Hydrophobic ZIF-8 Research Articles

Hydrophobic ZIF-8 nanoparticles loaded on chitosan for improved methanol adsorption from fermented wine.

Metal-organic frameworks (MOFs) have great potential for the adsorption of minor molecular alcohols in the vapor phase. However, the drawbacks of powdered MOFs, including low recyclability and problematic separation, limit their application in fermented wine. Chitosan (CS) is a low-cost, eco-friendly, moldable matrix used in the food industry. In this study, a novel CS@ZIF-8 adsorbent with excellent microporous surface area was successfully synthesized by incorporating hydrophobic ZIF-8 into CS. The results showed that CS@ZIF-8 beads had a high adsorption affinity for methanol at a Zn2+/2-methylimidazole molar ratio of 1:5. The adsorption mechanism of methanol on CS@ZIF-8 beads was systematically studied by X-ray photoelectron spectroscopy, isotherms, and kinetics. The Langmuir model calculated the maximum adsorption of methanol to 56.8mg/g. Adsorption kinetics are consistent with pseudo-second-order models. Furthermore, CS@ZIF-8 beads presented excellent recyclability for removing methanol for five consecutive cycles. It could treat 60 bed volumes of Chinese yellow wine in column filtration experiments to make the concentration below 50mg/L. In summary, the highly efficient CS@ZIF-8 adsorbent has great potential for methanol adsorption from fermented wines. PRACTICAL APPLICATION: Methanol will exhibit adverse symptoms such as weakness and headaches after it is ingested. Therefore, methanol control is an important safety factor in the production of fermented wine. The adsorption method is recognized as a widely used technique due to its high efficiency and selectivity. The CS@ZIF-8 adsorbent synthesized in this paper provides a new idea for methanol removal.

Triphase Enzyme Electrode Based on ZIF-8 with Enhanced Oxidase Catalytic Kinetics and Bioassay Performance.

Oxidase enzyme-based electrochemical bioassays have garnered considerable interest due to their specificity and high efficiency. However, in traditional solid-liquid diphase enzyme electrode systems, the low solubility of oxygen and its slow mass transfer rate limit the oxidase catalytic reaction kinetics, thereby affecting the bioassay performance, including the detection accuracy, sensitivity, and linear dynamic range. ZIF-8 nanoparticles (NPs) possess hydrophobic and high-porosity characteristics, enabling them to serve as oxygen nanocarriers. In this work, we constructed a solid-liquid-air triphase enzyme electrode by encapsulating ZIF-8 NPs within an oxidase network. Hydrophobic ZIF-8 NPs can provide a rapid and sufficient supply of oxygen for the oxidase-catalyzed reactions, which enhances and stabilizes the kinetics of oxidase-catalyzed reactions. This approach eliminates the issue of "oxygen deficiency" at the traditional solid-liquid diphase interface. Consequently, the triphase enzyme electrode exhibits a 12-fold higher linear detection range than the diphase system and possesses good detection accuracy in electrolytes even with fluctuating oxygen levels. This work proposes a novel approach to construct triphase reaction systems for addressing the gas deficiency problem in heterogeneous catalysis.

Nanoarchitectonics of S-Scheme Heterojunction Photocatalysts: A Nanohouse Design Improves Photocatalytic Nitrate Reduction to Ammonia Performance.

Photocatalytic nitrate reduction reaction (NitRR) is a promising route for environment remediation and sustainable ammonia synthesis. To design efficient photocatalysts, the recently emerged nanoarchitectonics approach holds great promise. Here, we report a nanohouse-like S-scheme heterjunction photocatalyst with high photocatalytic NitRR performance. The nano-house has a floor of plate-like metal organic framework-based photocatalyst (NH2-MIL-125), on which another photocatalyst Co(OH)2 nanosheet is grown while ZIF-8 hollow cages are also constructed as the surrounding wall/roof. Experimental and simulation results indicate that the positively charged, highly porous and hydrophobic ZIF-8 wall can modulate the environment in the nanohouse by (i) NO3 - enrichment/NH4 + discharge and (ii) suppression of the competitive hydrogen evolution reaction. In combination with the enhanced electron-hole separation and strong redox capability in the NH2-MIL-125@Co(OH)2 S-scheme heterjunction confined in the nano-house, the designed photocatalyst delivers an ammonia yield of 2454.9 μmol g-1 h-1 and an apparent quantum yield of 8.02 % at 400 nm in pure water. Our work provides new insights into the design principles of advanced photocatalytic NitRR photocatalyst.

CH4 Adsorption in Wet Metal-Organic Frameworks under Gas Hydrate Formation Conditions Using A Large Reactor

Nanoporous materials, such as metal-organic frameworks (MOFs), are renowned for their high selectivity as gas adsorbents due to their specific surface area, nanoporosity, and active surface chemistry. A significant challenge for their widespread application is reduced gas uptake in wet conditions, attributed to competitive adsorption between gas and water. Recent studies of gas adsorption in wet materials have typically used small amounts of powdered porous materials (in the milligram range) within very small reactors (1–5 mL). This leaves a gap in knowledge about gas adsorption behaviors in larger reactors and with increased MOF sample sizes (to the gram scale). Additionally, there has been a notable absence of experimental research on MOFs heavily saturated with water. In this study, we aimed to fill the gaps in our understanding of gas adsorption in wet conditions by measuring CH4 adsorption in MOFs. To do this, we used larger MOF samples (in grams) and a large-volume reactor. Our selection of commercially available MOFs, including HKUST-1, ZIF-8, MOF-303, and activated carbon, was based on their widespread application, available previous research, and differences in hydrophobicity. Using a volumetric approach, we measured high-pressure isotherms (at T = 274.15 K) to compare the moles of gas adsorbed under both dry and wet conditions across different MOFs and weights. The experimental results indicate that water decreases total CH4 adsorption in MOFs, with a more pronounced decrease in hydrophilic MOFs compared to hydrophobic ones at lower pressures. However, hydrophilic MOFs exhibited stepped isotherms at higher pressures, suggesting water converts to hydrate, positively impacting total gas uptake. In contrast, the hydrophobic ZIF-8 did not promote hydrate formation due to particle aggregation in the presence of water, leading to a loss of surface area and surface charge. This study highlights the additional challenges associated with hydrate-MOF synergy when experiments are scaled up and larger sample sizes are used. Future studies should consider using monolith or pellet forms of MOFs to address the limitations of powdered MOFs in scale-up studies.

Eco-friendly hydrophobic ZIF-8/sodium alginate monolithic adsorbent: An efficient trap for microplastics in the aqueous environment

Microplastics (MPs), a newly emerging class of environmental contaminants, pose a severe threat to the entire ecosystem. The development of efficient and environmentally responsible adsorbents for removing the MPs is a particularly urgent research. Herein, a kind of monolithic ZIF-8 based adsorbents featuring stable hydrophobicity and micropore-mesopore-macropore hierarchical porous structure were fabricated by in situ growth of ZIF-8 nanoparticles on sodium alginate (SA) framework, and using polydimethylsiloxane (PDMS) as a hydrophobic agent. The monolithic nature of ZIF-8/SA allowed an easy solid–liquid separation process for adsorbents from water environment compared to powdered materials. The hierarchical porous structure ensures a remarkable MPs removal performance. The ZIF-8/SA showed high adsorption capacities of 594, 585, and 282 mg/g for polymethyl methacrylate (PMMA), poly (vinylidene difluoride) (PVDF), and polyvinyl chloride (PVC) respectively, and rapid adsorption kinetic progress within 120 min. The ZIF-8/SA adsorbents also exhibited excellent stability in the presence of interfering ions, acid/alkali, and humic acid, and displayed adsorption performance of > 70 % even in actual aquatic environment such as tap water, river water, and seawater. The results of characterizations showed that the synergistic effect of electrostatic interaction, hydrogen bonding, hydrophobic force, and van der Waals force was the main adsorption mechanism. The well-designed hydrophobic ZIF-8/SA monolithic materials would be promising to rapidly remove the MPs from the water environment.

Effect of Crystallite Size on the Flexibility and Negative Compressibility of Hydrophobic Metal-Organic Frameworks.

Flexible nanoporous materials are of great interest for applications in many fields such as sensors, catalysis, material separation, and energy storage. Of these, metal-organic frameworks (MOFs) are the most explored thus far. However, tuning their flexibility for a particular application remains challenging. In this work, we explore the effect of the exogenous property of crystallite size on the flexibility of the ZIF-8 MOF. By subjecting hydrophobic ZIF-8 to hydrostatic compression with water, the flexibility of its empty framework and the giant negative compressibility it experiences during water intrusion were recorded via in operando synchrotron irradiation. It was observed that as the crystallite size is reduced to the nanoscale, both flexibility and the negative compressibility of the framework are reduced by ∼25% and ∼15%, respectively. These results pave the way for exogenous tuning of flexibility in MOFs without altering their chemistries.

Hydrophilic-hydrophobic bilayer interlayer for high performance thin-film composite reverse osmosis membranes

The strategy of modifying substrates with hydrophilic interlayers has been widely used to improve the performance of thin-film composite (TFC) nanofiltration (NF) membranes. However, the preparation of TFC reverse osmosis (RO) membranes with excellent performance on hydrophilic substrates through conventional interfacial polymerization (IP) method has proven to be very challenging. In this work, a hydrophilic polycarboxylic acid – hydrophobic ZIF-8 nanoparticles bilayer interlayer was developed to enhance the performance of TFC RO membranes. Based on this, the interlayer was designed to improve the performance of TFC RO membranes by creating a synergistic effect between the hydrophilic polycarboxylic acid and the hydrophobic ZIF-8 nanoparticles. The hydrophilic polycarboxylic acid interlayer was used to heal defects in the PSF substrate and provide growth sites for the in-situ growth of ZIF-8 nanoparticles. Hydrophobic ZIF-8 nanoparticles weakened the inhibition of the hydrophilic polycarboxylic acid interlayer on the diffusion of MPD, thus promoting the IP reaction and forming a dense PA separation layer (NaCl rejection 98.8%). The modulation of MPD erupted from the pores of the modified substrate by the bilayer interlayer results in the formation of an asymmetric PA layer, which has a dense PA in the upper region and loose PA encapsulating ZIF-8 nanoparticles in the lower region. ZIF-8 nanoparticles encapsulated by PA not only provided a low-resistance channel for water to pass through the separation layer but also enhanced the compaction resistance of the RO membrane, thus improving the permeance of the TFC RO membrane (4.2 L m−2 h−1·bar−1). In addition, thanks to the good compatibility between ZIF-8 nanoparticles and the PA matrix, as well as the smoother PA layer, TFC RO membranes with the bilayer interlayer presented excellent long-term stability and antifouling ability. This work presents a new idea to improve the performance of TFC RO membranes using interlayer strategies.

Kinetic study of methane storage in hydrophobic ZIF-8 by adsorption-hydration hybrid technology

Adsorption-hydration hybrid (AHH) technology combining methane adsorption and hydrate formation has attracted extensive attention for methane storage/transportation. This work explored the AHH kinetic properties in the hydrophobic metal-organic framework ZIF-8, using a visualization platform, to elucidate the relationship between adsorption and hydrate formation. A two-stage adsorption process of methane physisorption and hydrate formation-adsorption occurred, in which hydrate fibers and hydrate chunks were formed successively. To investigate the effects of water content (Rw) and pressure on AHH kinetic properties, the mass transfer coefficient of methane and kinetic constant of hydrate formation in two stages were calculated, respectively. Increasing Rw from 0.3 to 1.0 resulted in a significant decrease of 68.2% and 89.8% in the mass transfer coefficient of methane in the first stage and the kinetic constant of hydrate formation in the second stage, respectively. The higher Rw hindered hydrate fiber formation by impeding methane diffusion within the pore space, while raising the initial pressure promoted methane diffusion. Specifically, when the pressure was increased from 5.3 MPa to 7.0 MPa, the methane physisorption rate and hydrate formation rate could increase by up to 1.77 and 1.35 times, respectively. Furthermore, it was found that the decrease of physisorption rate further reduced the hydrate formation rate, revealing the relationship between physisorption and hydrate formation. A combined analysis of initial pressure and water content suggested that the inhibitory effect of Rw on mass transfer outweighed the promoting effect of initial pressure.

Investigating the performance of surface-engineered membranes for direct contact membrane distillation

ABSTRACT Direct contact membrane distillation (DCMD) is an emerging technology gaining attraction in seawater desalination and concentration of aqueous solutions. In this study, a facile surface modification strategy using hydrophobic ZIF-8 and a fluoroalkylsilane (FAS) was employed to improve the performance of commercial PVDF and PVDF/PTFE blend membranes. The PVDF/PTFE membrane modified using 10 wt./vol % hydrophobic ZIF-8 and 1 H, 1 H, 2 H, 2 H-perfluorooctyltriethoxysilane (PFOTES) exhibited the highest water contact angle (121 ± 4.7°), improved surface roughness (51.6 ± 1.4 nm), most significant vapor flux (17.6 ± 2 L/m2h), and salt rejection of 99.98% with 10,000 ppm NaCl synthetic feed solution at the optimum operating conditions. The surface-engineered membranes exhibited excellent anti-fouling (360 minutes) and anti-wetting performance (240 minutes) when challenged with saline feed solution containing 50 ppm sodium alginate solution and 0.1 mM sodium dodecyl sulfate, respectively. The surface engineered membranes produced permeate of uniform quality for>10 h and could recover~31% water during actual seawater desalination (10 h). Moreover, these membranes could concentrate propylene glycol by a factor of 1.24 within 6 h and retain>80% of it. This facile surface modification strategy holds an excellent potential to be further explored for commercial applications.

Hydrophobic ZIF-8 covered active carbon for CO2 capture from humid gas

The performance of activated carbon (AC) will be severely affected for carbon dioxide (CO2) capture in flue gas, as they usually suffer from competitive adsorption of water vapor. Establishment of a barrier against moisture on the surface of porous adsorbent material could potentially address this issue. Zeolite-like metal–organic frameworks (ZIF-8) as a promising adsorbent material demonstrates hydrophobic properties, large specific surface area, and highly porous structure. Here, by further growth of ZIF-8 on polydopamine (PDA)-coated bio-based carbon (AC@PDA), we fabricate hydrophobic final product (AC@ZIF-8). The CO2 capture capacities of AC@ZIF-8 was 41.69 cm3/g, which is only 13.61% lower than that of the initial AC under dry conditions. The hydrophobic ZIF-8 layer can effectively prevent water molecules from reaching the interior AC. Therefore, the adsorption of CO2 for AC@ZIF-8 decreased by only 16.74% under high relative humidity, while it decreased by 61.27% for bare AC. This strategy will broaden the applications of carbon-based adsorbents for CO2 capture under severely humid conditions. We believe that this approach is also applicable for an extensive set of CO2 capture materials that suffer from water instability.

Product selectivity and mass transport in levulinic acid transfer hydrogenation by monolithic MIL-100, MIL-88B and ZIF-8@Pd MOFs.

The diffusion processes between adsorbent and adsorbate naturally play a significant role in the efficiency and selectivity of the heterogenous catalytic process. This paper considers the importance of diffusion processes in the transfer hydrogenation reaction of levulinic acid to γ-valerolactone by MIL-88B, MIL-100, and ZIF8@Pd monolithic catalysts. Over a period of five catalytic cycles, it was shown that the Fe-based catalysts can achieve similar conversions to the ZIF-8 supported Pd, with the only current limitation being the lower aqueous stability of these MOFs. Diffusion constants were calculated using the ZLC method, with micropore diffusion limitation found for ZIF-8 and MIL-100 monolithic frameworks at 2.7 x 10-8 and 4.6 x 10-8cm2s-1 respectively. This diffusion limitation was also confirmed by IR spectroscopy with an increasing concentration of C-H bands on the MOF substrate post-reaction. Mass transfer coefficients, also calculated by ZLC, revealed increased mass transport for the hydrophobic ZIF-8 framework, which perhaps aids in the γ-valerolactone selectivity over side products that are produced in the absence of catalytic material, as seen for MIL-88B and MIL-100 after multiple uses.

A new route for ZIF-8 synthesis and its application in MMM preparation for toluene removal from water using PV process

Pervaporation (PV) is one of the most effective methods for removing volatile organic compounds (VOCs). The application of hydrophobic membrane in PV is of significant industrial value. This study used a novel method to synthesis hydrophobic zeolitic nanoparticles (ZIF-8) and incorporate them into the polymer matrix (PEBA). The prepared mixed matrix membranes (MMM) were characterized by various techniques (FTIR, FESEM, XRD, AFM, contact angle, TGA, and DSC) and utilized for toluene/water separation in a PV process. The operational findings in terms of separation factor, total permeate flux, component flux, and PSI value were studied for nanocomposites with different filler content (5–25 wt%) at different feed concentrations and temperatures. The best separation performance was achieved for MMM with 15% ZIF-8 at 30 °C and 300 ppm. The total flux enhanced from 302 to 343 gm2h compared to the neat membrane. In this condition, separation factor, and PSI value were obtained as 446, and 153120 gm2h, respectively. Incorporating of 15% hydrophobic ZIF-8 significantly improved separation factor, and PSI value by 904, and 1065%, respectively, compared to the pure membrane.

Assembly of Hydrophobic ZIF-8 on CeO2 Nanorods as High-Efficiency Catalyst for Electrocatalytic Nitrogen Reduction Reaction.

The electrocatalytic nitrogen reduction reaction (NRR) can use renewable electricity to convert water and N2 into NH3 under normal temperature and pressure conditions. However, due to the competitiveness of the hydrogen evolution reaction (HER), the ammonia production rate (RNH3) and Faraday efficiency (FE) of NRR catalysts cannot meet the needs of large-scale industrialization. Herein, by assembling hydrophobic ZIF-8 on a cerium oxide (CeO2) nanorod, we designed an excellent electrocatalyst CeO2-ZIF-8 with intrinsic NRR activity. The hydrophobic ZIF-8 surface was conducive to the efficient three-phase contact point of N2 (gas), CeO2 (solid) and electrolyte (liquid). Therefore, N2 is concentrated and H+ is deconcentrated on the CeO2-ZIF-8 electrocatalyst surface, which improves NRR and suppresses HER and finally CeO2-ZIF-8 exhibits excellent NRR performance with an RNH3 of 2.12 μg h−1 cm−2 and FE of 8.41% at −0.50 V (vs. RHE). It is worth noting that CeO2-ZIF-8 showed excellent stability in the six-cycle test, and the RNH3 and FE variation were negligible. This study paves a route for inhibiting the competitive reaction to improve the NRR catalyst activity and may provide a new strategy for NRR catalyst design.

Accelerated formation of hydrate in size-varied ZIF-8 for CH4 storage by adsorption-hydration hybrid technology

CH4 storage by the adsorption-hydration hybrid is considered as the most potential method in CH4 storage/transportation. Metal-organic frameworks (MOFs) as porous materials have significant potential in CH4 storage. However, little is known with respect to the rapid formation and spatial growth of hydrate in MOFs. In this work, microstructures of hydrophobic ZIF-8 demonstrated inner cavities could act as CH4 physisorption sites. The experiment of CH4 adsorption-hydration hybrid in three particle sizes of ZIF-8 was carried out in visualization system, suggesting hydrate nucleation and growth preferentially occurred in micro bulges and surface gaps. Three morphologies of fog-like hydrate, hydrate fibers and hydrate chunks were observed in ZIF-8, depending on material surface and particle sizes. On this basis, a novel approach to facilitate hydrate formation was proposed by using different particle sizes ZIF-8 enhanced CH4 physisorption. The CH4 storage capacity and kinetics of adsorption-hydration hybrid under different water content were further investigated, providing suitable water content for exploring the effects of ZIF-8 particle size on hydrate formation kinetics. Compared with the three particle sizes range of ZIF-8, an extremely short hydrate induction time is 1.08 min, corresponding to the particle size of 0.5 ∼ 1.5 mm. In the particle sizes range studied, the rate of gas consumption demonstrated that CH4 physisorption is higher with ZIF-8 particle size of 0.5 ∼ 1.5 mm, and the rate of physisorption is negatively correlated with hydrate induction time. Finally, the similar kinetics effect of CH4 adsorption-hydration hybrid could be attained with three particle sizes of recycled ZIF-8. The property of the ZIF-8 is stable confirmed from the scanning electron microscope measurements after it undergoes two cycles. This study would shed light on the understanding of CH4 rapid storage by adsorption-hydration hybrid in MOFs, which provided new perspective to improve the efficiency of the natural gas storage.

Meso/microporous MOF@graphene oxide composite aerogels prepared by generic supercritical CO2 technology

The increasing complexity in composition and structure of modern porous nanocomposite materials requires the development of advanced technologies that allow the simultaneous treatment of dissimilar compounds, not only with unlike composition but also involving different classes of pores, e.g., micro and mesopores. This work shows that supercritical CO 2 (scCO 2 ) technology can be used as generic processing aid to obtain composites involving non-reduced graphene oxide (GO) and metal organic frameworks (MOFs) in the form of aerogels with hierarchical porosity. Hybrid aerogels are formed by either depositing ( ex situ ) or growing ( in situ ) MOF nanocrystals onto the surface of 2D GO nanosheets. The archetypal hydrophilic HKUST-1 and UiO-66 and hydrophobic ZIF-8 microporous MOFs are chosen to exemplify the method possibilities. The ex situ route was adequate to prepare hydrophilic MOFs@GO homogeneous composites, while the in situ approach must be used to prepare hydrophobic MOFs@GO aerogels. Moreover, the scCO 2 methodology should be adjusted for each studied MOF in regard of the organic solvent used to disperse the nanoentities constituting the composite. The end-products are obtained in the form of aerogels mimicking the shape of the recipient in which they are contained. The products are characterized in regard of structure by X-ray diffraction, textural properties by low temperature N 2 adsorption/desorption and morphology by electronic microscopy. • scCO 2 as a synthetic platform for fabrication of meso/microporous MOF@GO aerogels. • MOF hydrophobic/hydrophilic nature defines the choice of ex situ/in situ scCO 2 method. • The ex situ route can be applied to a large number of MOFs with hydrophilic nature. • The in situ method can be also applied to hydrophobic MOFs to reduce time/resources. • MOF@GO composites were homogenous with hierarchical micro/meso porosity.

Molecular insights into hybrid CH4 physisorption-hydrate growth in hydrophobic metal–organic framework ZIF-8: Implications for CH4 storage

Adsorption-hydration hybrid method has been widely concerned due to its great application potential in CH4 storage/transportation. Monte Carlo and molecular dynamics simulations were performed to investigate the hybrid CH4 physisorption-hydrate growth in ZIF-8. The two-way migration phenomenon between water molecules inside the cavities and CH4 molecules outside the cavities first occurs in the physisorption process, which increases the CH4 adsorption capacity to a level close to that of dry ZIF-8. Due to the competitive adsorption for CH4 between ZIF-8 and hydrate surface, it is not conducive to the stability of intergranular CH4 hydrate before the CH4 adsorption capacity of ZIF-8 attains the maximum. After the maximum, intergranular hydrate could exist stably and grow continuously with the dissolution of CH4. Meanwhile, partially adsorbed CH4 molecules in the cavities migrate outwards and promote hydrate growth. These constitute the link between physisorption and hydrate growth. Because of the phase separation of CH4 and water molecules, hydrate cannot form in the ZIF-8 cavities. As a result, under the synergistic effect of physisorption and intergranular hydrates, CH4 storage capacity is significantly increased in H2O-oversaturated ZIF-8 compared with that in dry ZIF-8. Further, hydrophobic ZIF-8 surface facilitates hydrogen bonds formation in interfacial water by inducing ordered structures, and interfacial water as a medium promotes the contact between hydrate cage and ZIF-8 surface. An analysis of the diffusion properties of CH4/water molecules reveals that ZIF-8 cavities, hydrate cages, and intergranular liquid water exert inhibition on their self-diffusion coefficients in different degree. This study provides important microscopic insight into CH4 storage by adsorption-hydration hybrid in ZIF-8.

High-performance thin-film nanocomposite (TFN) forward osmosis (FO) membranes incorporated with porous hydrophobic-core/hydrophilic-shell nanoparticles

The current article discusses some unprecedented information about the improvement in forward osmosis (FO) performance of polyethersulfone/polyamide (PES/PA) membranes, mainly focused on water flux and selectivity along with resistance to fouling phenomenon; which itself is brought in by the introduction of pre-modified zeolitic imidazolate framework-8 MOF nanoparticles. An investigation has been conducted on ZIF-8 nanoparticles surface with hydrophilicity feature to evaluate their potential for utilization in active polyamide layer of FO membranes for the first time, free from any decrease in water flux value (when hydrophobic ZIF-8 is exploited solely) and selectivity (when mSiO2 with unselective channels is employed). Correspondingly, to fulfill the desired goal, MOF nanocrystals were coated with a thin mSiO2 shell at first, so they can be modified in the next step by GPTMS and ultimately aspartic acid. Feasibility of applied strategy (using hydrophobic-core/hydrophile-shell nanofillers) in FO membranes' desalination performance was assessed after incorporating ZIF-8@mSiO2-GPTMS-Asp nanoparticles of various concentrations in the polyamide rejection layer throughout the interfacial polymerization (IP) process. The obtained results divulge that the optimal membrane (TFN400) has the highest water flux and selectivity as well as superior resistance to BSA and SA foulant.

ZIF-8 engineered bismuth nanosheet arrays for boosted electrochemical reduction of nitrate.

Removal of nitrate in wastewater is of great importance to environmental protection and humanity. However, the competitive reaction of hydrogen evolution (HER), which could occupy most active sites of the electrocatalyst, is one of the big challenges for nitrate removal. In this study, a novel zeolitic imidazolate framework-8 film engineered bismuth nanosheet electrocatalyst (ZIF-8/Bi-CC) was designed and synthesized for the electrochemical reduction of nitrate. The water contact angle and electrochemical tests demonstrated that the construction of the hydrophobic ZIF-8 film effectively weakened the competition of HER. And the nitrate removal efficiency and ammonium selectivity increased by 25.9% and 34.2% respectively after bismuth nanosheets were embedded into the ZIF-8 film. Besides, the bismuth concentration detection results indicated that the ZIF-8 film as the protective shell could effectively prevent the leaching of bismuth into the solution. More importantly, the final nitrate removal rate of ZIF-8/Bi-CC was close to 90% after 5 h when treating actual garbage fly ash wastewater, the NITRR efficiency stability and the obtained product were confirmed by five electrochemical cycles. The metal-organic framework film engineered electrocatalyst is a promising strategy for designing a new catalyst for the removal of nitrate in industrial wastewater.

Enhanced stability and hydrophobicity of LiX@ZIF-8 composite synthesized environmental friendly for CO2 capture in highly humid flue gas

Decreased adsorption capacity and complicated synthetic procedures with expensive or toxic raw chemicals are two major challenges faced by physical adsorbents for carbon capture in highly humid flue gas. In this study, a novel core-shell composite using LiX with high CO2 adsorption capacity as core and superior hydrophobic ZIF-8 as shell is proposed. The overall synthesis process is conducted under ambient temperature and pressure by adopting deionized water as green solvent. Experimental results show that the adsorption performance of the core-shell structure is enhanced along with the improvement of hydrophobic performance in highly humid flue gas. The performance of ZIF-8 shells from monolayer to multilayers (up to three layers) are investigated. In particular, LiX@ZIF-8-I with single layer of ZIF-8 exhibit the highest CO2 adsorption capacity of 1.73 mmol/g in humid flue gas. The monolayered adsorbent not only exhibit superior hydrophobicity and CO2 adsorption capacity but also maintain excellent hydrothermal stability in humid flue gas over 50 adsorption/desorption cycles, which promote its application to practical in a green, energy-saving and economical way.

Tumor-Activated and Metal–Organic Framework Assisted Self-Assembly of Organic Photosensitizers

Tumor accumulation and intratumoral singlet oxygen (1O2) generation efficiency of photosensitizers (PSs) are two essential factors that determine their photodynamic therapy (PDT) efficacies. How to maximize the PS performance at the tumor site is of great research interest. Herein, we report a metal-organic framework (ZIF-8, ZIF = zeolitic imidazolate framework) assisted in vivo self-assembly nanoplatform, ZIF-8-PMMA-S-S-mPEG, as an effective tool for organic PS payloads to achieve efficient PDT. Using an organic PS with aggregation-induced emission as an example, under intratumoral bioreduction, PS-loaded ZIF-8-PMMA-S-S-mPEG (PS@ZIF-8-PMMA-S-S-mPEG) was self-assembled into large ordered hydrophobic clusters, which greatly enhance tumor retention and accumulation of the PS. Moreover, hydrophobic ZIF-8 assemblies greatly isolate the loaded PSs from water and improve O2 transport for the PSs to effectively produce 1O2 inside tumors under light irradiation. The organic PS is therefore endowed with optimal tumor accumulation and intratumoral 1O2 production, demonstrating the effectiveness of the developed self-assembly strategy in PDT application.