Sorption Kinetics Research Articles

Rapid extraction of trace benzene by a crown-ether-based metal-organic framework

ABSTRACT Due to almost identical boiling points of benzene and cyclohexane, the extraction of trace benzene from cyclohexane is currently performed via the energy-intensive extractive distillation method. Their adsorptive separation by porous materials is hampered by their similar dimensions. Metal-organic frameworks (MOFs) with versatile pore environments are capable of molecular discrimination, but the separation of trace substrates in liquid-phase remains extremely challenging. Herein, we report a robust MOF (NKU-300) with triangular channels decorated with crown ether that can discriminate trace benzene from cyclohexane, exhibiting an unprecedented selectivity of 8615(10) for the mixture of benzene/cyclohexane (v/v = 1/1000). Remarkably, NKU-300 demonstrates exceptional selectivities for the extraction of benzene from cyclohexane over a wide range of concentrations of 0.1%–50% with ultrafast sorption kinetics and excellent stability. Single-crystal X-ray diffraction and computational modelling reveal that multiple supramolecular interactions cooperatively immobilise benzene molecules in the triangular channel, enabling superior separation performance. This study will promote the application of advanced sorbents with tailored binding sites for challenging industrial separations.

U(Ⅵ) sorption by porous sodium zirconium phosphate pellets from aqueous solution

Zirconium phosphate is the first artificially produced layered phosphate that can sorb a variety of nuclides from solutions. Sodium zirconium phosphate (NZP) was a type of α-zirconium phosphate (α-ZrP). The porous sodium zirconium phosphate pellets (p-NZP-P) with a diameter of more than ∼3 mm were prepared and used for uranium sorption. The p-NZP-P could be immersed in solutions for more than 5 days without dissolving and structurally collapsing. The sorption properties of U(Ⅵ) on p-NZP-P in solutions were investigated by both static and dynamic sorption tests. Synthetic p-NZP-P was analyzed in detail using various characterizations to investigate their character and structural changes. In the static sorption experiment, the equilibrium sorption capacity reached the 77.5 ± 1.5 mg·g−1 when the initial concentration of U(Ⅵ) was 100 mg/L, pHinitial = 4.5, T = 25 ℃. Uranium sorption increased by ∼69 % and ∼215 %, respectively, when the initial uranium concentration was increased from 100 to 300 mg·L−1 and the temperature was increased from 15 to 55 °C. Furthermore, uranium sorption increased by ∼541 % when the initial pH increased from 2.5 to 4.5, while it decreased by ∼39 % when the initial pH increased from 4.5 to 7.0. The sorption data corresponded to the pseudo-second-order kinetic model and the Langmuir isotherm model, as well as the theoretically predicted value of sorption capacity (∼199.9 mg·g−1). The results of the dynamic sorption experiment showed that decreasing the quality, increasing the flow rate and the initial U(Ⅵ) concentration would shorten the breakthrough time. The dynamic sorption data agreed well with the Thomas model. The characterization confirmed the porous properties, while the U(Ⅵ) sorption mechanisms relate to –OH coordination and ion exchange. A radioactive rare earth wastewater treatment test suggested that p-NZP-P could be the potential uranium sorbent due to its good stability and efficiency. This paper opened opportunities for the development of practical materials for treating radioactive wastewater in the application of actual scenarios.

Effect of Soil-pH, temperature and moisture content on sorption dynamics of Metformin and Erythromycin.

The rising soil-groundwater quality issues due to pharmaceuticals and personal care products (PPCPs) have spurred significant concern. To understand the sorption characteristics of metformin (MTN) and erythromycin (ETM) in sandy and sandy loam soils with varying organic matter and particle composition, sorption kinetics (single and competitive), isotherms, and thermodynamics were studied. The effects of pH and soil moisture content (SMC) were also investigated at environmentally relevant concentrations. The equilibrium time of MTN and ETM sorption by the three soils in a competitive solute system was about 4 h, and the sorption process was in line with a pseudo-second-order model. The rate-determining step in the process involved both intraparticle diffusion and liquid film diffusion mechanisms for the two PPCPs. The highest pollutant uptake occurred in soils with higher organic matter, driven by enhanced H-bonding, electrostatic interactions, and π-π and n-π interactions facilitated by the organic matter. The equilibrium data in the three soils was well described by the Freundlich model and confirmed favourable adsorption (1/nf = 1.01 - 1.90). The sorption coefficient (Kd) on the three soils ranged from 2.1 to 332 L/kg for MTN and from 6.25 to 845 L/kg for ETM. The adsorption process was feasible at 293 K and 303 K (ΔG° = - 0.16 to -10.24 kJ/mol), physical and exothermic in nature (ΔH° = -75.21 to -10.30 kJ/mol) for both the contaminants. Observed alterations in Qe with pH confirmed the participation of electrostatic interactions. A low SMC favoured both MTN and ETM sorption onto the sandy soil. Overall, ETM exhibits higher expected sorption, whereas MTN has a greater tendency for migration in the soils and is thus liable to contaminate the groundwater. The study accentuates novel insights into the transport and fate of MTN and ETM in soil-groundwater systems at environmentally relevant concentrations.

Continuous and multicyclic sorption-based atmospheric water harvesting with heat recovery in arid climate

Nowadays, two-thirds of the global population are grappling with water scarcity. Sorption-based water harvesting (SAWH), which does not depend on conventional water sources and provides decentralized clean water, is steadily gaining popularity. However, the contradiction between the low daily water production in arid climates and the high energy consumption of large-scale devices has become a pivotal limitation for efficient water harvesting. Here, we report a multicyclic SAWH device with heat recovery equipped with 3 sorbent beds that alternatively desorb in automatic switching mode to achieve all-day continuous water harvesting. Furthermore, based on the rapid sorption and desorption kinetics of the adsorbent in the initial stages, employing a rapid-cycling operation strategy contributes to realize an outstanding water productivity of 8.07 kg day−1 and 0.21 kg kgsorbent−1 day−1 under practical arid conditions (15 °C/25 % RH). Besides, the apparatus equipped with heat regenerator showed a significant decrease in energy consumption from 12.17 kWh to 10.65 kWh during a desorption cycle (4 h). Moreover, a hybrid desorption mode driven by a combination of solar collector and electric heater is demonstrated in an island. This SAWH system is anticipated to provide a promising approach for large-scale efficient water harvesting in all-day arid regions (RH<35 %).

In-situ activation of persulfate by emplaced magnetite nanoparticles for degradation of 1,2-dichloroethane in porous media

In this study, column experiments were conducted to explore on the method of emplacement of magnetite nanoparticles (MNPs) for in situ activation of persulfate (PS) in sand porous media to degrade 1,2-dichloroethane (DCA), a typical recalcitrant chlorinated compound. Different molar ratios between PS and DCA (0:1, 2:1, 5:1 and 20:1) and mass contents of MNPs in the sand (0%, 1.9% and 5.4%) were tested. In the absence of MNPs, degradation of DCA was negligible for a hydraulic retention time of 7 h. Presence of MNPs at the content of 1.9% enhanced degradation of DCA and the highest removal efficiency (34.2%) was observed at the PS-to-DCA molar ratio of 5:1. At the MNPs content of 5.4%, increase of the PS-to-DCA molar ratio from 2:1 to 20:1 lead to not only increase in DCA removal efficiency but also substantial enhancement in chloride production, indicating that high PS concentration could cause significant degradation of the Cl-containing intermediates. In contrast to MNPs, Fe3O4 solids with much larger size (∼1 μm) were much less effective in activating PS for DCA removal even at a significantly higher content in the medium. The transport data could be well fitted by the one-site chemical nonequilibrium model, which showed kinetic DCA sorption to the MNPs as a key process for the transport. In the long-term injection experiment, a stable and significant removal of DCA (∼50%) was observed for 254 days at the MNP content of 1.9 %. The results of this study show the potential of MNPs as a sustainable PS activator in injection-based in situ chemical oxidation for groundwater remediation.

INVESTIGATION OF THE EFFICIENCY OF RHENIUM ION SORPTION USING ION-EXCHANGE RESINS POLYACRYLIC ACID: POLY-4-VINYLPYRIDINE IN VARIOUS RATIOS

This study is devoted to the study of the efficiency of sorption of rhenium ions using ion-exchange resins containing polyacrylic acid (PAK) and poly-4-vinylpyridine (P4VP) in various composition ratios. Goals and objectives. To investigate synthesized resins with different ratios of PAK:P4VP and to study their sorption capacity, kinetics and selectivity with respect to rhenium ions. Methods. Thanks to a comprehensive experimental analysis, including periodic sorption experiments and characterization methods such as spectrophotometry and atomic emission spectroscopy, the effect of resin composition on sorption efficiency was clarified during the study. Results and discussion. Optimal ratios have been determined to ensure maximum efficiency of rhenium ion removal. In addition, the study examines the main mechanisms governing sorption properties, with an emphasis on the relationship between resin composition, surface chemical composition and ion interaction. Conclusion. The results obtained contribute not only to the development of special ion-exchange materials for the effective extraction and purification of rhenium, but also contribute to a deeper understanding of ion sorption processes. This research has important implications for rhenium-dependent industries, offering strategies for solving problems related to its extraction, purification and use.

Kinetics of Low Molecular Substances Sorption by the Polymer Mixtures

The sorption capacity of polymer blends was analyzed on the basis of absorption kinetics. The study was carried out in an adsorption-active medium with different degrees of deformation. Heptane and butanol were used as adsorption-active media. The influence of the chemical nature of the adsorbate on the sorption process was studied. The free volume fractions for each sample of the composition were calculated. The ability of materials to absorb different amounts of substances allows us to identify the behavior peculiarities of the interfacial regions of different chemical compositions.

Assessment of the calcium-silicate Polonite as a sorbent for thin-layer capping of metal contaminated sediment

Sediments contaminated with hazardous metals pose risks to humans and wildlife, yet viable management options are scarce. In a series of laboratory experiments, we characterized Polonite® – an activated calcium-silicate – as a novel sorbent for thin-layer capping of metal-contaminated sediments. We tested a fine-grained by-product from the Polonite production as a cheap and sustainable sorbent. First, Polonite was reacted with solutions of Cu, Pb, and Zn, and the surface chemistry of the Polonite was examined using, e.g., scanning electron microscopy to investigate metal sorption mechanisms. Batch experiments were conducted by adding Polonite to industrially contaminated harbor sediment to determine sorption kinetics and isotherms. Importantly, we measured if the Polonite could reduce metal bioavailability to sediment fauna by performing digestive fluid extraction (DFE). Finally, a cap placement technique was studied by applying a Polonite slurry in sedimentation columns.The results showed rapid metal sorption to Polonite via several mechanisms, including hydroxide and carbonate precipitation, and complexation with metal oxides on the Polonite surface. Isotherm data revealed that the sediment uptake capacity (Kf) for Cu, Pb, and Zn increased by a factor of 25, 21, and 14, respectively, after addition of 5% Polonite. The bioavailability of Cu, Pb, and Zn was reduced by 70%, 65%, and 54%, respectively, after a 25% Polonite addition. In conclusion, we propose that sediment treatment with low doses of the Polonite by-product can be a cheap, sustainable, and effective remediation method compared to other more intrusive methods such as dredging or conventional isolation capping.

Iota-carrageenan as a regenerating system for Eu3+ recovery: adsorption/desorption cycles

ABSTRACT Renewable and biodegradable polysaccharides attract attention as environmentally friendly adsorbents for the removal of heavy metals from wastewater. One such group, is carrageenan, of which were recently successfully employed to adsorb representative lanthanide and actinide ions. Herein, iota-carrageenan-based hydrogels were used to adsorb europium ions (Eu3+) from water solutions, followed by desorption of the ions from the hydrogel beads and recycling of the beads three times. It was found that sorption yields from a 500 mg/L Eu3+ ion solution with beads that were prepared with 1 or 2 wt/v% aqueous solution of iota-carrageenan with CaCl2 (0.5 M) reached maximum sorption yield of 50% and 65%, correspondingly, after 1 h. In addition, the sorption kinetics followed the pseudo second-order model controlled by chemisorption. Desorption yields in the first cycle using NaNO3 (1 M) with both preparations were 57% and 74%, respectively. The sorption yields increased during the second and third cycles and were efficient in the overall pH range. Cryo-SEM, SEM, SEM-EDS and TGA analyses verified the adsorption and desorption of Eu3+ ions to and from the iota beads and that the Ca2+ ions that initially crosslinked the hydrogel were replaced during the cycles by Eu3+ or Na+ ions. In addition, the beads were stable and easily reusable for several sorption/desorption cycles. Furthermore, after sorption, the beads were characterised by a porous structure, such that beads prepared with a 2 wt/v% aqueous solution of iota-carrageenan yielded a more porous, ordered structure, and after desorption, the bead textures became even more porous.

Hygroscopic ionogel for enhanced thermoelectric generation performance

Improving thermoelectric generators (TEGs) performance remains challenging in the context of energy crisis and thermal-pollution. Here, we present a strategy for thermal management and performance enhancement of TEGs by sustainable evaporative cooling utilizing highly hygroscopic and adhesive ionogels (PIGs). Rational swelling and poly-[2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (PDMAPS) chains with group interactions prevent lithium chloride (LiCl) and 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) leakage, while carbon nanotubes (CNTs) and MIL-101(Cr) optimize the evaporative cooling of PIGs. PIGs possess high sorption (252.72% at 25 °C, 90% RH for 12 h) and steady sorption-desorption kinetics. Meanwhile, PIGs exhibit high adhesion (130.89 N m−1) on TEGs. The evaporative cooling of PIGs enhances the temperature difference of TEGs. The potential of PIG-TEG is increased by three times at heat source temperatures of 50–80 °C, and the output power density stabilizes at ∼706.25 mW m−2 after heating at 50 °C for 1 h. Moreover, the PIG-TEG maintains stable output enhancement for prolonged time (over 24 h). Additionally, we integrate PIG-TEGs for the durable power supply of devices and design a movable model car, which utilizes waste heat for self-powering. PIGs realize effective thermoelectric output enhancement of TEGs, and provide ideas in clean energy conversion, wearable devices, and mobile power.

Encapsulation of Bamboosa vulgaris culms derived activated biochar into hierarchical permeable, phosphate rich and functionalized alginate aerogel composites and its contribution in U(VI) adsorption

In this study, a facile methodology was designed to encapsulate Bamboosa vulgaris culms derived activated biochar (BVC) in a variable mass ratio, into a three-dimensional hierarchical porous and permeable and amino-thiocarbamated alginate (TSC) to prepare hybrid biosorbents (BVC-MSA). These ultralight and lyophilized phosphate rich macroporous sorbents were rationally characterized through FTIR, XRD, BET, SEM-EDS, elemental mapping, XPS techniques and employed for efficient UO22+ adsorption from aqueous solutions. The phytic acid (PA) was found to be a suitable hydrophilic and phosphorylating agent for the TSC matrix through hydrogen-bonded crosslinking when employed in a correct mass ratio (1:3). The SEM-EDS and XPS analyses confirmed the UO22+ sorption onto BVC-MSA-3 (the most suitable composite with a BVC/TSC mass ratio of 30.0 % w/w) and provided evidence of heteroatom involvement in developing the physico-chemical interactions. The BCV-MSA-3 exhibited the best response as a sorbent during kinetics/sorption process, therefore, it was selected to study the equilibrium sorption studies. The BCV-MSA-3 removal efficiency increased from 12.1 to 94.2 % using 0.2 to 1.8 g/L sorbent dose at pH (4.5). The mentioned sorbent displayed a significant maximum sorption capacity qm (309.55 mg/g at 35 °C) calculated through the best-fitted Langmuir and Temkin models (R2 ≈ 0.99). The sorption kinetics followed the pseudo-second-order (PSORE) model and exhibited fast sorption rate teq (180 min). Thermodynamic parameters clarified that the sorption process is feasible ΔGo (−25.3 to −27.6 kJ/mol kJ/mol), endothermic ΔHo (27.17 kJ/mol), and proceeds with a positive entropy (0.176 kJ/mol.K). The study shows that BCV-MSA-3 could be an alternative and auspicious sorbent for uranium removal from aqueous solution.

Improving sample preparation by biochar-coated sampling tubes: proof-of-concept extraction of sex hormones from real waters

This work showcases a novel application of biochar for analytical sample treatment. The carbonaceous material, obtained by pyrolysis of orange peel waste (550°C) without any post-synthesis treatment or functionalization, was thoroughly characterized and easily immobilized on the inner wall of sampling tubes in order to perform a sort of “in-vial” solid-phase extraction (SPE). The as-obtained device was tested for the extraction of seven sexual steroids, as probe water pollutants, from tap, lake, river water and wastewater treatment plant effluent samples spiked with 0.2-5 µg L−1 of each compound. The sorption kinetics profiles showed quantitative uptake from the sample (25 mL) in 20 min contact time, followed by complete elution in pure ethanol (2 mL, 15 min), thanks to the proper balance between sorption affinity and ease of elution. Under the selected conditions, recovery was in the range 60-123 %, with good inter-day precision (RSD 10-18 %, n=3). As evidence of the excellent reproducibility, an overall RSD below 15 % was observed from inter-day inter-batch recovery tests on three individually prepared sampling tubes. The procedure, carried out on a roller mixer, allows 10 samples to be extracted simultaneously, improving the sample throughput. Moreover, reusability tests showed that the same device maintains its efficiency for 10 consecutive sorption/desorption cycles. The greenness assessment, carried out by two dedicated software, further supported the sustainability of this biochar-based sample preparation as an alternative SPE.

A novel membrane-based absorber for sorption heat transformers: A comparative experimental study of a thin-film absorbent and salt-impregnated adsorbents

The present study proposes a novel membrane-based sorber bed with stationary solution film for oscillatory sorption heat transformers. A custom-built gravimetric large pressure jump setup is used to experimentally compare the performance of the novel membrane-based sorber bed with a Lithium Bromide/Silica gel solid composite sorbent synthesized using the salt-impregnation method. It is shown that the current membrane-based sorber bed provides up to about four times the specific cooling power and more than twice the cooling power density of solid sorbents, demonstrating the capability of the present sorber bed as a promising alternative to solid sorbents. The specific cooling power, cooling power density, and energy storage density of about 2.8 kW/kg, 470 kW/m3, and 269 MJ/m3 are experimentally obtained, respectively. According to experimental results, it is observed that the film thickness plays a significant role in sorption dynamics, while the effect of membrane mass transfer resistance on sorption dynamics is less than 10%. In addition, the present membrane-based sorber bed is analytically modeled, and the results are validated with present experimental data. The present analytical model is also used to investigate the effects of design parameters on the performance metrics.

Analysis of Courie-GAB-Peleg Models and Neural Networks in Jelly Candy by Corn Starch: Drying Kinetic and Moisture Sorption Isotherms

Analysis of Courie-GAB-Peleg Models and Neural Networks in Jelly Candy by Corn Starch: Drying Kinetic and Moisture Sorption Isotherms

New porous adsorbents based on natural polymers for treatment of motor oil contaminated wastewaters

AbstractThis study aims to develop efficient adsorptive materials for retaining used 5w40 motor oil using xanthan (XG), xanthan esterified with acrylic acid (XGAC), Lignoboost lignin (LB), and LB esterified with oleic and stearic acids. The adsorption capacities of these materials were systematically evaluated, revealing a hierarchical efficacy with XG exhibiting the highest performance (60.16 g/g), followed by XGAC/LB (59.92 g/g) and XGAC (55.79 g/g). These capacities were correlated with the materials' surface area and morphology. Additionally, accelerated weathering studies assessed the degradation process of the adsorptive materials over time, revealing that all of them undergo significant structural changes, which suggests potential pathways for environmentally friendly disposal. Kinetic studies indicated that the experimental data fit well with the pseudo‐second‐order (PSO) model. The high correlation coefficient values for the PSO model (0.9318–0.9998) confirmed its suitability for describing the kinetics of oil sorption. FTIR spectra of the used motor oil‐loaded materials confirmed the physical nature of the adsorption process, involving interactions such as hydrogen bonding, van der Waals forces, and π–π interactions. SEM analysis demonstrated that materials with larger pore sizes showed less efficient oil adsorption despite having high porosity, highlighting the importance of optimal pore size distribution for effective adsorption.

Ensemble surrogate modeling of advective-dispersive transport with intraparticle diffusion model for column-leaching test

Column-leaching tests are a common approach for assessing the leaching behavior and resulting environmental risks of contaminated soils and waste materials, which are frequently reused for various construction purposes. The observed breakthrough curves of the contaminants are influenced by the complex dynamics of solute transport and kinetic inter-phase mass transfer. Disentangling these interactions necessitates numerical models. However, inverse modeling and sensitivity analysis can be time-consuming, especially when sorption kinetics are explicitly described by intraparticle diffusion, which requires discretizing the domain both in the flow direction along the column axis and inside the grains. To circumvent the need for such computationally intensive models, we have developed two different ensemble surrogate models. These models employ two separate ensemble methods: random forest stacking and inverse-distance weighted interpolation. Each method is applied to base surrogate models that cover different parts of the parameter space. The base surrogate models use the method of Extremely randomized Trees (ExtraTrees). The defined parameter range is based on the German standard for column-leaching tests. To optimize the base surrogate models, we utilized adaptive-sampling methods based on three distinct infill criteria: maximizing the expected improvement, staying within a certain Mahalanobis distance to the best estimate (both for exploitation), and maximizing the standard deviation (for exploration). The ensemble surrogate model demonstrates excellent performance in emulating the behavior of the original numerical model, with a relative root mean squared error of 0.09. We applied our proposed ensemble surrogate model to estimate the complete posterior parameter distribution using Simulation-Based Inference, specifically Neural Posterior Estimation, to determine the full parameter distribution conditioned on copper-leaching data from two different soils. Samples drawn from the posterior distribution align perfectly with the observed data for both the surrogate and original models.

Performance evaluation and sensitivity analysis of polyethyleneimine-based sorbent in a circulating fluidized bed carbon dioxide capture unit

Greenhouse gases, particularly carbon dioxide, have increased the Earth’s average temperature by 1 °C, which has resulted in significant consequences for human life. To prevent further global warming and maintain a stable lifespan, it is imperative to achieve carbon neutrality. Post-combustion capture using an amine-based aqueous solvent is an advanced technology that has gained attention, but there are challenges such as corrosion, environmental impact, and energy consumption associated with it. This study aims to evaluate the performance of a polyethyleneimine-based sorbent in a circulating fluidized bed carbon dioxide capture unit and to determine the optimal operating conditions through sensitivity analysis. Various variables, including carbon dioxide concentration, water vapor content, desorber temperature, and sorbent residence time, were analyzed. The unit was continuously operated for 128 h even under challenging conditions with higher oxygen concentrations than the actual flue gases, and sorbent degradation was negligible. The results showed a 55 % carbon dioxide removal efficiency, a dynamic sorption capacity of 0.041 g-CO2/g-sorbent, and a regeneration heat energy of 4.2 GJ/tCO2. Sensitivity analysis revealed that there was minimal improvement even with changes in the absorber structure and physical properties of the sorbent. Only an increase in the sorbent reaction rate had a significant effect. If the reaction rate were to double, the carbon dioxide removal efficiency would reach 90 %, with a dynamic sorption capacity of 0.068 g-CO2/g-sorbent and regeneration heat energy of 2.9 GJ/tCO2.

Enhanced continuous atmospheric water harvesting with scalable hygroscopic gel driven by natural sunlight and wind

Sorption-based atmospheric water harvesting (SAWH) has received unprecedented attention as a future water and energy platform. However, the water productivity of SAWH systems is still constrained by the slow sorption kinetics at material and component levels and inefficient condensation. Here, we report a facile method to prepare hygroscopic interconnected porous gel (HIPG) with fast sorption-desorption kinetics, high scalability and stability, and strong adhesion property for highly efficient SAWH. We further design a solar-wind coupling driven SAWH device with collaborative heat and mass enhancement achieving continuous water production. Concentrated sunlight contributes to enhancing the desorption and condensation synergistically, and natural wind is introduced to drive the device operation and improve the sorption kinetics. The device demonstrated record high working performance of 14.9 Lwater m−2 day−1 and thermal efficiency of 25.7% in indoor experiments and 3.5–8.9 Lwater m−2 day−1 in outdoor experiments by solar concentration without any other energy consumption. This work provides an up-and-coming pathway to realize highly efficient and sustainable clean water supply for off-grid and arid regions.

Ternary composite of polyacrylamide-chitosan-montmorillonite: Characterization and adsorptive features for thorium and BSA

The aim of this study was to prepare a hydrogel composite of chitosan and montmorillonite entrapped in PAAm (PAAmChMt) and to investigate its adsorption properties for Th4+ and bovine serum albumin (BSA). The structural characteristics of PAAmChMt were determined by a number of methods including FT-IR, XRD, SEM-EDX, TGA, BET-porosity analysis. The parameters defining adsorptive properties were consolidated by inspection of adsorption dependence on pH, concentration, kinetics, thermodynamics, and ionic strength.The structural evaluation tests affirmed the formation of the composite in a ternary combination. The isotherms acquired from the adsorption dependency on concentration of Th4+ and BSA were Type-I of IUPAC classification pointing out the high affinity of Th4+ and BSA to PAAmChMt. The concordance of experimentally obtained isotherms with the considered adsorption models was significant for both species. The magnitude of adsorption energy strengthened that the physicochemical nature of the sorption of Th4+ or BSA was Coulomb electrostatic interactions.The enthalpy and entropy changes were ΔH>0 and ΔS>0 for Th4+ and BSA sorption on PAAmChMt. This indicated that the Gibbs free enthalpy change was ΔG<0, i.e. the adsorption process was spontaneous. The coherence of the sorption kinetics with the first-order model was established by the Langmuir kinetics of Liu and Shen, after finding its interesting coherence with both pseudo-first/second-order models.

Unveiling the water sorption kinetics, thermodynamics, and air dehumidification performance of sustainably synthesized metal–organic frameworks

This study focuses on the feasibility of sustainably synthesized MIL-100(Fe) as an alternative to conventional desiccants, such as silica gel and zeolites, which have low adsorption capacity and poor thermal characteristics for air dehumidification. MIL-100(Fe), a metal–organic framework, shows promise due to its excellent adsorption and customizable thermal properties. However, its synthesis typically involves toxic materials and high temperature/pressure conditions, which restrict its bulk production for large-scale applications. This study aims to explore sustainable synthesis methods for MIL-100(Fe) using non-toxic materials and milder reaction conditions and investigate its material characteristics and dehumidification performance. Experimental analyses are carried out to measure adsorption isotherms, kinetics, sorption heat, activation energy, and cyclic stability, and numerical simulations are conducted in COMSOL Multiphysics platform to estimate dehumidification performance. The test results demonstrate that MIL-100(Fe) has a higher water adsorption capacity compared to silica gel, with a unique stepwise adsorption into its two types of mesoporous cages. Increased temperatures cause the adsorption and desorption isotherms to shift towards higher relative humidity levels. The heat of water adsorption and desorption ranges between 2630–2906 kJ/kg and 2763–2848 kJ/kg, respectively. MIL-100(Fe) demonstrates high stability and no significant loss in water uptake capacity. The simulated performance indicate that MIL–100(Fe) has superior reaction rates and is 82 % more effective than the silica gel rotary wheel dehumidifiers.