Sorption Properties Research Articles

Physico-Chemical Properties of Granular Sorbents Based on Natural Bentonite Modified by Polyhydroxocations of Aluminum and Iron (III) by Co-Precipitation.

The physicochemical and adsorption properties of granular sorbents based on natural bentonite and modified sorbents based on it have been studied. It was found that modification of natural bentonite with iron (III) polyhydroxocations (mod. 1_Fe_5 GA) and aluminum (III) (mod. 1_Al_5 GA) by the "co-precipitation" method leads to a change in their chemical composition, structure, and sorption properties. It is shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores measuring 1.5-8.0 nm, with a specific surface area of 55-65 m2/g. Modification of bentonite with iron (III) and aluminum compounds by the "co-precipitation" method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions and nickel cations by 5-10 times compared with natural bentonite. The obtained sorption isotherms were classified as Langmuir type isotherms. Kinetic analysis showed that at the initial stage the sorption process is controlled by an external diffusion factor, i.e. refers to the diffusion of sorbent from solution into a liquid film on the surface of the sorbent. Then the sorption process begins to proceed in a mixed diffusion mode, when it limits both the external diffusion factor and the internal diffusion factor (the diffusion of the sorbent to the active centers through the system of pores and capillaries). To determine the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions and nickel(II) cations with the studied granular sorbents, kinetic curves were processed using the equations of chemical kinetics (pseudo-second-order model). As a result, it was found that the adsorption of the studied anions by modified sorbents based on natural bentonite is best described by a pseudo-second-order kinetic model. It is shown that the use of natural bentonite for the development of technology for the production of granular sorbents based on it has an undeniable advantage, firstly, in terms of its chemical and structural properties, it is easily and effectively modified, and secondly, having astringent properties, granules are easily made on its basis, which turn into ceramics during high-temperature firing. The result is a granular sorbent with high physical and mechanical properties. Since bentonite is an environmentally friendly product, the technology of recycling spent sorbents is also greatly simplified.

УТИЛИЗАЦИЯ ОПАСНЫХ ШЛАМОВ ЛИТИФИКАЦИЕЙ ОПОКАМИ

In modern water treatment technologies, sorption methods play a key role in removing toxic components from wastewater. The most commonly used adsorbent is activated carbon, but its high cost and difficulty of disposal limit its use in water-intensive processes. Natural dispersed silica, such as opoca, provides an efficient and environmentally friendly alternative. The present paper is devoted to the study of a safe method of utilization of spent silica-based adsorbent by lithification method. The results of the analysis of the chemical composition of spent materials, the mechanism of encapsulation of toxic components and their subsequent use as a secondary material resource (SMR) are given. Various additives can be used to improve the effectiveness of opoka as a sorbent or component in waste management processes. These additives improve the sorption, mechanical and chemical properties of the material. International approaches to this task are reviewed. Comparative data with other disposal methods are given.

Merging and Clipping Nets for the Synthesis of Three- and Two-Merged Net Metal-Organic Frameworks.

Herein, we report how merging and clipping nets in metal-organic frameworks (MOFs) can be controlled in a single-crystal-to-single-crystal fashion using three different approaches─the merged net, clip-off chemistry, and linker reinstallation─to design and synthesize three- and two-merged net MOFs. Initially, we show the formation of three isoreticular three-merged net MOFs by linking a trimeric Sc3+ cluster, Sc3(μ3-Ο)(-COO)6, with ditopic zigzag and tritopic linkers. The resulting MOFs exhibit three-merged edge-transitive nets─kgd + hxl + pcu─for the first time. Then, using these three-merged net MOFs as precursors, we selectively remove one of these subnets, the hxl net, via clip-off chemistry to form two-merged net MOFs. This process involves the cleavage of olefinic groups via ozonolysis, providing the resulting two-merged net MOFs with free carboxylic acid groups that can be used to tune their sorption properties such as the removal of cationic organic pollutants. Finally, we use the linker reinstallation approach to convert the two-merged net MOFs back to the three-merged net MOFs. This approach allows for the postsynthetic addition of the previously removed hxl merged net, enabling recovery of the initial three-merged net MOFs or synthesis of new ones using novel ditopic zigzag linkers.

A Sustainable Route From Quartz to Bifunctional Material with Adsorbed Lanthanides for Enhanced Fluorescent Activation in Doxycycline Sensing

AbstractA nanosized bifunctional adsorbent with diamino and phenyl groups on its surface is synthesized through the functionalization of silica derived from quartz. The composition, morphology, and particle size of the functionalized silica are characterized using various physicochemical methods. The material demonstrates high sorption properties for La(III) and Ce(III), both found in Ni‐MH batteries, as well as Eu(III). The synthesized functionalized silica, with adsorbed lanthanides, is employed for sensor‐based detection of doxycycline in aqueous solutions. After sorbing lanthanides, the bifunctional adsorbent shows a linear response to doxycycline in the concentration range of 0.005–10.0 µm, with a detection limit of 0.15 µm L−1 and a quantification limit of 0.44 µm L−1. The increase in photoluminescence signal upon the addition of doxycycline is explained using Judd–Ofelt theory. Experimental W2 and W4 parameters of the Eu‐doped nanomatrix are determined to be 1.44 × 10−20 cm2 and 8.55 × 10−20 cm2, respectively, with these values increasing to 73.40 × 10−20 cm2 and 35.58 × 10−20 cm2 upon the addition of doxycycline. A significant increase in the radiative emission rate from 196 s−1 to 1977 s−1 is observed with doxycycline addition. It is demonstrated that the system containing the three lanthanides exhibits unique sensor properties, attributed to the co‐luminescence of the Eu(III) ion.

Modified Kapok Fibers (Ceiba pentandra (L.) Gaerth) for Oil Spill Remediation

The search for efficient oil spill remediation techniques leads to the use of physical, chemical, and biological methods, featuring both natural and modified lipophilic materials. Kapok fibers (Ceiba pentandra (L.) Gaerth) have been studied as a result of their unusual natural oil sorption capacity, which can be improved even further through physical or chemical treatments that augment their rugosity and alter their functional properties. Furthermore, the exact role of fiber morphology is not completely clear regarding the sorption process. Hence, this study investigated the efficacy of kapok fibers using different treatments, based on chemical and physical approaches, and characterized using advanced techniques (FTIR, SEM, AFM), aiming to improve the understanding of application possibilities in oil contamination scenarios. The results indicate that treatments using a low thermal intensity and low concentration do not lead to variation in sorption properties nor in surface structural features. Fiber rugosity varied from 4.40 to 12.35 nm, whereas an excessive increase in roughness was observed when the material was subject to more extreme conditions, such as a temperature of 120 °C and high concentrations (2.0 M) of both acid or alkali, accompanied by a loss in functionality and affecting the material sorption capacity. Thus, the study provides conditions to suggest that these treatments are not necessary for this type of material when inserted into sorption processes.

Titanium(IV), Zirconium(IV), and Cerium(IV) Phosphates Synthesized Under Mild Conditions-Composition Characteristics and Evaluation of Sorption Properties Towards Copper Ions in Comparison to Commercially Available Ion-Exchange Resins.

The removal of copper from wastewater of mine origin requires the use of an appropriate method. Sorption methods are considered to be one of the best solutions for removing copper from industrial wastewater at low levels. Metal(IV) phosphates have been reported as excellent sorption materials that can be highly selective for copper. Therefore, the aim of this research was to synthesize titanium(IV), zirconium(IV), and cerium(IV) phosphates with a wide range of P:Metal(IV) molar ratios (0.5-10) in the reaction mixture and under mild conditions, using a simple scalable approach which requires minimal financial outlays. The obtained materials were characterized using XRD, ATR-FTIR, SEM-EDS techniques, and pH titration. To evaluate the performance of the resulting materials, their sorption properties towards copper ions were examined in comparison with selected commercially available ion-exchange resins. In each group of metal(IV) phosphates, the best material has a high ion-exchange capacity: 16.9 meq/g for titanium sorbent, 8.8 meq/g for zirconium sorbent, and 7.0 meq/g for cerium sorbent. Zirconium phosphate synthesized at a P:Zr molar ratio in the reaction mixture of 10:1 exhibits the best sorption properties towards copper ions in a solution similar to mining wastewater (acidic, saline, and containing heavy metals), better than some commercial ion-exchange resins.

Synthesis and Study of Sorption Properties of Zinc-Imprinted Polymer.

Zinc-imprinted polymer (ZnIP) and non-imprinted polymer (NIP) were synthesized by radical polymerization, and their properties were studied. The novelty of the work lies in the use of humic acids isolated from coals of the Shubarkol deposit (Karaganda, Kazakhstan) as a basis for the imprinted polymer matrix, with methacrylic acid and ethylene glycol dimethacrylate as a functional monomer and a cross-linking agent, respectively. The composition and structure of ZnIP and NIP were characterized using various physicochemical methods. The specific surface area of ZnIP determined by the BET method was 40.60 ± 0.4 m2/g, which is almost twice as high as the similar indicator for NIP (21.50 ± 0.3 m2/g). In sorption tests of solutions with bimetallic ions, ZnIP demonstrates higher adsorption: 96.15% for Zn2+ and 74.88% for Pb2+, while NIP adsorbs only 81.33% and 60.11%, respectively. Sorption on both polymers is described by a pseudo-first-order equation (r > 0.99). The distribution coefficients for ZnIP are higher than for NIP. ZnIP has a relative selectivity that exceeds NIP by 2.90 times. The research results indicate the promise of using ZnIP for the selective removal of zinc ions from solutions of multicomponent systems, including wastewater, making it a valuable material for solving environmental and technological problems.

Effect of polyethylene microplastic biodegradation by algae on their sorption properties and toxicity.

Microplastics (MPs) in aquatic environments constitute an ideal surface for biofilm formation, facilitating or hindering the transport of contaminants. This study aims to provide knowledge on the sorption behavior of high-density polyethylene (μ-HDPE) after algal degradation toward UV filters. Up to now, the oxidation of μ-HDPE using the microalga Acutodesmus obliquus has not been studied. The results obtained by infrared spectroscopy (IR), scanning electron microscopy (SEM), and porosimetry analysis revealed a biofilm formation on the surface of μ-HDPE and the presence of carbonyl and double bond functional groups. Also, this is the first time that the simultaneous sorption of benzophenone (BPh), 4-methylbenzylidene camphor (4MBC), benzophenone 3 (BPh3), and benzophenone 2 (BPh2) onto biofilm-covered HDPE (biofilm-HDPE) in water have been studied. Filters' sorption on biofilm-HDPE particles follows pseudo-second-order kinetics, and film diffusion was the stage that limited the sorption rate. The Langmuir isothermal model describes the adsorption process for 4MBC, BPh, and BPh2 well, and the linear model is fit for the sorption of BPh3. Hydrophobic interactions, Van der Waals forces, electrostatic, and π- π bon are the main mechanisms responsible for the sorption. Biological analysis indicated that HDPE at concentrations of 500 mg L-1 inhibits A. obliquus growth and reduces the levels of proteins, sugars, and chlorophylls. In contrast, the activity of antioxidant enzymes and the contents of small molecular weight antioxidants significantly increased in algal cells treated with microplastic. These findings confirm the toxicity of μ-HDPE and demonstrate the induction of defense mechanisms in A. obliquus as a response to environmental pollutants.

Intermetallic Materials for High-Capacity Hydrogen Storage Systems.

In this article, we provide an overview of hydrogen storage materials, taking our previous results as examples. Towards the end of the paper, we present a case study in order to highlight the effects of substitutional alloying, compositional additives, and nanostructuring on the hydrogen sorption properties of magnesium-based intermetallics. Specifically, partial substitution of Mg by Li and d-elements by p-elements leads to structural changes, inducing disorder and the formation of high-entropy alloys. Our approach showcases the methodology to enhance the H2-capacity and to provide a positive boost to the H2-storage performance, including lower temperatures of H2 desorption, better thermodynamics and kinetics, lower temperatures of hydrogen uptake/ release for Metal-Hydride Hydrogen Storage (MHHS) systems and higher capacity of anodes for Metal-Hydride batteries (MHB) together with lower prices of raw materials.

RESEARCH OF PROCESSES OF SORPTION OF COPPER IONS BETWEEN NATURAL CLAY MATERIALS FOR PROTECTION AGAINST POLLUTION OF UNDERGROUND AQUIFER HORIZONS

Experimental experiments with white clay from three deposits of Mykolaiv and red clay from Cherkasy region regarding sorption properties in relation to Cu2+ ions confirmed the ability to use local natural materials in the processes of cleaning from pollution in the water environment. A comparative analysis of red and white clay samples showed that red clay has a greater sorption capacity. The experiment was performed for two stages of filtration - drip and suspended, which take place during the operation of reclamation facilities and treatment facilities. For the stage of supported filtration, the experiments conducted by the authors showed a decrease in the sorption capacity of all samples, which was also confirmed by the calculations of Freundlich adsorption constants, which quantitatively characterized the adsorption process for each sample, as well as an increase in the averaged filtration coefficients at the stage of supported filtration.Experimental studies on the extraction of heavy metal ions using Cu2+ as an example were carried out according to the standard method using the colometric method with the diethyldithiocarbamate reagent under the condition of an initial concentration of Cu2+ in the solution of 5.8 mg/dm3.Результати проведеного експерименту свідчать, що при облаштуванні екранованих спо-руд глинистим екраном, крім протифільтраційних властивостей облицювання, що залежать від його товщини, отриманої щільності та інших параметрів після укладки, слід враховувати сорбційні властивості такого облицювання, режиму роботи споруди і, відповідно, величину гідравлічного на-пору.The results obtained during this experiment can also be used in the installation of anti-filtration screens of settling tanks and tailings of various kinds, as well as in the sanitation of water bodies in order to prevent pollution of the underground aquifer.

ELECTROCHEMICAL AND CONFORMATIONAL PROPERTIES OF POLYACRYLIC ACID AND POLY-2-METHYL-5-VINYLPYRIDINE HYDROGELS DURING THEIR REMOTE INTERACTION IN AQUEOUS ENVIRONMENT

Introduction. Previous research on the intergel system of polyacrylicacid (PAA) and polyethyleneimine (PEI) revealed that at a hydrogel ratio of 3:3, significant activation occurs at 24 hours. This indicates substantial changes in electrochemical and conformational properties at this ratio. The purpose of this research is to investigate the remote interaction between the weak polyelectrolyte polyacrylic acid (PAA) and the weak polybase poly-2-methyl-5-vinylpyridine (P2M5VP) over time and at various molar ratios in an aqueous environment. The study seeks to explore the activation potential of these hydrogels by analyzing their electrochemical properties using conductometry and pH-metry, and to determine the effect of molar ratios on the specific conductivity and swelling degree of the hydrogels. The obtained results.The maximum conductivity of 14.4 µS/cm was achieved at a ratio of 2:4 at 2.5 hours, coinciding with the minimum pH value of 4.4. In the 6:0 ratio, where only the PAA hydrogel is present, the conductivity changes remained minimal within the range of 1-2 µS/cm, indicating the stability of this hydrogel in the absence of P2M5VP. The swelling coefficient also exhibited interesting dynamic changes depending on the time and component ratios. The swelling coefficient of PAA remained stable at 11-14 for the individual hydrogel but showed a maximum value of 41 at a ratio of 1:5 after 24 hours, indicating significant interaction between the hydrogels. The maximum swelling coefficient of P2M5VP, 7.5 and 7.6, was observed at ratios of 5:1 and 2:4, respectively, 2.5 hours into the study, suggesting optimal interaction of the hydrogels during these time intervals. Conclusion. The studies showed that initial differences in conductivity are minimal; however, significant changes occur over time due to intermolecular interactions between the components. The obtained results can be useful for optimizing the sorption properties of hydrogels in metal extraction processes.

Comparative Analysis of Physico-Chemical and Potassium Sorption Properties of Sensitive Clays

The paper analyses physico-chemical and geotechnical characteristics of four Scandinavian sensitive soils formed under different environmental depositional conditions, with the main aims to contribute to the knowledge of sensitive soils and assess the potassium sorption capacity among the investigated soils, as a basic characteristic to evaluate the effectiveness of treatment with KCl and to analyse potassium migration in such soils. The results show that, although the chemical composition of the four soils is very similar, their sensitivity is significantly different. The correlation from literature linking the specific surface, mineralogy, and plasticity in sensitive clays of Eastern Canada, was found to be qualitatively valid for the investigated Scandinavian sensitive clays, too. The highest value of the sensitivity index among the tested soils was found to be related to the lowest cation exchange capacity and to a limited amount of amorphous minerals. These characteristics contribute to explaining the highly sensitive behaviour of that soil affecting the structure formation during the deposition stage. The potassium sorption capacity has been experimentally investigated through batch tests specifically performed on the sensitive soils, as the first step to quantify the maximum sorption capacity and identify the main factors affecting it. The maximum potassium sorption capacity was always lower than that estimated by the cation exchange capacity, and it increased with the cation exchange capacity, plasticity index, and activity of the soils, as well as with the amount of phyllosilicates and amorphous minerals.

Unveiling the Sorption Properties of Graphene Oxide-M13 Bacteriophage Aerogels for Advanced Sensing and Environmental Applications.

GraPhage13 aerogels (GPAs) are ultralow density, porous structures fabricated through the self-assembly of graphene oxide (GO) and M13 bacteriophage. Given GPA's high surface area and extensive porous network, properties typically associated with highly adsorbent materials, it is essential to characterize its sorption capabilities, with a focus on unlocking its potential for advanced applications in areas such as biomedical sensing and environmental monitoring. Herein, the water, ethanol and acetone sorption properties of GPA were explored using dynamic vapor sorption (DVS). GPA was found to be highly hygroscopic, with a sorption capacity of 0.68 ± 0.02 g/g, double that of conventional desiccant silica gels and 20% higher than GO laminates. This remarkable sorption capacity, along with its sorption kinetics, was influenced by both GPA's morphology and the strong interactions between the water molecules and the functional groups on the GO within GPA. The low hysteresis and stability of GPA during repeated sorption-desorption cycles highlight the reversibility of water sorption. While GPA shows lower capacity for ethanol and acetone, its tuneability presents opportunities for improving acetone sorption, and its ethanol sorption capacity exceeds that of similar carbon-based materials. These findings underscore GPA's capability and versatility in vapor adsorption, paving the way toward its integration into graphene-based devices for sensing applications.

Composite Sorbents for CO2 Capture Based on Polyethyleneimine and Silica Gel: Study of Sorption Properties and Analysis of Thermal Energy Consumption

Studies of CO2 sorption by composite sorbents containing the active component (branched polyethylenimine) dispersed in the pores of mesoporous support (silica gel) have been carried out. It is shown that as silica gel pores are filled with polyethylenimine, the sorption efficiency of CO2 by the active component decreases, and the dynamic sorption capacity per 1 g of material passes through a maximum. The enthalpy values of CO2 sorption by composite sorbents have been determined. It is shown that the enthalpy values of CO2 sorption depend on the proportion of pore filling by the active component and on the characteristics of the porous structure of the support. Thermal energy consumption for regeneration of composite sorbents within the adsorption cycle was analyzed.

Ligand Circuit Concept for Developing Gas Separation Materials from Pore-Space-Partitioned Metal-Organic Frameworks.

Isoreticular chemistry is among the most powerful strategies for designing novel materials with optimizable pore geometry and properties. Of great significance to the further advance of isoreticular chemistry is the development of broadly applicable new concepts capable of guiding and systematizing the ligand-family expansion as well as establishing correlations between dissimilar and seemingly uncorrelated ligands for better predictive synthetic design and more insightful structure and property analysis. Here ligand circuit concept is proposed and its use has been demonstrated for the synthesis of a family of highly stable, high-performance pore-space-partitioned materials based on an acyclic ligand, trans, trans-muconic acid. This work represents a key step toward developing highly porous and highly stable pore-space-partitioned materials from acyclic ligands. The new materials exhibit excellent sorption properties such as high uptake capacity for CO2 (81.3cm3g-1) and C2H2 (165.4cm3g-1) by CPM-7.3a-NiV. CPM-7.3a-CoV shows C2H6-selective C2H6/C2H4 separation properties and its high uptakes for C2H4 (134.0cm3g-1) and C2H6 (148.0cm3g-1) at 1bar and 298K contribute to the separation potential of 1.35mmolg-1. The multi-cycle breakthrough experiment confirms the promising separation performance for C2H2/CO2.

Sodium aluminosilicate synthesised from rice straw as a sorption barrier to protect soil from antimony contamination

ABSTRACT A novel effective sorbent for the extraction of antimony(III) from rice straw has been generated, having a specific surface area of 470 m²/g. The material was subjected to a series of analyses, including scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction analysis, and FT-IR spectroscopy. The sorption properties relative to Sb(III) ions were characterised in dynamic conditions in a column experiment. The total dynamic exchange sorption capacity of 113.92 mg/g renders this material suitable for use as a permeable reactive barrier (sorption barrier) with the objective of protecting soils from antimony contamination. To identify the optimal conditions for soil protection, the chemical composition, acid-base properties, and sorption parameters of soils of varying types were characterised. The sorption properties of the soils were determined in static conditions to obtain the sorption isotherm. The maximal sorption capacity was identified for the soil sample with low base saturation and a high organic component content, a finding that was corroborated by DTA analysis. The results of the column experiment with layers of soil and aluminosilicate sorbent indicate the promising use of the new sorbent as a sorption barrier for the effective protection of soils from antimony contamination.

Durian waste valorization – some research tendencies: a review

Abstract This review aimed to present a general framework of some recent research trends and highlights reflecting the current status of durian waste valorization opportunities, applying the descriptive approach. In this regard, research was conducted on the keywords “durian waste” among the most used scientific databases, and the selected and included scientific publications are far from exhausting all the available and accessible literature on the subject under consideration, the complete detailed bibliographic description of which is beyond the scope of the present review. At the forefront, as a priority in many of the diverse researches, is the pursuit of achieving basic circular goals and sustainable principles related to reducing the total amount of durian waste, the search for effective methods for their safe treatment and storage, the development of methods to add value, the implementation of strategies to transform those considered as waste into useful raw materials and resources that can be subjected to recovery to obtain material goods with a view to their effective ecological valorization. As a result of the literature survey, among the main areas that are intensively worked on in the current conditions for the utilization of durian waste, the following could be mentioned: chemical compounds extraction and bioactivity characterization; activated carbon and sorption properties; nanoparticles; anaerobic digestion and biogas production; biodiesel; bioethanol; briquettes and pellets; ink; packaging; animal feed; food systems; as well as some other valorization directions and research tendencies. Conducting numerous studies in such diverse directions shows the overall importance for society of the subject under consideration, related to the proper treatment of durian waste, the application of appropriate strategies for their effective and successful utilization, emphasizing the need to summarize and systematize the recent state in the current progress regarding the valorization of durian waste, which allows and enables periodic renewal and updating of information.

The effect of cross-linking agent amount and type on the sorption properties of starch graft polyacrylamide and poly(acrylic acid) copolymers

Abstract In free radical polymerization initiated by 2,2’-azobis(2-methylpropionamidine) dihydrochloride, grafted starch copolymers with a weight ratio of acrylamide to acrylic acid of 1:2 were obtained. Three acrylic products were used to cross-linking starch copolymers: MBA, PETIA and EBECRYL 40 in amounts of: 0.2, 0.4, 0.6 and 1.0 wt.%. Materials were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry and reoviscometry. The sorption properties of starch copolymers were confirmed by sorption tests: water absorption, swelling in water and sorption of cations: trivalent iron and divalent copper. The highest water absorption is characteristic of materials cross-linked with MBA (1800%), then PETIA (1400%) and EBECRYL 40 (850%). On the other hand, the best swelling results are in the sequence PETIA > MBA > EBECRYL (1050% > 900% > 570%). The most effective sorbent of cations is the copolymer cross-linked with MBA. Solution purifications of 90% and 45% were obtained for Fe+3 and Cu+2, respectively.

Impregnated layer solution combustion synthesized CaO-based composite pellets with enhanced CO2 sorption property

The impregnated layer solution combustion synthesis (SCS) technique was employed to synthesize CaO-based sorbents supported by inert stabilizers so as to improve the cyclic CO2 uptake stability. Four different inert stabilizers were evaluated for their impact on the cyclic CO2 uptake stability of sorbents. It found that the Mg-based inert stabilizer significantly outperforms the other three in improving cyclic CO2 sorption capabilities of sorbents synthesized by the impregnated layer SCS method. Moreover, MgO-supported sorbent pellets were prepared via graphite hydrophobic layer-assisted casting, with the magnesia load within the pellets being regulated between 15 and 45 wt %. It is the addition of MgO stabilizer that significantly improves the performance of CaO-based sorbents, with the improvements being notably more pronounced at higher MgO loads. The calcium-based sorbent pellets containing 45 wt % MgO show extremely stable CO2 sorption performance; after 17 cycles, the carbonation conversion rate is 73.6%, about three times the rate of pellets without MgO loading. The uniform dispersion of MgO inert stabilizer inside pellets improves high-temperature sintering resistance and, concurrently, enhances the mechanical property. Furthermore, the use of waste cigarette butts as impregnated layer templates, rather than other organic additives, will significantly reduce the cost of synthesizing MgO-supported CaO-based sorbents.Graphical

Water Sorption Properties and Hydrothermal Stability of Al-Containing Metal-Organic Frameworks CAU-10 and MIL-96 Studied Using Quasi-Equilibrated Thermodesorption.

A novel experimental technique, quasi-equilibrated temperature-programmed desorption and adsorption (QE-TPDA), was used to study the water sorption properties and hydrothermal stability of aluminum trimesate MIL-96 and aluminum isophthalate CAU-10, which have been selected due to their remarkable sorption properties. The QE-TPDA profiles of water observed for MIL-96 and CAU-10 confirmed the hydrophilic nature of these materials. Complex QE-TPDA profiles indicate that water sorption in MIL-96 follows a three-step pore filling mechanism. The shape of single desorption peaks in the QE-TPDA profiles for CAU-10 confirms that water sorption involves a reversible phase transition. Based on the QE-TPDA profiles, the water adsorption heat was determined: 45-46 kJ/mol for CAU-10 and 43-56 kJ/mol for MIL-96, in the latter case depending on the adsorption extent. Hydrothermal stability tests revealed that MIL-96 retained its stable porosity-related sorption capacity for water after hydrothermal treatment up to 290 °C. Gradual changes in the QE-TPDA profiles due to the hydrothermal treatment above 290 °C, with decreasing the high-temperature desorption peak and increasing the low-temperature one, indicate minor structural changes occurring in this material. Only after 410 °C treatment was fast degradation of MIL-96 observed. CAU-10 exhibited high and unchanged hydrothermal stability up to 400 °C.