Sorption Kinetics Research Articles

Effect of Ion-Exchanger Monoporosity in the Kinetics of Oxygen Sorption by Silver-Containing Nanocomposites

The results of a study of the kinetics of oxygen sorption from water by silver-containing nanocomposites synthesized on the base of macroporous ion exchangers with different pore sizes are presented. In the case of the Lewatit K 2620 ion exchanger, the pore size was fixed (41 nm), and for KU-23, it varied in the range from 10 to 100 nm. The nanocomposite materials Ag0⸱KU-23 and Ag0⸱Lewatit K 2620 were prepared by chemical precipitation. Using the different physicochemical methods, it was found that due to the monoporosity of the ion exchanger, the average size of the silver particles in the Ag0⸱Lewatit K 2620 nanocomposite is smaller than for KU-23. This effect contributes to the intensification of oxygen absorption and is proved by the results of studying the rate and degree of oxygen sorption by nanocomposites in the entire studied range of their capacity on metal. On the other hand, the polyporosity of the KU-23 ion exchanger, due to its better diffusion permeability, contributes to the more uniform distribution of silver over the volume of nanocomposite grains and ensures the steady state of the sorption process. Based on the presented experimental results, the synthesized silver-containing nanocomposites can be recommended as multifunctional materials with bactericidal action and catalytic effect for different industrial applications, including the deep removal of dissolved oxygen in the production of ultrapure water for energetics and microelectronics.

Innovative microkinetic modelling-supported structure–activity analysis of Ni/ZSM-5 during vapor-phase hydrogenation of levulinic acid

The study examines Ni/ZSM-5 catalysts in vapor phase hydrogenation of levulinic acid (LA) under continuous flow conditions (ambient pressure, 210–250 °C). Advanced characterization revealed the interplay between Al and Ni. This was further reinforced by new approach of microkinetic modeling, which demonstrates a pioneering work on mathematical description of pulse H2 sorption, TPD kinetics, DRIFT-supported determination of sorption energy barriers and (de)sorption kinetics. The Ni/ZSM-5 (3.7 wt.% Ni, Si/Al = 28) emerged as the optimal choice for obtaining γ-valerolactone (GVL) as the desired product. Al-rich catalysts with high acid site amounts and low metallic Ni active site concentrations favored esterification, reducing hydrogenation activity, and impeding further hydrogenation of GVL to pentanoic/valeric acid (PA). To enhance PA formation, Ni/ZSM-5 (4 wt.% Ni, Si/Al = 750) with a high Si/Al ratio, was identified as crucial. The combination of described experiments and modelling is demonstrated beneficial for insightful investigation of the structure–activity relationship of Ni/ZSM-5 or any other mono/bi-functional catalysts.

Benefits and limits of biological nitrification inhibitors for plant nitrogen uptake and the environment

Plant growth and high yields are secured by intensive use of nitrogen (N) fertilizer, which, however, pollutes the environment, especially when N is in the form of nitrate. Ammonium is oxidized to nitrate by nitrifiers, but roots can release biological nitrification inhibitors (BNIs). Under what conditions does root-exudation of BNIs facilitate nitrogen N uptake and reduce pollution by N loss to the environment? We modeled the spatial–temporal dynamics of nitrifiers, ammonium, nitrate, and BNIs around a root and simulated root N uptake and net rhizosphere N loss over the plant’s life cycle. We determined the sensitivity of N uptake and loss to variations in the parameter values, testing a broad range of soil–plant-microbial conditions, including concentrations, diffusion, sorption, nitrification, population growth, and uptake kinetics. An increase in BNI exudation reduces net N loss and, under most conditions, increases plant N uptake. BNIs decrease uptake in the case of (1) low ammonium concentrations, (2) high ammonium adsorption to the soil, (3) rapid nitrate- or slow ammonium uptake by the plant, and (4) a slowly growing or (5) fast-declining nitrifier population. Bactericidal inhibitors facilitate uptake more than bacteriostatic ones. Some nitrification, however, is necessary to maximize uptake by both ammonium and nitrate transporter systems. An increase in BNI exudation should be co-selected with improved ammonium uptake. BNIs can reduce N uptake, which may explain why not all species exude BNIs but have a generally positive effect on the environment by increasing rhizosphere N retention.

Bio‐based macroporous polymer sorbents: Synthesis, physicochemical properties and sorption kinetics

AbstractMacroporous polymeric sorbents were synthesized via high internal phase emulsion (HIPE) templating. For this aim, water‐in‐oil (w/o) HIPEs were prepared with 80 vol.% of aqueous internal phase whereas plant‐based β‐myrcene (My) and D‐limonene (Lim) were used as renewable building blocks in the continuous oil phase. Moreover, biocompatible ethylene glycol dimetacrylate (EGDMA) was also added as a crosslinker comonomer. By varying the total volume fraction of My and Lim in the continuous phase composition between 90% and 50%, 14 different HIPE formulations were prepared. After polymerization of HIPE templates 28 different sorbents were obtained depending on the purification procedure (extraction & drying under vacuum or freeze drying). The effect of terpene composition in the obtained sorbents was investigated in terms of cross‐link density (υ), the molecular weight (Mc) and pore morphology. In this context, chemical structures and pore morphologies were characterized by FTIR spectroscopy and SEM analysis, respectively. The Brunauer‐Emmet‐Teller (BET) specific surface area was also measured to determine the relationship between pore morphology and surface area. Based on the characterization results, two sorbents were selected as model for sorption tests. Thereafter, solvent sorption tests were performed by immersing sorbents in either hexane, dichloromethane, deionized water, seawater, solvent/water mixture, or solvent/seawater mixture to determine maximum sorption capacities and determine reusability of the sorbents. Moreover, experimental data was fitted to pseudo‐first order and pseudo second order kinetic models, as well as Freundlich and Langmuir isotherms. In the end, it was found that varying My and Lim ratio is the key parameter of controlling pore morphology and physicochemical properties. Moreover, it was shown that resulting sorbents can be efficiently used in oil/water separation processes repeatedly for several cycles.

Comparative assessment of activated carbon and anion exchange resin for short- and long-chain per- and poly-fluoroalkyl substances sorption: Insight into performance and mechanism

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants that have adverse effects on human health. Even though numerous studies have evaluated the performance and sorption mechanisms of activated carbon and anion exchange resins for PFAS removal, a comparative study of the sorbents has not been reported thus far. In this study, we compared the sorption performance, selectivity, reusability, and sorption mechanisms of pulverized activated carbon (PAC) and a commercial anion exchange resin, A520E, for the removal of two short-chain PFAS [perfluorobutanoic acid (PFBA) and potassium nonafluoro-1-butanesulfonate (PFBS)] and two long-chain PFAS [pentadecafluorooctanic acid (PFOA) and perfluorooctane sulfonate (PFOS)] from water samples. Both showed good removal efficiencies at environmentally relevant concentrations. However, at higher concentrations, A520E exhibited higher sorption than PAC. Moreover, PAC demonstrated faster sorption kinetics (<5 min) owing to its lower Biot number, indicating the influence of both intraparticle and external diffusion. In contrast, A520E primarily involves intraparticle diffusion, particularly for short-chain PFAS, resulting in a slower sorption rate (48 h). Notably, the PFAS sorption efficiencies of PAC and A520E decreased in real-field water, especially PFBA removal by PAC. A520E demonstrated higher regeneration ability than PAC. Our results highlight the importance of sorbent selection for the removal of PFAS compounds from contaminated water and could promote the development of effective and sustainable PFAS removal strategies.

Rational Design of Pectin-Chitosan Polyelectrolyte Nanoparticles for Enhanced Temozolomide Delivery in Brain Tumor Therapy.

Conventional chemotherapeutic approaches currently used for brain tumor treatment have low efficiency in targeted drug delivery and often have non-target toxicity. Development of stable and effective drug delivery vehicles for the most incurable diseases is one of the urgent biomedical challenges. We have developed polymer nanoparticles (NPs) with improved temozolomide (TMZ) delivery for promising brain tumor therapy, performing a rational design of polyelectrolyte complexes of oppositely charged polysaccharides of cationic chitosan and anionic pectin. The NPs' diameter (30 to 330 nm) and zeta-potential (-29 to 73 mV) varied according to the initial mass ratios of the biopolymers. The evaluation of nanomechanical parameters of native NPs demonstrated changes in Young's modulus from 58 to 234 kPa and adhesion from -0.3 to -3.57 pN. Possible mechanisms of NPs' formation preliminary based on ionic interactions between ionogenic functional groups were proposed by IR spectroscopy and dynamic rheology. The study of the parameters and kinetics of TMZ sorption made it possible to identify compounds that most effectively immobilize and release the active substance in model liquids that simulate the internal environment of the body. A polyelectrolyte carrier based on an equal ratio of pectin-chitosan (0.1% by weight) was selected as the most effective for the delivery of TMZ among a series of obtained NPs, which indicates a promising approach to the treatment of brain tumors.

Synthesis of Sulfur-Grafted Chitosan Biopolymers and Improvement to Their Sorption of Silver Ions from Different Aqueous Solutions

A functionalized chitosan thiourea composite (CH-TU) was successfully synthesized using formaldehyde as a crosslinking agent for enhancing silver recovery from different aqueous solutions. Comparison sorption studies with a non-functionalized composite (CH-F) as a reference material were conducted. Grafting led to an improvement in the sorption performances, i.e., 0.763 mmol Ag g−1 for CH-F vs. 2.125 mmol Ag g−1 for CH-TU. The pseudo-first-order rate equation (PFORE) was fitted to the sorption kinetics at saturation times of 40 and 30 min for CH-F and CH-TU, respectively, while the sorption isotherms were fitted with Langmuir and Sips equations for both sorbents. Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), nitrogen sorption–desorption isotherms (BET-surface area), elemental analysis, thermogravimetric analysis (TGA) and pH of the zero charge (pHpzc) were used to characterize and investigate the sorption mechanism. Sorption was performed three times to check the reproducibility, while the sorption performances were stable over 20 cycles, with a limited decrease in performance (5 and 3% for CH-F and CH-TU, respectively). Nitric acid solution (0.3 M) was efficient for desorbing the adsorbed metal ions. The grafted sorbent with thiourea is considered as a promising tool for recovering Ag(I) from acidic waste leachate derived from waste spent films.

A microwave-regenerable multi-walled carbon nanotube/polyaniline/Fe3O4 ternary nanocomposite for quantifiable sorption of cationic and anionic dyes

The coexistence of toxic dyestuffs in the aquatic environment requires the urgent development of a multifunctional sorbent for their efficient sequestration from aqueous solutions. To achieve this objective, a ternary nanocomposite consisting of an amphoteric, multi-walled, carbon nanotube/polyaniline/magnetite (MWCNTs/PANI/Fe3O4) was successfully synthesized through the co-precipitation of magnetite (Fe3O4) onto the surface of a pre-existing binary composite of MWCNTs/PANI. The structural and morphological features of MWCNTs/PANI/Fe3O4 were scanned using a variety of analysis methods: Fourier transform infrared spectroscopy; both scanning and transmission electron microscopies; energy-dispersive X-ray analysis; thermogravimetric analysis. The capacity of MWCNTs/PANI/Fe3O4 to adsorb cationic dye (Methylene blue, MB), and anionic dye (Congo red, CR) were discerned inclusively under variable operational parameters. The sorption processes of both MB and CR dyes onto MWCNTs/PANI/Fe3O4 were pH-dependent. The sorption process of both dyes onto MWCNTs/PANI/Fe3O4 was reported to fit with the Langmuir model, while the sorption kinetics fitted with the pseudo-second-order kinetic model. The prepared MWCNTs/PANI/Fe3O4 exhibited satisfactory sorption capacities of 142.85 mg g−1 (initial solution pH (pH0): 2.94) and 166.66 mg g−1 (pH0 = 10.03) of the CR and MB dyes, respectively. Dye adsorption followed the monolayer chemisorption phenomenon. The sorption process was exothermic. The application of microwave irradiation caused effective regeneration, and this finding confirmed the renewability of the composite for at least 4 successive sorption/desorption cycles. Using MWCNTs/PANI/Fe3O4 ternary nanocomposite in dye removal looks promising, as its high adsorption capacity, magnetic properties, and renewability offer an efficient, sustainable, and easily recoverable solution for removing dyes from wastewater.

Comprehensive analysis of water vapor sorption kinetics and mechanisms using biosorbent pellets from canola meal and oat hull

Agricultural residues, specifically canola meal (CM) and oat hull (OH), have been innovatively utilized to develop biosorbents for sorbing water vapor from the air. These biomaterials are comprised of hydrophilic functional groups that effectively perform air dehydration. Air, being non-polar, was used as a model gas in this study to simulate gas dehydration. In the current research, these materials were formed into pellets to produce high-quality biosorbents with controlled size, shape, and enhanced moisture uptake capacity. CM (309.48 mg/g) and OH (233.07 mg/g) pellets had higher or comparable water sorption capacities than commercialized adsorbents used for drying gases. The mixed-order kinetic model described the sorption process well and identified both mass transfer and sorption on active site steps (R 2 > 0.991 and χ 2 < 16.0). Regarding the OH pellet, sorption on active sites was the predominant kinetic mechanism at the beginning, followed by intraparticle diffusion until equilibrium. However, sorption on CM pellets was delayed at 4.2 min at the initial stage, owing to the external mass transfer resistance; then, intraparticle diffusion controlled the process until equilibrium. Adding sodium lignosulfonate (LSNa) lowered the initial sorption rate but enhanced the water uptake and strength of pellets. The addition of LSNa resulted in a 25% and 14% increase in the water uptake capacity of oat hull and canola meal pellets, respectively; conversely, it also caused an increase in the delay time for sorption on CM pellets at the beginning of the process, extending it to 9.50 min.

Mercury Accumulation Pathways in a Model Marine Microalgae: Sorption, Uptake, and Partition Kinetics.

The accumulation of dissolved mercury (Hg) by phytoplankton is the largest concentration step along aquatic food chains. However, the cell uptake mechanisms remain unclear. In this study, the marine haptophyteTisochrysis lutea, a model phytoplankton species, was examined for its interactions with picomolar levels of dissolved inorganic divalent Hg (iHg) and monomethyl Hg (MMHg). For both these Hg species, the study observed their successive sorption and internalization over time, yielding Hg partition coefficients as well as sorption, uptake, and release rates. These results were integrated into a time-dependent, three-compartment model for marine cellular Hg accumulation that included exposure medium, phycosphere, and internalized mercury. Assuming equilibria and pseudo-first-order kinetics between compartments, this study obtained transfer rates of Hg between compartments. The results provide insight into the phycosphere as an intermediate compartment for Hg species accumulation and quantify its role in the internalization of Hg. Ultimately, the new model and its parametrization were successfully applied to literature data showing Hg cellular accumulation in different groups of marine phytoplankton, lending confidence in its robustness and potential contributions to help model the uptake of Hg in the aquatic food web.

Uncalcined Zn/Al Carbonate LDH and Its Calcined Counterpart for Treating the Wastewater Containing Anionic Congo Red Dye

In this investigation, Zn/Al carbonate layered double hydroxide (ZAC-LDH) and its derived material on calcination were synthesized for removing the anionic azo dye Congo red (CR) from wastewater. Numerous factors were methodically investigated, including temperature, adsorbent dosage, pH, starting Dye Concentration (DC), and contact time. The CR elimination percentage dropped as the initial DC increased from 25 mg/L to 100 mg/L at 30 °C for uncalcined LDH, and from 97.96% to 89.25% for calcined LDH. The pH analysis indicates that the highest level of dye removal was recorded within the acidic pH range through the electrostatic attraction mechanism. The sorption kinetics analysis results demonstrated that the pseudo-second-order kinetic model exhibited a stronger fit to both uncalcined LDH and CZA-LDH, with the maximum correlation coefficient value. The Van’t Hoff plots indicate the spontaneous nature of the physisorption process with a negative ΔG° (&lt;−20 kJ/mol), while the endothermic adsorption process exhibited a positive ΔH°. The X-ray diffraction of calcined LDH reveals a significant intercalation of CR dye molecules, both prior to and following adsorption, showcasing a distinctive memory effect. The Brunauer–Emmett–Teller (BET) gas sorption measurements were performed to support the mesoporous nature of ZAC-LDH and CZA-LDH. The FTIR spectrum confirms the interaction of dye molecules on the surface of uncalcined and calcined LDH. These findings emphasize the efficacy of both the synthesized LDHs in removing CR dye, with CZA-LDH demonstrating superior efficiency compared to uncalcined LDH in the context of CR removal from wastewater.

Relief effect of biochar on continuous cropping of tobacco through the reduction of p-hydroxybenzoic acid in soil

Biochar application to soil has proven to be an excellent approach for decreasing the concentration of auto-toxic compounds and promoting plant growth in continuous-cropping fields. However, the mechanisms underlying the action pathway among biochars, auto-toxic compounds and tobacco remain unknown. In this study, we conducted an experiment tracking the incidence rate of black rot and auto-toxic compounds for a 3-year continuous-cropping tobacco pot trial in response to biochar treatment intensity compared with that of non-biochar treatment. Biochar inhibited the incidence of black rot. Using ultra-high-performance liquid chromatography–mass spectrometry (UPLC‒MS/MS), we revealed that biochar can effectively decrease the concentration of p-hydroxybenzoic acid (PHA), which is associated with the incidence rate of black rot (R2 = 0.890, p < 0.05). The sorption kinetics and isotherm of PHA sorption on biochar indicate that the coexistence of heterogeneous and monolayer sorption plays an important role in the adsorption process. Using Molecular dynamics (MD), Density functional theory (DFT) and Independent gradient model (IGM) analyses, we provide evidence that van der Waals force (vdW), π–π bonds and H-bonds between biochar and PHAs are the dominant factors that affect adsorption capacity. Moreover, the molecular adsorption rate (Nbiochar: NPHAs = 1:4) was theoretically calculated. In contrast, biochar dramatically increased nutrient retention capacity and improved soil properties, further enhancing tobacco quality, including its agronomic and physiological traits. Therefore, we considered that biochar not only relieved continuous cropping but also improved soil properties suitable for tobacco growth. Together, we demonstrate that the action of biochar in continuously cropped soil improves soil traits and alleviates auto-toxic compound toxicity. These data contribute to the direction of modified biochar application to improve continuous-cropping soil.

The performance of iron-silicate-based biochar as a sorbent material towards 133Ba retention from radioactive liquid waste

Abstract The application of Phalaris seed peel (PSP) for the production of biochar involves the pyrolysis process in an N2 environment, resulting in the creation of a cost-effective sorbent. Two distinct modifications were conducted on the existing biochar (BC), employing just silicate (BC/SiO2) and in combination with iron-silicate (BC/SiO2/Fe). Several analytical methods were used to look at the modified biochar’s physical and chemical properties. These included scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis-differential thermal analysis (TGA-DTA), and surface area analysis. Based on the initial investigations, it has been revealed that the use of silica and iron as the second modification is a more suitable approach for effectively retaining 133Ba from liquid radioactive waste streams. The investigation of sorption kinetics and isotherms was conducted to enhance our understanding of the process. The Langmuir isotherm model demonstrates the most optimal correlation for sorption, yielding a maximum sorption capacity (Q max) of 31 mg/g. Furthermore, an evaluation was performed on the BC/SiO2/Fe sorbent material by subjecting it to a mixture of simulated radioactive liquid waste, which included 133Ba, 60Co, and 137Cs.The experimental results indicate that BC/SiO2/Fe exhibits a comparatively higher sorption capacity for 133Ba when compared to 60Co and 137Cs as competing ions.

Comparative Evaluation of Boron Sorption Dynamics on Zeolites in Irrigation Waters: An Isothermal Modeling Approach.

Efficient boron removal from irrigation waters is crucial for sustainable agriculture, as elevated levels of boron can be toxic to many plants, limiting growth and crop productivity. In this context, the present study investigated the sorption equilibrium of boron using zeolites in two types of aqueous matrices: a synthetic solution containing only boron and natural irrigation waters. Through the application of various isothermal sorption models (Langmuir, Freundlich, Sips, Toth, Jovanovic, Temkin, Dubinin-Radushkevich, and Redlich-Peterson), the efficacy of zeolite for boron removal under controlled and real conditions was evaluated. The results indicated a notable difference in sorption behavior between the two matrices, reflecting the complexity and heterogeneity of interactions in the boron-zeolite system. In the synthetic solution, the Freundlich model provided the best fit (R2 = 0.9917), suggesting heterogeneous and multilayer sorption, while the Sips model showed high efficacy in describing the sorption in both matrices, evidencing its capability to capture the complex nature of the interaction between boron and zeolite under different environmental conditions. However, in natural irrigation waters, the Jovanovic model demonstrated the most accurate fit (R2 = 0.999), highlighting the importance of physical interactions in boron sorption. These findings underscore the significant influence of the water matrix on the efficacy of zeolite as a boron removal agent, emphasizing the need to consider the specific composition of irrigation water in the design of removal treatments. Additionally, the results stress the importance of selecting the appropriate isothermal model to predict boron sorption behavior, which is crucial for developing effective and sustainable treatment strategies. This study provides a basis for optimizing boron removal in various agricultural and industrial applications, contributing to the design of more efficient and specific water treatment processes.

High-efficiency lanthanum-modified zeolite adsorbents for phosphorus control and algal suppression: Preparation, characterization and mechanistic insights

The use of lanthanum (La)-based materials for phosphate removal from water has received increasing attention. However, challenges remain to enhance phosphate (P) sorption capacities and remove P at low concentrations. In this study, lanthanum modified zeolite materials loaded with different lanthanum types were synthesized by hydrothermal method. Based upon preliminary screening of synthesized La-modified zeolite materials in terms of phosphate sorption capacity and La content, lanthanum chloride-modified zeolite (LZ) is chosen for further study. Specifically, for these materials, phosphate sorption kinetics and isotherm behavior, and solution matrix effects (solution pH, and ionic strength) are reported. The developed LZ has a high sorption capacity of 124.38 mg/g, which exceeds that of most La-based adsorbents currently available. P uptake by LZ was pH-dependent with the highest sorption capacities observed over a pH range of 3 ∼ 9. The presence of coexisting ions (Cl-, SO42-, HCO3–) does not significantly affect the adsorption capacity of LZ. In a real treated wastewater effluent with phosphate concentration of 1.92 mg/L and 0.155 mg/L, 0.1 g/L and 0.01 g/L of LZ efficiently reduced the phosphate concentration to below 0.01 mg P/L. Electrostatic attraction and inner-sphere complexation were identified as the sorption mechanisms of phosphate by LZ. The acute toxicity test confirms that the addition of LZ has no acute toxicity effect on aquatic organisms. However, LZ shows indirect and direct inhibitory effects on algae growth, which is beneficial for the control of eutrophic water. Moreover, the exhausted LZ can be easily regenerated with over 70 % adsorption capacity remained during five recycles. Overall, LZ shows great application potential, and this work provides new insights into the molecular-level mechanism of phosphate sequestration by LZ.

Highly porous metal-organic framework liquids and glasses via a solvent-assisted linker exchange strategy of ZIF-8

By combining the porosity of crystalline metal-organic frameworks (MOFs) with the unique processability of the liquid state, melt-quenched MOF glasses offer exciting opportunities for molecular separation. However, progress in this field is limited by two factors. Firstly, only very few MOFs melt at elevated temperatures and transform into stable glasses upon cooling the corresponding MOF liquid. Secondly, the MOF glasses obtained thus far feature only very small porosities and very small pore sizes. Here, we demonstrate solvent-assisted linker exchange (SALE) as a versatile method to prepare highly porous melt-quenched MOF glasses from the canonical ZIF-8. Two additional organic linkers are incorporated into the non-meltable ZIF-8, yielding high-entropy, linker-exchanged ZIF-8 derivatives undergoing crystal-to-liquid-to-glass phase transitions by thermal treatment. The ZIF-8 glasses demonstrate specific pore volumes of about 0.2 cm3g–1, adsorb large amounts of technologically relevant C3 and C4 hydrocarbons, and feature high kinetic sorption selectivities for the separation of propylene from propane.

Graphene oxide dots‐loaded chitin flask: A sustainable adsorbent for separating multiple dyes from water

AbstractThis research endeavors to comprehensively explore the sorption dynamics of dyes from aqueous solutions utilizing a graphene oxide‐chitin (GO‐chitin) biosorbent. The investigation systematically evaluates the influence of key parameters, including temperature, pH, duration of contact, and initial dye doses, on the sorption efficiency of the biosorbent. Results obtained indicated that at acidic pH range, the dye removal efficacy was more than 80% for methyl orange and Remazol Brilliant Blue. Maximum removal efficacy was achieved within the 30 min of adsorption studies. Notably, the study underscores the remarkable adsorption capacity of GO‐chitin, varies in the range of 75% and 95%, for all three dyes, positioning it as a highly promising material for the remediation of polluted aquatic environments. The adsorption follows pseudo‐second‐order kinetics and Freundlich isotherm. These findings contribute valuable insights into the potential application of GO‐chitin as an effective biosorbent in the context of wastewater treatment, emphasizing its role in addressing environmental challenges associated with dye contamination in aqueous systems.

Millisecond-resolved gas sorption kinetics and time-dependent diffusivity of coal

Millisecond-resolved gas sorption kinetics and time-dependent diffusivity of coal

The Preparation and Contact Drying Performance of Encapsulated Microspherical Composite Sorbents Based on Fly Ash Cenospheres.

Sorption technologies are essential for various industries because they provide product quality and process efficiency. New encapsulated microspherical composite sorbents have been developed for resource-saving contact drying of thermolabile materials, particularly grain and seeds of crops. Magnesium sulfate, known for its high water capacity, fast sorption kinetics, and easy regeneration, was used as an active moisture sorption component. To localize the active component, porous carriers with an accessible internal volume and a perforated glass-crystalline shell were used. These carriers were created by acid etching of cenospheres with different structures isolated from fly ash. The amount of magnesium sulfate included in the internal volume of the microspherical carrier was 38 wt % for cenospheres with ring structures and 26 wt % for cenospheres with network structures. Studies of the moisture sorption properties of composite sorbents on wheat seeds have shown that after 4 h of contact drying the moisture content of wheat decreases from 22.5 to 14.9-15.5 wt %. Wheat seed germination after sorption drying was 95 ± 2%. The advantage of composite sorbents is the encapsulation of the desiccant in the inner volume of perforated cenospheres, which prevents its entrainment and contamination and provides easy separation and stable sorption capacity in several cycles.

Unified mechanistic understanding on CO2 sorption by Na-doped Li4SiO4: Experimental and DFT study

The addition of molten Na2CO3 can drastically accelerated the extremely slow sorption kinetics of Li4SiO4-based CO2 sorbents in the sorption enhanced reforming process. However, the lack of a unified consensus about the effect of doped Na2CO3 on the CO2 capture process, now delays the development of more-effective Li4SiO4 sorbents. Here, sorption tests, sturactural characterzations and periodic density functional theory calculations were combined to develop a better mechanistic understanding CO2 sorption on Na-doped Li4SiO4. The Na-doped Li4SiO4 exhibited a better CO2 capture performance than pure Li4SiO4 even below the melting point of any eutectic mixtures. Structural characterizations revealed that rather than generating physical favorable characteristics, the Na doping substituted at the Li site and created lithium–sodium orthosilicates (Li4-xNaxSiO4). Theoretical calculations agreeing with experimental results further demonstrated that Li4-xNaxSiO4 presented a weaker Na-O bond and generated more active phases (quasi Li2O groups) for larger sorption energies, more charge transfers and stronger CO32– bond formation, in turn providing more reactive sites for enhanced CO2 chemisorption as comparing with pure Li4SiO4. Finally, we propose a new and unified sorption mechanism independent of the traditional “melting layer” explanation.