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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]

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]

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]

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]

[Display omitted] • A novel one-step process for enriching phenolics with high efficiency was developed. • NKA-Ⅱ resin was selected to enrich phenolics from Chaenomeles speciosa fruit. • Adsorption/desorption characteristics of phenolics on NKA-Ⅱ resin were studied. • A UPLC-QqQ-MS/MS-based quantification method was established for quality control. Chaenomeles speciosa (Sweet) Nakai fruit is a good source of phenolics with many health benefits. In this work, the enrichment of C. speciosa fruit total phenolics (CSFTP) using macroporous resins was studied. NKA-Ⅱ resin was selected for enriching CSFTP due to its highest adsorption/desorption quantity. Adsorption characteristics of CSFTP on NKA-Ⅱ resin exhibited a good fit with the Langmuir isotherm model and pseudo-second order kinetics model. This adsorption was spontaneous, exothermic, and entropy-decreasing through a physisorption mechanism. The breakthrough-elution curves were studied to optimize CSFTP enrichment conditions. One-step enrichment increased CSFTP content in the extracts from 26.51 % to 78.63 %, with a recovery of 81.03 %. A UPLC-QqQ-MS/MS method in multiple reaction monitoring (MRM) mode was established and validated for the simultaneous quantification of seven phenolic compounds. This study demonstrates the feasibility of industrial enrichment of CSFTP using NKA-Ⅱ resin and proposes a reliable method for quality control of CSFTP-rich products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Activated carbon (AC) from araçá fruit husks for atrazine adsorption. • It was a microporous material with a surface area of 431 m2 g−1. • The adsorption capacity was 35.67 mg g−1 at 328 K, and ΔH0 was 129.5 kJ mol−1. • Adsorption occurs due to electrostatic, H-bonds, π–π and n–π interactions. • The "araça" derived AC was promising in removing atrazine from aqueous solutions. The residual husks of the edible fruits of Psidium cattleianum were carbonized with FeCl 3 as an activating agent and used as an adsorbent to remove the toxic herbicide. After the carbonization step, changes in the material's structure were found. Activated carbon showed characteristics of microporous materials with a pore volume of 0.280 cm3 g−1 and surface area of 431 m2 g−1. Micrographs revealed the emergence of new cavities with a uniform and circular shape. The FTIR spectra showed the disappearance of some bands, remaining bands belonging to functional groups containing carbon, oxygen, and hydrogen. The XRD patterns confirmed the amorphous structure of the material even after the carbonization step, composed of amorphous graphitic carbon. EDS analysis showed that the carbon percentage increased and the oxygen decreased after the carbonization. The experiments were performed at neutral pH using 1 g L−1 of adsorbent. In equilibrium isotherms, the temperature played a considerable role in the adsorption capacity, increasing from 26.39 mg g−1 to 35.67 mg g−1 when the temperature varied from 298 to 328 K. The Liu isotherms were the ones that best fit the isotherm data. The changes in the adsorption enthalpy were endothermic (ΔH° 129.5 kJ mol−1). The general order kinetic model was the most adequate for kinetic data, presenting the lowest values of the Bayesian Information Criterion. Thus, activated carbon developed from the residues of the "araça" fruit showed promise in removing atrazine from aqueous solutions, with the great advantage of its high efficiency under neutral pH solutions and mild temperatures. [ABSTRACT FROM AUTHOR]

Process chromatography modelling for process development, design, and optimization as well as process control has been under development for decades. Still, the discussion of scientific potential and industrial applications needs is open to innovation. The discussion of next-generation modelling approaches starting from Langmuirian to steric mass action and multilayer or thermodynamic consistent real and ideal adsorption theory or colloidal particle adsorption approaches is continued. [ABSTRACT FROM AUTHOR]

Waste residue of Chinese prickly ash seeds were simply treated with aqueous ZnCl2 to prepared the high-performed activated carbon. It was characterized by the methods of XRD, SEM, EDX, FT-IR, BET and XPS. The synergetic adsorption performance of Chinese prickly ash seeds activated carbon for Pb2+, Ni2+ and Acid Orange IΙ (AO) was studied. In the single-component system, the adsorption capacity of Pb2+, Ni2+ and AO were 15.1, 10.7 and 188.4 mg/g, respectively. In the AO-Pb2+ system, the maximum adsorption capacity of Pb2+ and AO were 79.40 and 332.68 mg/g under temperature of 30°C and pH of 5.0, respectively. For AO-Ni2+ system, it was 375.6 and 38.3 mg/g, respectively. The adsorption kinetics was satisfactorily fitted by the pseudo-second-order model. The synergic adsorption process can be smoothly described by the non-modified Sips isotherm. [ABSTRACT FROM AUTHOR]

The thermodynamics and kinetics of the adsorption of Cd(II) ions onto oxidized activated carbon derived from mahogany pericarp were studied. The activated carbon was prepared via initial carbonization and activation by phosphoric acid, followed by oxidization using different concentrations of nitric acid (HNO3; 2.5 M, 5.0 M, and 10.0 M). With increasing concentration of HNO3, the number of carboxylic acid groups increased while the number of phenolic groups decreased. Adsorption equilibrium studies revealed that the maximum adsorption capacity for Cd(II) increased with the increasing degree of oxidation of carbon material. The adsorption of Cd2+ ions onto the oxidized carbon was best described by the Freundlich model. Results of kinetic studies showed that the adsorption of Cd(II) ions onto the oxidized activated carbon is limited by film diffusion; for the unmodified carbon, Cd(II) adsorption was limited by intraparticle diffusion. The adsorption process onto the oxidized activated carbon materials was determined to be spontaneous, at the temperature range studied (25-50 °C). [ABSTRACT FROM AUTHOR]

• Mesoporous SiO 2 adsorbents combined with Fe-oxide nanoparticles (~10 nm). • Detailed MB adsorption behaviors of Fe-oxide/SiO 2. • Kinetics, thermodynamics of MB adsorption on Fe-oxide/SiO 2. • Thermodynamic parameters of MB adsorption on Fe-oxide/SiO 2. • pH dependency of MB adsorption on Fe-oxide/SiO 2. Fe-oxide nanoparticles with a diameter of ~10 nm embedded into the porous structure of mesoporous SiO 2 particles using temperature regulated chemical vapor deposition and a subsequent annealing process. The kinetics and thermodynamics of MB adsorption on bare SiO 2 and Fe-oxide/SiO 2 particles were investigated. MB adsorption kinetics of both SiO 2 particles can be described by pseudo first order and intra particle diffusion plot. Thermodynamic parameters were calculated based on the modified Langmuir isotherm model. Equilibrium constant and spontaneity of MB adsorption was increased with the presence of Fe-oxide nanoparticles inside the SiO 2 pores , which can be ascribed to the more negative values of ΔH of Fe-oxide/SiO 2 particles compared to bare SiO 2. A higher affinity of Fe-oxide nanoparticles for MB adsorption facilitated the intra particle diffusion of MB molecules at a longer time of MB adsorption and improve the maximum MB adsorption capacities of Fe-oxide/SiO 2 compared to bare SiO 2. The maximum MB adsorption capacities of bare SiO 2 and Fe-oxide/SiO 2 particles reduced as the initial pH of MB solution increased, however, Fe-oxide/SiO 2 particles always exhibited the higher capacity of MB adsorption than bare SiO 2. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher 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.)

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department 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.)

In this paper, a novel efficient dye adsorbent, functional loofah cellulose (FL) was successfully prepared using loofah cellulose as matrix and hyperbranched polyethylenimine(HBPEI) as functionalizing reagent. Its structure was characterized by various tools. The adsorption behavior of FL to reactive brilliant red K–2BP was further discussed under different pH, different amounts of adsorbent, and interfering ion intensity. The results showed that the adsorption process belonged to Langmuir's isothermal adsorption. When the initial concentration of dye was 500 mg/L, the maximum saturated adsorption capacity was 1552 mg/g. The adsorption process conforms to the quasi-second-order adsorption kinetics and belongs to spontaneous adsorption. In addition, FL has excellent recycling and regeneration ability. [Display omitted] • An efficient dye adsorbent was synthesized. • The maximum K–2BP adsorption capacity was 1552 mg/g at 298 K. • The adsorption process was endothermic and spontaneous. • The adsorbent has excellent regeneration properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MOF derivate adsorbent of Co-MIL-300 with rich surface groups was fabricated. • It can effectively remove TCH from water by adsorption with q max = 321.5 mg/g. • The adsorption process is a spontaneous endothermic process. • It keeps a high adsorption capacity in a wide pH range (pH = 2–11). • The covalent-bonding based adsorption mechanism is supported. Metal-organic framework (MOF) based materials have aroused much research interest owing to their unique structural features in the field of environmental purification. Herein, a MOF derivate of Co-MIL-300 was prepared by sintering the cobalt-modified MIL-125(Ti) (Co-MIL) precursor at 300 °C in an air atmosphere and used as adsorbent to remove tetracycline hydrochloride (TCH, a typical emergent pollutant) from water. The Co-MIL-300 adsorbent possesses a large specific surface area, the rich surface oxygen-containing groups, the benzene-ring structure with rich π-electrons and surface cobalt ions benefiting for TCH adsorption. The TCH adsorption on Co-MIL-300 satisfies the pseudo-second-order kinetic model and Langmuir mode well, and is found to be a spontaneous endothermic and monolayer chemical adsorption process based on covalent bonding (such as π-π conjugation interactions, hydrogen bonding, π-cation interactions, coordination bonding) adsorption mechanism. Co-MIL-300 reveals a much higher adsorption capacity than Co-MIL (2.3 times of the latter) with q max = 321.5 mg⋅g−1 at 30 °C, and it also keeps a high adsorption capacity in a wide pH range (pH = 2–11). The coexisting CO 3 2–, PO 4 3-, Al3+ and Fe3+ ions can greatly inhibit TCH adsorption. Most of its adsorption capacity can be recovered in five cycles after regeneration, showing great application potential for antibiotics removal. [ABSTRACT FROM AUTHOR]

The magnetic activated carbon (MAC) from eucalyptus sawdust was prepared by one-step method and utilized to remove amoxicillin (AMX) from wastewater. MAC was characterized by N 2 adsorption-desorption, XRD, FT-IRS, Raman, XPS, FESEM, SEM-EDS, vibrating sample magnetometer (VSM) and the point of zero charges (pH pzc). The magnetic parameters of MAC were found Hc of 55.92 O e , M s of 21.68 emu g 1 and M r of 0.63 emu g 1, which resulted from existence of α-Fe and γ-Fe 2 O 3. MAC existed micropores and mesopores, the specific surface area (S BET) and average pore width were 1263.7 m2 g 1 and 2.07 nm, respectively. Batch adsorption experiments was designed to investigate AMX adsorption behavior on MAC, the adsorption mechanism was also investigated. The AMX removal efficiency was more than 94.3% when 50 mL 400 mg L 1 AMX aqueous solution (3 of pH) was adsorbed by 0.055 g MAC for 6 h at 25 °C. The AMX adsorption process was consistent with Langmuir isotherm model and the pseudo-second order kinetic model, with maximum adsorption capacities of 485.4 mg g 1 for AMX, the process was affected by the intraparticle diffusion, membrane diffusion and surface adsorption. The AMX adsorption on MAC was spontaneous nd endothermic. The adsorption of AMX on MAC was based on electrosttic interactions, π–π conjugation interactions, and hydrogen bond interactions. MAC had satisfactory adsorption capacity for AMX and recyclability. This work provides a green and environment-friendly method on antibiotic contamination wastewater treatment and a low-carbon green chemical technology for the high-value utilization of eucalyptus residues. [Display omitted] • KOH and FeCl 3 activated magnetized simultaneously ES to prepare MAC for AMX removal. • AMX adsorption on MAC was a spontaneous and endothermic chemisorption process. • MAC exhibited the maximum adsorption capacity of 485.4 mg g−1 for AMX. • Electrostatic interaction, π–π conjugation and hydrogen bond was adsorption force. • MAC is an economy and environment-friendly adsorbent. [ABSTRACT FROM AUTHOR]

Environmental behavior, bioavailability, and risks posed by Fe3O4, magnetic nanoparticles (Fe3O4 NPs) in surface waters are affected by complex geochemistry, including pH and inorganic and organic matter. This work provides a systematic analysis of adsorption of fulvic acid (FA) on surfaces of Fe3O4 NPs with adsorption kinetics, adsorption thermodynamic, and adsorption isotherm. Adsorption of FA on surfaces of Fe3O4 NPs is consistent with assumptions of Langmuir and Freundlich adsorption isotherm models. The adsorption amount of FA was inversely proportional to solution pH, and the maximum amount is 128.6 mg g−1. Adsorption of FA on surfaces of Fe3O4 NPs is a spontaneous endothermic process. FA plays an important role in aggregation and suspension/sedimentation behavior of Fe3O4 NPs in aquatic environmental. With continuous adsorption of FA, electrostatic repulsion between the particles and the steric hindrance of FA significantly decreased aggregation and increased suspension of Fe3O4 NPs. The results of FTIR and XPS indicated that FA was adsorbed on Fe3O4 NPs mainly through chemical reactions, and carbohydrates particularly play an important role in adsorption. [ABSTRACT FROM AUTHOR]

Abstract Adsorption thermodynamics of N 2 and O 2 on two most commonly used zeolites (5A and Li-LSX) under plateau special conditions of wide ranges of temperature (238–298 K) and pressure (0–300 kPa) for pressure swing adsorption (PSA) oxygen production were studied based on molecular simulations and theoretical model fitting. Adsorption isotherms for each adsorbate-adsorbent pair at different temperatures were fitted by Langmuir, Freundlich and Sips models, obtaining equilibrium parameters including adsorption capacity, strength, heterogeneity and N 2 /O 2 selectivity. Thermodynamic parameters such as Gibb's free energy, enthalpy, and entropy changes were numerically derived, and isosteric adsorption heats and distributions of potential energy were simulated. The results suggest that the adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX, leading to higher N 2 /O 2 selectivity on Li-LSX compared to 5A. For Li-LSX, N 2 /O 2 selectivity increases significantly with temperature above 273 K due to the difference in adsorption thermodynamics of N 2 and O 2 varying with temperature in terms of different adsorption heterogeneities. For 5A, the homogeneous distributions of N 2 and O 2 as well as the wide scopes of affinities from Na+ and Ca2+ exhibit N 2 /O 2 selectivity with negligible temperature dependence, which is beneficial for stable oxygen production with a fixed PSA process under large day-and-night temperature difference. This study provides theoretical basis for obtaining an optimal balance between efficiency and stability of oxygen production by using a proper mixture of Li-LSX and 5A. Highlights • Adsorption equilibrium of N 2 and O 2 on zeolites at plateau conditions are obtained. • N 2 /O 2 selectivity is higher with greater temperature dependence on Li-LSX than on 5A. • Adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX. • Advantage of thermodynamic stability of 5A over wide temperature range is discussed. [ABSTRACT FROM AUTHOR]

The adsorption properties of highly homogeneous microcrystalline cellulose pellets were investigated. The removal of the cationic dye Methylene Blue from aqueous solutions using a batch adsorption technique was studied as a typical application. Equilibrium and kinetic adsorption processes are studied. Equilibrium data were best fitted by Langmuir isotherm with an adsorption capacity about 82 mg/g. The model that best describes the kinetics of adsorption process is the pseudo-second order. Microcrystalline adsorbent regeneration using acetic acid or sulphuric acid was shown to be promising. Finally, microcrystalline cellulose pellets as a regenerable adsorbent can lead to viable application in environmental ecotechnology. [ABSTRACT FROM AUTHOR]

This paper describes instrumentation of a spectrophotometric system and its application for in-situ, real-time measurement of adsorption thermodynamics in aqueous solution by use of laboratory-constructed fiber-optic measurements. A measurement vessel was assembled from an adsorption bag, stirring and thermostatic devices, and a fiber-optic dipping probe. A macroporous adsorption resin and rutin were selected as the model adsorbent and adsorbate. In-situ liquid phase adsorption measurement of the system was achieved through monitoring of the absorption by dipping the probe in a broad range of concentrations. In-situ measurement of the AB-8 resin adsorption at temperatures from 303 K to 323 K was systematically carried out, showing that temperature was an influencing factor for the adsorption capacity and initial adsorption rate. The adsorption thermodynamic parameters for AB-8 indicated that the results well fitted the Freundlich model. In addition, a favorable, exothermic, spontaneous, physical process of rutin was demonstrated on AB-8. The obtained results showed that this method was successful at keeping the adsorption temperature constant. The application of fiber-optic sensing to the in-situ measurement of liquid phase adsorption enables automated and real-time monitoring of adsorption thermodynamics. [ABSTRACT FROM AUTHOR]

A series of functional hyper-cross-linked resins were successfully synthesized by incorporating anhydride, sulfoacid and menthanone groups into post-cross-linked polymer. They were evaluated for adsorption of 2-amino-4-methylbenzothiazole (2A4MBT) from aqueous solution. The five resins were efficient for adsorption of 2A4MBT from aqueous solution. The adsorption process includes both physical adsorption and irreversible chemical adsorption. The absolute value of adsorption enthalpy had an order of PRLMR (3.24 kJ mol−1) < IDLMR (7.96 kJ mol−1) < TMAMR (9.72 kJ mol−1) < PAMR (−13.1 kJ mol−1) < SAMR (21.8 kJ mol−1). Phthalic anhydride-modified resin could be regenerated by 10% HCl/methanol solution after adsorption equilibrium. [ABSTRACT FROM AUTHOR]

Mg-Al, Zn-Al and Mg-Fe magnetic layered double hydroxide (LDH) adsorbents were synthesized. The adsorption effect and influencing factors of these adsorbents were explored, and the adsorption mechanism of phosphorus was studied with advanced instruments. The results showed that the best adsorption performance was observed when the molar ratio of metals was 3 for the magnetic LDH adsorbents, and the maximum adsorption amount for phosphorus was 74.8, 80.8 and 67.8 mg/g for Mg-Al, Zn-Al and Mg-Fe LDHs, respectively. Pseudo-second-order kinetics could be used to describe the adsorption process of phosphorus onto the magnetic LDHs. The adsorption of phosphorus onto the magnetic LDHs was an exothermic process. Lower temperatures were favourable for adsorption, and the adsorption of phosphorus onto the magnetic LDHs was a spontaneous process. When the solid-liquid ratios were 0.10 g/L, 0.10 g/L and 0.05 g/L for Mg-Al, Zn-Al and Mg-Fe magnetic LDHs, respectively, the highest adsorption amount of phosphorus was achieved for each magnetic LDH. The maximum adsorption amount was observed at pH values of 6.0-8.0. The inhibitory effect of HCO3− on the adsorption capacity of phosphorus onto the magnetic LDHs was the strongest at a higher HCO3− concentration level. The relative content of -OH significantly reduced after adsorption of phosphorus by the FTIR analysis, which indicated that the mechanism of phosphorus removal was mainly through the exchange between hydroxyl on the adsorbent surface and phosphorus in water. XPS studies showed that oxygen provided electrons during the adsorption of phosphorus. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department 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.)

In this study, the molecularly imprinted polymers (MIPs) of capsaicin are prepared by bulk polymerization (MIPs1), precipitation polymerization (MIPs2), and surface imprinting technology based on SiO2/Fe3O4 particles (MIPs3), respectively. MIPs are characterized by scanning electron microscopy and fourier transform infrared spectroscopy. The adsorption kinetics and thermodynamics of these composites are also investigated to estimate their capacity to rebind capsaicin. The adsorption kinetics show that the adsorption process of MIPs1 is fitted to pseudo first‐order kinetic model, while the kinetic properties of MIPs2 and MIPs3 are well described by pseudo second‐order kinetic model. Adsorption thermodynamics analysis indicated that there are two kinds of binding sites with different affinity in each MIPs, whereas only one kind of binding site in non‐imprinted polymers. All adsorption isotherms of MIPs are fitted to Freundlich models, illustrated that binding sites are distributed heterogeneously in the surface of the materials, and the adsorption might occur in the multimolecular layers. Comparisons of experimental data of three MIPs are achieved and the results show that MIPs3 has the best affinity and absorption capacity to capsaicin. Moreover, the MIPs3 maintain the magnetic properties of Fe3O4 particles, which will be applied to the rapid separation of capsaicin from chili peppers samples. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 157–164 Capsaicin Molecularly Imprinted Polymers are synthesized based on bulk polymerization, precipitation polymerization, and surface molecular imprinting technique, respectively. The structures and adsorption characteristic of these polymers are investigated. The synthesized polymers based on surface molecular imprinting technique exhibit the best affinity and absorption capacity to capsaicin, which will be applied to the rapid separation of capsaicin from chili peppers samples. [ABSTRACT FROM AUTHOR]

In this study, Monascus pigments were separated from the extractive fermentation broth by the combination of reverse micellar extraction and macroporous resins (MACR) adsorption with the alkalizing S-8 MACR (S-8 ALR). A 95.07% pigment adsorption was achieved together with a relative low Triton X-100 co-adsorption that was only 2.53%. The liquid intraparticle diffusion and film diffusion limit the pigment adsorption rate. A 79.48-84.03% of the pigment could be eluted from the resin using the methanol solution containing a 0.5% (w/v) hydrochloric acid. The S-8 ALR could be recovered for cycle use without a deficit of the adsorption or desorption efficiency. Abbreviations: ACR—Acidified resin; ALR—Alkalizing resin; HPLC—High performance liquid chromatography; PSM—pigment- surfactant micelle; TEM—Transmission electron microscopy. [ABSTRACT FROM AUTHOR]

The adsorption rate, capacity, affinity of CH 4 and CO 2 in the competitive adsorption system are controlled by their adsorption thermodynamic and kinetic property. In this work, the experimental results of isothermal adsorption and adsorption kinetic experiments at different temperature and pressure are utilized to investigate the thermodynamic and kinetic mechanism of the adsorption difference between CH 4 and CO 2. Ten thermodynamic models and seven kinetic models are employed to fit the experimental data, and the thermodynamic and kinetic parameters obtained from the fitting process are used to characterize the diffusion ability, adsorption rate, adsorption capacity, adsorption strength, spontaneity of adsorption, difficulty of adsorption, and driver of adsorption in the gas adsorption process. Furthermore, their difference between CH 4 and CO 2 , temperature and pressure sensitivity, and the influence of shale property and pore structure are discussed to clarify the thermodynamic and kinetic mechanism of the higher adsorption affinity of CO 2. Results show that (i) the ability of CO 2 entering shale pores and contacting adsorption sites is greater than CH 4 , (ii) the adsorption capacity and adsorption strength of shale to CO 2 is higher, (iii) the adsorption of gas is spontaneous and enthalpy-driven, (iv) the selective coefficient of CO 2 relative to CH 4 decreases with higher experimental pressure and temperature and is caused by the higher pressure and temperature sensitivity of its thermodynamic and kinetic property. Results of this work are of specific reference for research on the adsorption thermodynamic and kinetic behavior of gases and designing schemes of CO 2 injection into shale gas reservoirs. • The adsorption of CH 4 and CO 2 are spontaneous and enthalpy-driven. • The adsorption intensity and spontaneity of CO 2 is greater than CH 4. • Complex pore structure is conducive to gases adsorption in shale reservoirs. • The adsorption thermodynamic and kinetic sensitivity of CO 2 is higher than CH 4. [ABSTRACT FROM AUTHOR]

The carbon dioxide adsorption behavior of synthesized chabazite-like M-SAPO-34 and modified with alkali metals (M = Li, Na, K, Cs), processed using volumetric method at different temperatures, was explored. The study allowed to see that the adsorption capacity increases according to the sequence: Na + > Li + > K + > Cs + , and all adsorption isothermal are type I according to Brunauer classification. Thermodynamic studies have been treated by the determination of the adsorption affinity, entropy and isosteric heat of these systems CO 2 -M-SAPO-34 with temperature variation between 273 and 298 K. The adsorption affinity shows the same trend for all the M-SAPO-34 at low coverage at 273 K. However, at high coverage, the isosteric heats of exchanged (H, Na, Li)-SAPO-34 present a homogeneous profile indicating dominance of adsorbate-adsorbate interaction. The differentials entropies were found to increase slightly with the coverage. Furthermore, the entropy of K-SAPO-34 at 273, exhibits values less than other exchanged M-SAPO-34. This Confirms pore blockage effect in the case of K-SAPO-34 and leads to reduction of free volume, while the Li-SAPO-34 shows the highest values of entropies with large free volume due to small size of Li + cation. [ABSTRACT FROM AUTHOR]

Adsorption capacity of three antimicrobial terephthaloyl thiourea cross-linked chitosan hydrogels for Congo red dye removal from its aqueous solution has been investigated for the first time in this work. These hydrogels were prepared by reacting chitosan with various amounts of terephthaloyl diisothiocyanate cross-linker. The effect of the hydrogel structural variations and several dye adsorption processing parameters to achieve the best adsorption capacity were investigated. The hydrogels' structural variations were obtained by varying their terephthaloyl thiourea moieties content. The processing variables included initial concentration of the dye solution, temperature and time of exposure to the dye. The adsorption kinetics and isotherms showed that the sorption processes were better fitted by the pseudo-second-order equation and the Langmuir equation, respectively. On the basis of the Langmuir analysis Congo red dye gave the maximum sorption capacity of 44.248 mg/g. The results obtained confirmed that the sorption phenomena are most likely to be controlled by chemisorption process. The adsorption reaction was endothermic and spontaneous according to the calculated results of adsorption thermodynamics. [ABSTRACT FROM AUTHOR]

This study investigated the efficiency of rice husk carbon (RHC) for lead (Pb (II)) adsorption. The developed RHC was characterized by CHNS analyser, FTIR and FESEM. BET surface area, micropore area, micropore volume and average pore diameter of RHC were 58.54 m/g, 14.53 m/g, 0.007209 mL/g, and 45.46 Å, respectively. Batch adsorption experiments were conducted to assess the effect of initial pH, contact time, initial Pb (II) concentration and RHC dose on Pb (II) removal. A contact time of 120 min and a pH value of 5 were found as optimum for Pb (II) adsorption; maximum adsorption occurred at 8 g/L of RHC dose. Artificial neural network (ANN) was applied to model Pb (II) adsorption. For prediction of Pb (II) adsorption from aqueous solution by RHC, the smallest mean square error (MSE) and the largest coefficient of determination (R) values were, respectively, obtained as 6.0053 and 0.988567 with Levenberg-Marquardt algorithm (LMA). Hence, it was selected as the best training algorithm. Traincgf and traincgp functions followed this function with a MSE of 6.1496 and 6.2967, respectively. Adsorption of Pb (II) by RHC followed pseudo-second-order kinetics. The experimental data were described well by both Langmuir and Freundlich isotherm models. Thermodynamics study revealed that Pb (II) adsorption by RHC was spontaneous and endothermic, and the system randomness increased during the whole process. Pb (II) adsorption capacity of RHC was compared with different adsorbents. As evidenced by its high adsorption capacity, RHC can be used as an effective adsorbent for Pb (II) removal from aqueous solutions and wastewaters. [ABSTRACT FROM AUTHOR]

[Display omitted] • An H-substituted lithium manganese oxide-sepiolite composite (HMO-SEP) was prepared. • HMO-SEP has a microsphere structure with a specific surface area of 46.49 m2/g. • Sepiolite could improve the microstructure and ion transport channels of HMO-SEP. • HMO-SEP has high adsorption capacity and excellent selective adsorption for Li+. • Li+ sorption by HMO-SEP is a spontaneous endothermic process with increasing entropy. A novel spherical structure, hydrogen-substituted lithium manganese oxide (LMO)-sepiolite (HMO-SEP) composite assembled from nanorods was fabricated via hydrothermal method combined with solid-phase method. The structure and composition of the as-prepared HMO-SEP was analyzed by a series of characterization techniques, and its adsorption behavior and characteristics for Li+ adsorption from aqueous media and recyclability were investigated in detail. The as-prepared HMO-SEP showed a typical IV-type gas adsorption isotherm with H3-type hysteresis loop at high P / P 0 , with a specific surface area of 46.49 m2/g and a pore size of 18.31 nm. The isotherm adsorption data of Li+ adsorption by HMO-SEP conform well to the Langmuir model, and the maximum adsorption capacity of Li+ reached 52.41 mg/g at 298 K. Kinetic studies showed that the adsorption process complies well with the pseudo-second-order model, reaching adsorption equilibrium within 8 h. The adsorption of Li+ by the resulting HMO-SEP is a spontaneous endothermic process with increasing entropy, with an adsorption Δ H of 21.9432 kJ/mol and an adsorption activation energy of 19.8092 kJ/mol. A suitable amount of SEP could improve the microstructure of the HMO-SEP through the interface effect between SEP and LMO. Such effect could enlarge the specific surface area and pore volume and improve the ion transport channels, thus enhancing the adsorption capacity towards Li+, stability, and recycling performance. The resulting HMO-SEP possesses excellent selective adsorption performance for Li+, even under high concentrations of Na+, K+, Ca2+, and Mg2+, stability, and regeneration–recycling performance. It has excellent potential for efficient use in the extraction of Li+ from aqueous media. [ABSTRACT FROM AUTHOR]

Zero valent iron supported on mesoporous silicanano particles (NZVI/MSNs) was prepared by the aqueous phase borohydride reduction methods. Prior to the reduction, mesoporous silica nanoparticles (MSNs) were prepared through the activation of fumed silica with concentrated HCl by refluxing at 90 °C. FTIR, XRD, FESEM, EDX and BET were used to characterize theadsorbents prepared. BET surface areas of MSNs, NZVI, and NZVI/MSNs were 126, 41, and 72 m²/g for, respectively. The performance of NZVI/MSNs as adsorbent was examined by adsorption of methylene blue (MB), performed in series of batch experiments. In the kinetic studies, pseudo first order and pseudo second order kinetic models were examined. The pseudo second order equation provided the best fit with the experimental data. Thermodynamic studies indicated that the adsorption process is endothermic with ?H° was 90.53 kJ/mol. Positive ?S° (300 J/mol) and negative ?G° (-6.42 kJ/mol) was recorded, indicating the spontaneous of the adsorption process and naturally favorable. [ABSTRACT FROM AUTHOR]

In this study, the effect of nanoparticle size on adsorption thermodynamics was investigated. The results of theoretical and experimental studies show that particle size significantly affects the equilibrium constant and thermodynamic properties of nanoadsorption. Relationships between the equilibrium constant, thermodynamic properties and particle size were derived using the thermodynamic theory of nanoadsorption. The equilibrium constant and thermodynamic properties were obtained by investigating the adsorption of Cu 2+ onto different sizes of nano-ZnO and the adsorption of Ag + onto different sizes of nano-TiO 2 . Good agreement was achieved between results obtained by experiments and predicted by theoretical analyses. The equilibrium constant and the molar Gibbs free energy of nanoadsorption were found to increase with smaller nanoparticle size. However, the effects of particle size on the molar enthalpy and the molar entropy are uncertain. In addition, the molar Gibbs free energy, the molar enthalpy, the molar entropy and the logarithm of the equilibrium constant are linearly related to the reciprocal of the diameter of the nanoparticle . The thermodynamic properties revealed in this study may provide important guidelines for research and application in the field of nanoadsorption. [ABSTRACT FROM AUTHOR]

The ideal adsorbed solution theory (IAST) is the most widespread theory for multicomponent adsorption interpretation. It postulates the existence of an adsorbed phase which behaves as a Raoult ideal solution. The theory results in a system of nonlinear algebraic equations which are solved to know the composition of the adsorbed mixture at equilibrium. In this paper an investigation on an alternative method for the IAST equations solution is proposed which is based on the minimisation of an objective function representing the iso-spreading pressure condition. This approach to the solution of the IAST equations reduces in some cases the computational effort and mitigates the issues of the currently adopted approaches (inversion of functions and initial guess). For binary systems, direct search minimisation approach is faster than the classic IAST equations solution approach up to 19.0 (Dual Langmuir isotherm) and 22.7 times (Toth isotherm). In ternary systems, this difference decreases to 10.4 (O’Brien and Myers isotherm) times. Compared to FASTIAS approach, direct search minimisation is up to 4.2 times slower in ternary systems. [ABSTRACT FROM AUTHOR]

In this article, adsorption modelling was presented to describe the sorption of textile dye, Direct Red 75 (DR75), from coloured wastewater onto the natural and modified adsorbent, Posidonia oceanica. The formulation of the double-layer model with two energy levels was based on statistical physics and theoretical considerations. Thanks to the grand canonical ensemble in statistical physics some physico-chemical parameters related to the adsorption process were introduced in the analytical model expression. Fitting results show that the dye molecules are adsorbed in parallel position to the adsorbent surface. The magnitudes of the calculated adsorption energies show that the DR75 dye is physisorbed onto Posidonia. Both Van der Waals and hydrogen interactions are implicated in the adsorption process. Despite its simplicity, the model fits a wide range of experimental data, thereby supporting the underlying data that the grafted groups facilitate the parallel anchorage of the anionic dye molecule. Thermodynamic parameters, such as adsorption energy, entropy, Gibbs free adsorption energy and internal energy were calculated according to the double-layer model. Results suggested that the DR75 adsorption onto Posidonia was a spontaneous and exothermic process. [ABSTRACT FROM AUTHOR]

Highlights: [•] Brilliant Green (BG) was adsorbed on naturally existing red clay (RC). [•] RC possessed large surface area 100.3m2/g and pore volume 0.88cm3/g. [•] The maximum monolayer adsorption of BG on RC was found to be 125mg/g. [•] BG adsorption on RC was found favorable. [Copyright &y& Elsevier]

This study presents the kinetic and thermodynamic investigations of the adsorption of crystal violet (CV) on used black tea leaves (UBTL) from aqueous solution to evaluate the feasibility of the process. The effects of concentration, solution pH and temperature on adsorption kinetics were carried out in batch process. Kinetic studies have shown that the adsorption data partially follow simple first order, second order and pseudo second order kinetic equations for different initial concentrations at pH 2.0. The equilibrium amount adsorbed, equilibrium concentration and rate constant were calculated from better fitted pseudo second order kinetic plots for different initial concentrations. The equilibrium amount adsorbed (200 mg/g at 30 °C) increased with the increase of temperature, indicated endothermic nature of the adsorption. The apparent activation energy of adsorption was determined from Arrhenius plot using pseudo second order rate constant and the value, Ea = 83.1 kJ/mol, revealed the process is chemisorption. Thermodynamic parameters: ΔH°, ΔG° and ΔS°, were determined from the equilibrium adsorption constant and the results obtained confirmed that the adsorption process was feasible, less spontaneous and endothermic. The equilibrium amount adsorbed was found to be increased with increase of solution pH from 2.0 to 6.0 indicating electrostatic interaction between cationic CV with anionic surface of UBTL dominated at higher pH due to the low zero point charge pH of UBTL. [ABSTRACT FROM AUTHOR]

The present study uses biosorption technology to remove copper(II) ions from aqueous solutions. Mature leaves of neem ( Azadirachta indica) were developed into powder form of size 32-45 μm and used as the biosorbent, while copper(II) ion solutions were prepared to be used as adsorbates. Parameters varied include copper(II) ion concentration and adsorption temperature. The neem leaf powder (NLP) dosage which was kept constant at 1.0 g L and pH was between 5 and 6. Adsorption occurred at a high rate initially and reached equilibrium after 50 min. Adsorption seemed to be more favourable at higher temperatures. Optimal temperature was found to be 333 K, with a high adsorption capacity of 146.30 mg g. Thermodynamic studies showed that the system is spontaneous and endothermic in nature, based on the parameters of Gibbs free energy (∆ G°), biosorption enthalpy (∆ H°) and biosorption entropy (∆ S°) obtained, which gave values of −2.74, 26.70 and 0.07 kJ molK, respectively. The adsorption mechanism was found to be predominantly chemisorption. SEM and EDX results show that copper(II) ions were adsorbed on the micropores of NLP. Results indicate that NLP is a suitable biosorbent for removing copper(II) ions from solutions. [ABSTRACT FROM AUTHOR]

The thermodynamics of nicotinic acid adsorption from aqueous solution on carboxymethyl cellulose Ce(IV) molybdophosphate composite cation exchanger were studied. The composite cation exchanger was synthesized by sol-gel method and thereby characterized using scanning electron microscopy, thermogravimetric analysis, X-ray powder diffraction and fourier transform infra red spectroscopy. The analytical applicability and thermodynamic parameters, such as Freundlich constant, thermodynamic equilibrium constant ( K), standard free energy changes (Δ G°), standard enthalpy changes (Δ H°) and standard entropy changes (Δ S°) of this composite cation exchanger have been evaluated. The thermodynamic parameters showed that the adsorption of nicotinic acid onto composite cation exchanger is feasible, spontaneous and exothermic, suggesting their suitability for the potential application of nicotinic acid removal from waste water. [ABSTRACT FROM AUTHOR]

Adsorption behavior of sodium montmoriilonite ( Na - MMT) was evaluated on degumming of rapeseed oils. Na - MMT was prepared with calcium montmorillonite by sodium - modification, and was analyzed with X - ray dUfraction and thermal gravimetric. The static adsorption equilibrium, adsorption kinetics and thermodynamics of phospholipids (PL) on Na - MMT were also investigated. Results showed that the theoretical maximum adsorption of PL on Na - MMT was 833. 3mg/g. The PL adsorption process was favorable, endothemic and spontaneous. Freundlich model fiited well to the adsorption isotherm, and pseudo - second order kinetics model described well on the PL adsorption kinetics. [ABSTRACT FROM AUTHOR]

The aim of present study was to investigate the adsorption properties of chitosan for the removal of Fe(II) ions from aqueous phase in a batch equilibrium system. The effects of adsorbent dose, initial pH, concentration, and temperature of the solution on adsorption were investigated. Adsorption experiments were carried out at initial concentration range of 10-50mgl-1 in a temperatures range of 20-40°C. The adsorption isotherm data were well fitted with Langmuir-Freundlich model. The kinetics of Fe(II) on chitosan followed the nonlinear form of pseudo-first-order model and the model parameters were confidently recovered. The examination of kinetic data also revealed that the adsorption rate was dominated by intraparticle diffusion mechanism. The calculated negative values of standard Gibbs free energy and enthalpy changes confirmed the spontaneous and exothermic nature of Fe(II) adsorption on chitosan adsorbent. Finally, chitosan showed to be a good potential adsorbent for removing Fe(II) ion from aqueous solution with maximum loading capacity of 28.7mg g-1 with removal efficiency of 92.9%. [ABSTRACT FROM AUTHOR]

Expanded graphite (EG) adsorbent was prepared with 50 mesh graphite as raw materials, potassium permanganate as oxidant, and vitriol as intercalation compound. Three kinds of polyvinyl alcohol (PVA) with different degree of polymerization (DP) in aqueous solution were used as adsorbates. We have studied the influence of initial PVA concentration, temperature and ionic strength on adsorption capacity. Langmuir constants and Gibbs free energy change ( Δ G°) were calculated according to experimental data respectively. Thermodynamic analysis indicates the equilibrium adsorbance of PVA on EG increase with the rise of SO42- concentration. Adsorption isotherms of PVA with different degree of polymerization are all types and we deduce PVA molecules lie flat on EG surface. Adsorption processes are all spontaneous. Kinetic studies show that the kinetic data can be described by pseudo second-order kinetic model. Second-order rate constants and the initial adsorption rate rise with the increasing of temperature and half-adsorption time decreases with the increasing of temperature. The adsorption activation energy of each PVA is less than 20 kJ.mol-1, physical adsorption is the major mode of the overall adsorption process. [ABSTRACT FROM AUTHOR]

Abstract: Drug delivery mediated by nanodiamonds (NDs) has shown great promise in controlled drug release field. In present study, dipeptide (Phe-Lys) conjugated antitumor drug doxorubicin hydrochloride (DOX) with self-immolative p-aminobenzylcarbonyl (PABC) spacer was non-covalently bound to carboxylated NDs via the electrostatic interactions. HIV-1 trans-activating transcriptor peptide (TAT) was additionally integrated to this ND-based delivery system in order to enhance the transmembrane efficiency. Fourier transforms infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and zeta potentials were applied to characterize the DOX and TAT loaded ND delivery platform. The adsorption equilibrium, kinetics and thermodynamics for the adsorption of peptide conjugated DOX onto NDs were investigated. It was found that the adsorption fitted well with the Freundlich model and conformed to pseudo-second order kinetics. It also showed that the adsorption was a spontaneous and exothermic process. Therefore, our work offered a facile way to formulate a ND-based drug delivery platform with multifunctionality in a layer by layer adsorption fashion. [Copyright &y& Elsevier]

Abstract: This research involved the efficient adsorption of an anionic dye (Reactive Red 120) by natural untreated clay, a low-cost material abundant in highly weathered soils. The adsorption kinetics was investigated using the parameters such as contact time, stirring speed, initial dye concentration, initial pH, ionic strength, and solution temperature. According to these experiments the maximum removal is observed after 80 to 100min. The results showed that acid pH is favorable for the adsorption of dye and physisorption on broken edges of clay particles seemed to play a major role in the adsorption process. It was found that the rate of adsorption decreases with increasing temperature and the process is exothermic. The adsorption kinetics followed the pseudo-second-order equation for the dye investigated in this work. Furthermore the thermodynamic activation parameters such as the enthalpy and entropy were determined. Compared to adsorption experiments on other clays, the results show that the Fouchana natural clay is an efficient adsorbent for Reactive Red 120 dye. [Copyright &y& Elsevier]

Abstract: Benzoic acid removal is important for the water treatment, and adsorption is an efficient treatment process. Three kinds of modified bentonites, hydroxy-aluminum pillared bentonite (Al(OH)-Bent), octadecyl trimethyl ammonium chloride modified bentonite (OTMAC-Bent), and both octadecyl trimethyl ammonium chloride and hydroxy-aluminum modified bentonite (Al(OH)-OTMAC-Bent) were prepared and characterized by XRD, FTIR, and BET analysis. Experiments were conducted on the adsorption of benzoic acid by the prepared modified bentonites at different temperatures in batch experiments. The results show benzoic acid adsorption capabilities of Na-Bent and Al(OH)-Bent are even low, but high for OTMAC-Bent and Al(OH)-OTMAC-Bent. Optimal conditions for the adsorption of benzoic acid on OTMAC-Bent and Al(OH)-OTMAC-Bent were as follows: pH of 3.5, 0.04g/mL adsorbent, and contact time of 90min. Increased adsorption with temperature indicates that the adsorptions of benzoic acid onto Al(OH)-OTMAC-Bent and OTMAC-Bent are spontaneous and endothermic. The adsorption data could be well interpreted by the Langmuir model and Temkin Equation. The adsorption efficiency was higher than 85%, suggesting that OTMAC-Bent and Al(OH)-OTMAC-Bent are excellent adsorbents for effective benzoic acid removal from water. [Copyright &y& Elsevier]

Abstract: The present study explored the adsorptive characteristics of Brilliant Green dye from aqueous solution onto NaOH treated saw dust of Indian Eucalyptus wood, a timber industry waste. Batch studies were performed to evaluate the influence of various experimental parameters like initial pH, contact time, adsorbent dose, initial concentration and temperature on the removal of Brilliant Green. Optimum conditions were found to be initial pH=2.9, contact time=3h and adsorbent dose=4g/l. The pseudo-second-order kinetic model represented the adsorption kinetics of Brilliant Green onto NaOH treated saw dust. Equilibrium isotherms were analyzed by Freundlich, Langmuir, Redlich–Peterson and Temkin isotherm models using non-linear regression technique. NaOH treated saw dust which was used showed surface area=0.3742m2/g, pore volume=0.00836cm3/g and average pore diameter=893.6A0. Adsorption of Brilliant Green onto NaOH treated saw dust is favorably influenced by decrease in the temperature of the operation. Thermodynamics showed that the Brilliant Green adsorption was most favorable onto NaOH treated saw dust. [Copyright &y& Elsevier]

Abstract: The adsorption thermodynamic for the adsorption of trichloroacetic acid (TCA) from aqueous solutions on composite cation exchanger polypyrrole Th(IV) phosphate has been studied. Thermodynamics of adsorption process was studied considering equilibrium time, pH, cation exchanger doses, trichloroacetic concentration and temperature as controlling parameters. Freundlich isotherm is well fitted for the adsorption results of the trichloroacetic acid. As a result some thermodynamic parameters like Freundlich constants, thermodynamic equilibrium constants (K o), standard free energy changes (ΔG°), and standard enthalpy changes (ΔH°) and standard entropy changes (ΔS°) have been evaluated. [Copyright &y& Elsevier]

The reversible adsorption process occurring on patchwise heterogeneous bivariate surfaces is studied by Monte Carlo simulation and mean-field approximation. These surfaces are characterized by a collection of deep and shallow adsorbing patches with a typical length scale l. Patches can be either arranged in a deterministic chessboard structure or in a random way. Previous studies showed that the topography of a given surface can be obtained from the knowledge of the corresponding adsorption isotherm and a reference curve. In the present work, we discuss the advantages and disadvantages of using different reference curves. One of the main consequences of this analysis is to provide an improved method for the determination of the energetic topography of the surface from adsorption measurements. [ABSTRACT FROM AUTHOR]

In the present study, expanded graphite (EG) was prepared with 50 mesh crude graphite through chemical oxidation and its adsorption kinetics and thermodynamic characteristics for polyethylene glycol (PEG) with different molecular weight (MW) in aqueous solution was investigated. We studied the influence of initial PEG concentration, temperature, pH and ionic strength on adsorption capacity. Langmuir constants and Gibbs free energy change (DG°) were calculated according to experimental data, respectively. Thermodynamic study indicates that all the equilibrium adsorbance increase with the rise in ionic strength. However, solution acidity does not have an obvious effect. Adsorption of EG for PEG with different MW is all types and PEG molecule lies flat on EG surface. Adsorption processes are all spontaneous. Kinetic studies show that the kinetic data can be delineated by pseudo second-order kinetic model. Second-order rate constants and the initial adsorption rate rise with the increasing of temperature and half-adsorption time decreases with the increasing of temperature. The adsorption activation energy of each PEG is less than 30 kJ mol-1, physical adsorption is the major mode of the overall adsorption process. [ABSTRACT FROM AUTHOR]