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Expandable clay minerals play a pivotal role in the geological sequestration of greenhouse gases due to their contribution to storage capacity and caprock integrity. The charge-balancing cations in the interlayer space are known to influence carbon dioxide adsorption. The present study investigated the general adsorption behaviour and characteristics of montmorillonite towards CO2 adsorption at temperatures above critical point, typical to geological sequestration. Modelling on the excess isotherm and absolute isotherm was used to compare the variation of the adsorption behaviour of sodium, potassium and calcium montmorillonite. Excess isotherm modelling using the monolayer Ono-Kondo (O-K) model successfully captured the experimental adsorption. The lateral interaction of the adsorbed molecules on the montmorillonite surface, a variable with the type of cation, remarkably affected the strength of adsorption. The derived adsorbed phase density data confirmed the onset of swelling in montmorillonite at pressures below the critical point. Additionally, the study comprehended the influence of approximations used to derive the absolute isotherm from the experimental isotherm and investigated the validity of common theoretical models to represent adsorption. The study recommended the application of Dubinin-Astakhov (D-A) isotherm with reciprocal van der Waals density approximation or liquid density approximation to model the adsorption of CO2 on montmorillonite. [ABSTRACT FROM AUTHOR]

Tetracycline's accumulation in the environment poses threats to human health and the ecological balance, necessitating efficient and rapid removal methods. Novel porous metal–organic framework (MOF) materials have garnered significant attention in academia due to their distinctive characteristics. This paper focuses on studying the adsorption and removal performance of amino-modified MIL-101(Fe) materials towards tetracycline, along with their adsorption mechanisms. The main research objectives and conclusions are as follows: (1) NH2-MIL-101(Fe) MOF materials were successfully synthesized via the solvothermal method, confirmed through various characterization techniques including XRD, FT-IR, SEM, EDS, XPS, BET, and TGA. (2) NH2-MIL-101(Fe) exhibited a 40% enhancement in tetracycline adsorption performance compared to MIL-101(Fe), primarily through chemical adsorption following pseudo-second-order kinetics. The adsorption process conformed well to Freundlich isotherm models, indicating multilayer and heterogeneous adsorption characteristics. Thermodynamic analysis revealed the adsorption process as a spontaneous endothermic reaction. (3) An increased adsorbent dosage and temperature correspondingly improved NH2-MIL-101(Fe)'s adsorption efficiency, with optimal performance observed under neutral pH conditions. These findings provide new strategies for the effective removal of tetracycline from the environment, thus holding significant implications for environmental protection. [ABSTRACT FROM AUTHOR]

Fluoroquinolone antibiotics have been extensively used in clinical treatments for human and animal diseases. However, their long-term presence in the environment increases the risk of producing resistance genes and creates a potential threat to ecosystems and the health of humans and animals. Batch equilibrium experiments were utilized to investigate the adsorption and retention behavior and mechanism of the quinolone antibiotic enrofloxacin (ENR) in farmland soil in North China. The adsorption and desorption kinetics of ENR in soil were best fitted by pseudo-second-order model (R2 > 0.999). Both the adsorption and desorption processes of ENR in soil reached equilibrium in 1 h. The desorption amounts of ENR were significantly lower than the adsorption amounts, with the hysteresis coefficient (HI) being less than 0.7. The adsorption thermodynamic process of ENR followed the Linear and Freundlich models (0.965 < R2 < 0.985). Hydrophobic distribution and heterogeneous multimolecular layer adsorption were identified as critical factors in the adsorption process. The adsorption amount of ENR gradually decreased with increasing temperature and the initial concentration of ENR. The adsorption rate of ENR was above 80%, while the desorption rate remained below 15%, indicating strong retention ability. The adsorption rate of ENR in soil decreased with increasing pH, the adsorption rate reached 98.3% at pH 3.0 but only 31.5% at pH 11. The influence of coexisting ions on adsorption primarily depended on their properties, such as ion radius, ionic strength, and hydrolysis properties, and the inhibition of adsorption increased with increasing ionic strength. These findings contribute to understanding the fate and risk of veterinary antibiotics in loess soil in North China. [ABSTRACT FROM AUTHOR]

Methane adsorption is a critical assessment of the gas storage capacity (GSC) of shales with geological conditions. Although the related research of marine shales has been well-illustrated, the methane adsorption of marine-continental transitional (MCT) shales is still ambiguous. In this study, a method of combining experimental data with analytical models was used to investigate the methane adsorption characteristics and GSC of MCT shales collected from the Qinshui Basin, China. The Ono-Kondo model was used to fit the adsorption data to obtain the adsorption parameters. Subsequently, the geological model of GSC based on pore evolution was constructed using a representative shale sample with a total organic carbon (TOC) content of 1.71%, and the effects of reservoir pressure coefficient and water saturation on GSC were explored. In experimental results, compared to the composition of the MCT shale, the pore structure dominates the methane adsorption, and meanwhile, the maturity mainly governs the pore structure. Besides, maturity in the middle-eastern region of the Qinshui Basin shows a strong positive correlation with burial depth. The two parameters, micropore pore volume and non-micropore surface area, induce a good fit for the adsorption capacity data of the shale. In simulation results, the depth, pressure coefficient, and water saturation of the shale all affect the GSC. It demonstrates a promising shale gas potential of the MCT shale in a deeper block, especially with low water saturation. Specifically, the economic feasibility of shale gas could be a major consideration for the shale with a depth of <800 m and/or water saturation >60% in the Yushe-Wuxiang area. This study provides a valuable reference for the reservoir evaluation and favorable block search of MCT shale gas. [ABSTRACT FROM AUTHOR]

Theaflavins, as products of tea fermentation, exhibit significant applications in the fields of functional food, medicine, and others. This study aimed to screen ideal resin, further investigate its adsorption mechanisms, and optimize the dynamic purification process of ideal resin. Through static adsorption/desorption studies, LX-20B resin with great adsorption and desorption ability was screened from six macroporous resins. The adsorption mechanism of LX-20B resin was studied through static adsorption kinetics and thermodynamic experiments. The results showed that the adsorption of TFs on LX-20B resin corresponded to the pseudo-second-order kinetic model and Langmuir kinetic model, indicating that the adsorption is a high-temperature spontaneous, and monolayer adsorption process. After studying the adsorption mechanism of LX-20B resin, the process parameters for purifying TFs using LX-20B resin were further optimized. At a sample concentration of 150 mg/mL and a sample loading flow rate of 1.0 BV/h, sequential elution with 3.0 BV water, 4.0 BV of 30% (v/v) ethanol, and 2.0 BV of 60% (v/v) ethanol at a flow rate of 1.0 BV/h led to a significant increase in TFs purity from 14.28 ± 0.05% to 62.48 ± 0.37%, with a recovery rate of 52.98 ± 2.01%. The purity was 4.4 times greater than that of the crude material. [ABSTRACT FROM AUTHOR]

Samples of mesoporous silica gel doped with cerium and terbium and modified with silver were synthesized using the template method. The textural and morphological characteristics of the samples were studied using scanning electron microscopy, inductively coupled plasma mass spectrometry, X-ray diffraction analysis, Fourier-transform infrared (FT-IR) spectroscopy, and nitrogen adsorption-desorption analysis. Moreover, thermodynamic characteristics of adsorption (differential heats and entropies) of test organic compounds were obtained using the inverse gas chromatography method. It was established that the nature of the dopant leads to changes in the textural characteristics of the samples and the heat of adsorption for hydrocarbons and compounds prone to various types of specific interactions. [ABSTRACT FROM AUTHOR]

In this study, a systematic analysis was conducted to investigate the efficiency and mechanism of methylene blue (MB) removal from water using blue coke-based activated carbon (AC) as an adsorbent. The investigation encompassed several critical parameters, including adsorbent dosage, contact time, pH, temperature, initial MB concentration, and the regeneration capacity of the adsorbent. The adsorption mechanism of MB by AC was elucidated through instrumental analysis and theoretical models such as adsorption kinetics, isotherm models, and thermodynamic analysis. The experimental results demonstrated several key findings: the removal efficiency of MB increased with the adsorbent dosage, although the unit adsorption capacity decreased; the removal rate of MB rose rapidly with increasing contact time and reached equilibrium after 90 min; the highest removal efficiency was achieved at pH 6; the adsorption capacity increased with higher initial MB concentrations. The adsorption kinetics conformed to the pseudo-second-order model, indicating that chemical adsorption was the predominant control step. The adsorption process was identified as a spontaneous reaction, with the Langmuir model suggesting a maximum adsorption capacity of 2040.696 mg/g at 318 K. Furthermore, AC exhibited an abundant mesoporous structure and surface functional groups, contributing to the efficient removal of MB. The adsorption mechanism involved pore-filling, hydrogen bonding, π-π interactions, and electrostatic attraction. Additionally, AC demonstrated excellent regeneration performance. These findings suggest that AC prepared from blue coke holds significant potential for industrial applications in MB removal, owing to its high removal efficiency, low cost, and good regenerative properties, making it highly valuable for practical use.

The removal of ammonium from wastewater is a crucial process to mitigate the potential environmental issues associated with high nitrogen content in the water bodies. Natural zeolite, particularly clinoptilolite, has shown promise as an adsorbent for this purpose due to its unique surface properties. While zeolite has been studied extensively in this context, the current work represents an exploration of natural zeolite from The Tanggamus District, Indonesia. The study evaluated the impact of the desilication process on the ammonium adsorption capacity of this natural zeolite. The zeolites were characterized using XRD, XRF, and SEM. Batch adsorption studies revealed that the modified zeolite showed promising ammonium adsorption performance up to 35.4 mg/g. The adsorption data fit well with the pseudo-second-order kinetics and Freundlich isotherm model, suggesting chemisorption as the predominant mechanism. The effect of temperature and thermodynamic parameters highlighted the exothermic nature of the adsorption process. [ABSTRACT FROM AUTHOR]

The flow of graphene oxide (GO) into natural water systems can adversely affect water environments and ecosystems. In this study, the adsorption effect of calcite on GO under different conditions was studied using calcite as adsorbent. Meanwhile, characterized by a combination of microscopic experiments, including SEM, TEM, XRD, FTIR, Raman, XPS, and AFM, additional research on the performance and the mechanism of GO sorption by calcite was conducted. The findings indicated that the highest adsorption efficiency was observed at a temperature of 303 K, pH 3, a mass of 90 mg of calcite, with an initial concentration of 60 mg L−1 GO, resulting in a 95% adsorption rate. The adsorption isotherm conformed to the model of Langmuir and Temkin, and it is a heat absorption process dominated by monolayer adsorption. The thermodynamic analysis showed that the adsorption was spontaneous and heat-absorbing. The adsorption kinetics conformed to the pseudo-second-order kinetic model, and the sorption procedure is chemisorption. In conclusion, calcite has a good sorption capacity for GO, which can provide a reference for the removal of GO in the aqueous environment. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to remove Cu (II) ions from the aqueous solution by Natural Mixed Type Siirt Clay (NMTSC-2) from the aqueous solution. NMTSC-2 (clay containing chlorite, montmorillonite, vermiculite, muscovite, kaolinite and illite) was characterized by analysis methods of X-ray fluorescence spectroscopy (XRF), Fourier transform infrared, (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM-EDS), Brunauer–Emmett–Teller (BET) and thermogravimetric analysis (TGA). The data obtained as a result of the experimental studies were applied to the Freundlich, Langmuir, Temkin, Elovich and Dubinin–Radushkevich (D–R), Harkins–Jura adsorption isotherms. In the study, a new linear equation was derived from the Harkins–Jura model. The new form was applied to the NMTSC-2 adsorption experiment of Cu (II), the obtained constants and the plots were given in the study. In order to compare the models, the results were subjected to regression analysis. The new linear equation was found to be the most suitable model for the experimental data. The Langmuir model was the second most compatible with the experimental data. In adsorption experiments were performed at 298, 308 and 318 K temperatures, Cu (II) ion qm values were found as 21.146, 25.380 and 29.850 mg g−1, respectively. Thermodynamic data for 298,308 and 318 K temperatures were found as ΔG = − 24.394, − 33.724 and − 43.054 kJ mol−1 ΔH = 53.039 kJ mol−1, ΔS = 0.181 kJ mol−1 K−1. [ABSTRACT FROM AUTHOR]

In this work, models of elastic adsorption deformation of microporous adsorbents with different micropore geometries are proposed, which make it possible to relate changes in the relative linear dimensions of macroobjects (adsorbents) and micropores. Model No. 1 is a model of elastic adsorption deformation of microporous adsorbents upon interaction with gases. Model No. 2 corresponds to the model when the micropores are plane-parallel slots of limited size. Obviously, the proposed equations can be used in constructing the general thermodynamics of adsorption processes and adsorption theory, as well as in calculating the thermodynamic functions of adsorbents. In particular, changes in the internal energy, enthalpy, and entropy of the adsorbent during its deformation can be calculated. Thus, it will be possible to reveal the contribution of the non-inert adsorbent to the measured heats of adsorption. The developed approach contributes to the development of the thermodynamics of adsorption processes and the construction of a general theory of adsorption, taking into account the contribution of the adsorbent.

Oriented antibody immobilization has been widely employed in immunoassays and immunodiagnoses due to its efficacy in identifying target antigens. Herein, a heptapeptide ligand, HWRGWVC (HC7), was coupled to poly(glycidyl methacrylate) (PGMA) nanospheres (PGMA-HC7). The antibody immobilization behavior and antigen recognition performance were investigated and compared with those on PGMA nanospheres by nonspecific adsorption and covalent coupling via carbodiimide chemistry. The antibodies tested included bovine, rabbit, and human immunoglobulin G (IgG), while the antigens included horseradish peroxidase (HRP) and β-2-Microglobulin (β2-MG). The nanospheres were characterized using zeta potential and particle size analyzers, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and reversed-phase chromatography, proving each synthesis step was succeeded. Isothermal titration calorimetry assay demonstrated the strong affinity interaction between IgG and PGMA-HC7. Notably, PGMA-HC7 achieved rapid and extremely high IgG adsorption capacity (~3 mg/mg) within 5 min via a specific recognition via HC7 without nonspecific interactions. Moreover, the activities of immobilized anti-HRP and anti-β2-MG antibodies obtained via affinity binding were 1.5-fold and 2-fold higher than those of their covalent coupling counterparts. Further, the oriented-immobilized anti-β2-MG antibody on PGMA-HC7 exhibited excellent performance in antigen recognition with a linear detection range of 0–5.3 μg/mL, proving its great potential in immunoassay applications.

Tetracycline’s accumulation in the environment poses threats to human health and the ecological balance, necessitating efficient and rapid removal methods. Novel porous metal–organic framework (MOF) materials have garnered significant attention in academia due to their distinctive characteristics. This paper focuses on studying the adsorption and removal performance of amino-modified MIL-101(Fe) materials towards tetracycline, along with their adsorption mechanisms. The main research objectives and conclusions are as follows: (1) NH2-MIL-101(Fe) MOF materials were successfully synthesized via the solvothermal method, confirmed through various characterization techniques including XRD, FT-IR, SEM, EDS, XPS, BET, and TGA. (2) NH2-MIL-101(Fe) exhibited a 40% enhancement in tetracycline adsorption performance compared to MIL-101(Fe), primarily through chemical adsorption following pseudo-second-order kinetics. The adsorption process conformed well to Freundlich isotherm models, indicating multilayer and heterogeneous adsorption characteristics. Thermodynamic analysis revealed the adsorption process as a spontaneous endothermic reaction. (3) An increased adsorbent dosage and temperature correspondingly improved NH2-MIL-101(Fe)’s adsorption efficiency, with optimal performance observed under neutral pH conditions. These findings provide new strategies for the effective removal of tetracycline from the environment, thus holding significant implications for environmental protection.

The enhanced hydrothermal stability of leather, imparted by little Cr(III), has traditionally been ascribed to strong coordinate bonds. However, this explanation falls short when considering that the heat-induced shrinking of collagen fiber is predominantly driven by rupturing weak H-bonds. This study explored the stability source via adsorption thermodynamics using collagen fiber as an adsorbent. Eleven isotherm models were fitted with the equilibrium dataset. Nine of these models aptly described Cr(III) adsorption based on the physical interpretations of model parameters and error functions. The adsorption equilibrium constants from six models could be transformed into dimensionless thermodynamic equilibrium constants. Based on the higher R2 of the van't Hoff equation, thermodynamic parameters (∆G°, ∆H°, ∆S°) from the Fritz–Shluender isotherm model revealed that the adsorption process typifies endothermic and spontaneous chemisorption, emphasizing entropy increase as the primary driver of Cr(III) bonding with collagen. Thus, the release of bound H2O from collagen is identified as the stability source of collagen fiber modified by Cr(III). This research not only clarifies the selection and applicability of the isotherm model in a specific aqueous system but also identifies entropy, rather than enthalpy, as the principal stability source of Cr-leather. These insights facilitate the development of novel methods to obtain stable collagen-based material. [ABSTRACT FROM AUTHOR]

The main objective of this study was to produce low cost activated carbons for the adsorption of aromatic amino acids (AA) from feather hydrolysate. By optimizing the static adsorption conditions (time, pH and concentration) of amino acids, the adsorption amounts of tyrosine and phenylalanine reached 15.2 and 20.1 mg/g, respectively, under optimal conditions. Furthermore, it exhibits excellent reusability as it maintains a removal efficiency of 82.0% and 82.8% for tyrosine and phenylalanine after being reused 4 times. The effects of NaOH modified activated carbon (NA‐AC) on the adsorption capacity of AA in feather hydrolysate at different temperatures (298.15, 308.15, 318.15 K) were investigated, and the static adsorption kinetics curves were plotted. The adsorption isotherm (Langmuir, Freundlich model), kinetics (pseudo‐first‐order‐mode, pseudo‐second‐order‐mode, particle diffusion model) and thermodynamics were studied. The results shown that the adsorption process of AA onto NA‐AC accorded with the pseudo‐second‐order‐mode. The adsorption rate was mainly controlled by the liquid film diffusion and the particle diffusion. The adsorption isotherm accorded with the Langmuir adsorption isothermal model. Adsorption was an endothermic process, and increasing temperature was conducive to adsorption. Gibbs energy ΔG indicated that the adsorption process was spontaneous, and enthalpy △H indicated that the adsorption process was mainly physical adsorption. The proposed adsorption mechanisms provide a theoretical basis for the optimization of AA separation and purification process in feather hydrolysate by NA‐AC, which may further improve the separation and purification efficiency of other amino acids in feather hydrolysate. [ABSTRACT FROM AUTHOR]

The representative radioactive elemental iodine and methyl iodine are selected as adsorbates and the static adsorption capacity, adsorption heat and kinetics of silver based molecular sieves are investigated. The micro morphology, element composition and adsorption mechanism of the materials are characterized and analyzed by SEM, EDX mapping and XPS tests. The results show that the adsorption capacity of the material for elemental iodine and methyl iodine at room temperature can reach 1000 mg/g and 380 mg/g respectively, and the adsorption process for methyl iodine conforms to the quasi second order kinetic equation and Langmuair adsorption isotherm model. Silver based molecular sieves process trace radioactive iodine through chemical adsorption, while the main adsorption mode for higher concentration radioactive iodine is physical adsorption. [ABSTRACT FROM AUTHOR]

In order to understand the adsorption mechanism of chitosan microflower (CSMF) on procyanidins (PC), CSMF was used as an adsorbent to adsorb PC solutions under different adsorption conditions. The drug-loaded particles were characterized by scanning electron microscopy (SEM), Fourier infrared (FTIR), X-ray diffraction (XRD), etc. Through adsorption kinetics, adsorption isotherm, and adsorption thermodynamics, the mechanism of CSMF adsorption PC was systematically studied. The results showed that the FTIR pattern of the drug-loaded particles produced a new characteristic peak at 1456 cm−1, indicating that the PC was successfully loaded onto the CSMF. The results of SEM and XRD analysis showed that the morphology and crystallinity of CSMF did not change after loading. The adsorption kinetics showed that the adsorption of PC by CSMF conformed to the pseudo-second-order kinetic model, and the adsorption rate was affected by the interaction between particle diffusion and boundary layer diffusion. The adsorption isotherm showed that the Freundlich adsorption isotherm model could more accurately reflect the entire adsorption process, indicating that the adsorption process of CSMF to PC was multilayer adsorption with surface energy inhomogeneity. Finally, adsorption thermodynamics showed that the adsorption of PC by CSMF was a spontaneous physical adsorption process with reduced entropy.

O—butyl—N—isobutyl thionocarbamate (NBIB) is a novel collector for copper sulfur flotation separation. The adsorption capacity of NBIB was measured using a UV–vis spectrophotometer. The effects of the adsorption temperature, pH value, stirring time, and collector concentration on the adsorption capacity of NBIB on chalcopyrite surfaces, as well as its adsorption thermodynamics and kinetics, were investigated. Results of a pure mineral flotation experiment indicate that NBIB has a high recovery rate for chalcopyrite, strong collection capacity, and little influence by pH. The adsorption capacity of NBIB on a chalcopyrite surface increases with an increase in the collector concentration at 288, 298, and 308 K and pH 6, 9, and 12, respectively. When the equilibrium concentration reaches 0.5×10−4 mol·L−1, the adsorption capacity has a small increase range. At the same pH value, the adsorption capacity increases with an increase in the adsorption temperature. It is speculated that NBIB adsorption on a chalcopyrite surface is an endothermic process. At pH 6 and 9, little difference exists in adsorption capacity, which slightly decreases when pH increases to 12. Meanwhile, the pulp pH value has little effect on the adsorption capacity, which is consistent with the flotation test results. The adsorption capacity data were linearly fitted by Langmuir and Freundlich isotherms, and the Langmuir equation has a better correlation coefficient of the fitting curve. The adsorption process of NBIB on the chalcopyrite surface is more consistent with the Langmuir adsorption model, and it is speculated that the adsorption process may be monolayer adsorption. The parameters of the Langmuir equation are considered based on a thermodynamic formula. The results indicate that the linear fitting results are good, ∆G is negative, and ∆H and ∆S are positive. Therefore, the process of chalcopyrite adsorbing NBIB may be spontaneous, entropy-driven, and endothermic chemical adsorption. Meanwhile, the adsorption capacity of NBIB on the chalcopyrite surface increases with an increase in the adsorption time at temperatures from 288 K to 308 K. The increasing trend of adsorption capacity slows down after the adsorption time reaches 20 min. Moreover, the adsorption capacity increases with increasing temperature. Evidently, the adsorption is an endothermic process, which is consistent with the results of the thermodynamic analysis. The kinetic calculation shows that the correlation coefficients of the second-order reaction fitting curve are greater than those of first-order reaction, indicating that the second-order reaction rate equation has a better linear fitting result. The equilibrium adsorption capacity calculated by the second-order reaction rate equation is closer to the experimental equilibrium adsorption capacity. Therefore, it is speculated that the NBIB adsorption on the chalcopyrite surface conforms to the second-order adsorption kinetic model.

Doping-modified coal samples can effectively enhance the adsorption of CO2. In order to investigate the micro-mechanism of the adsorption of different gases by the synergistic effect of N/S atomic doping and functional groups in coal, the microporous constructed by N/S doping with different functional groups in coal at different temperatures and pressures were investigated based on a series of grand canonical Monte Carlo (GCMC) computational simulations. The adsorption amount, heat of adsorption, diffusion coefficient, interaction energy and relative density distribution of CO2/CH4/N2 by the model. It was found that coal samples with more N-doped carboxyl groups could adsorb CO2 better, and coal samples with more N-doped aliphatic functional groups should be selected for adsorption of CH4 and N2, and the N-COOH system had the most stable adsorption state of CO2, and the amount of N-modified coal samples adsorbed CO2 was higher than that of CH4 and N2 at the adsorption temperature of 293.15 K.The diffusion coefficients of the gas molecules showed an increasing trend with the adsorption temperature, and the relative density distributions of CO2/CH4/N2 in the N-doped micropore model were larger than those in the S-doped system. These noteworthy findings provide a valuable theoretical foundation for the advancement of novel adsorbent materials.

In this study, the adsorption experiments of water vapour on deep reservoir were conducted. The thermodynamics for water vapour adsorption were analysed. Results illustrate that primary binding centres have stronger affinity than secondary binding centres. Water molecule will be preferentially trapped at primary binding centres in low-pressure region. In high-pressure region, secondary adsorption predominates. Primary adsorption spontaneity increases with pressure. At secondary binding centres and total binding centres, the spontaneity degree quickly improves and then slowly decreases as pressure increases. The transfer of water molecules from the more energetic binding centres to the less binding centres leads to the initial reduction in entropy loss (ΔS) and isosteric heat of adsorption (Qst). The late enhancement in ΔS and Qst is caused by the growing water clusters. Water vapour adsorption can promote CH4 desorption. By occupying adsorption sites and reducing pore connectivity, water vapour adsorption causes an unfavourable effect on CO2 sequestration.

The adsorption thermodynamics and kinetics of CO2 and six combustion products (H2O, SO2, N2, O2, NO and NO2) of two most commonly used commercial zeolites (13X and 5A) were studied based on validated molecular simulations. Adsorption isotherms at wide range of temperatures (253–333 K) were fitted by a Langmuir model, obtaining equilibrium parameters including the adsorption capacity, strength, heterogeneity and CO2 selectivity from the mixture. The diffusion coefficients, isosteric adsorption heats and distributions of potential energy were simulated for further explanation. The comprehensive evaluation results suggest that, in actual combustion product mixtures, the presence of H2O in combustion products has a significant impact on CO2 capture efficiency. Under the influence of water, the adsorption capacity of CO2 was reduced by over 80%. [ABSTRACT FROM AUTHOR]

Adsorbed natural gas (ANG) storage is a promising solution to the problem of uneven supply and consumption of natural gas. ANG storages are relatively simple, safe and do not require complex infrastructure. The paper investigates the properties of activated carbon of wood origin synthesized by the method of chemical activation, as well as the theoretical capacity and thermodynamic properties of ANG storage facilities equipped with this adsorbent. An original graphical method for calculating the parameters and processes of ANG storage facilities is presented using the example of synthesized active carbon. Various types of ANG storage charging are considered: adiabatic processes of charging with compressed and liquefied gas, isothermal and pseudo-isothermal processes. So adiabatic charging with liquefied gas allows reaching a storage capacity of 150 m3/m3 at a pressure of 3.5 MPa. A number of recommendations were made regarding the choice of the charging type from the standpoint of the ANG storage facility design. [ABSTRACT FROM AUTHOR]

In this study, a novel mesoporous adsorption composite namely G-SMS/ZIF-67(C) was synthesized by coating the ZIF-67 doped with graphene oxide (GO) on the surface of spherical mesoporous silica (SMS) and finally modified by high-temperature calcination. Compared with activated carbon (AC), the synthesized adsorption composite exhibited a good adsorption capacity of methyl orange (MO) in low-temperature aqueous environment. The adsorption process was consistent with the pseudo-first-order kinetics and Freundlich model. It revealed that the formed mesoporous structure and hydrophobic interactions of the G-SMS/ZIF-67(C) after calcination effectively improved the adsorption performance, with the average adsorption rate and maximal adsorption capacity of G-SMS/ZIF-67(C) 1.8 and 2.91 times higher than that of the ones without calcination, respectively. Moreover, the maximal adsorption capacity of the G‑SMS/ZIF-67(C) composite was positively correlated with the temperature. The thermodynamics and mechanism of the adsorption process have been investigated and rationalized. [ABSTRACT FROM AUTHOR]

The Brazil nut shell was used as a precursor material for preparing activated carbon by chemical activation with potassium hydroxide. The obtained material (BNSAC) was characterized, and the adsorptive features of phenol were investigated. The characterization showed that the activated carbon presented several rounded cavities along the surface, with a specific surface area of 332 m2 g–1. Concerning phenol adsorption, it was favored using an adsorbent dosage of 0.75 g L–1 and pH 6. The kinetic investigation revealed that the system approached the equilibrium in around 180 min, and the Elovich model represented the kinetic curves. The Sips model well represented the equilibrium isotherms. In addition, the increase in temperature from 25 to 55 °C favored the phenol adsorption, increasing the maximum adsorption capacity value (qs) from 83 to 99 mg g–1. According to the estimated thermodynamic parameters, the adsorption was spontaneous, favorable, endothermic, and governed by physical interactions. Therefore, the Brazil nut shell proved a good precursor material for preparing efficient activated carbon for phenol removal. [ABSTRACT FROM AUTHOR]

The discharge of diethylenetriamine (DETA) into aqueous environment poses a threat to public health and environment. Therefore, it is imperative to take effective measures to remove DETA from water. The elimination of DETA from water may be realized via the way of adsorption with activated carbon. In this paper, the adsorption of DETA from water by activated carbon originated from coconut shell has been explored in batchwise operation. The effects of stirring speed, temperature, pH, DETA concentration, carbon dosage and particle size on DETA adsorption have been determined by experiment. The adsorption results exhibit that the DETA adsorption rate increases with its concentration in the aqueous solution and temperature. However, the amount of DETA adsorbed on the carbon at equilibrium decreases slightly with temperature. The DETA adsorbed increases with pH changing from 8 to 11 and remains constant if pH rising over 11. The kinetic study shows that DETA adsorption on the activated carbon is in good agreement with the pseudo-second-order kinetic model with a correlation coefficient of 0.999. The DETA removal from the solution increases with the carbon dosage. The Langmuir equilibrium isotherm model has been found to provide a better fitting of the adsorption data than the Freundlich equilibrium isotherm model with a maximum adsorption of 90.50 mg g−1. The thermodynamic parameters evaluated from the experiments are ΔS 14.49 J∙mol−1∙K−1, ΔH −11.32 kJ mol−1 and ΔG changing from −15.71 from −16.15 kJ mol−1with the temperature rising from 30°C to 60°C. The thermodynamic study suggests the exothermic and spontaneous natures of DETA sorption on activated carbon. [ABSTRACT FROM AUTHOR]

Phosphoric acid-activated biochar has been proven to be a promising adsorbent for pollutant removal in an aqueous solution. It is urgent to understand how surface adsorption and intra-particle diffusion synergistically contribute to the adsorption kinetic process of dyes. In this work, we prepared a series of PPC adsorbents (PPCs) from red-pulp pomelo peel under different pyrolysis temperatures (150–350 °C), which have a broad specific surface area range from 3.065 m2/g to 1274.577 m2/g. The active sites on the surface of PPCs have shown specific change laws of decreasing hydroxyl groups and increasing phosphate ester groups occurring as the pyrolysis temperature rises. Both reaction models (PFO and PSO models) and diffusion models (intra-particle diffusion models) have been applied to simulate the adsorption experimental data to verify the hypothesis deduced from the Elovich model. PPC-300 exhibits the highest adsorption capacity of MB (423 mg/g) under given conditions. Due to its large quantities of active sites on the external and internal surfaces (1274.577 m2/g), a fast adsorption equilibrium can be achieved within 60 min (with an initial MB concentration of 100 ppm). PPC-300 and PPC-350 also exhibit an intra-particle-diffusion-controlled adsorption kinetic process with a low initial MB concentration (100 ppm) or at the very beginning and final stage of adsorption with a high initial MB concentration (300 ppm) at 40 °C, considering that the diffusion is likely hindered by adsorbate molecules through internal pore channels at the middle stage of adsorption in these cases. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFAS) have concerned the public due to their worldwide distribution and the threat they pose to drinking water safety and human health. Temperature and DC field-induced electroosmotic flow (EOF) are powerful tools to regulate organic contaminant adsorption and control PFOS (as a typical PFAS) transport in porous media. However, the co-driven mechanisms of temperature–electrokinetic transport of contaminants are still unclear. Here, we investigated the synergistic mechanisms of temperature–electrokinetic co-driven PFOS adsorption on zeolite and activated carbon as model geo-adsorbents. We found that DC fields increased PFOS adsorption on activated carbon by up to 19.8%, while they decreased PFOS adsorption on zeolite by up to 21.4%. Increasing the temperature decreased the adsorption of PFOS by activated carbon and zeolite. The temperature and electrokinetic synergistically drive EOF velocity to control PFOS adsorption. Synergistic mechanisms of temperature–electrokinetic regulated kinetic and temperature-regulated thermodynamic (the Gibbs free energy change ΔG) and kinetic (liquid viscosity) under various temperatures and DC field situations were analyzed with models. A kinetic approach interlinking viscosity, EOF velocity, and the kinetic adsorption constants was established to interpret the synergistic mechanisms which can be further adopted to estimate temperature–electrokinetic induced PFOS adsorption benefits to mineral and carbonaceous adsorbents. We concluded that such kinetic regulation may provide support for controlling the transmission of PFOS. [ABSTRACT FROM AUTHOR]

To investigate the process of RE3+ anti-adsorption on ion-adsorption type rare earth tailings, the thermodynamics, adsorption kinetics and infrared spectroscopy of these materials were investigated. The results indicate that the initial reaction rate of anti-adsorption of rare earth tailings is fast, but it reaches a balance in 6 min. The formula 1 − 2a/3 − (1 − a)2/3 = k2t (k represents rate constant of the reaction, a represents anti-adsorption rate of rare earth ore, t represents anti-adsorption time) of internal diffusion can be used to predict the kinetics of anti-adsorption in IATRE tailings. Because ΔH < 0, ΔG < 0, ΔS > 0 (ΔH, ΔG, ΔS represent change of enthalpy, Gibbs free energy and entropy, respectively), the anti-adsorption of RE3+ on ion-adsorption type RE tailings is a spontaneous physical adsorption process. The effects of ligand exchange and strong chemical bond are not found in this process. Because the anti-adsorption process is exothermic, heating will inhibit the reaction and decrease the anti-adsorption performance. According to the infrared spectrum analysis, there are no significant changes in the mineral surface after anti-adsorption. Based on these findings, the anti-adsorption of rare earth tailings is physical adsorption. [ABSTRACT FROM AUTHOR]

The purpose of this work was to investigate the thermodynamic characteristics of carbon dioxide (CO2) adsorption on a promising nitrogen‐doped biochar at constant temperature and isopiestic pressure. The biochar was prepared as a CO2 adsorbent based on catalytic pyrolysis of pristine coconut shells using urea as the nitrogen source and moderate temperature ionic liquid as a catalyst. The results showed that CO2 adsorption on the biochar was a spontaneous, dominantly physical, exothermic, and entropy decrement process that could be well described by the slip model and the dual‐site Langmuir model. Those thermodynamic parameters, including interface potential, exhibited a series of interesting tendencies with the changes in adsorption temperature and pressure. Under the conditions of 273 K and 100 kPa, the adsorption capacity and the interface potential were 4.6 mmol/g and −16.7 J/g, respectively. And the site energy ranged from 2.57 to 5.13 kJ/mol in the test conditions, which became narrow with increasing temperature. The temperature exhibited positive effects on interface potential, enthalpy change, entropy change, enthalpy change, internal energy change but negative effects on adsorption capacity, Gibbs free energy change, and Helmholtz free energy change. Interestingly, the pressure exhibited the opposite effect trends. The peak pressure with maximum temperature effect at a given temperature and the peak temperature with maximum pressure effect at a given pressure were found to exist for some thermodynamic parameters. These exhibited a different but significantly beneficial perspective to understand the mass and energy transfer during CO2 adsorption on the biochar at constant temperature and isopiestic pressure, which have rarely been reported before. [ABSTRACT FROM AUTHOR]

The adsorption isotherms, kinetics, and thermodynamics of fluoride ions (F−) on FeOOH powders in water were investigated to obtain fundamental information on FeOOH powders, which are used as F− adsorbents in drinking and industrial water, and industrial wastewater. FeOOH powders were prepared as precipitates by mixing aqueous FeCl3 and NaOH solutions (1:3 mol/mol) in the presence of 2,2,6,6,-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibrils (TOCNs), carboxymethylcellulose (CMC), or TEMPO-oxidized cellulose (TOC) fibers (without nanofibrillation), and subsequent drying and pulverizing. The FeOOH:TOCN, FeOOH:CMC, and FeOOH:TOC dry mass ratios were controlled at 87:13. The amount of F− adsorbed by the FeOOH/TOCN powder per FeOOH mass was higher than those adsorbed by FeOOH, FeOOH/CMC, or FeOOH/TOC. The F− adsorption isotherms on the FeOOH-containing powders showed higher correlation coefficients with the Langmuir model than with the Freundlich model. This indicates that F− adsorbed on FeOOH initially formed a monolayer, predominantly via physical adsorption. Pseudo-second-order kinetics fitted well to the time-dependent F− adsorption behaviors on the FeOOH-containing powders. Thermodynamic analysis of F− adsorption on the FeOOH-containing powders showed that the ΔG values were negative, which indicates that F− adsorption on the FeOOH-containing powders proceeded spontaneously in water. The negative ΔG value for FeOOH/TOCN was higher than those for FeOOH, FeOOH/CMC, and FeOOH/TOC at the same temperature. This shows that the FeOOH/TOCN powder can be used as an excellent and efficient F− adsorbent in water. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A low-cost and environmental-friendly sodium alginate-melamine@zeolitic imidazolate framework-67 (SA-ME@ZIF-67) adsorbent was fabricated by chemical grafting and in situ growth for the removal of lead ions in wastewater. Firstly, melamine (ME) was grafted onto sodium alginate (SA) by amide reaction, and then SA-ME was dropped into a solution of calcium chloride to form hydrogel bead, and ZIF-67 was grown on the SA-ME hydrogel bead by the in situ growth method. The SA-ME@ZIF-67 adsorbent was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The SA-ME@ZIF-67 adsorbent was used to effectively adsorb Pb(II) from aqueous solutions. The initial concentrations of lead ions, adsorbent dose, initial pH of lead ion solution, temperature, and adsorption time for the material were optimized. The adsorption isotherms and kinetics fitted to Langmuir isotherm model (R2 = 0.9281, 0.9420, and 0.9623 at the temperatures of 288.15 K, 298.15 K, and 308.15 K, respectively) and pseudo-second-order kinetic model (R2 = 0.9901) respectively. According to the Langmuir model at 308.15 K, the maximum adsorption capacity of the adsorbent for Pb(II) was 634.99 mg/g. The recycling application of the adsorbent was possible as it was easily collected and reused after five adsorption-regeneration cycles. In addition, the Pb(II) in real wastewater samples has been efficiently removed using the fabricated hydrogel. The results showed that the SA-ME@ZIF-67 adsorbent had high adsorption capacity, removal efficiency, and easy recyclability for Pb(II). [ABSTRACT FROM AUTHOR]

The objective of this study is to prepare magnetic composites as adsorbents for Cr(VI) from wastewater. The prepared composites are magnetic activated carbon (M-AC), magnetic ash (M-ASH), and magnetic sand (M-SAND). These composites were characterized using XRF, FTIR, XRD, and TGA, and then tested as adsorbents for toxic Cr(VI) ions from synthetic wastewater. The elemental analysis of the composites showed a crucial increment in the Fe content of about 6425%, 3600%, and 93% for M-SAND, M-AC, and M-Ash, respectively. Their FTIR spectrum showed the existence of the Fe–O bond vibration, indicating the presence of Fe3O4 particles as confirmed by the XRD pattern. The pseudo-second-order model best described the adsorption kinetic results and the Redlich-Peterson isotherm model accurately described the equilibrium data of ion adsorption by the three composites at 25 and 40 °C with relatively high values of R2. The composites showed their highest adsorption capacities for Cr(VI) ions at 40 °C with an average adsorption capacity of the composites was about 50 mg/g. These relatively high values demonstrate the adsorption ability of the magnetic composites and present a strategy to use the adsorption process for Cr(VI) ions by these composites as efficient adsorbents.

The enhanced hydrothermal stability of leather, imparted by little Cr(III), has traditionally been ascribed to strong coordinate bonds. However, this explanation falls short when considering that the heat-induced shrinking of collagen fiber is predominantly driven by rupturing weak H-bonds. This study explored the stability source via adsorption thermodynamics using collagen fiber as an adsorbent. Eleven isotherm models were fitted with the equilibrium dataset. Nine of these models aptly described Cr(III) adsorption based on the physical interpretations of model parameters and error functions. The adsorption equilibrium constants from six models could be transformed into dimensionless thermodynamic equilibrium constants. Based on the higher R2 of the van’t Hoff equation, thermodynamic parameters (∆G°, ∆H°, ∆S°) from the Fritz–Shluender isotherm model revealed that the adsorption process typifies endothermic and spontaneous chemisorption, emphasizing entropy increase as the primary driver of Cr(III) bonding with collagen. Thus, the release of bound H2O from collagen is identified as the stability source of collagen fiber modified by Cr(III). This research not only clarifies the selection and applicability of the isotherm model in a specific aqueous system but also identifies entropy, rather than enthalpy, as the principal stability source of Cr-leather. These insights facilitate the development of novel methods to obtain stable collagen-based material.

In order to reveal the thermodynamic properties of CO2 adsorption on a promising nitrogen-doped biochar under isothermal and isovolumetric conditions, the adsorption isotherms based on 391 data points were experimentally obtained to investigate the mass and energy transfer process during CO2 adsorption by combining with model analysis. Then a series of interesting phenomena were found by analyzing those thermodynamic parameters in the equilibrium and non-equilibrium states. The capacity of CO2 on the biochar non-linearly increases with an increase of the initial pressure and volume-mass ratio but the decrease of the adsorption temperature. It can be up to 7.6 mol/kg at 273 K and 100 kPa. The adsorption system exchanges the energy with the surrounding environment mainly by heat transfer. And the interfacial energy of the adsorbent can be affected by the adsorbate system in three parts: pressure change from gas phase, molecular force from adsorbed phase and heat transfer. Then the conditions with low adsorption temperature, high initial pressure and large volume-mass ratio can provide a strong driving force for CO2 adsorption. These phenomena that have not been reported before will help us get a better technical process for CO2 capture.

In this study, the adsorption experiments of water vapour on deep reservoir were conducted. The thermodynamics for water vapour adsorption were analysed. Results illustrate that primary binding centres have stronger affinity than secondary binding centres. Water molecule will be preferentially trapped at primary binding centres in low-pressure region. In high-pressure region, secondary adsorption predominates. Primary adsorption spontaneity increases with pressure. At secondary binding centres and total binding centres, the spontaneity degree quickly improves and then slowly decreases as pressure increases. The transfer of water molecules from the more energetic binding centres to the less binding centres leads to the initial reduction in entropy loss (ΔS) and isosteric heat of adsorption (Qst). The late enhancement in ΔS and Qst is caused by the growing water clusters. Water vapour adsorption can promote CH4 desorption. By occupying adsorption sites and reducing pore connectivity, water vapour adsorption causes an unfavourable effect on CO2 sequestration. [ABSTRACT FROM AUTHOR]

In this study a new type of adsorbent bead precursor was reached using chitosan and pretreated clay. The pretreated clay was produced from the clay of the "Tsogt-Ovoo" deposit in the Umnugovi province of Mongolia. It was produced by acid and heat treatment to remove its mechanical impurities. The mixtures of chitosan and pretreated clay were taken with various ratios (8:1, 8:2, and 8:3) for chemical processing to obtain a chitosan-based adsorbent bead for recovery of (Pt(IV)) from aqueous solution. It was examined that the adsorption capacity of the adsorbent bead when the chitosan and pretreated clay mass ratio 8:2 was the highest for platinum ion (Pt (IV)). The adsorption properties of Pt (IV) were studied depending on the solution pH, contacting time, temperature, initial concentration of platinum ion solution, and amount of adsorbent material. The adsorption efficiency was the highest (93.29%) when the initial concentration of the platinum ion was 50 mg/l at the following condition; pH=3, temperature 250C, time 3 hours, and the amount of the adsorbent material 0.1 g. It represents that the chitosan clay bead can be applied for the recovery of platinum (Pt (IV)) from aqueous solution. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Firstly, spherical magnesium oxide was synthesized by simple magnesium salt and specific reaction conditions. Then, lanthanum-modified spherical magnesium oxide (LSMO) was prepared by impregnation of lanthanum salt. The adsorption mechanism of the adsorbent was investigated by XRD, SEM, XPS, and FT-IR. Through the study of fluorine removal performance, for the solution with fluoride ion concentration of 10 mg·L−1, the fluorine removal efficiency of lanthanum-modified spherical magnesium oxide (15LSMO) (93.1%) with 15% impregnation mass ratio is higher than that of SMO (82.7%). In addition, in the pH range of 2–11 or in the presence of interfering ions, the fluoride removal effect of 15LSMO still meets the fluoride removal efficiency of more than 90%. The research enhanced the profound insights into the effect and mechanism of fluorine removal of lanthanum modified materials. [ABSTRACT FROM AUTHOR]

Environmental deoxyribonucleic acid (eDNA), which includes antibiotic resistance genes, is ubiquitous in the environment. The interactions between eDNA and biochar, a promising material widely used in soil amendment and water treatment, greatly affect the environmental behavior of eDNA. Hitherto few experimental evidences are available yet, especially on the information of thermodynamics and energy distribution to explains the interactions between biochar and eDNA. This study investigated the adsorption of herring sperm DNA (hsDNA) on pine sawdust biochar, with a specific emphasis on the adsorption thermodynamics and site energy distribution. The adsorption of hsDNA on biochar was enhanced by an increase in the pyrolysis and adsorption temperatures. The higher surface area, stronger π-π interaction, and weaker electrostatic repulsion between hsDNA and biochars prepared at high pyrolysis temperatures facilitated the adsorption of hsDNA. The thermodynamics indicated that the adsorption of hsDNA on biochar was spontaneous and endothermic. Therefore, higher temperature was beneficial for the adsorption of hsDNA on biochar; this was well explained by the increase in E* and F(E*) with the adsorption temperature. These results are useful for evaluating the migration and transformation of eDNA in the presence of biochar. [ABSTRACT FROM AUTHOR]

In this study, a systematic analysis was conducted to investigate the efficiency and mechanism of methylene blue (MB) removal from water using blue coke-based activated carbon (AC) as an adsorbent. The investigation encompassed several critical parameters, including adsorbent dosage, contact time, pH, temperature, initial MB concentration, and the regeneration capacity of the adsorbent. The adsorption mechanism of MB by AC was elucidated through instrumental analysis and theoretical models such as adsorption kinetics, isotherm models, and thermodynamic analysis. The experimental results demonstrated several key findings: the removal efficiency of MB increased with the adsorbent dosage, although the unit adsorption capacity decreased; the removal rate of MB rose rapidly with increasing contact time and reached equilibrium after 90 min; the highest removal efficiency was achieved at pH 6; the adsorption capacity increased with higher initial MB concentrations. The adsorption kinetics conformed to the pseudo-second-order model, indicating that chemical adsorption was the predominant control step. The adsorption process was identified as a spontaneous reaction, with the Langmuir model suggesting a maximum adsorption capacity of 2040.696 mg/g at 318 K. Furthermore, AC exhibited an abundant mesoporous structure and surface functional groups, contributing to the efficient removal of MB. The adsorption mechanism involved pore-filling, hydrogen bonding, π-π interactions, and electrostatic attraction. Additionally, AC demonstrated excellent regeneration performance. These findings suggest that AC prepared from blue coke holds significant potential for industrial applications in MB removal, owing to its high removal efficiency, low cost, and good regenerative properties, making it highly valuable for practical use. [ABSTRACT FROM AUTHOR]

Two carbon composite materials were prepared by mixing avocado biochar and methyl polysiloxane (MK). Firstly, MK was dissolved in ethanol, and then the biochar was added at different times. In sample 1 (R1), the time of adding biochar was immediately after dissolving MK in ethanol, and in sample 2 (R2), after 48 h of MK dissolved in ethanol. The samples were characterized by nitrogen adsorption/desorption measurements obtaining specific surface areas (SBET) of 115 m2 g−1 (R1) and 580 m2 g−1 (R2). The adsorbents were further characterized using scanning electron microscopy, FTIR and Raman spectroscopy, adsorption of vapors of n-heptane and water, thermal analysis, Bohem titration, pHpzc, and C H N elemental analysis. R1 and R2 adsorbents were employed as adsorbents to remove the antibiotic ciprofloxacin from the waters. The t1/2 and t0.95 based on the interpolation of Avrami fractional-order were 20.52 and 246.4 min (R1) and 14.00 and 157.6 min (R2), respectively. Maximum adsorption capacities (Qmax) based on the Liu isotherm were 10.77 (R1) and 63.80 mg g−1 (R2) for ciprofloxacin. The thermodynamic studies showed a spontaneous and exothermic process for both samples, and the value of ΔH° is compatible with physical adsorption. [ABSTRACT FROM AUTHOR]

A novel adsorbent of CuAl-carbonate layered double hydroxide (CuAl-LDH) was synthesized by coprecipitation method and applied to remove redundant perfluorooctanoic acid (PFOA) from water. The physical and chemical properties of as-prepared CuAl-LDH and CuAl-CLDH were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and Fourier-transform infrared (FT-IR) analysis. The TEM results and XRD analysis confirm that CuAl-LDH presents the crystalline nature and CuAl-CLDH owns memory effect. The FT-IR analysis indicates that PFOA can be removed through entering interlayer of CuAl-CLDH. In order to understand the adsorption process profoundly, the mechanism was studied by adsorption thermodynamics and kinetics. The results indicate that the CuAl-CLDH can be effectively utilized to remove PFOA from water, where the maximum adsorption quantity (1,526.1 mg/g) could be achieved and the adsorption equilibrium could be reached in 2 h. The thermodynamic data are well-fitted to the Freundlich isotherm model while pseudo-second-order model provides better correlation of the kinetic data. From the thermodynamic analysis, the adsorption process is exothermic and spontaneous. Based on TEM, XRD and kinetic analysis, the memory effect probably takes an important part in early adsorption phase while chemisorption may control the adsorption rate at the second adsorption phase. Because of the excellent adsorption quantity showed by CuAl-CLDH, they are anticipated to remove PFOA from water in pollution control. [ABSTRACT FROM AUTHOR]

In recent years, there has been significant interest in the study of spandex in high-elasticity sensors. As a new kind of special spandex, dyeable spandex shows strong adsorption capacity for anions. In this study, neutral red G was used as an anion adsorption simulator to study the adsorption mechanism of dyeable spandex on anionic materials. The structure of dyeable spandex was characterized by the modern instrumental analysis method, and the adsorption kinetics and thermodynamics of neutral red G on dyeable spandex were discussed. The results show that the use of mixed amines as chain extenders for dyeable spandex reduced the regularity of molecules and the crystallinity of spandex, which was beneficial to the diffusion adsorption of anions. On the other hand, the number of secondary amino groups increased, providing more adsorption sites under acidic conditions. The adsorption of neutral red G on dyeable spandex satisfied the quasi-second-order kinetics and the Langmuir adsorption model, indicating that dye adsorption on spandex was mainly electrostatic. The diffusion coefficient and equilibrium adsorption capacity of neutral red G on dyeable spandex increased significantly, whereas enthalpy and entropy decreased. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oriented antibody immobilization has been widely employed in immunoassays and immunodiagnoses due to its efficacy in identifying target antigens. Herein, a heptapeptide ligand, HWRGWVC (HC7), was coupled to poly(glycidyl methacrylate) (PGMA) nanospheres (PGMA-HC7). The antibody immobilization behavior and antigen recognition performance were investigated and compared with those on PGMA nanospheres by nonspecific adsorption and covalent coupling via carbodiimide chemistry. The antibodies tested included bovine, rabbit, and human immunoglobulin G (IgG), while the antigens included horseradish peroxidase (HRP) and β-2-Microglobulin (β2-MG). The nanospheres were characterized using zeta potential and particle size analyzers, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and reversed-phase chromatography, proving each synthesis step was succeeded. Isothermal titration calorimetry assay demonstrated the strong affinity interaction between IgG and PGMA-HC7. Notably, PGMA-HC7 achieved rapid and extremely high IgG adsorption capacity (~3 mg/mg) within 5 min via a specific recognition via HC7 without nonspecific interactions. Moreover, the activities of immobilized anti-HRP and anti-β2-MG antibodies obtained via affinity binding were 1.5-fold and 2-fold higher than those of their covalent coupling counterparts. Further, the oriented-immobilized anti-β2-MG antibody on PGMA-HC7 exhibited excellent performance in antigen recognition with a linear detection range of 0-5.3 μg/mL, proving its great potential in immunoassay applications.

Deoxynojirimycin (DNJ) is an α-glucosidase inhibitor with high food values. However, the complex and costly enrichment processes have greatly prevented its application. Herein, this study aimed to propose a simple and efficient enrichment process for DNJ from Morus alba L. extracts using cation exchange resins. The LSI and D113 resins were chosen due to their excellent adsorption and desorption properties. The adsorption characteristics agreed with the pseudo-first-order kinetic model and the Langmuir isotherm model. This adsorption was chemisorption, spontaneous, endothermic and entropy-driven. Furthermore, the concentration and pH of the extracts, desorption solvent, breakthrough and elution curves, sample loading and elution rate were investigated to optimize the enrichment process by resin column chromatography. The results also showed that the purity of DNJ was improved to 44.00 % with a total recovery of 78.21 % using the LSI-D113 combination strategy. This research demonstrated the industrial feasibility of DNJ enrichment using cation exchange resins., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Phosphoric acid-activated biochar has been proven to be a promising adsorbent for pollutant removal in an aqueous solution. It is urgent to understand how surface adsorption and intra-particle diffusion synergistically contribute to the adsorption kinetic process of dyes. In this work, we prepared a series of PPC adsorbents (PPCs) from red-pulp pomelo peel under different pyrolysis temperatures (150–350 °C), which have a broad specific surface area range from 3.065 m2/g to 1274.577 m2/g. The active sites on the surface of PPCs have shown specific change laws of decreasing hydroxyl groups and increasing phosphate ester groups occurring as the pyrolysis temperature rises. Both reaction models (PFO and PSO models) and diffusion models (intra-particle diffusion models) have been applied to simulate the adsorption experimental data to verify the hypothesis deduced from the Elovich model. PPC-300 exhibits the highest adsorption capacity of MB (423 mg/g) under given conditions. Due to its large quantities of active sites on the external and internal surfaces (1274.577 m2/g), a fast adsorption equilibrium can be achieved within 60 min (with an initial MB concentration of 100 ppm). PPC-300 and PPC-350 also exhibit an intra-particle-diffusion-controlled adsorption kinetic process with a low initial MB concentration (100 ppm) or at the very beginning and final stage of adsorption with a high initial MB concentration (300 ppm) at 40 °C, considering that the diffusion is likely hindered by adsorbate molecules through internal pore channels at the middle stage of adsorption in these cases.