Near-IR study of the impact of alkyl-ammonium and -phosphonium cations on the hydration of montmorillonite

Tröger's Base-Enriched Conjugated Cyclopentannulated Copolymers: Prominent Adsorbents of CO2, H2, and Iodine

Three copolymers with conjugated structures, PTB1-PTB3, were produced utilizing a palladium-catalyzed cyclopentannulation polymerization by reacting a specially designed diethynyl Tröger's base surrogate with different dihalogenated polycondensed aromatic hydrocarbons. Brunauer, Emmet, and Teller nitrogen gas adsorption investigation revealed the surface areas of the copolymers, attaining ∼365 m2 g-1. Gas uptake studies demonstrated a considerable carbon dioxide uptake for PTB2 of 44.41 mg g-1 at 273 K and a promising H2 gas uptake of 3.18 mg g-1 at 77 K. PTB1-PTB3 displayed a sizable iodine adsorption capacity, achieving 4000 mg g-1, and mechanistic investigations demonstrated the prevalence of a pseudo-second-order kinetic model. Recyclability experiments proved the effective regeneration of the copolymers, even after performing several adsorption and desorption tests.

Iodine and Nickel Ions Adsorption by Conjugated Copolymers Bearing Repeating Units of Dicyclopentapyrenyl and Various Thiophene Derivatives

The synthesis of three conjugated copolymers TPP1-3 was carried out using a palladium-catalyzed [3+2] cycloaddition polymerization of 1,6-dibromopyrene with various dialkynyl thiophene derivatives 3a-c. The target copolymers were obtained in excellent yields and high purity, as confirmed by instrumental analyses. TPP1-3 were found to divulge a conspicuous iodine adsorption capacity up to 3900 mg g-1, whereas the adsorption mechanism studies revealed a pseudo-second-order kinetic model. Furthermore, recyclability tests of TPP3, the copolymer which revealed the maximum iodine uptake, disclosed its efficient regeneration even after numerous adsorption-desorption cycles. Interestingly, the target copolymers proved promising nickel ions capture efficiencies from water with a maximum equilibrium adsorption capacity (qe) of 48.5 mg g-1.

Physicochemical and thermomechanical performances study for Timahdite sheep wool fibers application in the building's insulation

The present research focuses on the development and thermomechanical characterization of unfired solid bricks based on clay (white and red) and Timahdite sheep wool, which are local, durable, abundant, and economical materials. As this clay material is incorporated with sheep wool in the form of yarn multi-layers in opposite directions. It achieves good thermal and mechanical performance and a lightness of these bricks as acquired progress. This new method of reinforcement offers significant thermo-mechanical performance for the composite for thermal insulation in sustainable buildings. Several physicochemical analyses to characterize the raw materials were used. Thermomechanical measurements to characterize the elaborated materials. The wool yarn effect was significant on the mechanical behavior of the developed materials at 90 days, with flexural strength from 18 to 56% for the white clay. And 8-29% for the red one. Decrease in compressive strength from 9 to 36% for the white clay and 5-18% for the red one. These mechanical performances are accompanied by thermal conductivity gain ranging from 4 to 41% for the white and 6-39% for the red for wool fractions: 6-27 g. This green multi-layered bricks from abundant local materials with optimal thermo-mechanical properties, qualified for the intended use for thermal insulation and energy efficiency in the construction and development of local economies.

Influence of Surface-Modified Montmorillonite Clays on the Properties of Elastomeric Thin Layer Nanocomposites

In recent years, polyurethane nanocomposites have attracted more attention due to the massive demand for materials with increasingly exceptional mechanical, optical, electrical, and thermal properties. As nanofillers have a high surface area, the interaction between the nanofiller and the polymer matrix is an essential issue for these materials. The main aim of this study is to validate the impact of the montmorillonite nanofiller (MMT) surface structure on the properties of polyurethane thin-film nanocomposites. Despite the interest in polyurethane-montmorillonite clay nanocomposites, only a few studies have explored the impact of montmorillonite surface modification on polyurethane's material properties. For this reason, four types of polyurethane nanocomposites with up to 3% content of MMT were manufactured using the prepolymer method. The impact of montmorillonites on nanocomposites properties was tested by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), contact angle measurement, X-ray diffraction (XRD), and optical coherence tomography (OCT). The results showed that chemical and physical interactions between the polymer matrix and functional groups on the montmorillonite surface have a considerable impact on the final properties of the materials. It was noticed that the addition of MMT changed the thermal decomposition process, increased T_2% by at least 14 °C, changed the hydrophilicity of the materials, and increased the glass transition temperature. These findings have underlined the importance of montmorillonite surface structure and interactions between nanocomposite phases for the final properties of nanocomposites.

Synthesis and Iodine Adsorption Properties of Organometallic Copolymers with Propeller-Shaped Fe(II) Clathrochelates Bridged by Different Diaryl Thioether and Their Oxidized Sulfone Derivatives

Three organometallic copolymers, ICP1-3, containing iron(II) clathrochelate units with cyclohexyl lateral groups and interconnected by various thioether derivatives were synthesized. The reaction of the latter into their corresponding OICP1-3 sulfone derivatives was achieved quantitatively using mild oxidation reaction conditions. The target copolymers, ICP1-3 and OICP1-3, were characterized by various instrumental analysis techniques, and their iodine uptake studies disclosed excellent iodine properties, reaching a maximum of 360 wt.% (q_e = 3600 mg g^-1). The adsorption mechanisms of the copolymers were explored using pseudo-first-order and pseudo-second-order kinetic models. Furthermore, regeneration tests confirmed the efficiency of the target copolymers for their iodine adsorption even after several adsorption-desorption cycles.

Synthesis of Metalorganic Copolymers Containing Various Contorted Units and Iron(II) Clathrochelates with Lateral Butyl Chains: Conspicuous Adsorbents of Lithium Ions and Methylene Blue

We report the synthesis of three highly soluble metalorganic copolymers, TCP1-3, that were made from a one-pot complexation of iron(II) clathrochelate units that are interconnected by various thioether-containing contorted groups. TCP1-3 were converted into their poly(vinyl sulfone) derivatives OTCP1-3 quantitatively via the selective oxidation of the thioether moieties into their respective sulfones. All of the copolymers, TCP1-3 and OTCP1-3, underwent structural analysis by various techniques; namely, ¹H- and ¹³C-nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC). The copolymers were tested as potent lithium ions adsorbents revealing a maximum adsorption (q_m) value of 2.31 mg g^-1 for OTCP2. Furthermore, this same copolymer was found to be a promising adsorbent of methylene blue (MEB); an isothermal adsorption study divulged that OTCP2's uptake of MEB from an aqueous solution (following the Langmuir model) was, at maximum adsorption capacity, (q_m) of 480.77 mg g^-1; whereas the kinetic study divulged that the adsorption follows pseudo second-order kinetics with an equilibrium adsorption capacity (q_e,cal) of 45.40 mg g^-1.

Herbal plants- and rice straw-derived biochars reduced metal mobilization in fishpond sediments and improved their potential as fertilizers

Fishpond sediments are rich in organic carbon and nutrients; thus, they can be used as potential fertilizers and soil conditioners. However, sediments can be contaminated with toxic elements (TEs), which have to be immobilized to allow sediment reutilization. Addition of biochars (BCs) to contaminated sediments may enhance their nutrient content and stabilize TEs, which valorize its reutilization. Consequently, this study evaluated the performance of BCs derived from Taraxacum mongolicum Hand-Mazz (TMBC), Tribulus terrestris (TTBC), and rice straw (RSBC) for Cu, Cr, and Zn stabilization and for the enhancement of nutrient content in the fishpond sediments from San Jiang (SJ) and Tan Niu (TN), China. All BCs, particularly TMBC, reduced significantly the average concentrations of Cr, Cu, and Zn in the overlying water (up to 51% for Cr, 71% for Cu, and 68% for Zn) and in the sediments pore water (up to 77% for Cr, 76% for Cu, and 50% for Zn), and also reduced metal leachability (up to 47% for Cr, 60% for Cu, and 62% for Zn), as compared to the control. The acid soluble fraction accounted for the highest portion of the total content of Cr (43-44%), Cu (38-43%), and Zn (42-45%), followed by the reducible, oxidizable, and the residual fraction; this indicates the high potential risk. As compared with the control, TMBC was more effective in reducing the average concentrations of the acid soluble Cr (15-22%), Cu (35-53%), and Zn (21-39%). Added BCs altered the metals acid soluble fraction by shifting it to the oxidizable and residual fractions. Moreover, TMBC improved the macronutrient status in both sediments. This work provides a pathway for TEs remediation of sediments and gives novel insights into the utilization of BC-treated fishpond sediments as fertilizers for crop production.

Study on Preparation of Polymer-Modified Bentonite and Sand Mixtures Based on Osmotic Pressure Principle

Polymer-modified bentonite and sand mixtures (PMBS) are widely used in the engineering field due to their low cost and low permeability. In this study, different ionic types of polyacrylamides were used to modify bentonite to improve its swelling properties and impermeability. The physicochemical properties of polymer-modified bentonite were characterized by X-ray diffraction, particle size distribution, IR spectroscopy, SEM, and free swell index (FSI) to further demonstrate the successful organic modification of bentonite. To investigate the impermeability mechanism of PMBS from the perspective of osmotic pressure, the colloidal osmotic pressure of bentonite and hydraulic conductivity were compared. The results showed that anionic polyacrylamide (APAM) had the most obvious improvement on the swelling properties of bentonite, and 3% APAM increased the FSI of bentonite from 15 mL/2 g to 41 mL/2 g. With the increase in polymer dosage, the colloidal osmotic pressure of bentonite increased and the hydraulic conductivity of PMBS decreased significantly. The interior of PMBS is equivalent to a highly concentrated bentonite–sand–water system. When the colloidal osmotic pressure in the restricted space is higher than the external hydraulic pressure, it will prevent infiltration from occurring. When the external hydraulic pressure exceeds the high concentration of bentonite colloid osmotic pressure, the hydraulic conductivity may increase rapidly. Therefore, the impermeability of PMBS depends on the colloidal osmotic pressure of bentonite. Finally, it was confirmed that PMBS had a self-healing capacity by simulating damage to PMBS.

Amination of Non-Functional Polyvinyl Chloride Polymer Using Polyethyleneimine for Removal of Phosphorus from Aqueous Solution

The eutrophication of freshwater environments caused by an excess inflow of phosphorus has become a serious environmental issue because it is a crucial factor for the occurrence of harmful algal blooms (HABs) in essential water resources. The adsorptive removal of phosphorus from discharged phosphorus containing effluents has been recognized as one of the most promising solutions in the prevention of eutrophication. In the present study, a polyvinyl chloride (PVC)-polyethyleneimine (PEI) composite fiber (PEI-PVC) was suggested as a stable and recoverable adsorbent for the removal of phosphorus from aqueous phases. The newly introduced amine groups of the PEI-PVC were confirmed by a comparison between the FT-IR and XPS results of the PVC and PEI-PVC. The phosphorus sorption on the PEI-PVC was pH dependent. At the optimum pH for phosphorus adsorption (pH 5), the maximum adsorption capacity of the PEI-PVC fiber was estimated to be 11.2 times higher (19.66 ± 0.82 mg/g) than that of conventional activated carbon (1.75 ± 0.4 mg/g) using the Langmuir isotherm model. The phosphorus adsorption equilibrium of the PEI-PVC was reached within 30 min at pH 5. From the phosphorus-loaded PEI-PVC, 97.4% of the adsorbed amount of phosphorus on the PEI-PVC could be recovered by employing a desorption process using 1M HCl solution without sorbent destruction. The regenerated PEI-PVC through the desorption process maintained a phosphorus sorption capacity almost equal to that of the first use. In addition, consistently with the PVC fiber, the PEI-PVC fiber did not elute any toxic chlorines into the solution during light irradiation. Based on these results, the PEI-PVC fiber can be suggested as a feasible and stable adsorbent for phosphorus removal.