Sorption Thermodynamics Research Articles

Hydrogen bonds between the oxygen-containing functional groups of biochar and organic contaminants significantly enhance sorption affinity

Sorption affinity is an essential parameter to immobilize contaminants, but the controlling structures of biochar with strong sorption affinity to organic compounds are unidentified, hindering targeted biochar modification. In the face of multiple types and structures of organic contaminants in the aquatic environment, it is urgent to prepare biochar which can remove a large number of contaminants by targeted biochar modification. This study compared the sorption and desorption of five different type organic contaminants on biochar and graphite to understand sorption affinity and to inform the structural regulation of biochar. The sorption capacity of organics on biochar was 3–7 times higher than graphite, and the desorption ratios of organics on biochar were approximately one-fourth of those on graphite. Hydrophobic areas and aromatic rings were confirmed to be low-energy sorption sites, and most pores were inaccessible. The stronger sorption affinity was thus attributed to the hydrogen bonds between biochar surface functional groups and organics. Furthermore, sorption capacity and desorption ratios correlated positively with calculated sorption thermodynamics and binding energies, aligning with theoretical models based on oxygen- and nitrogen-containing groups. Further verification experiments revealed that functionalized graphite with hydroxyl and carboxyl groups showed the most significantly increased sorption capacity and rate, and decreased desorption ratios, enhancing sorption affinity through hydrogen bonds. These findings offer valuable insights into biochar sorption affinity to organics and guide its structural regulation for organic pollution control in the aquatic environment

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.

Trivalent lanthanide sorption onto illite in the presence of carbonate: A study combining thermodynamic sorption modeling, time-resolved laser fluorescence spectroscopy, and parallel factor analysis

Formation of aqueous actinide complexes with dissolved inorganic carbon (DIC) in groundwater decreases the sorption of actinides onto clay minerals in a geological disposal environment. Hence, the effect of DIC on actinide sorption must be evaluated quantitatively. In this study, batch sorption experiments using Eu(III) and Sm(III) as the chemical analogs of trivalent actinides were performed to assess their sorption behavior onto illite in the presence of DIC. In the studied pH region between 8.4 and 11, the sorption was significantly lower in the presence of DIC, with the largest effect being observed at pH 9–10. The effect increased with increasing DIC from 10 to 50 mM. A thermodynamic sorption model (TSM) was used to evaluate the results of batch sorption experiments. The experimental results can only be predicted when ternary-surface complexes with carbonate ions are considered. Moreover, information on the chemical forms of sorbed Eu on illite was obtained via time-resolved laser fluorescence spectroscopy (TRLFS) measurements. Parallel factor analysis of TRLFS data indicated the presence of two chemical species of Eu. These chemical species exhibited pH dependence, which is consistent with that of the surface species predicted using the TSM. In the presence of DIC, the dominant chemical species showed a long fluorescence lifetime and was inferred to coordinate with carbonate ions, supporting the validity of the TSM.

Thermodynamics of sorption of drugs on chitosan: low- and high-concentration analysis

Thermodynamics of sorption of drugs on chitosan: low- and high-concentration analysis

Ultrafine CuO/graphene oxide cellulose nanocomposites with complementary framework for polycyclic aromatic hydrocarbon pollutants removal

Efficient and sustainable methods for eliminating polycyclic aromatic hydrocarbon pollutants (PAHPs) are in highly desired. Proven technologies involve physical and chemical reactions that absorb PAHPs, however they encounter formidable challenges. Here, a bottom-up refining-grain strategy is proposed to rationally design ultrafine CuO/graphene oxide-cellulose nanocomposites (LCelCCu) with a mirror-like for tetracycline (TC) to substantially improve the efficient of the purification process by active integrated-sorption. The LCelCCu captures TC with a higher affinity and lower energy demand, as determined by sorption kinetic, isotherms, thermodynamics, and infrared and X-ray Photoelectron Spectroscopy. The resulting material could achieve ultra-high sorption capacity (2775.23 mg/g), kinetic (1.2499 L g−1 h−1) and high selectivity (up to 99.9 %) for TC, nearly surpassing all recent adsorbents. This study simultaneously unveils the pioneering role of simultaneous multi-site match sorption and subsequent advanced oxidation synergistically, fundamentally enhancing understanding of the structure-activity-selectivity relationship and inspires more sustainable water purification applications and broader material design considerations.

Thermodynamics of solvent sorption by layers of carbon-chain polymers in damping rubber blankets

The paper addresses the study of the thermodynamic compatibility of carbon-chain polymer compositions of offset rubber blankets with low-molecular-weight liquids, paint solvents and care agents for rubber damping machine parts used in transport, mechanical engineering and printing industries. The Flory-Huggins parameters χ were determined by inverted gas chromatography and calculation performed using the mathematical model of sorption, and the correlation between χ obtained by these two independent methods was found. The excess thermodynamic characteristics of the studied systems G E, H E and S E were calculated to predict the compatibility of components in these systems. The relationship was found between χ that characterizes the thermodynamic quality of the solvent and the equilibrium swelling index of polymer networks.

Uranium capture from aqueous solution using palm-waste based activated carbon: sorption kinetics and equilibrium

Carbonaceous materials produced from agricultural waste (palm kernel shell) by pyrolysis can be a proper type of low-cost adsorbent for wide uses in radioactive effluent treatment. In this context, the as-produced bio-char (labeled as PBC) and its sub-driven sulfuric acid and zinc oxide activated carbons (labeled as PBC-SA, and PBC-Zn respectively) were employed as adsorbents for uranium sorption from aqueous solution. Various analytical techniques, including SEM (Scanning Electron Microscopy), EXD (X-ray Diffraction), BET (Brunauer–Emmett–Teller), FTIR (Fourier Transform Infrared Spectroscopy), and Zeta potential, provide insights into the material characteristics. Kinetic and isotherm investigations illuminated that the sorption process using the three sorbents is nicely fitted with Pseudo-second-order-kinetic and Langmuir isotherm models. The picked data display that the equilibrium time was 60 min, and the maximum sorption capacity was 9.89, 16.8, and 21.9 mg/g for PBC, PBC-SA, and PBC-Zn respectively, which reflects the highest affinity for zinc oxide, activated bio-char, among the three adsorbents, for uranium taking out from radioactive wastewater. Sorption thermodynamics declare that the sorption of U(VI) is an exothermic, spontaneous, and feasible process. About 92% of the uranium-loaded PBC-Zn sorbent was eluted using 1.0 M CH3COONa sodium ethanoate solution, and the sorbent demonstrated proper stability for 5 consecutive sorption/desorption cycles.

Thermodynamics of water vapor sorption of fiber-reinforced starch films

Thermodynamics of water vapor sorption of fiber-reinforced starch films

Kinetic and Thermodynamic Studies of Precious Metals Sorption on Impregnated Lewatit VP OC 1026 from Chloride Solutions.

Precious metals are used in many branches of industries. Due to their rarity and diminishing natural resources, more and more new methods are being sought to recover them from secondary sources, which can be electronic waste or spent car exhaust converters. This paper presents the research on the recovery of precious metals from chloride solutions using the Aliquat 336-impregnated Lewatit VP OC 1026 sorbent. The study used a warm impregnation method without toxic solvents, which is beneficial for the environment. The maximal sorption capacities obtained for model solutions in 0.1 M HCl were: 95.6 mg/g for gold, 38.2 mg/g for palladium, and 36.2 mg/g for platinum. There were studied: kinetics and thermodynamics of sorption, as well as amounts of the sorbent, effects of phase contact time and HCl concentration on the sorption of precious metals. Positive values of enthalpy change ΔH° validate that the process is endothermic. The research was also carried out on a real leaching solution obtained by digesting a spent catalytic converter, containing small amounts of platinum group metals. Desorption of precious metal ions was conducted using 1 M thiourea in 1 M hydrochloric acid. The obtained impregnated sorbent proved to be effective for sorption of Au(III), Pd(II), Pt(IV) ions.

Characterization of the Purified Ca-type Bentonil-WRK Montmorillonite and Its Sorption Thermodynamics With Cs(I) and Sr(II)

Characterization of the Purified Ca-type Bentonil-WRK Montmorillonite and Its Sorption Thermodynamics With Cs(I) and Sr(II)

Sorption Isotherms and Thermodynamic Characteristics of Gelatin Powder Extracted from Whitefish Skin: Mathematical Modeling Approach.

Moisture adsorption and desorption isotherms of gelatin extracted from whitefish skin powder (FSGP) at different temperatures across a wide range of water activity were determined along with their thermodynamic properties. Nine mathematical models were utilized for fitting the experimental data and simulating the adsorption and desorption behavior. The thermodynamic properties were determined and fitted to the experimental data. The results showed that Peleg and GAB models were the best fit for FSGP. The energies involved in the adsorption and desorption process of FSGP indicated a stronger dependence on equilibrium moisture content (Xe). When Xe decreased, there was a consistent trend of increasing thermodynamic properties. Both the moisture adsorption and desorption behaviors of FSGP were, therefore, non-spontaneous processes. Linear correlations between the changes in enthalpy and entropy for adsorption and desorption were observed, indicating the presence of enthalpy-entropy compensation for FSGP. For preserving FSGP quality, it should be stored with Xw ≤ 8 (gw/gdm, d.b.) at temperatures below 53 °C and an RH of 50% to avoid it becoming rubbery. These findings are crucial for providing insight into the optimal drying and storage conditions.

Modelling relative humidity and temperature effects on CO2 gas transport in polyetherimide

The aim of this work is to study the effect of relative humidity (RH) on CO2 gas transport in polyetherimide (PEI) membranes. The Non-Random Hydrogen Bonding model, extended to the case of non-equilibrium glassy polymers (NETGP-NRHB model), is used to interpret the sorption thermodynamics in glassy polymer/penetrant mixtures. Furthermore, a new diffusion model (namely NETGP-NRHB-DM), in the spirit of the Free Volume Theory, is used in combination with the NETGP-NRHB model to interpret the gas permeation. The parameters of the two models have been obtained partly from the literature and partly from a dedicated experimental campaign. The full set of parameters is used in a predictive manner to calculate the permeability coefficient of CO2 in PEI at different temperatures and relative humidity conditions. The model results are validated against a complete set of experimental data specifically carried out for the present investigation. The CO2 permeability predictions are satisfactory, but a slight deviation between the calculated results and the experimental data is observed when the average amount of water in the membrane is high, probably due to the onset of water clustering. In fact, the phenomenological expression of the mobility coefficient of NETGP-NRHB-DM is not properly suited to describe the complex picture involving different kind of water mers starting from the water clustering concentration onset.

Fate of atrazine in soybean (Glycine max L.) and corn (Zea mays L.) succession in Brazilian subtropical conditions

This work aimed to evaluate the distribution of atrazine via surface runoff, leaching, and retention in a Rhodic Ferralsol and to analyze the effect of a succession of corn and soybean crops in Brazilian subtropical edaphoclimatic conditions on the distribution of this herbicide. The mobility of atrazine was evaluated using a drainage lysimeter under conditions of intensely simulated precipitation, carried out 24 h and 48 h after a single herbicide application at 17 days after corn emergence. Surface runoff and leaching were sampled during the rainfall simulations at intervals of 5 min until completing 1 h. Corn foliar analyses were carried out to measure the residual amounts of atrazine. In addition, laboratory studies of sorption (equilibrium and thermodynamics) and dissipation were carried out to understand the dynamics of atrazine in the soil. Freundlich's non-linear isotherms presented an excellent fit in the description of atrazine sorption in a Rhodic Ferralsol. The high content of organic matter in the soil and the temperature variation directly influences the retention of atrazine in the soil. The half-life (t1/2) of atrazine in soil under controlled conditions indicates a non-persistent pesticide, with 14.44 days. However, the herbicide can persist in deep soil layers for more than 93 days after spraying. When high-intensity rainfall occurs 24 h after application, large proportions of atrazine are lost by runoff within the first 20 min of rain. At the same time, significantly inferior losses are observed when rainfall occurs 48 h after spraying. High-intensity rainfall within 24 h of atrazine application leads to substantial losses, causing an approximate 84% reduction in its concentration in corn leaves and a 94% reduction in soil. Conservationist agronomic practices that protect the soil, especially during the initial periods of corn cultivation, are essential to reduce atrazine losses by runoff or leaching. In addition, increasing the concentration of organic matter in the soil can be extremely promising in increasing the retention of this pesticide to soil colloids, preventing its loss in soils with a low content of clay minerals.

Thermodynamics of Sorption of Organic Compounds by Sorbents Based on Supramolecular Liquid Crystal HPFAB and β-Cyclodextrin Derivatives under Gas Chromatography Conditions

Thermodynamics of Sorption of Organic Compounds by Sorbents Based on Supramolecular Liquid Crystal HPFAB and β-Cyclodextrin Derivatives under Gas Chromatography Conditions

Biodegradation, Water Sorption Isotherms and Thermodynamic Properties of Extruded Packaging Composed of Cassava Starch with Tomato Peel

Biodegradation, Water Sorption Isotherms and Thermodynamic Properties of Extruded Packaging Composed of Cassava Starch with Tomato Peel

Thermodynamics of Sorption of Organic Compounds by Sorbents Based on Supramolecular Liquid Crystal HPFAB and β-Cyclodextrin Derivatives under Gas Chromatography Conditions

Using gas chromatography, we studied the influence of the nature of substituents in the β-cyclodextrin (CD) molecule on the sorption properties and the possibility of complex formation with the macrocycle of 26 organic compounds (hydrocarbons and alcohols) in binary sorbents based on the smectic–nematic supramolecular liquid crystal 4-(3-hydroxypropyloxy)-4'-formylazobenzene (HPOFAB) and four derivatives β-CD. It has been established that the nature of the substituents in the β-CD molecule significantly affects the manifestation of solvation interactions between LC and macrocyclic additive and, as a consequence, the mesomorphic, sorption, and selective properties of the studied composite sorbents.

Review of Thermodynamic Sorption Model for Radionuclides on Bentonite Clay

Review of Thermodynamic Sorption Model for Radionuclides on Bentonite Clay

A literature review on thermodynamic sorption models of radionuclides with some selected granitic minerals

The literature for radionuclide sorption on four common granitic minerals have been surveyed. Mainly, such studies were modelling using Thermodynamic Sorption Models were investigated. Although the studies give a far from concerted results, they agree on the necessity to model radionuclide uptake by granitic minerals with a combination of ion exchange and surface complexation reactions. For the sheet-silicates biotite and chlorite alkaline and alkaline earth mainly bind by ion exchange but there is also a clear pH effect for this, which shows the importance of protons competing with metal cations for the exchange sites. For multivalent metal cations, surface complexation is the model of choice since the binding to mineral surfaces seems to be strongly dependent on pH and to be little affected by an increase in ion strength. Anion sorption seems to be taking place also by surface complexation, where the sorption mainly takes place at low pH. For the feldspar minerals K-feldspar and plagioclase the sorption is also modelled by the two reaction mechanisms ion exchange and surface complexation. Surface complexation seems to be especially prevalent for the M(III) and M(VI) state, while ion exchange probably dominates M (II) uptake. Although the literature on these minerals is sparse, the studies show that also these minerals have considerable sorption capacity and must be considered if sorption onto granite is to be modelled from single mineral data. What is usually missing from these studies are more systematic variations in pH, ion strength and temperature. Instead, there is a certain overemphasis on the establishment of sorption isotherms.

Kinetics and Thermodynamics of Sorption of Methylene Blue Dye Onto Raw Groundnut Shell Biosorbent

Dyes are one of the hazardous chemicals found in wastewater produced by textile and allied industries that need to be removed from the wastewater before it is released into water bodies. The sorption efficiency of raw groundnut shell (RGS), an agricultural waste, was tested on methylene blue (MB) dye through a batch adsorption experiment. Physicochemical analysis of the RGS indicated good biosorbent properties. Fourier transform infrared (FTIR) spectroscopy analysis of the RGS revealed the presence of heterofunctional groups. The effect of various biosorption parameters such as initial dye concentration, contact time, and biosorbent dosage was systematically investigated. The quantity of MB adsorbed increased as the initial concentration and contact time increased and decreased with an increase in biosorbent dose. A maximum uptake capacity of 29.3 mg/g was recorded for 50 mg/L MB initial concentration. The equilibrium data from the batch adsorption experiments were fitted well into Freundlich isotherm and pseudo-second-order kinetic models. The results from this study indicate that RGS can serve as an alternative, low-cost, eco-friendly and efficient adsorbent for the removal of MB dye from wastewater.

Bamboo sawdust-derived high surface area activated carbon for remarkable removal of paracetamol from aqueous solution: sorption kinetics, isotherm, thermodynamics, and regeneration studies

Abstract Due to its widespread consumption, paracetamol (PCT) has emerged as one of the leading contaminants that pollute water. Herein, a PCT removal of 99.6% was achieved using chemically activated carbon (CAC), derived from bamboo sawdust using KOH/FeCl3 as an activating agent, at optimal conditions of PCT (20 mg/L), CAC (0.5 g/L), contact time (90 min), and pH (8). Kinetic study revealed that the PCT adsorption process followed the pseudo-second-order kinetic model (R2 = 0.99), indicating that chemical adsorption dominated the adsorption mechanism. On the other hand, isotherm experimental data were best described by the Langmuir (R2 = 0.98) and Freundlich (R2 = 0.96) models. CAC had a maximum Langmuir monolayer capacity of 188.67 mg/g at a PCT concentration of 120 mg/L. Moreover, the Redlich–Peterson model gave the best fit (R2 = 0.99) to the experimental data, confirming that PCT adsorption was monolayer adsorption onto the heterogeneous surface. Thermodynamically, the PCT adsorption was exothermic, spontaneous, and favorable. The reusability study depicted that CAC can be successfully reused for five consecutive adsorption–desorption cycles. Furthermore, the application of CAC to environmental samples showed interesting results. The overall adsorption study indicated that CAC could serve as a promising adsorbent for eliminating PCT from water.