Zeolitic Imidazole Framework/Graphene Oxide Hybrid Functionalized Poly(lactic acid) Electrospun Membranes: A Promising Environmentally Friendly Water Treatment Material

Tungsten-based nanocatalysts with different structures for visible light responsive photocatalytic degradation of bisphenol A

Environmental pollution, such as water contamination, is a critical issue that must be absolutely addressed. Here, three different morphologies of tungsten-based photocatalysts (WO3 nanorods, WO3/WS2 nanobricks, WO3/WS2 nanorods) are made using a simple hydrothermal method by changing the solvents (H2O, DMF, aqueous HCl solution). The as-prepared nanocatalysts have excellent thermal stability, large porosity, and high hydrophilicity. The results show all materials have good photocatalytic activity in aqueous media, with WO3/WS2 nanorods (NRs) having the best activity in the photodegradation of bisphenol A (BPA) under visible-light irradiation. This may originate from increased migration of charge carriers and effective prevention of electron‒hole recombination in WO3/WS2 NRs, whereby this photocatalyst is able to generate more reactive •OH and •O2- species, leading to greater photocatalytic activity. About 99.6% of BPA is photodegraded within 60 min when using 1.5 g/L WO3/WS2 NRs and 5.0 mg/L BPA at pH 7.0. Additionally, the optimal conditions (pH, catalyst dosage, initial BPA concentration) for WO3/WS2 NRs are also elaborately investigated. These rod-like heterostructures are expressed as potential catalysts with excellent photostability, efficient reusability, and highly active effectivity in different types of water. In particular, the removal efficiency of BPA by WO3/WS2 NRs reduces by only 1.5% after five recycling runs and even reaches 89.1% in contaminated lake water. This study provides promising insights for the nearly complete removal of BPA from wastewater or different water resources, which is advantageous to various applications in environmental remediation.

The potential of zeolite nanocomposites in removing microplastics, ammonia, and trace metals from wastewater and their role in phytoremediation

Nanocomposites are emerging as a new generation of materials that can be used to combat water pollution. Zeolite-based nanocomposites consisting of combinations of metals, metal oxides, carbon materials, and polymers are particularly effective for separating and adsorbing multiple contaminants from water. This review presents the potential of zeolite-based nanocomposites for eliminating a range of toxic organic and inorganic substances, dyes, heavy metals, microplastics, and ammonia from water. The review emphasizes that nanocomposites offer enhanced mechanical, catalytic, adsorptive, and porosity properties necessary for sustainable water purification techniques compared to individual composite materials. The adsorption potential of several zeolite-metal/metal oxide/polymer-based composites for heavy metals, anionic/cationic dyes, microplastics, ammonia, and other organic contaminants ranges between approximately 81 and over 99%. However, zeolite substrates or zeolite-amended soil have limited benefits for hyperaccumulators, which have been utilized for phytoremediation. Further research is needed to evaluate the potential of zeolite-based composites for phytoremediation. Additionally, the development of nanocomposites with enhanced adsorption capacity would be necessary for more effective removal of pollutants.

Graphene oxide dispersed mesoporous ZIF-8-encapsulated laccase for removal of toluidine blue with multiple enhanced stability

The extensive use and discharge of toluidine blue have caused serious problems to the water environment. As a green biocatalyst, laccase has the ability to decolorize the dyes, but it is limited by poor reusability and low stability. Metal-organic frameworks (MOFs) are a good platform for enzyme immobilization. However, due to the weak dispersion of MOFs, the enzyme activity is inevitably inhibited. Herein, we proposed to use graphene oxide (GO) as the dispersion medium of mesoporous ZIF-8 to construct MZIF-8/GO bi-carrier for laccase (FL) immobilization. On account of the narrower bandgap energy of FL@MZIF-8/GO (4.07 eV) than that of FL@MZIF-8 (4.69 eV), electron transport was enhanced which later increased the catalytic activity of the immobilized enzyme. Meanwhile, the improved hydrophilicity characterized by contact angle and full infiltration time further promoted the efficiency of the enzymatic reaction. Benefiting from such regulatory effects of GO, the composite showed excellent storage stability and reusability, as well as multifaceted enhancements including pH, thermal, and solvent adaptation. On the basis of the characterized synergistic effect of adsorption and degradation, FL@MZIF-8/GO was successfully applied to the degradation of toluidine blue (TB) with a removal rate of 94.8%. Even in actual treated wastewater, the highest removal rate still reached more than 80%. Based on the inner mechanism analysis and the universality study, this material is expected to be widely used in the degradation of pollutants in real water under complex environmental conditions.

Decoration of polylactic acid on graphene oxide for efficient adsorption of methylene blue and tetracycline

Decorating nanomaterials on graphene oxide (GO) can enhance its adsorption capacity and removal efficiency of water pollutants. In this study, for the first time, nano-sized polylactic acid (PLA) has been successfully decorated on the surface of GO through a facile synthesis approach. The adsorptive efficiency of GO-PLA for removing methylene blue (MB) and tetracycline (TC) from an aqueous solution was examined. The characterization confirmed the successful decoration of PLA on GO nanosheets with the nano size of PLA. It was hypothesized that the PLA was decorated on the surface of GO through covalent bonding between oxygen-containing functional groups and lactide molecules. The optimum adsorption parameters determined were at the adsorbent dose of 0.5 g L^-1, pH 4, contact time of 120 min, and temperature of 318 K. The pseudo-second-order kinetic model described the contaminants' adsorption behaviour, and the intraparticle diffusion model revealed that both surface adsorption and intraparticle diffusion controlled the adsorption process. Langmuir isotherm model best described the adsorption behaviour of the pollutants on GO-PLA and demonstrated the maximum monolayer uptake capacities of MB (332.5 mg g^-1) and TC (223.7 mg g^-1). The adsorption results indicated that the uptake capacities of GO-PLA in comparison to GO have increased by approximately 70% and 110% for MB and TC, respectively. These observations reflect the remarkable role of nano-sized PLA that enhanced the adsorption capacity due to its additional functional group and larger surface area.

Highly efficient degradation of reactive black KN-B dye by ultraviolet light responsive ZIF-8 photocatalysts with different morphologies

Zeolitic imidazolate framework ZIF-8, a type of metal-organic framework, has diverse applications in multiple catalytic fields due to its outstanding properties. Herein, ZIF-8 photocatalysts with three different morphologies (dodecahedral, pitaya-like, and leaf-like) are successfully synthesized under ambient conditions from zinc salts by altering the volume ratio of methanol and water used as a solvent. The as-synthesized ZIFs have high crystallinity with distinct BET surface areas. The experiments indicate that the ZIFs have high photocatalytic efficiency, in which the leaf-like structure (ZIF-8-F3) is the most efficient in the degradation of reactive black KN-B dye (RB5) under 365 nm UV irradiation. This is due to the efficient inhibition of electron-hole recombination or the higher migration of charge carriers in ZIF-8-F3, thus producing more reactive oxygen species, resulting in greater photocatalytic efficiency. At pH = 11, more than 95% of RB5 is degraded within 2 hours when using 1.0 g L^-1 of ZIF-8-F3. Besides, the photocatalytic and kinetic performances of ZIF-8-F3 are also investigated by optimizing the pH, initial RB5 concentration, and dosage of the used catalyst. These ZIF-8-F3 plates have been shown to be a promising material with high photostability and effective reusability, beneficial to various potential applications in environmental remediation issues.

Advanced Polymeric Nanocomposite Membranes for Water and Wastewater Treatment: A Comprehensive Review

Nanomaterials have been extensively used in polymer nanocomposite membranes due to the inclusion of unique features that enhance water and wastewater treatment performance. Compared to the pristine membranes, the incorporation of nanomodifiers not only improves membrane performance (water permeability, salt rejection, contaminant removal, selectivity), but also the intrinsic properties (hydrophilicity, porosity, antifouling properties, antimicrobial properties, mechanical, thermal, and chemical stability) of these membranes. This review focuses on applications of different types of nanomaterials: zero-dimensional (metal/metal oxide nanoparticles), one-dimensional (carbon nanotubes), two-dimensional (graphene and associated structures), and three-dimensional (zeolites and associated frameworks) nanomaterials combined with polymers towards novel polymeric nanocomposites for water and wastewater treatment applications. This review will show that combinations of nanomaterials and polymers impart enhanced features into the pristine membrane; however, the underlying issues associated with the modification processes and environmental impact of these membranes are less obvious. This review also highlights the utility of computational methods toward understanding the structural and functional properties of the membranes. Here, we highlight the fabrication methods, advantages, challenges, environmental impact, and future scope of these advanced polymeric nanocomposite membrane based systems for water and wastewater treatment applications.

Recent Developments of Electrospinning-Based Photocatalysts in Degradation of Organic Pollutants: Principles and Strategies

Electrospinning is a simple and cheap process for forming one-dimensional (1D) nanofibers with controllable size, morphology, and chemistry. Besides these, the ultrahigh surface area with industrialization capability has attracted extensive interest in the research community. On the other hand, a photocatalytic process is a promising method for degrading organic pollutants that cannot be removed by conventional wastewater treatment. This review focuses on the recent progress of electrospun nanofibers for the photocatalytic degradation of water pollutants. The linkage between the electrospinning technique and the photocatalytic process is classified into two main categories: (1) polymeric electrospun nanofibers as a sacrificed template to form 1D photocatalysts and (2) polymeric electrospun nanofibers as a carrier of photocatalyst materials. We have thoroughly discussed the principles and fundamental issues of electrospinning as well as two main strategies to design and fabricate nanofiber-based photocatalysts for the ideal photodegradation of organics pollutants. The results of data mapping using VOSviewer demonstrated the recent trend and the importance of this field among researchers and engineers. Moreover, we have elaborated on the limitations and potential benefits of the two categories of electrospinning-based photocatalyst fabrication and practical application that will open new directions for future research.

A comprehensive review on fused deposition modelling of polylactic acid

Fused Deposition Modelling (FDM) is one of the additive manufacturing (AM) techniques that have emerged as the most feasible and prevalent approach for generating functional parts due to its ability to produce neat and intricate parts. FDM mainly utilises one of the widely used polymers, polylactic acid, also known as polylactide (PLA). It is an aliphatic polyester material and biocompatible thermoplastic, with the best design prospects due to its eco-friendly properties; when PLA degrades, it breaks down into water and carbon dioxide, neither of which are hazardous to the environment. However, PLA has its limitations of poor mechanical properties. Therefore, a filler reinforcement may enhance the characteristics of PLA and produce higher-quality FDM-printed parts. The processing parameters also play a significant role in the final result of the printed parts. This review aims to study and discover the properties of PLA and the optimum processing parameters. This review covers PLA in FDM, encompassing its mechanical properties, processing parameters, characterisation, and applications. A comprehensive description of FDM processing parameters is outlined as it plays a vital role in determining the quality of a printed product. In addition, PLA polymer is highly desirable for various field industrial applications such as in a medical, automobile, and electronic, given its excellent thermoplastic and biodegradability properties.

Electrospun Polymer Materials with Fungicidal Activity: A Review

In recent years, there has been special interest in innovative technologies such as polymer melt or solution electrospinning, electrospraying, centrifugal electrospinning, coaxial electrospinning, and others. Applying these electrokinetic methods, micro- or nanofibrous materials with high specific surface area, high porosity, and various designs for diverse applications could be created. By using these techniques it is possible to obtain fibrous materials from both synthetic and natural biocompatible and biodegradable polymers, harmless to the environment. Incorporation of low-molecular substances with biological activity (e.g., antimicrobial, antifungal) is easily feasible. Moreover, biocontrol agents, able to suppress the development and growth of plant pathogens, have been embedded in the fibrous materials as well. The application of such nanotechnologies for the creation of plant protection products is an extremely promising new direction. This review emphasizes the recent progress in the development of electrospun fungicidal dressings and their potential to be applied in modern agriculture.

Design, synthesis, and characterization of a novel Zn(II)-2-phenyl benzimidazole framework for the removal of organic dyes

A novel Zn (II) organic framework comprising 2-phenyl benzimidazole (ZPBIF-1) was synthesized by using a solvothermal method. The characterization of the synthesized MOF was performed utilizing XRD, SEM, FT-IR, ¹H-NMR, ¹³C-NMR, MS, XPS, TG/DTA, and N₂ sorption analysis. ZPBIF-1 was successfully utilized to remove Acid red 88, Basic Violet 14, Basic Blue 54, and Congo red dyes in aqueous solutions. In this study, some parameters, including adsorbent dosage, initial dye concentration, contact time, temperature, and pH, were examined. To evaluate the experimental data, Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich isotherm models were used. In this case, Langmuir is the most suitable model. Several kinetic models, including First-order, pseudo-first-order, second-order, and Pseudo-second-order kinetic models, Elovich's, and Weber's intraparticle diffusion models, were utilized to comprehend the detailed adsorption process. According to the pseudo-second-order kinetic model, dye sorption kinetics is best described. In addition, thermodynamic parameters like enthalpy (ΔH°), Gibbs free energy (ΔG°), and entropy (ΔS°) were also achieved and analyzed. The experimental studies thus suggest that Zn (II) metal-organic framework based on 2-phenyl benzimidazole could be a promising candidate for eliminating dyes from aqueous solution. Hence, the experimental studies suggest that a Zn (II) metal-organic framework based on 2-phenylbenzimidazole could be a promising candidate for eliminating dyes from aqueous solution. The maximum adsorption capacity of ZPBIF-1 was 1666.66, 1250, 1000, and 1250 mg/g for Acid red 88, Basic violet 14, Basic blue 54, and Congo red dyes, respectively. Furthermore, this method was used to remove contaminant dyes from textile wastewater, and an acceptable result was obtained.

An ingenious turn-on ratiometric fluorescence sensor for sensitive and visual detection of tetracyclines

To achieve facile and rapid detection of tetracyclines (TCs), herein, we fabricated an ingenious turn-on ratiometric fluorescence sensor (Ru@ZIF-8) based on embedding red-emitting Ru(bpy)₃²⁺ into zeolitic imidazolate framework-8 (ZIF-8). With the introduction of TCs, Ru@ZIF-8 system held the impervious red fluorescence, and generated green fluorescence which originated from the interaction between ZIF-8 and TCs, thereby achieving ratiometric fluorescence strategy through turn-on response signal and stable reference signal. Moreover, the ratiometric response accompanied discernible color change from red to green-yellow, which facilitated detection by naked eyes. The developed sensor exhibited prominent specificity and sensitivity, with detection limits of 2.4, 4.2, 1.6 and 7.2 nM for tetracycline, chlortetracycline, oxytetracycline and doxycycline, respectively. In addition, the satisfactory recoveries were obtained during detecting TCs in drink water, milk and beef, and the test paper-based sensor was successfully applied in real-time visual detection of TCs. All results indicated the feasibility and potential application of Ru@ZIF-8.

Poly (lactic acid)-based pH responsive membrane combined with chitosan and alizarin for food packaging

A poly (lactic acid) (PLA) -based functional partition composite membrane (PLA/CA) containing chitosan (CS) and alizarin (AL) was designed by solution casting method. The PLA/CA membrane contains the antibacterial zone of the edge part (PLA/CS) and the pH response detection zone of the central part (PLA/AL). At the same time, the environmentally friendly plasticizer tributyl citrate (TBC) was added to make the prepared PLA/CA composite membrane have good flexibility and high transparency. The results of FE-SEM and FTIR showed that CS and AL were uniformly dispersed in PLA matrix and had good compatibility with PLA. The antioxidant activities of PLA/CS and PLA/AL composite films were 43.3 % and 72.8 %, respectively. At the same time, the inhibitory rates of PLA/CS membrane against Escherichia coli and Staphylococcus aureus were as high as 87.91 % and 75.17 %, respectively. PLA/AL films exhibit excellent UV barrier properties. When the environmental pH (ammonia and acetic acid vapor) changed repeatedly, the PLA/AL membrane showed reversible color change of yellow under acidic condition and purple under alkaline condition. During the packaging and storage of chicken breast meat, the freshness of chicken breast meat can be detected by the color change of functional PLA/CA composite membrane.

A comprehensive review on electrospun nanohybrid membranes for wastewater treatment

Electrospinning, being a versatile and straightforward method to produce nanofiber membranes, has shown significant advancement in recent years. On account of the unique properties such as high surface area, high porosity, mechanical strength, and controllable surface morphologies, electrospun nanofiber membranes have been found to have a great potential in many disciplines. Pure electrospun fiber mats modified with different techniques of surface modification and additive incorporation have exhibited enhanced properties compared to traditional membranes and are even better than the as-prepared electrospun membranes. In this review, we have summarized recently developed electrospun nanohybrids fabricated by the incorporation of functional specific nanosized additives to be used in various water remediation membrane techniques. The adsorption, filtration, photocatalytic, and bactericidal capabilities of the hybrid membranes in removing common major water pollutants such as metal ions, dyes, oils, and biological pollutants have been discussed. Finally, an outlook on the future research pathways to fill the gaps existing in water remediation have been suggested.

Nanoparticle Shape Influence over Poly(lactic acid) Barrier Properties by Molecular Dynamics Simulations

Climate change is leading us to search for new materials that allow a more sustainable environmental situation in the long term. Poly(lactic acid) (PLA) has been proposed as a substitute for traditional plastics due to its high biodegradability. Various components have been added to improve their mechanical, thermal, and barrier properties. The modification of the PLA barrier properties by introducing nanoparticles with different shapes is an important aspect to control the molecular diffusion of oxygen and other gas compounds. In this work, we have described changes in oxygen diffusion by introducing nanoparticles of different shapes through molecular dynamics simulations. Our model illustrates that the existence of curved surfaces and the deposition of PLA around them by short chains generate small holes where oxygen accumulates, forming clusters and reducing their mobility. From the several considered shapes, the sphere is the most suitable structure to improve the barrier properties of the PLA.

Application of Electrospinning in Antibacterial Field

In recent years, electrospun nanofibers have attracted extensive attention due to their large specific surface area, high porosity, and controllable shape. Among the many applications of electrospinning, electrospun nanofibers used in fields such as tissue engineering, food packaging, and air purification often require some antibacterial properties. This paper expounds the development potential of electrospinning in the antibacterial field from four aspects: fiber morphology, antibacterial materials, antibacterial mechanism, and application fields. The effects of fiber morphology and antibacterial materials on the antibacterial activity and characteristics are first presented, then followed by a discussion of the antibacterial mechanisms and influencing factors of these materials. Typical application examples of antibacterial nanofibers are presented, which show the good prospects of electrospinning in the antibacterial field.

Biodegradable polylactic acid (PLA)

Polylactic acid (PLA) is a biodegradable material that can be processed using the common processing techniques, such as injection molding, extrusion, and blow molding. PLA has widely been researched and tested due to its biodegradable nature. As a biodegradable material, PLA can be subject to some inherently poor qualities, such as its brittleness, weak mechanical properties, small processing windows, or poor electrical and thermal properties. In order to nullify some of these issues, nanofiller composites have been added to the polymer matrix, such as nanocellulose, nanoclays, carbon nanotubes, and graphene. Dye-clay hybrid nanopigments (DCNP) have been used to explore potential applications in the food packaging industry with promising results. Several different compatibilizers have been studied as well, with the goal of increasing the mechanical properties of blends. A key application for PLA is in wound healing and surgical work, with a few studies described in the present chapter. Finally, the superwettability of dopamine modified PLA is examined, with promising results for separation of oily wastewater.

Polydimethylsiloxane/ZIF-8@GO sponge headspace solid-phase extraction followed by GC-MS for the analysis of lavender essential oil

A novel microwave-assisted (MA) headspace solid-phase extraction (HS-SPE) based on polydimethylsiloxane (PDMS)/ZIF-8@GO sponge was developed for the simultaneous extraction and determination of essential oil constituents in lavender. The PDMS/ZIF-8@GO sponge with a high surface area and excellent adsorption capacity was successfully applied in the HS-SPE process. Microwave-assisted coupled with PDMS/ZIF-8@GO sponge headspace solid-phase extraction followed by GC-MS was proposed. Different experimental parameters were investigated. The optimal conditions were found to be as follows: 2:1 as the quality ratio of ZIF-8 to GO, ZIF-8@GO dosage of 30 mg, microwave power of 600 W, extraction time of 10 min and desorption solvent of n-hexane. This method was successfully applied to the analysis of 11 samples of lavender in different varieties. A total of 52 compounds were identified by the proposed method. A good linearity was observed from 14 to 800 ng with a correlation coefficient (R²) value of >0.99. Multivariate statistical analysis was used to establish the relationship between the varieties and the volatile components for further discriminant analysis. These results demonstrated that the MA-PDMS/ZIF-8@GO is an efficient, sensitive and small sample consumption method for the determination of the essential oil in dried plant materials.

Synthesis of graphene oxide nanosheets decorated by nanoporous zeolite-imidazole (ZIF-67) based metal-organic framework with controlled-release corrosion inhibitor performance: Experimental and detailed DFT-D theoretical explorations

For the first time, the zeolite-imidazole (ZIF-67) framework, a new subfamily of metal-organic frameworks (MOFs), is synthesized on the graphene oxide (GO) platform. Co²⁺ (as a central atom) and 2-methylimidazole (as organic ligands) were assembled to fabricate ZIF-67/GO NPs for providing epoxy-based anti-corrosion coatings with both active (self-healing) and passive (barrier) performance. Also, the ZIF-67/GO NPs were modified by 3-Aminopropyl triethoxysilane (APS) to improve the particles compatibility with the epoxy matrix and control their solubility in saline media. The FE-SEM, FT-IR, UV-Vis, Raman, TGA, and low-angle XRD techniques were used to prove the successful ZIF-67 particles growth onto the GO platforms. Tafel (potentiodynamic) polarization test demonstrated that the ZIF-67/GO@APS NPs could protect the surface of steel through mixed anodic/cathodic type (O₂ reduction/Fe oxidation) mechanisms and the corrosion current density of the iron sample decreased to 1.41 µA·cm^-2. Interestingly, the epoxy coatings containing ZIF-67/GO and ZIF-67/GO@APS particles revealed long-term corrosion protection durability and outstanding self-healing anti-corrosion performance, which were well studied via EIS, salt spray, cathodic delamination, and pull-off techniques. The impedance value at the lowest frequency for the coating containing ZIF-67/GO@APS after 50 days decreased from 10.7 Ω·cm² to 10.2 Ω·cm² that showed the lowest reduction among the studied samples.

Synthesis of Fe3O4@chitosan@ZIF-8 towards removal of malachite green from aqueous solution: Theoretical and experimental studies

Discharges of dyes-containing wastewater from industries have created global concern. Removal of these substances from aqueous solution is very important and essential. Magnetic chitosan coated with ZIF-8 was prepared successfully and used to eliminate cationic dye malachite green in various conditions. To find the effectiveness of ZIF-8 towards malachite green removal, their surface interaction was investigated using density functional theory (DFT) calculations for the first time which the results show physisorption of malachite green on ZIF-8. The characteristics of adsorbent synthesized were evaluated using XRD, FTIR, FE-SEM, TEM and TGA analysis. In addition, the influence of different parameters on malachite green removal was investigated. The results showed that pH = 7, 40 mg of adsorbent dosage, 10 mg/L initial concentration, 40 min contact time and temperature of 25 °C were obtained as an optimum values for Fe₃O₄@chitosan@ZIF-8. The equilibrium data were in good agreement with the Langmuir model having maximum capacity (q_m) value of 3.282 mg/g. The experimental data revealed that the adsorption process obeyed to pseudo-second order kinetic model. It was concluded that Fe₃O₄@chitosan@ZIF-8 can be utilized as an efficient and effective adsorbent for removal of toxic malachite green dye from aqueous solution.

High-Strength, Low-Permeable, and Light-Protective Nanocomposite Films Based on a Hybrid Nanopigment and Biodegradable PLA for Food Packaging Applications

Herein, a multifunctional filler, a dye (organic)-clay (inorganic) hybrid nanopigment (DCNP), was embedded into polylactic acid (PLA) to fabricate a colored biodegradable/biocompatible film, which is explored as a high thermomechanical resistant as well as a superior light and mass transport barrier for food packaging applications. In this respect, the DCNP was synthesized through a wet chemical process with a reaction yield of 76% and incorporated into a PLA matrix at various concentrations using a solution casting method. The morphological characterizations revealed partially intercalated/exfoliated structure for PLA-DCNP films. The samples filled with DCNP showed up to 20% and 12 °C improvements in storage modulus (E') and glass transition temperature (T g), respectively, compared to those with neat PLA. Incorporation of a small amount of DCNP into the PLA matrix significantly declined the water vapor and gas permeability of PLA by 36 and 54%, respectively. The optical property investigations indicated remarkable color characteristics and light protection performance of the samples containing DCNP. The results also showed better performance of the PLA-DCNP film compared to that of the PLA-Cloisite 20A sample at an identical filler loading. In conclusion, the desirable properties of the resulting films highlighted the potential application of such nanocomposite films as a promising option for food packaging materials.

In situ growth of ZIF-8 nanoparticles on chitosan to form the hybrid nanocomposites for high-efficiency removal of Congo Red

The zeolitic imidazole framework (ZIF-8) dotted chitosan (CS) nanocomposites (ZIF-8@CS) were fabricated via in-situ growth method. The morphology, structure and chemical state of ZIF-8@CS were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform IR spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption behavior of ZIF-8@CS composites on Congo Red (CR) in aqueous solution was systematically investigated. The adsorption isotherm data showed that the adsorption of CR by ZIF-8@CS was single-layer adsorption, which was consistent with the Langmuir isotherm model. The maximum adsorption capacity of ZIF-8@CS was 922 mg/g. The kinetics parameters were in accord with pseudo-second-order equation, which implied that the adsorption rate was mainly controlled by the chemisorption mechanism. The removal of CR was attributed to the participation of hydrogen bonds, electrostatic interactions, π-π conjugation and zinc coordination effects.