Evolution of the Surface Structure and Functional Properties of the Electroconducting Polymer Coatings onto Porous Films

Composite systems containing electroconducting polymer coatings (polyaniline and polypyrrole) applied to porous films of semicrystalline polymers (polyethylene, polypropylene, and polyvinylidene fluoride) have been prepared. Porous supports were obtained in the process based on polymer melt extrusion with subsequent annealing, uniaxial extensions, and thermal stabilization. Conducting coatings were formed by the oxidative polymerization of the monomers directly onto the porous supports. The structure (overall porosity, permeability, pore sizes, factor of orientation) and morphology (specific surface and character of the film surface) of the supports were characterized by sorptometry, filtration porosimetry, atomic force microscopy (AFM), and X-ray scattering techniques. It was observed that the porous supports have a strongly developed relief surface which is formed in the pore formation process. It was proven by scanning electron microscopy (SEM) that the porous supports have an oriented structure, and the surface of the composites is defined by the morphology inherent in the conducting component. It was shown that these composites (porous support/conducting coating) demonstrate electric conductivity both along the surface and between surfaces. It was demonstrated that the deposition of conducting coatings leads to an increase in the water wettability of the composites compared with pronounced hydrophobic supports. The composites are characterized by good adhesion between components due to a relief film surface as well as high mechanical strength and elasticity provided by the oriented character of the supports.

On the Degradation of Glyphosate by Photocatalysis Using TiO2/Biochar Composite Obtained from the Pyrolysis of Rice Husk

In this study, titanium dioxide (TiO2) nanoparticles are immobilized onto rice husk biochar (RHB), as a porous support, for the photodegradation of glyphosate under UV light irradiation. The TiO2/RHB composites are prepared by pyrolysis and the sol-gel method. The SEM, XRD, EDX, and FT-IR results confirm the graphene structure of RHB and the formation of 10.61 nm TiO2 nanoparticles on the catalyst support. The effects of operating conditions, including catalyst dosage (3 g L−1, 5 g L−1, 10 g L−1, and 20 g L−1) and different illumination conditions (9 W lamp, 2 × 9 W lamps), on the removal of glyphosate from aqueous solutions were investigated. The photodegradation efficiency of 15 mg L−1 of commercial glyphosate was up to 99% after 5 h of irradiation at pH 3.0, with a TiO2/RHB dosage of 10 g L−1. However, the mineralization efficiency under this condition was lower than the decomposition efficiency of glyphosate, proving the partial degradation of glyphosate into AMPA and other metabolites after 5 h of reaction.

Tertiary Amine-Mediated Polyvinyl Alcohol Membrane Over the Porous Support of Polyvinyl Chloride Membrane for CO2 Separation

Great attention has been paid to membrane-based separation technology in various separation fields, including gas separation. It provides the benefits of energy efficiency, environmental friendliness, easy scale-up, and convenience in operation. Different division advancements are being utilized for the expulsion of acid gas carbon dioxide (CO2). The aim of this work is to synthesis the membrane using polyvinyl alcohol (PVA) with treatment (WT) and without treatment (WOT) of the additive that is triethanolamine (TEA), to study the effect of additive on the permeance of membrane towards CO2 and the morphology changes of each membrane. In this research, virgin PVA and PVA with TEA were cast upon the porous support membrane of polyvinyl chloride (PVC). PVA was used as the polymer matrix, and TEA was used as a CO2 facilitating agent. Distilled water was used as a solvent for TEA and PVA in preparing the solution. Dimethyl acetamide (DMAc) and Tetrahydrofuran (THF) were used as solvents for PVC porous membranes. These membranes were tested on CO2 to find out the permeability and flux rates (J). For the morphology of the membrane, we performed SEM; for thermal analysis, we performed DSC and TGA, and for the strength, we performed the tensile test. The results reveal that the presence of TEA changes the morphology and thermal behavior increases the strength and the permeability of CO2. In a nutshell, the presence of TEA enhanced the performance and the morphology of the membrane.

Synthesis and Characterisation of Photocatalyst Silver/Silver Halide Nanocomposites

<p>The photochemical activity of silver halides forms the basis of photography and latent image formation. More recently it has been used to create hybrid silver/silver halide nanoparticles. These are formed through partial reduction of Ag⁺ to Ag⁰ by a photochemical self-sensitisation when irradiated with light. This gives the silver/silver halide nanoparticles interesting photocatalytic properties. As such, these silver/silver halide nanoparticles have seen to be part of group of photocatalysts known as plasmonic photocatalysts. Where, the photocatalytic mechanism is enhanced by the surface plasmon resonance of noble metal nanodomains on the surface of the silver halide nanoparticle. The silver/silver halide nanoparticles of Cl⁻, Br⁻ and I⁻ were synthesised and characterised. Silver/silver halide nanoparticles were then incorporated into porous support materials creating silver/silver halide nanocomposite materials. This was through a straight forward aqueous synthesis method, where silver halide nanoparticles precipitated from solution, and nanoparticle size, shape and stabilisation was controlled by the porous support material. Silver/silver halide nanocomposite samples using Cl⁻, Br⁻ and I⁻ were synthesised using wool fibres, kraft paper fibres and nanostructured calcium silicate as supports. UV/Vis and XRD showed Ag⁰ nanodomains were formed during the self-sensitisation process. SEM showed the morphology of the nanocomposites and that the nanoparticles were distributed within the nanocomposite matrix, not deposited on the surface. Preliminary photocatalytic activity of Ag/AgCl nanoparticles and nanocomposites was evaluated through the degradation of methylene blue when irradiated with light. All samples showed increased photocatalytic activity with the Ag/AgCl nanoparticles.</p>

Synthesis and Characterisation of Photocatalyst Silver/Silver Halide Nanocomposites

<p>The photochemical activity of silver halides forms the basis of photography and latent image formation. More recently it has been used to create hybrid silver/silver halide nanoparticles. These are formed through partial reduction of Ag⁺ to Ag⁰ by a photochemical self-sensitisation when irradiated with light. This gives the silver/silver halide nanoparticles interesting photocatalytic properties. As such, these silver/silver halide nanoparticles have seen to be part of group of photocatalysts known as plasmonic photocatalysts. Where, the photocatalytic mechanism is enhanced by the surface plasmon resonance of noble metal nanodomains on the surface of the silver halide nanoparticle. The silver/silver halide nanoparticles of Cl⁻, Br⁻ and I⁻ were synthesised and characterised. Silver/silver halide nanoparticles were then incorporated into porous support materials creating silver/silver halide nanocomposite materials. This was through a straight forward aqueous synthesis method, where silver halide nanoparticles precipitated from solution, and nanoparticle size, shape and stabilisation was controlled by the porous support material. Silver/silver halide nanocomposite samples using Cl⁻, Br⁻ and I⁻ were synthesised using wool fibres, kraft paper fibres and nanostructured calcium silicate as supports. UV/Vis and XRD showed Ag⁰ nanodomains were formed during the self-sensitisation process. SEM showed the morphology of the nanocomposites and that the nanoparticles were distributed within the nanocomposite matrix, not deposited on the surface. Preliminary photocatalytic activity of Ag/AgCl nanoparticles and nanocomposites was evaluated through the degradation of methylene blue when irradiated with light. All samples showed increased photocatalytic activity with the Ag/AgCl nanoparticles.</p>

A comprehensive overview of dual-layer composite membrane for air (O2/N2) separation

The separation of air (O2/N2) via a polymeric membrane has recently piqued the interest of academic researcher as well as the industrial sector. Because of its remarkable characteristics, the polymeric membrane has emerged as one of the innovative and fast growing technology. However, two major problems faced by membrane technology, which hinder its growth in the commercial sector are, 1): The trade-off between permeability and selectivity. 2): Maintaining physical and chemical structural stability in a long-term commercial scale process. Recent advancements in membrane material, structural, and process design have enabled the development of dual-layer composite (DLC) membranes. This concept combines the benefits of both thinner mixed matrix membranes (MMMs) based active layer and porous support substrate. Due to these properties, the membrane exhibits higher perm-selectivity with enhanced mechanical strength as compared to single layer polymeric membrane. This review article mainly focused on the developmental progress of DLC membrane throughout the years. In which membrane structural details, selection criteria, fabrication methodologies, application [e.g., air (O2/N2) separation] were critically reviewed. In addition, challenges arising in the DLC membrane production and future prospects for the development of these membranes were also thoroughly discussed in this literature. This creates a paradigm for future research in the commercial development of these membranes for the air (O2/N2) separation process, which can be utilized in both medical and industrial sectors. [Formula: see text]

Polycyclic Aromatic Hydrocarbon Sorption by Functionalized Humic Acids Immobilized in Micro- and Nano-Zeolites

Polycyclic aromatic hydrocarbons (PAHs) are hazardous compounds originating from anthropogenic activity. Due to their carcinogenic properties for humans, several technologies have been developed for PAH removal. Sorption with natural and organic materials is currently one of the most studied due to its low cost and its environmentally friendly nature. In this work, a hybrid sorbent involving functionalized humic acids (HAs) and nano-zeolite is proposed to entrap PAHs. The use of functionalized HAs immobilized in a porous support is designed to address the instability of HAs in solution, which has been already reported. HA functionalization was carried out to increase the non-polarity of HAs and aliphatic group formation. The HAs were functionalized by esterification/etherification with alkyl halides, and their chemical changes were verified by FTIR and NMR. The sorption isotherms of the functionalized HAs in micro- and nano-zeolites were used to assess the performance of the nano-zeolites in adsorbing these HAs. The hybrid support allowed the removal of anthracene and pyrene at percentages higher than 90%; fluoranthene, of angular molecular structure, was adsorbed at 85%. PAHs are ubiquitous in the environment, and a stable sorption of them in solid matrices will allow their removal from the environment through effective and environmentally friendly methods.

Porous Materials Confining Single Atoms for Catalysis

In recent years, single-atom catalysts (SACs) have received extensive attention due to their unique structure and excellent performance. Currently, a variety of porous materials are used as confined single-atom catalysts, such as zeolites, metal-organic frameworks (MOFs), or carbon nitride (CN). The support plays a key role in determining the coordination structure of the catalytic metal center and its catalytic performance. For example, the strong interaction between the metal and the carrier induces the charge transfer between the metal and the carrier, and ultimately affects the catalytic behavior of the single-atom catalyst. Porous materials have unique chemical and physical properties including high specific surface area, adjustable acidity and shape selectivity (such as zeolites), and are rational support materials for confined single atoms, which arouse research interest in this field. This review surveys the latest research progress of confined single-atom catalysts for porous materials, which mainly include zeolites, CN and MOFs. The preparation methods, characterizations, application fields, and the interaction between metal atoms and porous support materials of porous material confined single-atom catalysts are discussed. And we prospect for the application prospects and challenges of porous material confined single-atom catalysts.

Unraveling Structural Details in Ga-Pd SCALMS Systems Using Correlative Nano-CT, 360° Electron Tomography and Analytical TEM

We present a comprehensive structural and analytical characterization of the highly promising supported catalytically active liquid metal solutions (SCALMS) system. This novel catalyst shows excellent performance for alkane dehydrogenation, especially in terms of resistance to coking. SCALMS consists of a porous support containing catalytically active low-melting alloy particles (e.g., Ga-Pd) featuring a complex structure, which are liquid at reaction temperature. High-resolution 3D characterization at various length scales is required to reveal the complex pore morphology and catalytically active sites’ location. Nano X-ray computed tomography (nano-CT) in combination with electron tomography (ET) enables nondestructive and scale-bridging 3D materials research. We developed and applied a correlative approach using nano-CT, 360°-ET and analytical transmission electron microscopy (TEM) to decipher the morphology, distribution and chemical composition of the Ga-Pd droplets of the SCALMS system over several length scales. Utilizing ET-based segmentations of nano-CT reconstructions, we are able to reliably reveal the homogenous porous support network with embedded Ga-Pd droplets featuring a nonhomogenous elemental distribution of Ga and Pd. In contrast, large Ga-Pd droplets with a high Ga/Pd ratio are located on the surface of SCALMS primary particles, whereas the droplet size and the Ga/Pd ratio decreases while advancing into the porous volume. Our studies reveal new findings about the complex structure of SCALMS which are required to understand its superior catalytic performance. Furthermore, advancements in lab-based nano-CT imaging are presented by extending the field of view (FOV) of a single experiment via a multiple region-of-interest (ROI) stitching approach.