Exchange Properties Research Articles

Ion Exchange Properties of Crosslinked and Carboxylated Peanut (Arachis Hypogaea L.) Testa Extract

After polymerization via polycondensation of catechin units in the acetone extract of peanut (arachis hypogaea L.) testa (PTE) using phosphorus oxychloride (POCl3) as a crosslinking agent, POCl3-crosslinked PTE (Crosslinked-PPTE) was functionalized by etherification (PC-PTE) using monochloroacetic acid (MCAA) in the presence of an alkali according to the method of Williamson ether synthesis. Subsequent to characterization by Fourier Transform Infrared spectroscopy (FTIR) as well as physical properties, Crosslinked-PPTE was assessed for cation exchange capacity (CEC) and pH at point of zero charge (ZPHC) following demonstrated capacity to remove heavy metal ions in single and multi-elements aqueous solutions by Atomic Absorption Spectrometry (AAS) technique while functionalized (carboxymethylated) Crosslinked-PPTE (PC-PTE) was further characterized by degree of substitution (DS). FTIR absorption bands due to -C-O-P=O, -P=O, P-O-C- and R-O-P-OH stretching vibrations were seen at 1350/1250, 1244/1246, 997/993 cm-1 respectively. Asymmetric and symmetric stretching vibrations of the -C=O of a COOH, Ar-O-C- of an aromatic ether as well as -P-O-C - of an aromatic PO43-, R-P=O of a -PO43-, -R-O-P- and R-O-P-OH of a PO43- ester created by crosslinked and carboxymethylated PTE respectively were seen at 1743, 1377, 1278, 1190, 1062 and 823 cm-1. The results obtained showed that 0.6 was the DS of PC-PTE while 6.72 meq/g and 3.57 defined the CEC and pH (zpc) respectively of Crosslinked-PPTE. Quantitative removal of Fe2+, Ni2+, Pb2+, Cu2+ and Zn2+ in laboratory simulated metal ion wastewater (LSW) to the levels of 84.4, 81.7, 76.5, 72.0 and 75.1% respectively was achieved using Crosslinked-PPTE resin in batch adsorption experiments in which the efficiency was found to depend significantly on the temperature and pH of the water as well as initial adsorbate concentration and contact time but partially on the amount of adsorbent used was observed to be independent of the speed of stirring of the wastewater. Stable, Matakana and fine powder crosslinked-PPTE which is insoluble in water and common laboratory solvents holds great potential in the purification of heavy metal ions polluted water

Ideals with Linear Quotients and Componentwise Polymatroidal Ideals

If I is a monomial ideal with linear quotients, then it has componentwise linear quotients. However, the converse of this statement is an open question. In this paper, we provide two classes of ideals for which the converse of this statement holds. First class is the componentwise polymatroidal ideals in K[x, y] and the second one is the componentwise polymatroidal ideals with strong exchange property.

Plasma-catalytic steam reforming of benzene as a tar model compound over Ni-HAP and Ni-γAl2O3 catalysts: Insights into the importance of steam and catalyst support

Non-thermal plasma (NTP) coupled Ni-based catalysts are a promising method for tar steam reforming to syngas. In this work, Ni-based catalysts supported on hydroxyapatite (Ni-HAP) and γAl2O3 (Ni-γAl2O3) coupled with a coaxial dielectric barrier discharge (DBD) plasma were used to degrade biomass tar, and benzene was selected as a typical unbranched benzene ring structured tar model compound. In the NTP alone system, an increase in discharge power leads to benzene deep cracking to carbon deposition. In the NTP-catalytic system, the reaction temperature is a critical factor for catalysis, and the catalyst leads to a significant increase in benzene conversion and total gas yield, prompting the conversion of more cracking intermediates to gaseous products. Steam in the system has both positive and negative effects: a certain amount of steam can increase the amount of H· and ·OH, promoting benzene decomposition and carbon deposit elimination; excessive steam will compete for energetic electrons or oxidize the active metal in the catalyst, inhibiting benzene conversion. The Ni3-HAP catalyst exhibits the maximum benzene conversion (92.13 %) and energy efficiency (8.49 g/kWh), thanks to the formed Ni2+[I] and Ni2+[II] in the lattice due to the flexible ion exchange properties of the HAP support. The main reason for the catalyst activity degradation is carbon deposition rather than catalyst sintering. A good match among tar conversion rate, degree of decomposition, steam content and steam decomposition rate is critical for efficient and stable operation of the NTP-catalytic system.

Resolving set and exchange property in nanotube

<abstract><p>Give us a linked graph, $ G = (V, E). $ A vertex $ w\in V $ distinguishes between two components (vertices and edges) $ x, y\in E\cup V $ if $ d_G(w, x)\neq d_G (w, y). $ Let $ W_{1} $ and $ W_{2} $ be two resolving sets and $ W_{1} $ $ \neq $ $ W_{2} $. Then, we can say that the graph $ G $ has double resolving set. A nanotube derived from an quadrilateral-octagonal grid belongs to essential and extensively studied compounds in materials science. Nano-structures are very important due to their thickness. In this article, we have discussed the metric dimension of the graphs of nanotubes derived from the quadrilateral-octagonal grid. We proved that the generalized nanotube derived from quadrilateral-octagonal grid have three metric dimension. We also check that the exchange property is also held for this structure.</p></abstract>

Виды предгеометрий ациклических теорий

The article is devoted to the description of types of pregeometries with an algebraic closure operator for acyclic theories. In these theories we describe conditions of violation of the exchange property for a pregeometry. Taking into account these conditions, we introduce new concepts that do not rely on the exchange property: 𝑎- pregeometry, 𝑎-modularity, etc. The dependence conditions for an 𝑎-modular and 𝑎- locally finite 𝑎-pregeometry on the number of non-isomorphic trees and special points are established. Sufficient conditions of dependence for a 𝑎-local finite 𝑎-pregeometry on the vertices of the 𝑎-type are established, too.

A New Method for the Synthesis of Layered Europium Hydroxide Using Propylene Oxide as the Precipitating Agent

A new method for the synthesis of layered europium basic chloride in up to 90% yield was developed. The method is based on hydrolysis of europium chloride in the presence of propylene oxide. The effect of reaction temperature on the yield and composition of the products of europium chloride hydrolysis in the presence of propylene oxide was analyzed. The obtained layered europium basic chloride had pronounced anion exchange properties. The possibility of intercalation of the isonicotinate anion into a layered rare earth hydroxide was demonstrated for the first time. The intercalation of the benzoate or isonicotinate anions into layered europium hydroxide led to luminescence sensitization and decrease in the Eu3+ local symmetry.

Flat tube heat exchangers: Experimental analysis of frosting and water retention

In air source heat pumps, frost may form on the surface of the evaporator at low ambient air temperatures. If significant amounts of frost accumulate, the heat pump efficiency decreases so the heat exchanger needs to be defrosted. The aim of this work is an experimental analysis of different flat tube heat exchanger designs for use as direct evaporators in heat pumps. The analysis will quantify heat pump efficiency potentials in the context of cyclic frosting and defrosting conditions. For the purpose of direct evaporators in heat-release controlled heat pumps, the heat exchanger designs are studied in a heat carrier circuit under constant air heat absorption control during the frosting processes. Previous published investigations assume a constant inlet temperature, whereby the heat absorption degrades as frosting occurs. The effect of heat exchanger design on water retention from defrosting and the impact this has on the length of the refrosting phase, is analyzed experimentally. The evaluation criteria for a heat exchanger are the rate of obstruction of the air path due to frost formation and the retention of as small a mass of melt water as possible after defrosting. The heat exchanger properties fin pitch, fin overlap, and heat exchanger depth, as well as the omission of louvers and different surface coatings, are analyzed experimentally using the evaluation criteria. It is found that heat exchangers with louvered fins and an uncoated surface are advantageous for an efficient cyclic frosting and defrosting process. In the excecuted experiments a larger fin pitch of 1.4 mm can extend the frosting process up to 36% compared to a fin pitch of 1.15 mm. An increase in heat exchanger depth from 28 mm to 34 mm lenghens the frosting process by 26%. • Experimental analysis of flat tube heat exchangers under frosting conditions with constant heat absorption. • Experimental analysis of melt water drainage behaviour in vertical flat tube heat exchangers. • Investigations of heat exchanger properties fin pitch, fin overlap, depth, coatings, and omission of louvers .

The role of tertiary amines as internal catalysts for disulfide exchange in covalent adaptable networks

True effects of internal tertiary amines on disulfide exchange in cross-linked networks are explored, which provides the knowledge for the creation of functional materials with efficient bond exchange properties.

Influence of finned charges on melting process performance in a thermal energy storage

• Performance of the melting process of PCMs (thermal charge period) inside the enclosure with and without fins attached to thermal chargers is studied numerically. • Enthalpy-porosity method is used for numerical simulation. • The effects of fins’ number and fins’ location on the charging process have been scrutinized. • Optimal location of the charger with necessary fins’ number for effective charging period has been found. Thermal energy storages based on the phase change materials are considered as bright technologies because they have more advantages than other energy storage methods. In addition to the thermal parameters of phase change materials, the performance of the thermal energy storage system using latent heat depends on the heat exchanger properties. Here, several different parameters related to the use of fins in the thermal energy storage devices have been studied. Using enthalpy-porosity method, the process of phase-change material melting into a square cavity is evaluated. Cylindrical thermal chargers with a circular cross-section that transfer heat energy to the phase change material are installed inside the chamber. Longitudinal fins are placed on the heat charger surface to assist the heat charging process. By increasing the fins number to four compared with two fins, the melting process shows a significant increase for the position where the heat charger is located in the center and at the bottom of the cavity. Also for these conditions, higher temperature gradients and a thinner boundary layer are observed at the melting point. Also, the heat transfer rate increases and the melting process is accelerated.

Adsorption of Arsenic, Lead, Cadmium, and Chromium Ions from Aqueous Solution Using a Protonated Chabazite: Preparation, Characterization, and Removal Mechanism

The adsorption of As(V), Pb(II), Cd(II), and Cr(III) ions from aqueous solutions on natural and modified chabazite was studied. The functionalization of chabazite was performed via a protonation and calcination with the aim of generating Lewis acid sites to improve its anion exchange properties. The surface and physicochemical properties of both adsorbents were studied and compared. The adsorption isotherms of tested heavy metal ions were quantified and modeled to identify the best isotherm equation. Steric parameters for the adsorption of these ions were also calculated with a monolayer statistical physics model. Natural chabazite showed the maximum adsorption capacity for Pb(II), while the modified zeolite improved its As(V) properties in 79%. These results showed that the modified zeolite was able to remove both cations and anions from aqueous solution. The application of this functionalized chabazite can be extended for the removal of other anionic pollutants from water, thus opening the possibility of preparing new adsorbents with tailored properties for water treatment.

Mathematical modeling of adsorption isotherms of water vapour on polymeric ionites used in agrochemical practice

Polymeric ion-exchange materials (ionites) are used in agriculture to make substrates for complete and long-term plant nutrition. The main nutrients in bound form are contained on the ion-exchange groups of the ionite. The degree of dissociation of these groups, and thus the release of ions into the soil, depends on the moisture content. In case of heavy rainfall and during drought, the exchange properties of the ionite will be different. Therefore, the study of water adsorption in such ionites is a rather urgent problem. In this work, the water vapour adsorption by ionites is studied using a thermodynamic model that incorporates the interplay between changes in the energy of dissociation of ion-exchange groups and the osmotic effect. Within the framework of this approach adsorption isotherms are built in the range of air humidity from 0,1 to 1 at physically reasonable values of system parameters. Isotherms have a characteristic inflection point in the area of medium humidity, which allows them to be attributed to isotherms of the fifth type. The obtained model isotherms describe adsorption in mesoporous and microporous materials, which are ionites, and fully correspond to experimental adsorption isotherms of this type.

CARACTERIZAÇÃO DE RESÍDUOS SÓLIDOS INDUSTRIAIS POR ANÁLISE TÉRMICA: PERSPECTIVAS DE USO COMO MATERIAL FILTRANTE PARA ÁGUAS RESIDUÁRIAS

CHARACTERIZATION OF SOLID RESIDUES THROUGH THERMAL ANALYSIS: UTILIZATION PERSPECTIVE AS FILTER MATERIAL FOR WASTEWATER TREATMENT. Metallurgical waste and vermiculite are solid residues that have potential of utilization as filtering material. Nevertheless, they are commonly discarded. These materials have chemical sites like Si-O, Si-O-Si in vermiculite or have good ionic exchange properties like iron oxide compounds that can be used in adsorption processes. When these materials are combined with a synthetic blanket (OH, C=C, CO and C-H groups), it composes a filter layer with potential to be used in wastewater treatment. In this article, these materials were chemically treated and characterized by Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and coupled TG-FTIR. The results suggest that organic compound contamination was not found after chemical treatment, which could have remained over the unity operations in the Metallurgical processes. The thermal and acid treatments influenced a major formation of iron oxide formation, but its oxidation degree (FeO, Fe2O3, or Fe2O3.FeO) were dependent on the sample granulometry. The Vermiculite shows an irreversible chemical modification after thermal treatment. The characterization of these residues shows its potential use as material in filter construction. Hence, it is fundamental to minimize the environmental impacts as well as to diminish the production costs in wastewater treatment.

Enhancing heat transfer performance of automotive radiator with H2O / activated carbon nanofluids

The deionized (DI) water and activated carbon (AC) nanofluids were produced at different volume concentrations (VCs) such as 0.1, 0.25, and 0.4 %. ACNMs were produced through the pyrolysis process of deadly available Kigelia Africana leaves in a muffle oven at 500 °C. The structural properties of the activated carbon nanomaterials (ACNMs) were described through the usage of SEM, EDS, XRD, and FTIR analyzers. Thermal exchange properties that as density (ρ), thermal conductivity (TC), specific heat (SH), and viscosity (µ) of DI water - AC-based nanofluids were evaluated experimentally. The five various mass flow rates (MFRs) namely 20, 40, 60, 80, and 100 g/sec were applied with different VCs of DI water - AC nanofluids in this study. In addition, the hot fluid (nanofluid) inlet temperature was constantly maintained with the help of a hot DI water bath at 50, 60, and 70 °C, respectively. The highest thermal conductivity (TC) augmentation attains up to 9.134 % is detected at 0.4 vol% of ACNMs loading at 70 °C. The addition of ACNMs augments the specific heat (SH) of the nanofluids substantially, and this augmentation diminutions with an increase in the ACNMs concentration. The addition of ACNMs in the DI water augments the Nusselt number by 21.76 %, 24.71 %, and 32.47 % for 50, 60, and 70 °C respectively, at a VCs of 0.4 % and mass flow rate of 0.1 kg/sec in the car radiator. In addition, turn up a palpable reduction in Reynolds number for specified MFRs for all the ACNM nanofluids.

Enhancing the stability and homogeneity of non-ionic polymer nanodiscs by tuning electrostatic interactions

The nanodisc technology is increasingly used for structural studies on membrane proteins and drug delivery. The development of synthetic polymer nanodiscs and the recent discovery of non-ionic inulin-based polymers have significantly broadened the scope of nanodiscs. While the lipid exchange and size flexibility properties of the self-assembled polymer-based nanodiscs are valuable for various applications, the non-ionic polymer nanodiscs are remarkably unique in that they enable the reconstitution of any protein, protein–protein complexes, or drugs irrespective of their charge. However, the non-ionic nature of the belt could influence the stability and size homogeneity of inulin-based polymer nanodiscs. In this study, we investigate the size stability and homogeneity of nanodiscs formed by non-ionic lipid-solubilizing polymers using different biophysical methods. Polymer nanodiscs containing zwitterionic DMPC and different ratios of DMPC:DMPG lipids were made using anionic SMA-EA or non-ionic pentyl-inulin polymers. Non-ionic polymer nanodiscs made using zwitterionic DMPC lipids produced a very broad elution profile on SEC due to their instability in the column, thus affecting sample monodispersity which was confirmed by DLS experiments that showed multiple peaks. However, the inclusion of anionic DMPG lipids improved the stability as observed from SEC and DLS profiles, which was further confirmed by TEM images. Whereas, anionic SMA-EA-based DMPC-nanodiscs showed excellent stability and size homogeneity when solubilizing zwitterionic lipids. The stability of DMPC:DMPG non-ionic polymer nanodiscs is attributed to the inter-nanodisc repulsion by the anionic-DMPG that prevents the uncontrolled collision and fusion of nanodiscs. Thus, the reported results demonstrate the use of electrostatic interactions to tune the solubility, stability, and size homogeneity of non-ionic polymer nanodiscs which are important features for enabling functional and atomic-resolution structural studies of membrane proteins, other lipid-binding molecules, and water-soluble biomolecules including cytosolic proteins, nucleic acids and metabolites.

Modeling the Conductivity and Diffusion Permeability of a Track-Etched Membrane Taking into Account a Loose Layer.

The microheterogeneous model makes it possible to describe the main transport properties of ion-exchange membranes using a single set of input parameters. This paper describes an adaptation of the microheterogeneous model for describing the electrical conductivity and diffusion permeability of a track-etched membrane (TEM). Usually, the transport parameters of TEMs are evaluated assuming that ion transfer occurs through the solution filling the membrane pores, which are cylindrical and oriented normally to the membrane surface. The version of the microheterogeneous model developed in this paper takes into account the presence of a loose layer, which forms as an intermediate layer between the pore solution and the membrane bulk material during track etching. It is assumed that this layer can be considered as a "gel phase" in the framework of the microheterogeneous model due to the fixed hydroxyl and carboxyl groups, which imparts ion exchange properties to the loose layer. The qualitative and quantitative agreement between the calculated and experimental concentration dependencies of the conductivity and diffusion permeability is discussed. The role of the model input parameters is described in relation to the structural features of the membrane. In particular, the inclination of the pores relative to the surface and their narrowing in the middle part of the membrane can be important for their properties.

Ion Exchange in Natural Clinoptilolite: Aspects Related to Its Structure and Applications

Clinoptilolite is one of the most common, widespread and abundant zeolites in nature. Its availability, low cost, and outstanding ion exchange properties make clinoptilolite an excellent candidate for both direct use and various modifications to create new low-cost functional materials for sustainable development. Specific applications in which clinoptilolite is already being used include water treatment and heavy metal ion removal, agricultural purposes, storage and conversion of unwanted gaseous emissions into the atmosphere, production of catalysts and photocatalysts, bioactive materials, and a number of others. Unlike some other zeolites, clinoptilolite is difficult to synthesize, which is why most publications refer to this zeolite in its natural form, either directly from the deposit or after applying various processes to this mineral to improve its properties. Among the modification methods used, ion exchange stands out. This review is devoted to the study of ion exchange processes in natural clinoptilolite with two goals: first, as its strategic property for use in processes in which cation exchange is fundamentally necessary; second, as a way to modify it to create composite materials with predetermined desired properties.

Peritoneal Oxygenation as a Novel Technique for Extrapulmonary Ventilation; A Review and Discussion of the Literature.

The COVID-19 crisis has highlighted the difficulties that might occur when attempting to oxygenate patients who have suffered a severe pulmonary insult, including in the development of acute respiratory distress syndrome (ARDS). Traditional mechanical ventilation (MV) is effective; however, in severe cases of hypoxia, the use of rescue therapy, such as extracorporeal membrane oxygenation (ECMO), may be required but is also associated with significant complexity and complications. In this review, we describe peritoneal oxygenation; a method of oxygenation that exploits the peritoneum's gas exchange properties in a fashion that is similar to peritoneal dialysis and has shown considerable promise in animal models. We have conducted a review of the available literature and techniques, including intraperitoneal perfluorocarbons, intraperitoneal jet ventilation, a continuous low-pressure oxygen system (PEROX) and the use of phospholipid-coated oxygen microbubbles (OMBs) through peritoneal microbubble oxygenation (PMO). We conclude that peritoneal oxygenation is a promising technique that warrants further investigation and might be used in clinical settings in the future.

Study of the effect of treatment with non-equilibrium low-temperature plasma on the hygienic properties of lining leathers for shoe with genuine leather upper

the shoe grade is determined by the quality of the materials that make up the product package. Natural lining leathers for shoe with genuine leather upper should differ primarily by high moisture and vapor exchange properties to ensure an optimal microclimate of the inside of the shoe space. In the paper the application possibility of treatment of lining leathers for shoe with genuine leather upper with non-equilibrium low-temperature plasma to obtain a material with improved hygienic characteristics is justified. Because the operating conditions of lining materials for shoe with genuine leather upper are more determined by the process of contact with the surface of the foot than by environmental effect. Thus, the quality of lining materials for shoe with genuine leather upper is determined primarily by compliance with hygienic requirements, among which vapor and air permeability, hygroscopicity; resistance to sweat. In the study it was revealed that because of the treatment with NLTP HFC discharge of pigskin leathers, there is an increase in the parameter values of hygroscopicity by 34%, moisture-yielding capacity by 36%, vapor permeability by 38%, air permeability by 27%, the capacity to absorb sweat vapor by 33% and the capacity to exude sweat vapor by 42%. Consequently, the treatment with NLTP HFC discharge of pigskin leathers for shoe lining with genuine leather upper makes it possible to improve their quality by sequencing their structure, which in turn acts to increase the efficiency and intensity of moisture interchange processes between the material and the environment of the inside of the shoe space, increases the comfort of the latter and prevents potential adverse effect on human well-being.

Synthesis, Structural Characterization, and Guest Exchange Properties of Hydrogen-Bonded Organic Frameworks Based on Bis(benzimidazole)ZnCl2 Complexes.

Hydrogen-bonded organic frameworks (HOFs) based on coordination compounds constitute a developing class of interesting porous materials. Herein, we report on the synthesis, crystal structures, and guest exchange properties of four HOFs based on zinc dichlorido complexes that bear a bis(benzimidazolyl)methane ligand (bis(benzimidazole)ZnCl2). The porous structures of these bis(benzimidazole)ZnCl2-based HOFs are characterized predominantly by intermolecular N-H···Cl hydrogen bonds in conjunction with π-π interactions. One of these HOFs was found to exchange guest molecules via single-crystal-to-single-crystal transformations with or without structural change. A single-crystal X-ray diffraction study revealed that the guest exchange accompanied by a structural change is induced by the cleavage of the N-H···Cl hydrogen bonds between the bis(benzimidazole)ZnCl2 complexes, followed by the formation of alternate hydrogen bonds with guest molecules. This result suggests that the use of weaker N-H···Cl hydrogen bonds than those typically used for the construction of HOFs (e.g., carboxylic acid dimers, N-heterocycles, and charge-assisted moieties) may represent a convenient strategy to synthesize flexible HOFs.

Cataphoretic deposition of an epoxy coating with the incorporation of Ti3C2Tx@Mg-Al layered double hydroxide for long-term active corrosion protection effect

Epoxy composite coating with active corrosion inhibition property was prepared through cathodic electrophoretic deposition with the incorporation of Ti3C2Tx@Mg-Al layered double hydroxides (LDH) hybrid material. Hydrothermal method was adopted to synthesize molybdate (MoO42−)-intercalated MgAl LDH, which was self-assembled on the surface of Ti3C2Tx MXene through electrostatic interaction to improve the zeta potential of the Ti3C2Tx surface to positive value. Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscope, scanning electron microscope, X-ray photoelectron spectroscopy, zeta (ζ) potentials test and uv-vis spectroscopic analysis results showed that MgAl LDH and Ti3C2Tx@Mg-Al LDH were successfully prepared and Ti3C2Tx@Mg-Al LDH had ion exchange property. The prepared LDH and Ti3C2Tx@Mg-Al LDH were added to electrophoretic paint as anti-corrosive additives. After deposition process of 150 V for 2 min on the P110 steel surface, composite coatings had thicknesses of ~110 μm. Electrophoretic deposition has advantages in controlling coating thickness than traditional spray method. Moreover, Ti3C2Tx@Mg-Al LDH additive endowed composite coating with active corrosion inhibition capacity through ions exchange property between corrosive medium Cl− and MoO42− in the MgAl LDH interlayer. Electrochemical impedance spectroscopy (EIS) test results showed that Ti3C2Tx@Mg-Al LDH/epoxy coating exhibited outstanding corrosion protection property. This research provides a new way of using Ti3C2Tx MXene in the cathodic electrophoretic paint to prepare active anti-corrosive coating.