal of 93.3 ± 0.1% and 64.2 ± 2.8% was achieved for first and fifth cycle, respectively. The IBP removal on M‐RAR‐AC may be accomplished by a variety of interactions such as electrostatic attraction, pore‐filling, hydrogen bonding, and π‐π interaction. These findings provide new insights into the utilization of RAR for preparing AC and highlight the potential applications for treating industrial wastewater.

Synergistic Enhancement of Photocatalytic H2 Evolution over NH2-MIL-125 Modified with Dual Cocatalyst.

The construction of efficient photocatalysts for water splitting to enable H2 evolution is pivotal to alleviate energy issues and environmental concerns. In this work, carbon dots (CDs) were prepared by employing "green solvent" ionic liquids as carbon sources and then combined with Pt/NH2-MIL-125, resulting in the emergence of a high-efficiency photocatalyst termed CDs-Pt/NH2-MIL-125 for the first time. This composite photocatalyst exhibited outstanding photocatalytic activity in H2 production under visible light irradiation. Notably, the H2 production rate of CDs100-Pt/NH2-MIL-125 reaches up to 951.4 μmol/g/h, which was 3.1 times that of Pt/NH2-MIL-125. The characterization results indicate that CDs and Pt uniformly dispersed on the surface of NH2-MIL-125 and fabricated a synergistic compact structure, providing a high BET surface area (985 m2 g-1) and a suitable band gap. Furthermore, the distinctive embeddable-dispersed CDs and Pt, as dual cocatalyst, can harvest light and facilitate the transfer of photogenerated electrons, thereby significantly augmenting the exploitation of visible light. The plausible mechanism of photocatalytic H2 evolution over the CDs-Pt/NH2-MIL-125 catalyst was also discussed. This work introduces a promising strategy for designing high-performance CDs-MOFs-based photocatalysts, an innovative step toward achieving efficient photocatalytic water splitting for H2 production.

Fabrication of activated carbon from Acacia Crassicarpa bark by carbothermal functionalization for adsorptive removal the dyes in aqueous solution

Activated carbon adsorbent prepared from Acacia Crassicarpa bark has been successfully synthesized via carbonization and chemical activation processes to investigate the elimination of hazardous dyes in industrial wastewater, specifically the anionic dye methyl orange (MO) and the cationic dye methylene blue (MB) in this study. The Acacia Crassicarpa bark was washed with distilled water and dried it in an electric oven at 100 °C. The carbonization process was carried out at a temperature of 1050 °C in the Argon atmosphere and thoroughly was activated by NaOH. The results showed that a high BET surface area of 711.05 m2/g was obtained. XRD pattern presented that the high content of crystalline carbon was formed and carbon content was achieved approximately 83%. Also, SEM images illustrated the average size of carbon is 2.58 μm and surface structure of activated carbon appeared the pores inside the particle. The Langmuir was observed to fit the adsorption data well. The maximum equilibrium adsorption capacities predicted by the Langmuir isotherm were found to be 156.25 mg/g and 144.09 mg/g for MO and MB, respectively. All of those results confirm that the activated carbon originated from Acacia Crassicarpa bark can potentially be applied for water purification treatment. In comparison to traditional charcoal, this activated carbon presents numerous advantages. Notably, it can integrate into the biomass energy cycle, improve filtration capabilities, and result in cost savings.

The role of various preparation techniques and nickel loadings in ethanol steam reforming over mesoporous nanostructured Ni–Al2O3 catalysts

This study involved the preparation of Al2O3 support and Ni/Al2O3 catalysts through different methods such as mechanochemical, impregnation, and co-precipitation. These prepared samples were then assessed for their performance in the ethanol steam reforming (ESR) process. The results indicated that the 10Ni/Al2O3 catalyst, which was created using the impregnation method and exhibited a high BET surface area of 200.8 m2/g along with well-dispersed nickel, displayed exceptional performance in the ethanol steam reforming reaction. When compared to other catalysts, it exhibited greater activity and stability. A series of Ni/Al2O3 catalysts were prepared with nickel contents ranging from 2.5 to 20 wt%. The study showed that increasing the amount of nickel from 2.5 to 12.5 wt% led to a boost in the catalysts' ability to be reduced, which in turn resulted in improved catalytic performance. However, increasing the nickel content beyond 12.5 wt% led to a decline in catalytic performance. This decrease could be attributed to weaker Ni–Al2O3 interactions, an increase in particle size from 2.7 to 7.8 nm, and a significant reduction in the BET surface area from 198.3 m2/g to 166.4 m2/g. Temperature-programmed oxidation (TPO) profiles revealed that the carbon deposits on the catalyst's surface exhibited a whisker-like structure, and higher nickel contents correlated with increased oxidation peak temperatures and intensities. Moreover, the 12.5Ni/Al2O3 catalyst demonstrated remarkable stability over a 550-min reaction period. The study's findings indicated that as the Tcal. rose from 500 to 700 °C, the catalytic activity gradually lessened. The 12.5Ni/Al2O3 catalyst calcined at 500 °C, characterized by a small particle size and moderate Ni–Al2O3 interaction, exhibited the most favorable catalytic activity.

Ni Nanoparticles Supported Over Triazine Based Porous Organic Polymer for Selective CO2 Photo‐Reduction to Methanol

AbstractPorous organic polymers (POPs) have attracted substantial attentions over the years due to their exceptionally high specific surface areas, high chemical stability of the organic network and ease of surface functionalization with the desired organic groups. In this work, a triazine based POP (TrzPOP) was synthesized through Schiff base polycondensation reaction between a tetramine bearing triazine rings and phenolic–OH group rich dialdehyde. Ni nanoparticles (NiNP) synthesized independently were immobilized over TrzPOP to obtain the NiNP@TrzPOP composite catalyst. This TrzPOP possesses a high BET surface area of 1494 m2 g−1 and low band gap, which facilitates its role as visible light absorbent. NiNP@TrzPOP with N‐rich surfaces and phenolic–OH moieties displayed excellent photocatalytic activity in the CO2 photoreduction under mild reaction conditions. NiNP@TrzPOP composite selectively reduces CO2 to methanol. The turn over number (TON) for this photoreduction of CO2 under optimized reaction conditions is 270, which is considerably high comparing to other reported photocatalytic systems. Moreover, NiNP@TrzPOP composite catalytic system showed high recycling efficiency without noticeable decrease in its performance over five consecutive reaction cycles, suggesting its huge potential for large‐scale methanol synthesis from the renewable carbon source.

Trifloaluminate Ionic Liquids Supported UIO‐67 as Lewis Acidic Catalyst for Excellent Synthesis of Alkyl Levulinates

AbstractHerein, levulinate acid esters (LAEs) were efficiently synthesized from the α‐angelica lactone (α‐AL) esterification with trifloaluminate ionic liquids supported UIO‐67 MOF as Lewis acidic catalyst. A series of UIO‐67 catalysts with varied trifloaluminate ionic liquids loading were prepared via the post‐modification method and exhibited excellent catalytic activity for α‐AL esterification. Remarkable α‐AL conversion (100 %) and LAEs selectivity (>99 %) were achieved by UIO‐67 catalysts (0.2 mol %) with 12.4 %, trifloaluminate ionic liquids loading (UIO‐67‐TFA) at 70 °C and 90 min. The UIO‐67‐TFA catalyst can be reused at least 5 cycles without significant loss of catalytic activity. The UIO‐67‐TFA catalysts were fully characterized by XRD, SEM, XPS, TGA, IR, N2 physisorption, etc. The results indicated that the well‐distributed active trifloaluminate Lewis acid catalytic sites, high BET surface area, and good thermal stability could contribute to its excellent catalytic activity.

Construction of hierarchical porous carbons with Ph-POSS based polymers for highly efficient adsorption of polycyclic aromatic hydrocarbons

Fluid catalytic cracking (FCC) diesel provides most polycyclic aromatic hydrocarbons (PAHs) in diesel. The removal of PAHs by adsorption and separation method is an efficient way to obtained purified diesel. As a kind of green economy adsorbent, porous carbon materials (PCMs) have been widely used in the adsorption of gases, aromatics and organic pollutions. Here, by direct carbonization, the PCMs are prepared from the novel Ph-POSS based porous organic polymers (POPs) which possessed high BET surface areas (∼1000 m2/g). The PCMs possess abundant microporosity and O atoms in the skeleton. The PCMs exhibit high PAHs adsorption capacity because of the hierarchical micropore size, high degree of graphitization and abundant O atoms. The strategy of construction PCMs with hierarchical micropore and heteroatoms provides an effective method to remove PAHs in the FCC diesel.

Labile graphitic monolayers as a partition phase for containment of organic chemicals by graphene-based nanomaterials

Graphene-based nanomaterials (GBNMs) (e.g., graphene oxides and carbon nanotubes) display superior electronic and thermal conductivities and varying abilities to contain organic substances. This study sheds light to the idea that GBNMs behave as a dual sorbent, rather than a sole adsorbent, to extract nonionic organic solutes from water by both (competitive) adsorption and (noncompetitive) partition because of the solute interactions with various GBNM nanostructures formed by atomically-thin graphitic monolayers. Essential solute-sorption data with three model GBNMs from this research and similar data from the literature lead to a coherent view that labile graphitic monolayers in GBNMs undergo a liquid-like motion at room temperature to retain nonionic organic solutes by partition while structurally rigid graphitic clusters behave as adsorbents. Because the partition is noncompetitive, the GBNMs possessing high levels of labile graphene layers, as reflected by high BET surface areas, are capable of sequestering vastly higher levels of multiple organic solutes (especially, those of liquids) than conventional adsorbents, e.g., activated carbon (AC). Moreover, the postulated dual functionality of GBNMs makes sense of many otherwise puzzling phenomena, such as the highly concentration-dependent solute competitive effect with certain GBNMs and highly variable “adsorbed capacities” per unit surface area for different organic solutes with a GBNM versus those by a conventional adsorbent (e.g., graphite or AC).Graphical

A novel porous aromatic framework with mesopores for removal of antibiotics from water

Porous aromatic frameworks (PAFs) display high potential for wastewater treatment, due to their high surface area and extreme stability. PAF-134 was synthesized based on a 3-connected non-planar building unit, tris(4-bromophenyl)(phenyl)silane (PBTSi-3-Br), via Yamamoto coupling reaction. PAF-134 exhibited high BET surface area of 865.7 m2/g, large mesopore ratio of 69 % pore volume and excellent stability. Three tetracycline pollutants, tetracycline (TC), oxytetracycline (OTC) and chlortetracycline hydrochloride (CTC), were chosen to study the antibiotics adsorption performance for PAF-134. The adsorption isotherms, kinetics, and thermodynamics were measured and analyzed. Moreover, PAF-134 in removing antibiotics from actual water exhibited high efficiency and possessed outstanding recyclability and stability, thus showing that it is a promising adsorbent for wastewater treatment.

Thienoacene‐Based Conjugated Porous Polymer/TiO2 Hybrids as Photocatalysts in Artificial Photosynthesis

AbstractHerein, the design and synthesis of a couple of CPPs based on thienoacene units (named as IEP‐14 and IEP‐15, stand for IMDEA Energy Polymer numbers 14 and 15) are described, which show high BET surface areas, good photo(thermal) stabilities, and appropriate electronic alignment with TiO2 to prepare hybrids (named as IEP‐x@T‐10, X = 14 and 15, being 10 wt% of polymer loading). It is shown that the simultaneous UV–vis irradiation of both materials leads to better H2 production (ca. 925 and 827 µmol g−1 h−1 by IEP‐15@T‐10 and IEP‐14@T‐10, 12 and 11‐fold higher production than bare TiO2) than the solely irradiation at visible of the CPPs (ca. 124 and 90 µmol g−1 h−1 by IEP‐15@T‐10 and IEP‐14@T‐10 when TiO2 is photocatalytically inactive). The reason is attributed to the charge‐transfer mechanisms that occur between the counterparts of the hybrid material: in the first case it consists in a Z‐scheme charge transfer mechanism, while in the second one is a sensitization charge transfer mechanism. Both mechanisms are elucidated by advanced techniques. Furthermore, in a gas phase CO2 photoreduction test, IEP‐15@T‐10 shows sixfold higher CH4 evolution than TiO2, which result in a selectivity shift from CO to CH4 (i.e., >26% greater selectivity than bare TiO2).

Substitutional C and interstitial N in MnO2/NC catalysts enable high performance of formaldehyde oxidation at room temperature

Formaldehyde (HCHO) is a harmful gas that dangers the health of human kind. Catalytic oxidation provides a green approach converting HCHO to harmless CO2. In this work, we designed MnO2 catalysts by co-doping NC for HCHO catalytic elimination. The substitutional C and interstitial N in the MnO2 activate the surface lattice oxygen and weaken the Mn-O bond strength. The more active surface lattice oxygens and the more active adsorbed dioxygen species at the oxygen vacancies result in the greater HCHO oxidation performance over the MnO2/NC catalysts doping with NC than the MnO2 catalysts without doping. The performance enhancement is dependent on the crystal phase of MnO2, HCHO is fully converted at 30 ℃ over α-MnO2/NC catalyst, followed by 35 °C over the γ-MnO2/NC catalyst. The higher performance of the α-MnO2/NC catalyst is associated with its higher BET surface area, more active surface lattice oxygen and adsorbed dioxygen species than those of the γ-MnO2/NC catalyst. This work verifies the more effective HCHO elimination performance of MnO2-based catalysts by co-doping NC, and the strategy is applicable for other related oxidative reactions.

Conversion of fly-ash into pristine ZSM-5 and its application for methane dehydroaromatization reaction

Increasing Fly-Ash (FA) residues as a by-product in pulp/paper industries requires efficient routes for green and economical ash management. Converting FA into zeolite shows great potential for its efficient utilization. In this work, FA received from Indian paper mills was converted into pristine ZSM-5, support in methane dehydroaromatization (MDA). Following acid leaching, Fe and Al content were reduced to make ash residue, a precursor for ZSM-5 synthesis. Synthesized FA-derived ZSM-5 consisted of a highly crystalline structure (91 %) and high BET surface area (468 m2/g) comparable to commercial ZSM-5. Synthesized ZSM-5 (FA) possessed micropores/mesopores, with comparatively smaller particle size as confirmed by pore size distribution analysis/N2-sorption isotherms and SEM analysis. NH3-TPD study confirmed the acidity content (1.16 mmol/gcat) over ZSM-5 (FA) and was found to be compatible with that of commercial ZSM-5 (1.58 mmol/gcat). Further, the activity of ZSM-5 (FA) with 5 wt% Mo loading was evaluated towards MDA reaction and compared its activity with conventional Mo/HZSM-5. Higher activity was achieved with 5Mo/HZSM-5 (FA-derived) exhibiting a higher benzene production rate than the 5Mo/HZSM-5 due to effective textural properties and suitable acidity, which provides sites for dispersion of MoOx species in case of Mo/ZSM-5 (FA) thereby conferring improved activity.

A novel phosphorylated hyper-crosslinked porous polymer for efficient uranium adsorption in water

As the nuclear resource industry rapidly progresses, efficient adsorbents play a vital role in separating and eliminating uranium from aqueous solutions. Herein, 9,9-dimethyl-fluorenylphosphonic acid was designed as a phosphate functional monomer and the triptycene as a rigid backbone monomer. Through the “knitting” strategy, a novel triptycene-based phosphorylated hyper-crosslinked porous polymer (TPP-DFP) was obtained by the above monomers. The resulted polymer TPP-DFP has a high BET surface area of 1397.62 m2/g with a rich porosity. The porous polymer TPP-DFP was the first time used for uranium adsorption from water and showed outstanding adsorption performance. The maximum uranium adsorption capacity of TPP-DFP was 414.26 mg/g, which was higher than that of most of other porous adsorbents. In the presence of impurity ions such as Ca2+, Mg2+, Al3+, Co2+, Ni2+, V5+, NO3−, CO32− etc., TPP-DFP exhibited high selectivity (Su up to 99%) for uranium. In addition, TPP-DFP has excellent reusability, and the removal percentage of uranium can reach more than 95% after 5 adsorption–desorption cycles. According to the XPS experiment, the mechanism of interaction between TPP-DFP and U(VI) was mainly due to the complex formed by the phosphate functional groups and U(VI). The theory DFT calculation indicated a 1:2 ratio of U(VI) and phosphate functional group on the two-distinct graft chain, which was consistent with the experimental results. Accordingly, the “knitting” polymerization technique showed potential for preparation effective adsorbents for uranium extraction from water.

2D/1D ZnIn2S4/attapulgite hybrid materials for enhanced photocatalytic performance under visible light

The 2D/1D structure of ZnIn2S4/attapulgite was constructed by anchoring ZnIn2S4 nanosheets on the surface of attapulgite nanorods for the removal of tetracycline hydrochloride (TC) and rhodamine B (RhB). The 2D ZnIn2S4 was closely combined with the 1D attapulgite, and ZnIn2S4/attapulgite had a higher BET surface area (83.6 m2/g) than pure ZnIn2S4 (13.6 m2/g). The combination of ZnIn2S4 and attapulgite promoted pollutant adsorption by providing more exposed active sites and a larger contact area, which also contributed to enhanced photocatalytic performance. Under visible light irradiation, the as-prepared ZnIn2S4/attapulgite composites exhibited enhanced photocatalytic activity when compared with pure ZnIn2S4. After 9 min (50 min) of irradiation, the optimized ZnIn2S4/attapulgite photocatalyst removed about 99.9% RhB (82.1% TC). In addition, the ZnIn2S4/attapulgite photocatalyst demonstrated excellent photostability and availability. Compared with other photocatalysts, the samples in this work used natural minerals as the carrier, which significantly improved the dispersibility and adsorption performance of the catalyst, and was conducive to the improvement of catalytic performance. This work contributed to the development of photocatalysis for the removal of environmental liquid-phase pollutants.

Synthesis of mesoporous Zn-doped MnCo2O4 nanoparticles for high-energy density solid-state asymmetric supercapacitor

This study aims to determine how Zn doping at the cobalt site of MnCo2O4 (MCO) affects its electrochemical properties. Synthesized MnZn0.4Co1.6O4 (0.4ZMCO) sample's electrode provides an enormous improvement in electrochemical characteristics as compared to that of MCO because of its higher BET surface area (74 m2/ g) and mesoporous distribution of pore sizes. The 0.4ZMCO exhibits specific capacitances of 720 F g−1 at 0.5 A g−1, along with satisfactory rate capability. In addition, this electrode exhibits outstanding cyclability, maintaining a capacitance retention of 91 % and a coulombic efficiency of 99.78 % throughout 10,000 continuous cycles, even under high current density of 10 A g−1. An asymmetric supercapacitor (ASC) device is constructed using 0.4ZMCO as the cathode and activated carbon as the anode electrode. This ASC device performs with a good specific energy density of 49 Wh kg−1 and a power density of 8.64 kW kg−1. Furthermore, the ASC device exhibits 99.40 % coulombic efficiency and 91.84 % capacitance retention up to 30,000 GCD cycles in PVA/KOH gel electrolyte at a specific current density of 8 A g−1. Additionally, a single device illuminates a red LED, while connecting two devices in series illuminates red and green LED for more than 15 and 12 min, respectively. We believe Zn-doped MCO has great potential in constructing higher-performance supercapacitor devices due to its straightforward synthesis process and excellent electrochemical properties.

Synthesis of porous and activated carbon from lemon peel waste for CO2 adsorption

The concentration of CO2 in the atmosphere has been increasing and is soon to reach a threatening level for life on the planet. Porous carbons made from biobased materials including from waste resources can be applied to selectively adsorb CO2 from large industrial sites and then lower atmospheric CO2 emissions. In this work, we synthesized highly porous carbons from lemon-peel wastes using two-step activation process involving hydrothermal carbonization followed by chemical activation with KOH, and KOH + alum at 800 °C. The sample activated with KOH + alum has the highest BET surface area (2143 m2/g) and total pore volume of 1.3 cc/g. Although the KOH activated sample has a lower surface area (1113 m2/g), it has better CO2 adsorption capacity ranging up to 4.5 mmol/g because of its well-developed pore structures and a high proportion (90 %) of micropore distributions. The isosteric heat of adsorption lower than 40 kJ/mol indicated that adsorption is mainly driven by physisorption. Better CO2/N2 selectivity suggested a high affinity of the activated carbons towards CO2. Particularly, the sample activated with KOH had selectivity in the range of 20 at the highest adsorption temperature (40 °C), making it a potentially viable option for direct CO2 adsorption applications from large industrial sources.

Construction of N-Rich Aminal-Linked Porous Organic Polymers for Outstanding Precombustion CO2 Capture and H2 Purification: A Combined Experimental and Theoretical Study.

A large number of scientific investigations are needed for developing a sustainable solid sorbent material for precombustion CO2 capture in the integrated gasification combined cycle (IGCC) that is accountable for the industrial coproduction of hydrogen and electricity. Keeping in mind the industrially relevant conditions (high pressure, high temperature, and humidity) as well as good CO2/H2 selectivity, we explored a series of sorbent materials. An all-rounder player in this game is the porous organic polymers (POPs) that are thermally and chemically stable, easily scalable, and precisely tunable. In the present investigation, we successfully synthesized two nitrogen-rich POPs by extended Schiff-base condensation reactions. Among these two porous polymers, TBAL-POP-2 exhibits high CO2 uptake capacity at 30 bar pressure (57.2, 18.7, and 15.9 mmol g-1 at 273, 298, and 313 K temperatures, respectively). CO2/H2 selectivities of TBAL-POP-1 and 2 at 25 °C are 434.35 and 477.93, respectively. On the other hand, at 313 K the CO2/H2 selectivities of TBAL-POP-1 and 2 are 296.92 and 421.58, respectively. Another important feature to win the race in the search of good sorbents is CO2 capture capacity at room temperature, which is very high for TBAL-POP-2 (15.61 mmol g-1 at 298 K for 30 to 1 bar pressure swing). High BET surface area and good mesopore volume along with a large nitrogen content in the framework make TBAL-POP-2 an excellent sorbent material for precombustion CO2 capture and H2 purification.

Fabrication of high-performance poly(benzoxazole-co-imide) membrane by utilizing synergistic effect of thermal rearrangement and Zn2+ modification

Developing membranes that combine excellent gas separation performance with robust resistance to plasticization is highly demanded for membrane separation but remains a challenge. Herein, a series of Zn2+ functionalized poly(benzoxazole-co-imide) membrane was constructed via co-polymerizing (4,4′-hexafluoroisopropylidene) diphthalic anhydride (6FDA) with o-hydroxyl diamine 2,2′-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (BisAPAF) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) followed by thermal rearrangement (TR) and Zn2+ modification processes. The TR conversion opened the polymer chains with larger d-spacing and higher BET surface area, thus, greatly increased the gas permeability. Meanwhile, the post Zn2+ modification resulted in a huge improved selectivity because of the π-complexation reactions between Zn2+ and CO2 and the formation of a Zn2+ coordination crosslinking network. As a result, due to the synergistic effect of TR and Zn2+ modification, the overall gas transport properties of these newly developed membranes were greatly improved. Furthermore, the dual network structures that arise from the remaining network PI and the Zn2+ coordination crosslinking contribute to the resultant membrane with excellent anti-plasticization capability. A represent membrane termed as PBOI-Zn2+-14h membrane exhibits great CO2/CH4 separation performance, delivering a CO2 permeability of 1048.1 Barrer and a CO2/CH4 selectivity of 46.1 that is exceeded the 2008 Roberson limitation. Furthermore, this membrane possesses remarkable resistance to CO2-induced plasticization, withstanding pressures above 35 Bar. Overall, this study presents an effective way for constructing polymer membranes with both high gas separation performance and strong resistance to plasticization issue.

Interfacial engineered, hierarchically porous, and underwater superelastic nanofibrous aerogels with rime-mimetic structure for superior micropollutant extraction

Developing nanofibrous aerogels with high surface area, nanoscale porosity, and robust underwater stability has been considered as one of the most promising strategies for designing the next-generation of high-efficiency extraction media, yet still facing great challenges. Herein, we report a size rearrangement of porous organic polymers (POPs) into superelastic rime-mimetic structured aerogels based on bacterial cellulose nanofibers (BCNs)-assisted interfacial engineering strategy. This strategy facilitates micro-interlocking between POP and BCN, significantly enhancing the attaching strength of POP particles at the POP/BCN interface. Thus, the optimized aerogels (PNAs) exhibit excellent underwater elasticity and compression fatigue resistance (∼0% plastic deformation after 500 compression cycles), as well as high BET surface area (305.44 m2/g) and hierarchical porosity (containing micro/meso/macropores), mainly due to the ultrahigh loading of POP particles (83.33 wt%). Given the possession of the abovementioned features and the careful selection of elution solvents guided by Hansen solubility parameter theory, PNAs exhibit a superior micropollutant adsorption capability (∼250 mg/g) and elution efficiency (concentrate sample volume by 50 times). The successful preparation of such material could inspire the development of next-generation hierarchically porous nanofibrous aerogel-based extraction media for water treatment.