Adsorption最新文献

Deliquescent salts are well known for their high-water vapor adsorption capacity, but they form crystalline hydrates and dissolve in adsorbed water; therefore, they cannot be used in most water vapor adsorption applications. To counter this issue, we fabricated solid polymer desiccants comprising polyacrylic acid (PAA) and sodium chloride (NaCl), which were able to capture water vapors from humidity in large quantities and avoid the dissolution of NaCl by keeping it intact inside the polymer matrix. Polymer desiccants, i.e., super-porous hydrogels (SPHs), were synthesized using gas-blowing and foaming techniques to create a porous structure. Due to dense capillary channels, the polymer matrix alone (i.e., without NaCl salt) could capture a high amount of water vapors (0.82 g_w/g_ads). Introducing NaCl salt in the polymer matrix drastically improved desiccant performance (3.1 g_w/g_ads). Further, the polymer matrix avoided salt dissolution in the adsorbed water and kept it intact within the polymer matrix. Adsorption isotherm was found to be type-III isotherm and best explained using GAB and FHH isotherm models, suggesting that the high desiccant performance of synthesized solid polymeric adsorbents was due to the presence of dense capillary channels in the polymer structure and the presence of NaCl salt within the polymer matrix. The adsorption kinetics followed the linear driving force (LDF) model and the case-II type diffusion mechanism. The desorption performance and kinetics of water release from fully hydrated desiccant samples after capturing water vapors were studied at different temperatures, suggesting that the water release rate depends highly on desorption temperature. Furthermore, the synthesized desiccants exhibited good cyclic performance for six adsorption cycles with a little loss in the desiccant performance.

Wastewater containing heavy metal ions poses great harm to human health and the environment. The adsorption materials used in traditional adsorption methods, such as starch and cellulose, are prone to hydrolysis, causing secondary pollution to water bodies. Nylon@Fe₃O₄@PAA adsorption material was obtained by using nylon as a substrate, activating nylon with sodium carbonate/hydrochloric acid, depositing a Fe₃O₄ magnetic layer by coprecipitation, and grafting polyacrylic acid. The adsorption material was used to explore the effects of different conditions (adsorption material dosage, Cu²⁺ concentration, pH value, and adsorption time) on the adsorption efficiency, adsorption capacity, and total adsorption amount of copper ions through changing the adsorption conditions. The research results showed that the adsorption material dosage was 31.25 mg (suspension solution with a concentration of 62.5 mg/mL was added with 300 μL), the concentration of Cu²⁺ solution was 20.48 mg/L, the adsorption time was 60 min, and the pH value was 9. The optimal adsorption efficiency was 82.29%, the optimal adsorption capacity was 154.87 mg/g, and the optimal total adsorption amount was 343.91 mg. After fitting thermodynamic and kinetic equations, the adsorption process of nylon@Fe₃O₄@PAA for Cu²⁺ ions dominated by chemical adsorption, with good adsorption rate and adsorption performance.

Investigating fluid behavior in nanoporous materials is essential for gas storage, separation, and catalysis applications. Here, we present a comparison of two computational methods for fluid–structure analysis in amorphous nanoporous carbon materials: three-dimensional (3D) classical density functional theory (cDFT) and grand canonical Monte Carlo (GCMC) simulations. We extended our recent development of 3D-cDFT to allow density-profile analysis without symmetry assumptions, enhancing its applicability to a broader range of porous materials. We provide a theoretical overview and discuss the advantages and limitations of each method. Our results highlight the accuracy of both 3D-cDFT and GCMC simulations while emphasizing differences in computational cost, precision, and scope. We also explore the impact of the non-crystalline structure of amorphous carbon nanopores on fluid structure and adsorption isotherms, as well as fluid–fluid and fluid–solid interactions. We offer insights for selecting computational methods in fluid structure analysis of nanoporous materials, guiding future research and optimization in advanced material development for diverse applications.

In this research, a one-step xanthation process was used to synthesize biosorbents from persimmon leaves (Diospyros kaki). The resulting biosorbents, referred to as MPM, exhibited high sorption capacities for Hexavalent chromium and Cd(II) at different pH values. Specifically, at pH 3, the Langmuir maximum adsorption capacity for Cr(VI)-MPM was determined to be 710 mg/g, while at pH 7, it was 622 mg/g for Cd(II)-MPM systems. The adsorption kinetics of both the metal ions followed the pseudo-2nd-order model, with R² values close to 1 (0.99). Through FT-IR and XPS studies, it was determined that ion exchange, surface complexation, and chelation were the primary mechanisms responsible for removing the analytes from water using MPM as sorbent. The presence of the -CS₂-Na group in MPM played a crucial role in these removal mechanisms. Additionally, MPM displayed notable antibacterial efficacy against S. aureus and E. coli. Considering its rapid kinetics, wide pH range applicability, impressive sorption capacity, recyclability, and effective antibacterial properties, MPM proves to be a highly suitable adsorbent for removing Hexavalent chromium and Cd(II) from industrial wastewater.

Carbon based nano TiO₂-ZnO composite adsorbents were developed and evaluated for simultaneous adsorption of ammonia (NH₃) and hydrogen sulphide (H₂S). Screening of composites with different ZnO and TiO₂ loadings in terms of adsorption capacities identified a composite with 10% ZnO and 5% TiO₂ (10ZnO-5TiO₂-AC) as the most suitable. Breakthrough experiments with pre-mixed gases containing 50 to 550 mg L^− 1 of each NH₃ and H₂S at 22 to 280 °C showed that increase in NH₃ and H₂S concentrations led to higher equilibrium adsorption capacities for both gases. Increase of temperature decreased NH₃ equilibrium adsorption capacity but for H₂S higher values were observed at higher temperatures. The highest equilibrium adsorption capacity of 5.71 mg NH₃ g^− 1 was obtained with a mixture of 500 ppmv NH₃ and 550 ppmv H₂S at 22 °C, while for H₂S the highest value of 29.64 mg H₂S g^− 1 was seen with a mixture of 300 ppmv NH₃ and 300 ppmv H₂S at 280 °C. Multicomponent Langmuir isotherm described the simultaneous adsorption of NH₃ and H₂S with the high level of accuracy. The negative value of enthalpy of adsorption for NH₃ confirmed the exothermic and potentially physical nature of ammonia adsorption, while a positive value for H₂S adsorption pointed out to the endothermic and chemisorption nature of this process. Examination of fresh and exposed composite adsorbents by XRD and FTIR confirmed the chemical nature of H₂S adsorption.

Immunoglobulin G (IgG) is an antibody used in numerous therapeutic indications. For this reason, high-purity IgG is required, which implies the use of selective adsorption chromatographic purification techniques. Although, before using chromatography, it is highly important to study the interaction between IgG and the adsorbent. Due to its characteristics, biopolymeric adsorbents are widely studied. However, there are no studies in the literature that evaluate IgG adsorption onto fibroin, a natural polymer that can be used as an ion exchange adsorbent. Thus, the aim of this work was to evaluate the adsorption of human IgG on fibroin microparticles. The microparticles were prepared from fibroin solution using the atomization method, with an average diameter of 108.5 μm. Three buffers (MOPS, MES and Tris–HCl), with different pH, were used, and for the best conditions, the influence of ionic strength (NaCl from 0 to 1 mol L⁻¹), temperature (4 °C to 37 °C) and rotation (20 rpm to 40 rpm) were studied. The highest adsorption capacity (906.45 mg g⁻¹) was reached with the MOPS buffer at pH 8.0, without NaCl, 25 °C and 30 rpm, which is higher than typical adsorption capacities found in the literature for other adsorbents. The adsorption capacity reduced with increasing temperature from 25 °C to 37 °C and rotation rate from 30 to 40 rpm. The thermodynamic parameters demonstrated that adsorption is spontaneous and endothermic. These results open up new possibilities of application of fibroin microparticles, considering the medium in which they are inserted, and highlights the improvement of IgG chromatographic purification for uses in pharmaceutical field.

Graphical abstract

This work reports for the first time the use of MOF-808 for the adsorption of glyphosate from a diluted herbicide formulation (Roundup®). MOF-808 was synthesized in organic solvent (MOF-808(DMF)) or in water (MOF-808(H₂O)) to compare the influence of textural characteristics on the adsorption process. In addition, the adsorption performances of these materials were compared to those of the UiO-66 and UiO-66(NH₂) series materials, which have the same SBU, allowing us to evaluate the influence of the topicity and functionalization of the ligand on the adsorption capacity of glyphosate. MOF-808 showed the highest adsorption capacity, reaching a q_max equal to 277.01 mg g⁻¹, and good kinetic performance, removing 70.3% of the glyphosate from solution in 10 min and 99.5% after 3 h of contact. MOFs UiO-66 and UiO-66(NH₂) had lower q_max values than MOF-808, possibly due to the blockage of their narrow pores by GLY, which prevents them from accessing Zr sites. The results showed an important relationship between the hydrodynamic diameter and the pore size distribution with access to active sites, consequently influencing the adsorption performance of these porous materials.

Copper ions are prevalent in the natural environment and possess toxicity as heavy metal ions. The removal of Cu²⁺ from aqueous solutions can be achieved through adsorption, which is considered a straightforward method. In this study, we employed a facile approach to synthesize pig-bone hydroxyapatite material (pHAP), and the synthesized materials were subjected to characterization using XRD, SEM, FTIR, and BET techniques. The results showed that pHAP has a pure HAP structure, and the surface of HAP has a certain porosity, which provides good conditions for the adsorption of copper ions. Batch adsorption equilibrium experiments were conducted to investigate the various influencing factors, adsorption kinetics, and isotherms. The findings revealed that the optimal adsorption condition of Cu²⁺ (50 mg/L) on pHAP was pH 7, 318.15 K, the maximum adsorption capacity was 50.25 mg/g, and the adsorption capacity was superior to some adsorbents of the same type. Moreover, it can retain 74.15% of its reusability after being reused 5 times. The adsorption mechanism primarily involves monolayer adsorption through chemical processes, particularly ion exchange, coprecipitation, and complexation reactions. Therefore, pHAP has industrial application potential in the field of copper ion adsorption.

In this study, activated carbon (AC) obtained from biomass waste materials (sunflower seed shells -SSS) was synthesized by combining chemical (H₃PO₄ 80% wt.) and thermal activation (at 544 °C). Synthesized AC exhibited a BET surface area of 1531 m² g⁻¹, and pore volume of 0.98 cm³ g⁻¹. The material exhibited various surface functional groups, such as P₂O₇, C-O-P and -COOH, O = C, as well as a moderate graphitization degree (I_D/I_G < 1) and acidity caused by H₃PO₄ treatment. Moreover, its morphology and physicochemical features were evaluated by SEM–EDS, TGA, XPS, Raman, and FT-IR techniques. The material was used to study the adsorption of anti-inflammatory pharmaceutical compounds such as ibuprofen (IBF) and diclofenac (DIF) present in natural groundwater samples. The effects of parameters such as pH, activated carbon dose, temperature, and IBF or DIF initial concentration were optimized by using a central composite design (CCD). The results revealed that optimum conditions to remove DIF and IBF from natural groundwater samples were pH of 8.0 and 7.0, an AC dose of 0.79 and 1.0 g L⁻¹, and a contact time of 60 min for DIF and IBF, respectively. A successful procedure to desorb both pollutants from adsorbent by using acetonitrile solutions was achieved, allowing the reuse study whose main results were that after four reusing cycles AC reduced its efficiency to remove DIF and IBF in 28 and 34%, respectively. Finally, the effect of ions, such as nitrate, bicarbonate, and sulfate at concentrations commonly found in natural groundwater on the adsorption of both pollutants onto AC was studied using deionized water. As a result, this study suggests considerable interest of AC in real applications due to its versatility and prolonged reuse to effectively remove anti-inflammatory compounds from natural aqueous solution.

Graphical Abstract

Exfoliated graphite (EG) is a promising macroporous sorbent for oils and liquid hydrocarbons on water surfaces. The preparation of EG includes a synthesis of graphite intercalation compounds, expandable graphite and its thermal exfoliation. The structure of the initial graphite intercalation compound (GIC) has a significant influence on the structure of exfoliated graphite and its sorption properties: sorption capacity and selectivity of water/octane sorption. Thus, the aim of this work was to investigate the relationship between the structure of EG based on 1st stage, 2nd stage, 3rd stage, 4th stage GICs and EG sorption properties and water wettability. The influence of the GIC stage number on the EG sorption and surface properties is studied. EG obtained from 1st stage GIC at 1000 °C is characterized by a higher sorption capacity toward octane than EG from 4th stage GIC. The selectivity of octane/water sorption reduces when decreasing the GIC stage number from 4 to 1. The high sorption of water can be explained by a higher surface area of EG and the presence of remaining oxygen groups on the edges of graphite crystallites in the EG structure. The EG structure was investigated by XRD, SEM, nitrogen adsorption–desorption method, FTIR and Raman spectroscopy.