Cellulose acetate-based membranes by interfacial engineering and integration of ZIF-62 glass nanoparticles for CO2 separation

A Short Review of Advances in MOF Glass Membranes for Gas Adsorption and Separation

The phenomenon of melting in metal-organic frameworks (MOFs) has recently garnered attention. Crystalline MOF materials can be transformed into an amorphous glassy state through melt-quenching treatment. The resulting MOF glass structure eliminates grain boundaries and retains short-range order while exhibiting long-range disorder. Based on these properties, it emerges as a promising candidate for high-performance separation membranes. MOF glass membranes exhibit permanent and accessible porosity, allowing for selective adsorption of different gas species. This review summarizes the melting mechanism of MOFs and explores the impact of ligands and metal ions on glassy MOFs. Additionally, it presents an analysis of the diverse classes of MOF glass composites, outlining their structures and properties, which are conducive to gas adsorption and separation. The absence of inter-crystalline defects in the structures, coupled with their distinctive mechanical properties, renders them highly promising for industrial gas separation applications. Furthermore, this review provides a summary of recent research on MOF glass composite membranes for gas adsorption and separation. It also addresses the challenges associated with membrane production and suggests future research directions.

Facilitating Proton Coupled Electron Transfer Reaction through the Interfacial Micro Electric Field with Fe─N4 ─C in FeMOFs Glass

The proton-coupled electron transfer(PCET) reaction plays a crucial role in the chemical transformation process andhas become one of the most concerned elementary reactions. However, the complex kinetics of PCET reaction, which requires the simultaneous transfer of protons and electrons, leads to the dilemma that thermodynamics and kinetics cannot bebalanced and restricts its further development. In this, an interface micro-electric field (IMEF) basedon Fe─N4 in FeMOFs (Fe-Based Metal-Organic Frameworks) glass is designed tosynchronize proton/electron interface behavior for the first time to realizeefficient PCET reaction and optimize reaction thermodynamics and kinetics. The IMEF facilitates the separation of photogenerated electrons and holes, and accelerates Fe(III)/Fe(II) cycle. Driven by near-surface electric field force, the protons near surfacemigrate to Fe sites and participate in Fe(IV)═O formation and reaction, lowering the reaction energy barrier. Based on the interface regulation ofIMEF, a high-efficiency PCET reaction is realized, and kinetic reactionrate constant of photocatalytic oxidation of emerging contaminants is increasedby 3.7 times. This study highlights a strategy for IMEFs to modulate PEC Treactions for a wide range of potential applications, including environmental and ecological applications.

Leveraging Diffusion Kinetics to Reverse Propane/Propylene Adsorption in Zeolitic Imidazolate Framework-8

The separation challenge posed by propylene/propane mixtures arises from their nearly identical molecular sizes and physicochemical properties. Metal-organic frameworks (MOFs) have demonstrated potential in addressing this challenge through the precision tailoring of pore sizes and surface chemistry. However, introducing modifications at the molecular level remains a considerable hurdle. This work presents an approach to reversibly tune the propylene/propane adsorption preference in zeolitic imidazolate framework-8 (ZIF-8) by manipulating the particle size and gas flow rate. Systematically increasing the ZIF-8 crystals from 9 to 224 μm restricts propane diffusion, thereby reversing its preferential adsorption over propylene. Furthermore, raising the gas flow rate of mixed propylene/propane shifts the rate-determining breakthrough step from thermodynamic equilibrium to kinetics, again reversing the adsorption preference in a particular ZIF-8 sample. We propose "dynamic selectivity (Sd(t))" as a concept that incorporates both thermodynamic and kinetic factors to elucidate these unexpected findings. Moreover, the driving force equation, grounded on the concept of Sd(t), has improved the precision and stability of the computational simulation for fixed-bed adsorption processes. This work underscores the potential of diffusion-based modulation, implemented through manageable external changes, as a viable strategy to optimize separation performance in porous adsorbent materials.

A review of cellulose-based derivatives polymers in fabrication of gas separation membranes: Recent developments and challenges

Due to low-cost, sustainability and good mechanical stability, cellulose-based materials are frequently used in fabrication of polymeric gas separation membrane as potential carbohydrate polymers to substitute traditional petrochemical-based materials. In this review, the performance of cellulose-based polymeric membranes i.e. cellulose acetate, cellulose diacetate, cellulose triacetate, ethyl cellulose and carboxymethyl cellulose in the separation of different gases were investigated. This review paper provides the main features and advantages in the fabrication of cellulose-based gas separation membranes. The influence of the functionalization of cellulose on gas separation and permeability performance of related membranes is considered. Influence of different modification procedures such as blending with polymers, nanomaterials and ionic liquids on the gas separation ability of cellulose-based membranes were reviewed. Moreover, a brief inquiry of the potential of cellulose-based gas separation membranes for industrial applications, by examining the performance of different cellulose derivatives and identifying potential strategies for membrane modification and optimization are given, along with the current restrictions and the future perspectives are discussed.

Structural insights into hybrid immiscible blends of metal-organic framework and sodium ultraphosphate glasses

Recently, increased attention has been focused on amorphous metal-organic frameworks (MOFs) and, more specifically, MOF glasses, the first new glass category discovered since the 1970s. In this work, we explore the fabrication of a compositional series of hybrid blends, the first example of blending a MOF and inorganic glass. We combine ZIF-62(Zn) glass and an inorganic glass, 30Na2O-70P2O5, to combine the chemical versatility of the MOF glass with the mechanical properties of the inorganic glass. We investigate the interfacial interactions between the two components using pair distribution function analysis and solid state NMR spectroscopy, and suggest potential interactions between the two phases. Thermal analysis of the blend samples indicated that they were less thermally stable than the starting materials and had a Tg shifted relative to the pristine materials. Annular dark field scanning transmission electron microscopy tomography, X-ray energy dispersive spectroscopy (EDS), nanoindentation and 31P NMR all indicated close mixing of the two phases, suggesting the formation of immiscible blends.

Metal-organic framework glass composites

The melting phenomenon in metal-organic frameworks (MOFs) has been recognised as one of the fourth generation MOF paradigm behaviours. Molten MOFs have high processibility for producing mechanically robust glassy MOF macrostructures, and they also offer highly tunable interfacial characteristics when combined with other types of functional materials, such as crystalline MOFs, inorganic glass and metal halide perovskites. As a result, MOF glass composites have emerged as a family of functional materials with dynamic properties and hierarchical structural control. These nanocomposites allow for sophisticated materials science studies as well as the fabrication of next-generation separation, catalysis, optical, and biomedical devices. Here, we review the approaches for designing, fabricating, and characterising MOF glass composites. We determine the key application opportunities enabled by these composites and explore the remaining hurdles, such as improving thermal and chemical compatibility, regulating interfacial properties, and scalability.

Functions and applications of emerging metal-organic-framework liquids and glasses

Traditional metal-organic-frameworks (MOFs) have been extensively studied and applied in various fields across chemistry, biology and engineering in the past decades. Recently, a family of emerging MOF liquids and glasses have gained ever-growing research interests owing to their fascinating phase transitions and unique functions. To date, a growing number of MOF crystals have been found to be capable of transforming into liquid and glassy states under external stimuli, which overcomes the limitations of MOF crystals by introducing functional disorder in a controlled manner and offering some desirable properties. This review is dedicated to compiling recent advances in the fundamental understanding of the phase and structure evolution during crystal melting and glass formation in order to give insights into the underlying conversion mechanism. Benefiting from the disordered metal-ligand arrangement and free grain boundaries, various functional properties of liquid and glassy MOFs including porosity, ionic conductivity, and optical/mechanical properties are summarized and evaluated in detail, accompanied by the structure-property correlation. At the same time, their potential applications are further assessed from a developmental perspective according to their unique functions. Finally, we summarize the current progress in the development of liquid/glassy MOFs and point out the serious challenges as well as the potential solutions. This work provides perspectives on the functional applications of liquid/glassy MOFs and highlights the future research directions for the advancement of MOF liquids and glasses.

ZIF-62 glass foam self-supported membranes to address CH4/N2 separations

Membranes with ultrahigh permeance and practical selectivity could greatly decrease the cost of difficult industrial gas separations, such as CH₄/N₂ separation. Advanced membranes made from porous materials, such as metal-organic frameworks, can achieve a good gas separation performance, although they are typically formed on support layers or mixed with polymeric matrices, placing limitations on gas permeance. Here an amorphous glass foam, a_gfZIF-62, wherein a, g and f denote amorphous, glass and foam, respectively, was synthesized by a polymer-thermal-decomposition-assisted melting strategy, starting from a crystalline zeolitic imidazolate framework, ZIF-62. The thermal decomposition of incorporated low-molecular-weight polyethyleneimine evolves CO₂, NH₃ and H₂O gases, creating a large number and variety of pores. This greatly increases pore interconnectivity but maintains the crystalline ZIF-62 ultramicropores, allowing ultrahigh gas permeance and good selectivity. A self-supported circular a_gfZIF-62 with a thickness of 200-330 µm and area of 8.55 cm² was used for membrane separation. The membranes perform well, showing a CH₄ permeance of 30,000-50,000 gas permeance units, approximately two orders of magnitude higher than that of other reported membranes, with good CH₄/N₂ selectivity (4-6).

Reinforcement of single-walled carbon nanotubes on polydimethylsiloxane membranes for CO2, O2, and N2 permeability/selectivity

In this study, PDMS incorporated with SWCNTs have been fabricated via solution casting method for industrial applications and characterized by the analyses of SEM, FTIR, TGA, AFM, and MST. The modified membranes were further analyzed for CO₂, O₂, and N₂ gas permeability. The strategic membranes have five different weight ratios (0.013, 0.025, 0.038, 0.050, 0.063) compared to neat PDMS membranes. The even distribution of SWCNTs in PDMS provided results that showed improvement in thermal stability. However, mechanical strength has been weakened with increased concentration of nanofiller because of the increase in the number of SWCNTs by increases that imperfections become more severe. The designed polymeric membranes with good thermal stability and adequate mechanical strength can be used for the selectivity and permeability of CO₂, O₂, and N₂ gases. The effect of the PDMS-SWCNTs on gas permeability has been studied. 0.063 wt.% SWCNTs presented the maximum permeability of CO₂ gas while maximum O₂ and N₂ gas permeability have been obtained by 0.013 wt.% SWCNTs. The ideal selectivity of mixed (50:50) gas conditions has been tested. The maximum CO₂/N₂ ideal selectivity was obtained by 0.050 and 0.063 wt.% SWCNTs while maximum O₂/N₂ ideal selectivity obtained by 0.050 wt.% SWCNTs. Therefore, the fabrication of this novel SWCNTs-PDMS membrane may lead to separating the industrial exhaust and be used as a potential membrane for environmental remediation in the future.

Role of silica-based porous cellulose nanocrystals in improving water absorption and mechanical properties

Epoxy resins are important thermosetting polymers. They are widely used in many applications i.e., adhesives, plastics, coatings and sealers. Epoxy molding compounds have attained dominance among common materials due to their excellent mechanical properties. The sol-gel simple method was applied to distinguish the impact on the colloidal time. The properties were obtained with silica-based fillers to enable their mechanical and thermal improvement. The work which we have done here on epoxy-based nanocomposites was successfully modified. The purpose of this research was to look into the effects of cellulose nanocrystals (CNCs) on various properties and applications. CNCs have recently attracted a lot of interest in a variety of industries due to their high aspect ratio, and low density which makes them perfect candidates. Adding different amounts of silica-based nanocomposites to the epoxy system. Analyzed with different techniques such as Fourier-transformed infrared spectroscope (FTIR), thermogravimetric analysis (TGA) and scanning electronic microscopic (SEM) to investigate the morphological properties of modified composites. The various %-age of silica composite was prepared in the epoxy system. The 20% of silica was shown greater enhancement and improvement. They show a better result than D-400 epoxy. Increasing the silica, the transparency of the films decreased, because clustering appears. This shows that the broad use of CNCs in environmental engineering applications is possible, particularly for surface modification, which was evaluated for qualities such as absorption and chemical resistant behavior.

Emerging trends in direct air capture of CO2: a review of technology options targeting net-zero emissions

The increasing concentration of carbon dioxide (CO2) in the atmosphere has compelled researchers and policymakers to seek urgent solutions to address the current global climate change challenges. In order to keep the global mean temperature at approximately 1.5 °C above the preindustrial era, the world needs increased deployment of negative emission technologies. Among all the negative emissions technologies reported, direct air capture (DAC) is positioned to deliver the needed CO2 removal in the atmosphere. DAC technology is independent of the emissions origin, and the capture machine can be located close to the storage or utilization sites or in a location where renewable energy is abundant or where the price of energy is low-cost. Notwithstanding these inherent qualities, DAC technology still has a few drawbacks that need to be addressed before the technology can be widely deployed. As a result, this review focuses on emerging trends in direct air capture (DAC) of CO2, the main drivers of DAC systems, and the required development for commercialization. The main findings point to undeniable facts that DAC's overall system energy requirement is high, and it is the main bottleneck in DAC commercialization.

Establishing a high-performance anti-fouling PEI-ZIF-PAA membrane with improved Lewis acid-base interactions and hydrophilicity

Membrane fouling and the trade-off between membrane permeability and selectivity restrict the potential applications of membrane filtration for water treatment. ZIF-8 was found having great permeability and antibiofouling performance, but with issue on particle aggregation makes it difficult to achieve high ZIFs loading and fabricate a defect-free molecular sieving membrane in previous research. In this study, we formed a scalable antibiofouling surface with improved permeability and fouling resistance on a PEI-ZIF-PAA membrane using a layer-by-layer assembly technique. The synergistic effects of being sandwiched between two different polyelectrolyte layers with opposite charges endowed the ZIF nanoparticles with improved stability and scalability for membrane modification. The PEI-ZIF-PAA membrane exhibited a satisfactory water flux of 120.78 LMH, which was 46.97% higher than that of the pristine PES membrane. The normalized water flux loss was serious in the absence of ZIF-8, and the flux increased with the ZIF-8 concentration. Antifouling tests suggested that the PEI-ZIF-PAA membrane possessed good antifouling performance due to the much higher surface hydrophilicity and positive Lewis acid-base interactions with foulants. The HA rejection increased with the ZIF-8 concentration and reached a maximum of 92.1% in the presence of 1.00% (w/v) ZIF-8. The membrane regeneration was tested under physical and chemical cleaning with flux recovery rates of about 85% and 95%. XDLVO analysis showed that the total interaction energy between HA and the PEI-ZIF-8-PAA membrane was 26.45 mJ/m², and the superior antifouling performance was mainly attributed to Lewis acid-base interactions. This study indicates that ZIF-8 nanocrystals are promising materials for fabricating novel membranes for sewage treatment.

Technological advancements in the use of ionic liquid- membrane systems for CO2 capture from biogas/flue gas - A review

Carbon capture has become a very important method for curbing the problems associated with the release of carbon dioxide into the atmosphere, which in turn has detrimental effects on the planet and its inhabitants. Ionic liquids and membrane separation have been explored in this review paper as effective means of capturing carbon dioxide. An innovative approach to CO₂ capture is the use of Ionic liquids (ILs) since they exhibit certain significant traits such as good stability (thermal, mechanical and chemical), inflammability and high absorptive capacities. Ionic liquids (ILs) are widely regarded as nontoxic substances. Viscosity and thermal degradation of ILs at temperatures slightly above 100 °C are the major disadvantages of ILs. Membrane separation is a technique used for the effective separation of substances by materials bearing holes in a continuous structure. Membrane technology has gained significant improvements, over the years. Several ILs and membrane systems were considered in this work. Their weaknesses, strengths, permeability, selectivity, operating conditions and carbon capture efficiencies, were all highlighted in order to gain a good perspective on ways by which the individual systems can be improved upon. The study considered several polymer-Ionic liquid hybrid materials as viable options for CO₂ capture from a post-combustion process. Different ILs were scrutinized for possible integration in membranes by taking full advantage of their individual properties and harnessing their tune-able characteristics in order to improve the overall carbon capture performance of the system. Several options for improving the mechanical, chemical, and thermal stabilities of the hybrid systems were considered including the use of cellulose acetate membrane, nanoparticles (graphene oxide powder) alongside potential ionic liquids. Doping membranes with ILs and nanoparticulates such as graphene oxide serves as a potential method for enhancing the CO₂ capture of membranes and this review provides several evidences that serve as proofs for this concept.

Activated carbon fiber derived from wasted coal liquefaction residual for CO2 capture

Wasted coal liquefaction residual was used to synthesize activated carbon fibers (ACFs) for CO₂ capture, and the properties of the developed ACFs were optimized by adjusting the activation conditions, including the reaction temperature and soaking time. The yield, element distribution, pore structure, composition, functional group, morphology, and adsorption capacity of the as-synthesized ACFs were characterized by various apparatuses. In addition, static and dynamic adsorption experiments were conducted to investigate the adsorption capacity of CO₂ in flue gas. The results revealed that the synthesized ACFs are mainly composed of carbon, accounting for more than 90% of the total elements. The specific surface area, pore volume, and pore width distribution of the prepared ACFs were optimized by changing the activation conditions, and ACFs with a specific surface area higher than 1400 m²/g were successfully developed by activation at 950 for 3 h. The amount of micropores occupied more than 90% of the total pore volume. The pore width distribution dominated by micropores is beneficial for CO2 adsorption since the diameter of CO₂ is 0.33 nm. From FTIR and XPS analysis, it is found that the main structure of ACFs is a carbon skeleton composed of polycyclic aromatic hydrocarbons with a small number of oxygen-containing functional groups. The adsorption isotherm of ACFs for CO₂ conforms to the Langmuir model, indicating that the adsorption process of CO₂ by ACFs can be attributed to monolayer adsorption. Both the specific surface area and oxygen-containing functional groups have crucial effects on the adsorption capacity of CO₂. The dynamic adsorption experiment determined that ACFs-920-3 had the highest adsorption capacity for CO₂ in flue gas, and adsorption equilibrium was achieved after 7 min of adsorption. The adsorption process of CO₂ in flue gas by the as-synthesized ACFs fits well with the pseudosecond kinetic model. The CO₂ adsorption capacity of the obtained ACFs remained unchanged after 10 cycles of adsorption. A high-value-added route for synthesizing ACFs for CO₂ capture using CLR as a raw material was developed.

Constructing Dual-Transport Pathways by Incorporating Beaded Nanofillers in Mixed Matrix Membranes for Efficient CO2 Separation

Mixed matrix membranes (MMMs) have attracted significant attention in the field of CO₂ separation because MMMs have potential to overcome an undesirable "trade-off" effect. In this study, the beaded nanofillers of ZIF-8@aminoclay (ZIF-8@AC) were synthesized using an in situ growth method, and they were doped into a Pebax MH 1657 (Pebax) matrix to fabricate MMMs for efficient CO₂ separation. The beaded structure was formed by ZIF-8 particles joined together during the process of AC coating on the ZIF-8 surface. ZIF-8@AC played a vital role in the improvement of gas separation performance. It was mainly attributed to the following reasons: First, the inherent micropores of ZIF-8 constructed the internal pathways for gas transport in the beaded nanofillers, benefiting the improvement of gas permeability. Second, the staggered AC layers constructed the external pathways for gas transport in the beaded nanofillers, increasing the tortuosity of gas transport for larger molecules and favoring the improvement of gas selectivity. Therefore, the internal and external pathways of ZIF-8@AC co-constructed the dual-transport pathways for CO₂ transport in MMMs. In addition, the abundant amino groups of the beaded nanofillers provided abounding carriers for CO₂, facilitating CO₂ transport in the dual-transport pathways. Therefore, the CO₂ separation performance of Pebax/ZIF-8@AC-1 MMMs was significantly improved. The CO₂ permeability and CO₂/CH₄ separation factor of Pebax/ZIF-8@AC-1-7 MMM were 620 ± 10 Barrer and 40 ± 0.4, which were 2.3 and 1.6 times those of a pure Pebax membrane, respectively. Furthermore, the CO₂/CH₄ separation performance of Pebax/ZIF-8@AC-1-7 MMM overcame successfully the "trade-off" effect and approached the 2019 upper bound. It is a novel strategy to design a beaded nanofiller doped into MMMs for carbon capture.

Kinetic optimization of odor adsorption with acetate fiber cloth prepared from waste cigarette filter

Odor pollution with NH₃ as major contributor is a notorious issue that strongly influences our living environment. NH₃ removal with acetate fiber cloth (AFC) prepared from waste cigarette filter is an economic feasible approach for simultaneous solid wastes disposal. Herein, waste cigarette filter was used to prepare AFC through hot-pressing approach, which was convinced to have good adsorption efficiency on NH₃ due to large specific surface area. Effects of hot-pressing temperature, pressure and pressing time on AFC mechanical property and NH₃ adsorption efficiencies were optimized by response surface method. As results, hot-pressing treatment improved the specific surface area of AFC to 9.530 m²/g, and thus enhanced NH₃ adsorption efficiency to 68.73 % under hot-pressing temperature of 146 °C, pressure of 12.5 kPa and pressing time of 33 min. While the optimal tensile strength of AFC was obtained as 90.43 N under hot-pressing temperature of 140 °C, pressure of 15.0 kPa and pressing time of 30 min. The work provided an economic feasible approach for waste cigarette filter recycling and odor control.

Ultra-permeable intercalated metal-induced microporous polymer nano-dots rooted smart membrane for environmental remediation

Energy efficient CO₂ separation using ultrathin smart membranes must possess efficient permeation performance, higher surface area and hydrostatic stability at industrially relevant high pressures. However, ultrathin membranes are susceptible to lower surface area, plasticization and swelling which reduces the performance at higher pressure under humidified conditions. This paper evaluates the routes for the potential intercalated effect of metal-induced microporous polymers (MMPs) dots into a cellulose-based polymer matrix to enhance promising properties, including the surface area, CO₂ permeation performance, plasticization resistance and hydrostatic stability of ultrathin smart membranes at high pressure. The MMP dots-rooted smart membrane demonstrated 55 nm thickness of ultrathin selective layer with a higher surface of 220 cm². The enhancement of CO₂ permeability from 14.1 to 108.9 Barrer and CO₂/CH₄ ideal selectivity from 11.8 to 31.1 was observed due to the integration of MMP dots into the cellulose polymer. This result could be due to enhancement of nitrogen lone pair electron interactions with CO₂ followed by amines group which improved the CO₂ adsorption on the membrane surface. The MMP dots-rooted membrane demonstrated plasticization resistance up to 26 bar pressure, as compared to a pristine polymer membrane which is a percentage increase of 160% under humidified conditions. The resulting ultrathin smart membrane exhibited stable performance for a duration of 200 h under humidified conditions which confirmed the higher hydrostatic stability of the membrane. These findings confirmed the potential of MMP dots materials for the development of an industrial scale CO₂ separation process using intercalated membranes.

Modeling of Hexavalent Chromium Removal with Hydrophobically Modified Cellulose Nanofibers

Cellulose nanofibers (CNF) are sustainable nanomaterials, obtained by the mechanical disintegration of cellulose, whose properties make them an interesting adsorbent material due to their high specific area and active groups. CNF are easily functionalized to optimize the performance for different uses. The hypothesis of this work is that hydrophobization can be used to improve their ability as adsorbents. Therefore, hydrophobic CNF was applied to adsorb hexavalent chromium from wastewater. CNF was synthetized by TEMPO-mediated oxidation, followed by mechanical disintegration. Hydrophobization was performed using methyl trimetoxysilane (MTMS) as a hydrophobic coating agent. The adsorption treatment of hexavalent chromium with hydrophobic CNF was optimized by studying the influence of contact time, MTMS dosage (0-3 mmol·g^-1 CNF), initial pH of the wastewater (3-9), initial chromium concentration (0.10-50 mg·L^-1), and adsorbent dosage (250-1000 mg CNF·L^-1). Furthermore, the corresponding adsorption mechanism was identified. Complete adsorption of hexavalent chromium was achieved with CNF hydrophobized with 1.5 mmol MTMS·g^-1 CNF with the faster adsorption kinetic, which proved the initial hypothesis that hydrophobic CNF improves the adsorption capacity of hydrophilic CNF. The optimal adsorption conditions were pH 3 and the adsorbent dosage was over 500 mg·L^-1. The maximum removal was found for the initial concentrations of hexavalent chromium below 1 mg·L^-1 and a maximum adsorption capacity of 70.38 mg·g^-1 was achieved. The kinetic study revealed that pseudo-second order kinetics was the best fitting model at a low concentration while the intraparticle diffusion model fit better for higher concentrations, describing a multi-step mechanism of hexavalent chromium onto the adsorbent surface. The Freundlich isotherm was the best adjustment model.

Utilization of a double-cross-linked amino-functionalized three-dimensional graphene networks as a monolithic adsorbent for methyl orange removal: Equilibrium, kinetics, thermodynamics and artificial neural network modeling

Herein, it is aimed to develop a high-performance monolithic adsorbent to be utilized in methyl orange (MO) adsorption. Therefore, amino-functionalized three-dimensional graphene networks (3D-GN_f) fulfilling the requirements of reusability and high capacity have been fabricated via hydrothermal self-assembly approach followed by a double-crosslinking strategy. The potential utilization of 3D-GN_f as an adsorbent for removal MO has been assessed using both batch-adsorption studies and an artificial neural network (ANN) approach. Graphene oxide sheets have been amino-functionalized and cross-linked, by ethylenediamine (EDA) during hydrothermal treatment, following the glutaraldehyde has used as a double-crosslinking agent to facilitate the crosslinking of architecture. The successful fabrication of 3D-GN_f has been confirmed by field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR), Raman and X-ray photoelectron spectroscopy (XPS). Moreover, N₂ adsorption/desorption isotherms have revealed the high specific surface area (1015 m² g^-1) with high pore volume (1.054 cm³ g^-1) and hierarchical porous structure of 3D-GN_f. The effect of initial concentration, contact time, and temperature on adsorption capacity have been thoroughly studied, and the kinetics, isotherms, and thermodynamics of MO adsorption have been modelled. The MO adsorption has been well defined by the pseudo-second-order kinetic model and Langmuir isotherm model with a monolayer adsorption capacity of 270.27 mg g^-1 at 25 °C. The thermodynamic findings have revealed MO adsorption has occurred spontaneously with an endothermic process. The Levenberg-Marquardt backpropagation algorithm has been implemented to train the ANN model, which has used the activation functions of tansig and purelin functions at the hidden and output layers, respectively. An optimum ANN model with high-performance metrics (coefficient of determination, R² = 0.9995; mean squared error, MSE = 0.0008) composed of three hidden layers with 5 neurons in each layer was constructed to forecast MO adsorption. The findings have shown that experimental results are consistent with ANN-based data, implying that the suggested ANN model may be used to forecast cationic dye adsorption.

Metal-Organic Frameworks (MOFs)-Based Mixed Matrix Membranes (MMMs) for Gas Separation: A Review on Advanced Materials in Harsh Environmental Applications

The booming of global environmental awareness has driven the scientific community to search for alternative sustainable approaches. This is accentuated in the 13th sustainable development goal (SDG13), climate action, where urgent efforts are salient in combating the drastic effects of climate change. Membrane separation is one of the indispensable gas purification technologies that effectively reduces the carbon footprint and is energy-efficient for large-scale integration. Metal-organic frameworks (MOFs) are recognized as promising fillers embedded in mixed matrix membranes (MMMs) to enhance gas separation performance. Tremendous research studies on MOFs-based MMMs have been conducted. Herein, this review offers a critical summary of the MOFs-based MMMs developed in the past 3 years. The basic models to estimate gas transport, preparation methods, and challenges in developing MMMs are discussed. Subsequently, the application and separation performance of a variety of MOFs-based MMMs including those of advanced MOFs materials are summarized. To accommodate industrial needs and resolve commercialization hurdles, the latest exploration of MOF materials for a harsh operating condition is emphasized. Along with the contemplation on the outlook, future perspective, and opportunities of MMMs, it is anticipated that this review will serve as a stepping stone for the coming MMMs research on sustainable and benign environmental application.

Cellulose acetate in fabrication of polymeric membranes: A review

Developing biodegradable polymers to fabricate filtration membranes is one of the main challenges of membrane science and technology. Cellulose acetate (CA) membranes, due to their excellent film-forming property, high chemical and mechanical stability, high hydrophilicity, eco-friendly, and suitable cost, are extensively used in water and wastewater treatment, gas separation, and energy generation purposes. The CA is one of the first materials used to fabricate filtration membranes. However, in the last decade, the possibility of modification of CA to improve permeability and stability has attracted the researcher's attention again. This review is focused on the properties of cellulose derivatives and especially CA membranes in the fabrication of polymeric separation membranes in various applications such as filtration, gas separation, adsorption, and ion exchange membranes. Firstly, a brief introduction of CA properties and used molecular weights in the fabrication of membranes will be presented. After that, different configurations of CA membranes will be outlined, and the performance of CA membranes in several applications and configurations as the main polymer and as an additive in the fabrication of other polymer-based membranes will be discussed.

Future advances and challenges of nanomaterial-based technologies for electromagnetic interference-based technologies: A review

The emerging growth of the electronic devices applications has arisen the serious problems of electromagnetic (EM) wave pollution which resulting in equipment malfunction. Therefore, polymer-based composites have been considered good candidates for better EMI shielding due to their significant characteristics including, higher flexibility, ultrathin, lightweight, superior conductivity, easy fabrication processing, environmentally friendly, corrosion resistive, better adhesion with physical, chemical and thermal stability. This review article focused on the concept of the EMI shielding mechanism and challenges with the fabrication of polymer-based composites. Subsequently, recent advancements in the polymer composites applications have been critically reviewed. In addition, the impact of polymers and polymer nanocomposites with different fillers such as organic, inorganic, 2D, 3D, mixture and hybrid nano-fillers on EMI shielding effectiveness has been explored. Lastly, future research directions have been proposed to overcome the limitations of current technologies for further advancement in EMI shielding materials for industrial applications. Based on reported literature, it has been found that the low thickness based lightweight polymer is considered as a best material for excellent material for next-generation electronic devices. Optimization of polymer composites during the fabrication is required for better EMI shielding. New nano-fillers such as functionalization and composite polymers are best to enhance the EMI shielding and conductive properties.

RSM Modeling and Optimization of CO2 Separation from High CO2 Feed Concentration over Functionalized Membrane

The challenges in developing high CO₂ gas fields are governed by several factors such as reservoir condition, feed gas composition, operational pressure and temperature, and selection of appropriate technologies for bulk CO₂ separation. Thus, in this work, we report an optimization study on the separation of CO₂ from CH₄ at high CO₂ feed concentration over a functionalized mixed matrix membrane using a statistical tool, response surface methodology (RSM) statistical coupled with central composite design (CCD). The functionalized mixed matrix membrane containing NH₂-MIL-125 (Ti) and 6FDA-durene, fabricated in our previous study, was used to perform the separation performance under three operational parameters, namely, feed pressure, temperature, and CO₂ feed concentration, ranging from 3.5–12.5 bar, 30.0–50.0 °C and 15–70 mol%, respectively. The CO₂ permeability and CO₂/CH₄ separation factor obtained from the experimental work were varied from 293.2–794.4 Barrer and 5.3–13.0, respectively. In addition, the optimum operational parameters were found at a feed pressure of 12.5 bar, a temperature of 34.7 °C, and a CO₂ feed concentration of 70 mol%, which yielded the highest CO₂ permeability of 609.3 Barrer and a CO₂/CH₄ separation factor of 11.6. The average errors between the experimental data and data predicted by the model for CO₂ permeability and CO₂/CH₄ separation factor were 5.1% and 3.3%, respectively, confirming the validity of the proposed model. Overall, the findings of this work provide insights into the future utilization of NH₂-MIL-125 (Ti)/6FDA-based mixed matrix membranes in real natural gas purification applications.

Enhanced NO2 gas-sensing performance by core-shell SnO2/ZIF-8 nanospheres

Timely detection of harmful, poisonous and air pollutant gases is of vital importance to the protection of human beings from exposure to rigorous gases. The development of gas-sensing devices based on sphere-like porous SnO₂/ZIF-8 nanocomposites is required to overcome this challenge. Nanostructures with high surface area, more porosity and hollow interior provide plenty of active cites for high responses in metal oxide gas sensors. The engineered gas sensors have excellent sensing sensitivity (164), rapid response and recovery times (60, 45 s), and favorable selectivity for NO₂ gases under 300 °C. Consequently, NO₂ gas sensors based on core-shell SnO₂/ZIF-8 nanospheres are regarded viable capacity industrial applicants.

Adsorption behavior of fluoroquinolone(ciprofloxacin) using zinc oxide impregnated activated carbon prepared from jack fruit peel: Kinetics and isotherm studies

Ciprofloxacin is a pharmaceutical component used for treating various tract infections. This is considered as an emerging contaminant due to the release of unreacted components getting disposed into the water bodies. This component is effectively treated using renewable biomass, which is converted into a useful renewable low-cost adsorbent material. Discarded Jack Fruit Peel (JFP) is used as an activated carbon incorporated with zinc oxide nanocomposite. The prepared activated carbon in this experiment was characterized by determining their functional groups, morphological characters, and nature of the adsorbent material by analyzing the Fourier Transform InfraRed (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Diffraction (XRD) characterization. Further, the prepared composite's correlation coefficients and equilibrium sorption of the adsorption process were calculated using Ultra Violet (UV)-Visible Spectroscopy and analyzed with isotherm models (Langmuir model, Freundlich model, and Temkin model) and kinetic models (Pseudo-first-order kinetics, Pseudo-second-order kinetics, Intraparticle diffusion model, and Elovich model). Among the different models, the Zinc oxide impregnated activated carbon show Freundlich Isotherm and Pseudo Second order equation having a maximum correlation with experimental studies indicating double-layer adsorption, which suggests that the process is chemisorption. The operational parameters, including the effect of pH, dosage of activated carbon, and contact time of adsorption was calculated to identify the optimal condition for maximum adsorption.

Effect of process parameters over carbon-based ZIF-62 nano-rooted membrane for environmental pollutants separation

The paper evaluates the routes towards the evaluation of membranes using ZIF-62 metal organic framework (MOF) nano-hybrid dots for environmental remediation. Optimization of interaction of operating parameters over the rooted membrane is challenging issue. Subsequently, the interaction of operating parameters including temperature, pressure and CO₂ gas concentration over the resultant rooted membranes are evaluated and optimized using response surface methodology for environmental remediation. In addition, the stability and effect of hydrocarbons on the performance of the resulting membrane during the gas mixture separation are evaluated at optimum conditions to meet the industrial requirements. The characterization results verified the fabrication of the ZIF-62 MOF rooted composite membrane. The permeation results demonstrated that the CO₂ permeability and CO₂/CH₄ selectivity of the composite membrane was increased from 15.8 to 84.8 Barrer and 12.2 to 35.3 upon integration of ZIF-62 nano-glass into cellulose acetate (CA) polymer. Subsequently, the optimum conditions have been found at a temperature of 30 °C, the pressure of 12.6 bar and CO₂ feed concentration of 53.3 vol%. These optimum conditions revealed the highest CO₂ permeability, CH₄ permeability and CO₂/CH₄ separation factor of 47.9 Barrer, 0.2 Barrer and 26.8. The presence of hydrocarbons in gas mixture dropped the CO₂ permeability of 56.5% and separation factor of 46.4% during 206 h of testing. The separation performance of the composite membrane remained stable without the presence of hydrocarbons for 206 h.

Application of polysaccharide-based metal organic framework membranes in separation science

Polysaccharide/MOF composite membranes have captured the interests of many researchers during decontamination of polluted environments. Their popularity can be attributed to the relatively high chemical and thermal stabilities of these composite membranes. Chitosan is among the polysaccharides extensively used during the synthesis of hybrid membranes with MOFs. The applications of chitosan/MOF composite membranes in separation science are explored in detail in this paper. Researchers have also synthesised mixed matrix membranes of MOFs with cellulose and cyclodextrin that have proved to be effective during separation of a variety of materials. The uses of cellulose/MOF and cyclodextrin/MOF membranes for the removal of environmental pollutants are discussed in this review. In addition, the challenges associated with the use of these mixed matrix membranes are explored in this current paper.

Constructed sediment microbial fuel cell for treatment of fat, oil, grease (FOG) trap effluent: Role of anode and cathode chamber amendment, electrode selection, and scalability

For wastewater treatment, sediment microbial fuel cells (SMFCs) have advantages over traditional microbial fuel cells in cost (due to their membrane-less structure) and operation (less intensive maintenance). Nevertheless, the technical obstacles of SMFCs include their high internal electrical resistance due to sediment in the anode chamber and slow oxygen reduction reaction (ORR) in the cathode chamber, which is responsible for their low power density (PD) (0.2-50 mW/m²). This study evaluated several SMFC improvements, including anode and cathode chamber amendment, electrode selection, and scaling the chamber size up to obtain optimally constructed single-chamber SMFCs to treat fat, oil, and grease (FOG) trap effluent. The chemical oxygen demand (COD) removal efficiency, PD, and electrical energy conversion efficiency concerning theoretically available chemical energy from FOG trap effluent treatment (%EC^WW) were examined. Packing biochar in the anode chamber reduced its electrical resistance by 5.76 times, but the improvement in PD was trivial. Substantial improvement occurred when packing the cathode chamber with activated carbon (AC), which presumably catalyzed the ORR, yielding a maximum PD of 109.39 mW/m², 959 times greater than without AC in the cathode chamber. This SMFC configuration resulted in a COD removal efficiency of 85.80 % and a %EC^WW of 99.74 % in 30 days. Furthermore, using the most appropriate electrode pair and chamber volume increased the maximum PD to 1787.26 mW/m², around 1.7 times greater than the maximum PD by SMFCs reported thus far. This optimally constructed SMFC is low cost and applicable for household wastewater treatment.

Preparation of black cumin seed oil Pickering nanoemulsion with enhanced stability and antioxidant potential using nanocrystalline cellulose from oil palm empty fruit bunch

The groundbreaking innovation and industrialization are ushering in a new era where technology development is integrated with the sustainability of materials. Over the decade, nanocrystalline cellulose (NCC) obtained from lignocellulosic biomass had created a great value in various aspects. The abundantly available empty fruit bunch (EFB) in the palm oil industry has motivated us to utilize it as a sustainable alternative for the isolation of NCC, which is a worthwhile opportunity to the waste management of EFB. Taking advantage of the shape anisotropy and amphiphilic character, NCC has been demonstrated as a natural stabilizer for oil-in-water emulsion. In this work, preparation of highly stable Pickering nanoemulsion using black cumin seed oil and NCC was attempted. Black cumin seed oil is a class of plant oil with various nutritional and pharmaceutical benefits. However, its poor solubility could substantially lower the therapeutic effect, and thus, requires a delivery system to overcome this limitation. The role of NCC in the formation of stable Pickering nanoemulsion was investigated. The emulsification process was found crucial to the resulting droplet size, whereas NCC contributed critically to its stabilization. The droplet size obtained from ultrasonication and microfluidization was approximately 400 nm, as examined using transmission electron microscopy. The droplet (oil-to-water = 2:8) has long-term stability against creaming and coalescence for more than six months. The nanoemulsion stabilized by NCC could allow a better absorption by the human body, thereby maximizing the potential of black cumin seed oil in the personal care and food industries.

Self-healing epoxy coating synthesis by embedment of metal 2-methyl imidazole and acetylacetonate complexes with microcapsules

The restoration of mechanical properties is desired for creating the self-healing coatings with no corrosion capabilities. The encapsulation of epoxy resins is limited by various factors in urea and melamine formaldehyde microcapsules. An improved method was developed, where epoxy resin was encapsulated by individual wrapping of poly(melamine-formaldehyde) and poly(urea-formaldehyde) shell around emulsified epoxy droplets via oil-in-water emulsion polymerization method. The synthesized materials were characterized analytically. The curing of the epoxy was achieved by adding the [Ni/Co(2-MI)₆].2NO₃ as a latent hardener and iron acetylacetonate [Fe(acac)₃] as a latent accelerator. Isothermal and non-isothermal differential scanning calorimetric analysis revealed lower curing temperature (T_onset = 116 °C) and lower activation energies (Ea ≈ 69-75 kJ/mol). The addition of microcapsules and complexes did not adversely alter the flexural strength and flexural modulus of the epoxy coatings. The adhesion strength of neat coating decreased from 6310.8 ± 31 to 4720.9 ± 60 kPa and percent healing increased from 50.83 to 67.45% in the presence of acetylacetonate complex at 10 wt% of microcapsules.

Adsorptive removal of dyes from wastewater using a metal-organic framework: A review

Water pollution from synthetic dyes is a growing environmental concern because many dyes have carcinogenic effects on humans and aquatic life. Adsorption is a widely used technology for the separation and removal of dyes from wastewater. However, the dye removal process using conventional adsorbents is not sufficiently efficient for industrial wastewater. Metal-organic frameworks (MOFs) addresses these drawbacks. MOF showed excellent dye removal and degradation capacity owing to its multifunctionality, water-stability, large surface area, tunable pore size and recyclability. Magnetic MOFs retained excellent performance up to several consecutive cycles. Modified MOFs performed as Fenton-like catalysis process which generated abundant reactive radicals that degraded complex organic dyes into simple and less toxic forms which were further adsorbed onto the MOF. This review systematically compiles in-depth studies on the adsorptive removal of dyes from wastewater, MOF adsorption mechanisms, major influencing factors, to adsorption efficiency of MOFs. While all MOFs adsorb dyes through electrostatic attraction, the type of MOF, presence of functional groups, ligands, and pH significantly control the adsorption mechanism. Before developing an MOF, optimization and upgradation of factors and interaction between available adsorption site and adsorbate is needed. Finally, the prospects and new frontiers of MOFs in sustainable water treatment is discussed.

A biochar supported magnetic metal organic framework for the removal of trivalent antimony

Metal organic framework (MOF) nanoparticles are recognized for their effective removal of metal ions from aqueous systems. However, the application of nanoparticles in a powder form as synthesized is not practical and recovery is not easy. We prepared a recyclable magnetic MOF nanoparticle phase and used a widely available waste biomass to generate biochar to support magnetic nanoparticles applied in the treatment of aqueous antimony pollution. A mushroom waste biochar was used to support a magnetic UIO-66-2COOH (denoted as BSMU). Adsorption of trivalent antimony (Sb (III)) onto the BSMU was evaluated. The results showed that optimum conditions for preparation of the BSMU were the mass ratio of MMOF to biochar 4:1, the temperature 70 °C, the time 4 h, and the initiator 4 mM. Under such conditions, sorption capacity reached 56.49 mg/g for treatment of Sb (III) solution at 100 mg/L and pH 9.1. Alkaline conditions (such as pH 9.1) are more favorable for adsorption than acidic conditions, and coexisting ions including NO₃^-, Cl^-, SO₄^2-, and PO₄^3- had no significant negative effect in adsorption, and with the use of low dose, higher adsorption density achieved. The adsorption followed a pseudo second order kinetics model and Freundlich isotherm model. It resulted in a higher enthalpy changes (ΔH^θ) and activation energy (E_a) of 97.56 and 8.772 kJ/mol, respectively, and enhanced the rate pf random contact between antimony and the BSMU, as indicated by a higher entropy change (ΔS^θ) up to 360 J/mol·K. As a result, it readily absorbs antimony. These adsorption properties identified in this study would provide a valuable insights into the application of nanoparticles loaded biochar from abundant biomass in environmental remediation.

Assessing effectiveness of Komagataeibacter strains for producing surface-microstructured cellulose via guided assembly-based biolithography

In this study, a medical device made of surface microstructured bacterial cellulose was produced using cellulose-producing acetic acid bacteria wild-type strains in combination with guided assembly-based biolithography. The medical device aims at interfering with the cell's focal adhesion establishment and maturation around implantable devices placed in soft tissues by the symmetrical array on its surface. A total of 25 Komagataeibacter strains was evaluated over a three-step selection. In the first step, the ability of strains to produce a suitable bacterial cellulose layer with high production yield was examined, then nine strains, with a uniform and smooth layer of bacterial cellulose, were cultured in a custom-made silicone bioreactor and finally the characteristics of the symmetrical array of topographic features on the surface were analysed. Selected strains showed high inter and intra species variability in bacterial cellulose production. The devices obtained by K2G30, K1G4, DSM 46590 (Komagataeibacter xylinus), K2A8 (Komagataeibacter sp.) and DSM 15973^T (Komagataeibacter sucrofermentas) strains were pouched-formed with hexagonal surface pattern required for reducing the formation of fibrotic tissue around devices, once they are implanted in soft tissues. Our findings revealed the effectiveness of the selected Komagataeibacter wild-type strains in producing surface microstructured bacterial cellulose pouches for making biomedical devices.

Development of an extended model for the permeation of environmentally hazardous CO2 gas across asymmetric hollow fiber composite membranes

This study presents an extended thermodynamic and phenomenological combined model to mitigate the environmental hazardous acid gas over composite membranes. The model has been applied to an acid gas such as carbon dioxide (CO₂) for its permeation through polyetherimide incorporated montmorillonite (Mt) nanoparticles hollow fiber asymmetric composite membranes. The well-established non-equilibrium lattice fluid (NELF) model for penetrating low molecular weight penetrant in a glassy polyetherimide (PEI) was extended to incorporate the other important polymer/filler system features such as tortuosity in acid gas diffusion pathways resulted from layered filler aspect ratio and concentration. The model mentioned above predicts the behavior of acid gas in PEI-Mt composite membranes based on thermodynamic characteristics of CO₂ and PEI and tortuosity due to Mt. The calculated results are compared to experimentally determined values of CO₂ permeability through PEI-Mt composite asymmetric hollow fiber membranes at varying transmembrane pressures and Mt concentrations. A reasonable agreement was found between the model predicted behavior and experimentally determined data in terms of CO₂ solubility, Mt concentration and aspect ratio were calculated based on average absolute relative error (%AARE). The proposed modified model efficiently predicts the CO₂ permeance across MMMs up to 3 wt% Mt loadings and 6 bar pressure with ± 10%AARE.