Influence of Illite and Its Amine Modifications on the Self-Adhesive Properties of Silicone Pressure-Sensitive Adhesives

Obtaining new silicone self-adhesive in the presence of modified illite has been described. The filler was modified with N,N,4-trimethylaniline. The effect of illite content and modification on functional properties (adhesion, cohesion, stickiness, and shrinkage) was determined. Additionally, the thermal resistance (the SAFT test) of obtained silicone pressure-sensitive adhesives was evaluated. For all the systems tested, an increase in thermal resistance and shrinkage decrease were noted. Moreover, only a slight adhesion and tack decrease was revealed. Such self-adhesives could be applied for joining elements operating at increased temperatures, e.g., in heavy industry.

A p-n Junction by Coupling Amine-Enriched Brookite-TiO2 Nanorods with CuxS Nanoparticles for Improved Photocatalytic CO2 Reduction

Photocatalytic CO₂ reduction is a promising technology for reaching the aim of "carbon peaking and carbon neutrality", and it is crucial to design efficient photocatalysts with a rational surface and interface tailoring. Considering that amine modification on the surface of the photocatalyst could offer a favorable impact on the adsorption and activation of CO₂, in this work, amine-modified brookite TiO₂ nanorods (NH₂-B-TiO₂) coupled with Cu_xS (NH₂-B-TiO₂-Cu_xS) were effectively fabricated via a facile refluxing method. The formation of a p-n junction at the interface between the NH₂-B-TiO₂ and the Cu_xS could facilitate the separation and transfer of photogenerated carriers. Consequently, under light irradiation for 4 h, when the Cu_xS content is 16%, the maximum performance for conversion of CO₂ to CH₄ reaches at a rate of 3.34 μmol g^-1 h^-1 in the NH₂-B-TiO₂-Cu_xS composite, which is approximately 4 times greater than that of pure NH₂-B-TiO₂. It is hoped that this work could deliver an approach to construct an amine-enriched p-n junction for efficient CO₂ photoreduction.

Optimization of CO2 Sorption onto Spent Shale with Diethylenetriamine (DETA) and Ethylenediamine (EDA)

A novel technique was employed to optimize the CO₂ sorption performance of spent shale at elevated pressure-temperature (PT) conditions. Four samples of spent shale prepared from the pyrolysis of oil shale under an anoxic condition were further modified with diethylenetriamine (DETA) and ethylenediamine (EDA) through the impregnation technique to investigate the variations in their physicochemical characteristics and sorption performance. The textural and structural properties of the DETA- and EDA- modified samples revealed a decrease in the surface area from tens of m²/g to a unit of m²/g due to the amine group dispersing into the available pores, but the pore sizes drastically increased to macropores and led to the creation of micropores. The N-H and C-N bonds of amine noticed on the modified samples exhibit remarkable affinity for CO₂ sequestration and are confirmed to be thermally stable at higher temperatures by thermogravimetric (TG) analysis. Furthermore, the maximum sorption capacity of the spent shale increased by about 100% with the DETA modification, and the equilibrium isotherm analyses confirmed the sorption performance to support heterogenous sorption in conjunction with both monolayer and multilayer coverage since they agreed with the Sips, Toth, Langmuir, and Freundlich models. The sorption kinetics confirm that the sorption process is not limited to diffusion, and both physisorption and chemisorption have also occurred. Furthermore, the heat of enthalpy reveals an endothermic reaction observed between the CO₂ and amine-modified samples as a result of the chemical bond, which will require more energy to break down. This investigation reveals that optimization of spent shale with amine functional groups can enhance its sorption behavior and the amine-modified spent shale can be a promising sorbent for CO₂ sequestration from impure steams of the natural gas.

Reaction Kinetics of Photoelectrochemical CO2 Reduction on a CuBi2O4-Based Photocathode

The CO₂ reduction reaction (CO₂RR) is an essential step in natural photosynthesis and artificial photosynthesis to provide carbohydrate foods and hydrocarbon energy in the carbon-neutral cycle. However, the current solar conversion efficiencies and/or product selectivity of the CO₂RR are very sluggish due to its complicated multiple-step charge transfer reactions. Here, we systematically investigate the charge transfer reaction rate during CO₂ reduction on CuBi₂O₄ photocathodes, where the surface is modified with 3-aminopropyltriethoxysilane (APTES). We discover that the surface amine group increases the charge separation rate, significantly enhancing the surface charge transfer reaction rate. However, the surface acidity has less influence on the first-order reaction, indicating that a rate-determining step (RDS) exists in the early stage of the photoelectrochemical cell (PEC) processes. Moreover, the intensity-modulated photocurrent spectroscopy (IMPS) confirms that both surface charge transfer and the recombination rate on APTES-coated CuBi₂O₄ are larger than bare CuBi₂O₄ while possessing comparable charge transfer efficiencies. Overall, the surface charge transfer reactions under the PEC condition require designing more effective nanostructured photoelectrodes and powerful characterization methods to intrinsically increase the charge separation and transfer rate while reducing the recombination rate.

Preparation of Amine-Modified Cu-Mg-Al LDH Composite Photocatalyst

Cu-Mg-Al layered double hydroxides (LDHs) with amine modification were prepared by an organic combination of an anionic surfactant-mediated method and an ultrasonic spalling method using N-aminoethyl-γ-aminopropyltrimethoxysilane as a grafting agent. The materials were characterized by elemental analysis, XRD, SEM, FTIR, TGA, and XPS. The effects of the Cu²⁺ content on the surface morphology and the CO₂ adsorption of Cu-Mg-Al LDHs were investigated, and the kinetics of the CO₂ adsorption and the photocatalytic reduction of CO₂ were further analyzed. The results indicated that the amine-modified method and appropriate Cu²⁺ contents can improve the surface morphology, the increase amine loading and the free-amino functional groups of the materials, which were beneficial to CO₂ capture and adsorption. The CO₂ adsorption capacity of Cu-Mg-Al N was 1.82 mmol·g⁻¹ at 30 °C and a 0.1 MPa pure CO₂ atmosphere. The kinetic model confirmed that CO₂ adsorption was governed by both the physical and chemical adsorption, which could be enhanced with the increase of the Cu²⁺ content. The chemical adsorption was suppressed, when the Cu²⁺ content was too high. Cu-Mg-Al N can photocatalytically reduce CO₂ to methanol with Cu²⁺ as an active site, which can significantly improve the CO₂ adsorption and photocatalytic conversion.

Synthesis, characterization and free radical scavenging activity of modified silica-naringin hybrid system

This study aimed to develop a procedure for preparing a modified silica-naringin hybrid system. To accomplish, the properties of the obtained material were characterized by FT-IR analysis, UV-Vis spectrophotometry, thermogravimetry, scanning electron microscopy (SEM), and zeta potential. 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to characterize and evaluate the antioxidant activity. The naringin release profile at pH = 1.2 and 7.2 were determined. FT-IR studies confirmed the interaction between the naringin and present carrier. The release study indicated that a release an approximately 20% and 50% of the release occurred in the first 30 min in pH = 1.2 and 7.2, respectively. The thermogravimetry and UV-Vis spectrophotometry analysis allowed us to determine the amount of naringin in the studied hybrid material at the level of several percent. The proposed hybrid material shows good stability, as evidenced by the zeta potential of about +30 and -30 mV in an acidic and alkaline environment, respectively. Antioxidant properties are comparable to those of pure naringin. The results suggest that the obtained hybrid material is a promising product with antioxidant properties.

Ethylenediamine loading into a manganese-based metal-organic framework enhances water stability and carbon dioxide uptake of the framework

Metal-organic frameworks (MOFs) based on 2,5-dihydroxyterepthalic acid (DOBDC) as the linker show very high CO2 uptake capacities at low to moderate CO2 pressures; however, these MOFs often require expensive solvent for synthesis and are difficult to regenerate. We have synthesized a Mn-DOBDC MOF and modified it to introduce amine groups into the structure by functionalizing its metal coordination sites with ethylenediamine (EDA). Repeat framework synthesis was then also successfully performed using recycled dimethylformamide (DMF) solvent. Characterization by elemental analysis, FTIR and thermogravimetric studies suggest that EDA molecules are successfully substituting the original metal-bound DMF. This modification not only enhances the material's carbon dioxide sorption capacity, increasing stability to repeated CO2 sorption cycles, but also improves the framework's stability to moisture. Moreover, this is one of the first amine-modified MOFs that can demonstrably be synthesized using recycled solvent, potentially reducing the future costs of production at larger scales.

Amine Modification of Silica Aerogels/Xerogels for Removal of Relevant Environmental Pollutants

Serious environmental and health problems arise from the everyday release of industrial wastewater effluents. A wide range of pollutants, such as volatile organic compounds, heavy metals or textile dyes, may be efficiently removed by silica materials advanced solutions such as aerogels. This option is related to their exceptional characteristics that favors the adsorption of different contaminants. The aerogels performance can be selectively tuned by an appropriate chemical or physical modification of the aerogel's surface. Therefore, the introduction of amine groups enhances the affinity between different organic and inorganic contaminants and the silica aerogels. In this work, different case studies are reported to investigate and better understand the role of these functional groups in the adsorption process, since the properties of the synthesized aerogels were significantly affected, regarding their microstructure and surface area. In general, an improvement of the removal efficiency after functionalization of aerogels with amine groups was found, with removal efficiencies higher than 90% for lead and Rubi Levafix CA. To explain the adsorption mechanism, both Langmuir and Freundlich models were applied; chemisorption is most likely the sorption type taking place in the studied cases.

Synthesis of Porous Organic Polymers with Tunable Amine Loadings for CO2 Capture: Balanced Physisorption and Chemisorption

The cross-coupling reaction of 1,3,5-triethynylbenzene with terephthaloyl chloride gives a novel ynone-linked porous organic polymer. Tethering alkyl amine species on the polymer induces chemisorption of CO₂ as revealed by the studies of ex situ infrared spectroscopy. By tuning the amine loading content on the polymer, relatively high CO₂ adsorption capacities, high CO₂-over-N₂ selectivity, and moderate isosteric heat (Q_st) of adsorption of CO₂ can be achieved. Such amine-modified polymers with balanced physisorption and chemisorption of CO₂ are ideal sorbents for post-combustion capture of CO₂ offering both high separation and high energy efficiencies.

Double-Layer Structured CO2 Adsorbent Functionalized with Modified Polyethyleneimine for High Physical and Chemical Stability

CO₂ capture using polyethyleneimine (PEI)-impregnated silica adsorbents has been receiving a lot of attention. However, the absence of physical stability (evaporation and leaching of amine) and chemical stability (urea formation) of the PEI-impregnated silica adsorbent has been generally established. Therefore, in this study, a double-layer impregnated structure, developed using modified PEI, is newly proposed to enhance the physical and chemical stabilities of the adsorbent. Epoxy-modified PEI and diepoxide-cross-linked PEI were impregnated via a dry impregnation method in the first and second layers, respectively. The physical stability of the double-layer structured adsorbent was noticeably enhanced when compared to the conventional adsorbents with a single layer. In addition to the enhanced physical stability, the result of simulated temperature swing adsorption cycles revealed that the double-layer structured adsorbent presented a high potential working capacity (3.5 mmol/g) and less urea formation under CO₂-rich regeneration conditions. The enhanced physical and chemical stabilities as well as the high CO₂ working capacity of the double-layer structured adsorbent were mainly attributed to the second layer consisting of diepoxide-cross-linked PEI.