Mesoporous Sorbents Research Articles

Enhanced selective extraction of indium and gallium using mesoporous sorbents

Gallium (Ga) and indium (In) are essential elements in numerous industries, most notably in the rapidly evolving field of optical electronics. Due to their scarcity in natural resources coupled with escalating demand, there is an urgent need to develop sustainable technologies for extracting these elements from secondary sources. This study presents the innovative application of two highly efficient sorbents, namely mesoporous silica (SBA-15) and ligand-modified mesoporous silica, for the selective extraction of critical elements like indium and gallium from various multi-element solutions. The SBA-15 sorbent showcased remarkable efficiency in adsorbing gallium at a pH of 3, achieving an excellent adsorption capacity of approximately 90 mg/g, which surpasses previously reported values. Conversely, the ligand-modified silica demonstrated significant effectiveness in extracting indium, with an adsorption capacity of ∼ 32 mg/g at pH 3. Furthermore, SBA-15 exhibited remarkable selectivity for gallium in solutions containing Ga, In, and Zn, thereby significantly enhancing the possible recovery of Ga from In/Ga/ZnO semiconductor targets. Additionally, the sorbent displayed exceptional separation efficiency between Ga and Al as well as Ga and In. Similarly, ligand-modified silica showed high selectivity for indium in solutions containing Ga, In, and Zn, achieving excellent separation between In and Zn. Moreover, it effectively extracted indium in binary solutions of In and Sn ions, thereby advancing the recovery of indium from ITO (indium tin oxide) films. After ten cycles of reuse, the sorbents maintained their adsorption capacities, underscoring their potential for industrial applications.

The Influence of Freezing-thawing on the Properties of Sludge from Water Treatment Facilities and the Prospects for its Disposal

It has been shown that the freezing-thawing method allows a sharp increase in the water-yielding capacity of water treatment sludge (WTS sludge) and leads to an increase in the median particle size of the dispersed phase of sludge. The distribution of bound water types in WTP sludge was studied using thermogravimetry (TG), differential thermal thermogravimetry (DTG), differential scanning calorimetry (DSC) and mass spectrometry of gaseous thermolysis products (MS). It has been established that the release of water and carbon dioxide is completely completed at a temperature of 600°C. The specific surface area of the solid phase of WTP sludge before and after freezing-thawing was determined. The pore size distribution was studied. The BET isotherm of WTP sludge corresponds to mesoporous sorbents.

Preparation and stability of zinc‐based mesoporous sorbent modified with aluminium for high temperature coal gas desulphurization

AbstractZinc‐based sorbents with ordered mesoporous structure were modified with aluminium and the key factors in the preparation were optimized based on the results of desulphurization tests performed in a fixed‐bed reactor with simulated coal gas. It was shown that the sorbents for hydrogen sulphide removal reached an optimum sulphur capacity of 9.14% when prepared under conditions of 10.0 crystalline pH, 30:1 Si:Al molar ratio, 0.32:1 Zn:Si molar ratio, and 1:3 Zn:TAA molar ratio. The sorbent without aluminium was synthesized synchronously as a comparison sample to investigate the effect of aluminium addition on the desulphurization properties. The surface acidity of the sorbents is enhanced by the addition of aluminium, and the sulphur capacity of the aluminium‐doped sorbent is consequently lower compared to that of aluminium‐free sorbent. Nevertheless, the aluminium‐doped sorbent shows a significant advantage in stability of performance over multiple desulphurization–regeneration cycles and reaches an 81% retention rate of sulphur capacity after five desulphurization, while the aluminium‐free sorbent is only 51% in contrast. The characterization results manifest that aluminium enters the carrier skeleton and increases the wall thickness, which alleviates the collapse of the carrier pore channels and the agglomeration of the active components during the desulphurization process. Stable pore structures and highly dispersed active components facilitate the mass transfer in the reaction process after multiple desulphurization. As a result, the aluminium‐doped sorbent exhibits better performance stability in high temperature coal gas desulphurization.

Improving the estimation accuracy of confined vapor-liquid equilibria by fine-tuning the pure component parameter in the PC-SAFT equation of state.

We propose a thermodynamic model that combines the Young-Laplace equation and perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state to estimate capillary condensation pressure in microporous and mesoporous sorbents. We adjust the PC-SAFT dispersion-energy parameter when the pore size becomes comparable to the molecular dimension. This modelling framework is applied to diverse systems containing associating and non-associating gases, various sorbents, and a wide range of temperatures. Our simulation results show that under extreme confinement, a higher value of the dispersion-energy parameter (ε) is required. Furthermore, using the experimental saturation pressure data for 18 different associating and non-associating confined fluids, we find that the shift in the PC-SAFT dispersion energy correlates with the ratio of the sorbent mean pore size to the PC-SAFT segment size (rp/σ). By fitting to the capillary condensation data, the relative deviation between the confined and bulk PC-SAFT dispersion energy parameter is only 0.1% at rp/σ = 15; however, this deviation starts to increase exponentially as rp/σ decreases. For a sorbent with large pores, when rp/σ > 15, the capillary condensation pressure results from our model are similar to the predictions from the Kelvin equation. Using a dataset containing 235 saturation pressure data points composed of 18 pure gases and 4 binary mixtures, the overall AARD% from our model is 12.26%, which verifies the good accuracy of our model. Because the mean sorbent pore radius (rp), the PC-SAFT energy parameter (ε), and segment size (σ) are known a priori, our model estimates the corrected energy parameter for small pores and, thus, extends its applicability.

Liquid film coated porous sorbents to trap gaseous acetaldehyde

Acetaldehyde has been assigned as Group 2B carcinogen and it accounts for 70 % in aldehydes chemicals in the mainstream smoke that caused a serious environment pollution. To fabricate new effective capturer of acetaldehyde through physical rather than chemical modification, zeolites and other porous sorbents were assessed at first in the gaseous adsorption of acetaldehyde to select suitable carriers. Then MCM-22 zeolite, SBA-15 and activated carbon (AC), representing the sorbent with ordered microporous, mesoporous and gross porosity, were chosen for liquid film modification with glycerol to improve their adsorption capability through extending the contact between sorbent and adsorbate. MCM-22 among zeolites showed the best adsorptive quantity of acetaldehyde (1.3 mmol g−1), close to that of AC (1.4 mmol g−1) in gaseous phase, and the value increased about 60 % after the liquid film modification meanwhile a negative impact appeared on modified AC with the removal quantity of 1.0 mmol g−1. Similarly, the liquid film on the mesoporous sorbent SBA-15 made the adsorption capacity enhanced by 66 % (0.5 mmol g−1) than parent SBA-15 (0.3 mmol g−1), though this value is still inferior to that of AC and zeolite. Liquid film modified is proven to be efficient for zeolite to trap gaseous acetaldehyde, which offers an economic and eco-friendly strategy to control air pollution. Finally, these sorbents were tried to adsorb the acetaldehyde in cigarette smoke and among them SBA-15 showed a better performance than MCM-22 and AC, demonstrating the superior of mesopores in the face of hundreds of harmful substances.

Internal wettability investigation of mesoporous silica materials by ellipsometric porosimetry

Silica-based mesoporous films have been widely applied in the fabrication of advanced functional materials, such as anti-reflective coatings, bio-, and chemical sensing devices, due to their unique properties, e.g., high surface area, controlled porosity, and the ease and tailorability of their synthesis. Precise knowledge of their pore architecture is crucial, highlighting the need for accurate characterization tools. In this sense, ellipsometric porosimetry represents a powerful and versatile characterization platform, providing access to reliable information about total porosity, pore size, pore size dispersity, mechanical properties (Young's modulus) and surface area of a great variety of mesoporous thin films.While the underlying framework of modeling capillary condensation via the Kelvin equation is well established, one descriptor, the internal wettability of mesoporous architectures remains a challenging variable for reliable material characterization. Wetting on the nanoscale cannot be observed via the traditional drop-shape method, while approximating internal wetting by the macroscopic property can be inaccurate as the two wetting behaviors do not necessarily correlate. Herein, we present a method based on vacuum ellipsometric porosimetry for the determination of the internal contact angle of functionalized mesoporous silica thin films. Tuning of the surface energy for a known mesoporous architecture by methyl-functionalization enabled us to relate differences in the pore filling for various adsorptives (water, methanol, toluene, cyclohexane) to their internal contact angles. Our study serves as a guide for generalized internal contact angle determination suitable for a wide range of organic adsorptives and mesoporous sorbent materials.

Mesoporous silica nanocatalyst used in the preparation of the retention substance bentonite-sorbents sorption of isotherms research

In this study, the retention substance bentonite was used in the preparation of a mesoporous silica nanocatalyst. The analysis of sorbents from the sorption isotherm study and the results obtained were summarized. Also discussed are the chemical composition of bentonite from the Navbahor deposit, the types of sorbent isotherms obtained by the adsorption of various gases on sorbents, descriptions of sorbent isotherms in mesoporous sorbents, the phase composition of sorbent samples synthesized from textures, and the physic-chemical characteristics of the X-ray diffractometric catalyst, and the dependence of the characteristics of texturs of the characteristics of nanocomposite sorbents made from bentonite.

On-chip monitoring of toxic gases: capture and label-free SERS detection with plasmonic mesoporous sorbents.

The detection of the spread of toxic gas molecules in the air at low concentration in the field requires a robust miniaturized system combined with an analytical technique that is portable and able to detect and identify the molecules, as is the case with surface enhanced Raman scattering (SERS). This work aims to address capability gaps faced by first responders in real-time detection, identification and monitoring of neurotoxic gases by developing robust, reliable and reusable SERS microfluidic chips. Thus, the key performance attributes of a portable SERS detection system that must be addressed in detail are its limit of detection, response time and reusability. To this purpose, we integrate a 3D plasmonic architecture based on closely packed mesoporous silica (MCM48) nanospheres decorated with Au nanoparticle arrays, denoted as MCM48@Au, into a Si microfluidic chip designed and used for preconcentration and label-free detection of gases at a trace concentration level. The SERS performance of the plasmonic platform is thoroughly analyzed using DMMP as a model neurotoxic simulant over a 1 cm2 SERS active area and over a range of concentrations from 100 ppbV to 2.5 ppmV. The preconcentration-based SERS signal amplification by the mesoporous silica moieties is evaluated against dense silica counterparts, denoted as Stöber@Au. To assess the potential for applications in the field, the microfluidic SERS chip has been interrogated with a portable Raman spectrometer, evaluated with temporal and spatial resolution and subjected to several gas detection/regeneration cycles. The reusable SERS chip shows exceptional performance for the label-free monitoring of 2.5 ppmV gaseous DMMP.

Poly-condensation of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde for the synthesis of a highly efficient sorbent for Cs(I)

A new sorbent (ACES-F micro-particles) is readily synthesized by the one-pot reaction of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde (poly-condensation reaction). The mesoporous sorbent is characterized by BET analysis (SBET: ≈6 m2 g−1), SEM-EDX (N: ≈7–8 % and S: 5 %), FTIR spectroscopy (identification of amine, sulfonic groups and their interactions with metal ions), TGA, elemental analysis, and titration (pHPZC: ≈5.7). The study of pH effect on Cs(I) shows an optimum close to 8 (with intermediary optimum at pH 4, associated with different reactive groups). The micron-size sorbent shows fast sorption (equilibrium in 60 min) and the pseudo-first order rate equation fits the kinetic profile. The sorption isotherm reaches up to 1.99 mmol Cs g−1; the Langmuir equation models isotherm profiles. The sorption decreases with increasing temperature; sorption is exothermic. Cesium uptake is affected by the presence of NaCl; however, even in large excess of salt (i.e., 4 M) sorption remains relatively high (loss <60 %). Selectivity is confirmed by the remarkable preference of the sorbent for Cs against alkali and other competitor metal ions, especially at pHeq ≈7. Metal desorption is highly effective using 0.3 M HNO3 solutions: complete desorption occurs in 30 min. The sorbent can be recycled for at least five cycles (losses <3 %). The interest of ACES-F for cesium recovery from seawater is confirmed by the study of Cs(I) sorption (and other major elements) from Vietnam and Egypt samples. The safety of the sorbent for aqueous bodies is evaluated by the cytotoxicity of the sorbent (limited against normal cells but highly reactive for cancerous cells); while the sorbent shows interesting antimicrobial properties for Gram+, Gram- and pathogenic yeast.

Preparation of pyridine Schiff base grafted ion-imprinted mesoporous sorbent for selective separation of Pb(II) from aqueous medium

Preparation of pyridine Schiff base grafted ion-imprinted mesoporous sorbent for selective separation of Pb(II) from aqueous medium

Amine-Functionalized Mesoporous Silica Adsorbent for CO2 Capture in Confined-Fluidized Bed: Study of the Breakthrough Adsorption Curves as a Function of Several Operating Variables

Carbon capture, utilization, and storage (CCUS) is one of the key promising technologies that can reduce GHG emissions from those industries that generate CO2 as part of their production processes. Compared to other effective CO2 capture methods, the adsorption technique offers the possibility of reducing the costs of the process by setting solid sorbent with a high capacity of adsorption and easy regeneration and, also, controlling the performance of gas-solid contactor. In this work, an amine-functionalized mesoporous sorbent was used to capture CO2 emissions in a confined-fluidized bed. The adoption of a confined environment allows the establishment of a homogeneous expansion regime for the sorbent and allows to improve the exchange of matter and heat between gas and solid phase. The results illustrate how the different concentration of the solution adopted during the functionalization affects the adsorption capacity. That, measured as mg of CO2 per g of sorbent, was determined by breakthrough curves from continuous adsorption tests using different concentrations of CO2 in air. Mesoporous silica functionalized with a concentration of 20% of APTES proves to be the best viable option in terms of cost and ease of preparation, low temperature of regeneration, and effective use for CO2 capture.

Mesoporous magnesia sorbent for removal of organic contaminant methyl tert -butyl ether (MTBE) from water

ABSTRACT Methyl tertiary butyl ether (MTBE) is used as a gasoline additive formed by the reaction of isobutylene and methanol. Due to its high water solubility and low soil adsorption coefficient, leakages from storage facilities cause immediate groundwater contamination. The aim is to use alternative adsorbent for the removal of MTBE that causes various environmental and health problems. Mesoporous magnesia (MgO) that was synthesized via template-free hydrothermal method and commercial adsorbent Sepabeads-207 (SP-207) were used in this study. MTBE adsorption experiments were carried out at room temperature with a fixed sorbent/liquid ratio (0.1 g sorbent/10 mL aqueous solution) and 100–500 mg/L MTBE initial concentrations. Batch adsorption experiments showed that MgO and SP-207 have high MTBE adsorption capacity with a maximum adsorption amount of 333 and 233 mg MTBE/g adsorbent. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models of adsorption isotherms were used to investigate the adsorption behavior and the Langmuir isotherm model showed a better fit. Adsorption kinetic studies were also performed, and the pseudo-second-order kinetics fitted well with experimental data. Gibbs free energy changes of adsorption were obtained as −48.4 and −60.3 kJ/mol for MgO and SP-207, respectively. Methanol was used to regenerate the used adsorbents, and the re-use of MgO demonstrated good performance.

Hexagonal Cylinder Mesoporous Sorbent for Separation of Uranium Ions from Nitrate Media

AbstractThe synthesis of mesoporous silica monoliths‐based phosphonate groups (SiO2‐DPTS) through immobilization of diethylphosphatoethyltriethoxysilane using the post‐grafting approach to be applied as a sensitive sorbent for selective separation of U(IV) ions from aqueous solutions is described. The designed SiO2‐DPTS sorbent was characterized by Fourier transform infrared, scanning electron and high‐resolution transmission electron microscopy, scanning transmission electron microscopy/energy‐dispersive X‐ray spectroscopy, N2 adsorption‐desorption, and elemental analysis. The adsorption process was studied under different experimental conditions of pH, concentration, and time. The mechanism of interaction of SiO2‐DPTS with U(VI) ions was explored and supported by density functional theory (DFT) calculations. This synthesized sorbent allows highly efficient extraction of U(IV) ions from uranyl leach liquor.

Synthesis and characterisation of MCM-41@SiO2-NH-pydc as a new nano mesoporous sorbent: application for the simultaneous preconcentration of cationic dyes previous spectrophotometric determination, using taguchi experimental design

ABSTRACT In this study, a new nano mesoporous MCM-41@SiO2-NH-pydc was successfully synthesised and was used as a new and low-cost adsorbent for the simultaneous influential clean-up, preconcentration and determination of crystal violet (CV) and auramine O (AO) dyes. The as-synthesised sorbent was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), thermogravimetric (TGA) and derivative thermogravimetric (DTG) and Brunauer–Emmett–Teller (BET) techniques. The extraction performance was evaluated by dispersive solid phase micro extraction (DSPME) of CV and AO from real samples. The analysis was carried out by UV-Vis spectrophotometric. The analytical results confirmed that theMCM-41@SiO2-NH-pyd could be an appropriate candidate as asorbent forDSPME. The maximum recoveries (95.95% and 92.95% for CV and AO, respectively) was obtained at 0.015 g MCM-41@SiO2-NH-pydc sorbent, pH = 8.0, 500 μL DMF as eluent solvent, 20 and 10 min extraction and centrifuge time, respectively, and 50 second desorption time. After the optimum conditions, the limit of detection (LOD), quantification (LOQ) and linear range were obtained, 0.0010, 0.0033 and 0.008–0.6 mg L−1 for CV and 0.0056, 0.0187 and 0.03–1.5 mg L−1for AO, respectively. The relative standard deviations (RSD) for five analyses were 4.2% for CV and 4.6% for AO. In comprising with the previous reported methods, the developed method provided a relatively in expensive, time-saving and environmentally friendly advantages. The developed analytical method can be applied for the determination of CV and AO with sufficient sensitivity as well as acceptable reproducibility.

Лабораторные способы получения эффективных адсорбентов на основе диатомита для очистки воды от примесей хорошо растворимых органических соединений

Today there is the problem of fine water purification during its consumption and disposal in industry from impurities of water-soluble organic compounds that enter it with pharmaceutical, cosmetic preparations, food waste, waste from the textile and chemical industries. Diatomite is a good raw material for the production of these adsorbents. It is found that diatomite is the mesoporous sorbent. The permeability of diatomite can be increased by granulating of the rock. It is found that heat treatment is necessary to obtain more durable granules from diatomite: when the increasing in the temperature of heat treatment of granules the compressive strength of granules increases too. At the same time, when the temperature of the heat treatment is increasing, the equilibrium adsorption of methylene blue on diatomite granules is decreasing. The optimum temperature for the heat treatment of granules is 550 °C. It is found that the heat treatment and granulation of diatomite do not have a significant impact on the adsorptive-structural properties of the rock: up to 70 % of the pore volume of granules is the volume of mesopores. The powdered adsorbent from diatomite which can be obtained by the developed laboratory method can be used in industrial water purification schemes where static adsorption is used for fine water purification. Using the developed laboratory method for producing granular adsorbent from diatomite, it is possible to produce an adsorbent for water purification under dynamic adsorption conditions, where a high value of the sorbent permeability is important.

Radiochemical separation of no-carrier-added 186Re from proton irradiated tungsten target

Rhenium-186 [t½ = 3.7 d, 1.07 MeV β−-particles, 137 keV γ-ray] is an emerging radioisotope which holds tremendous potential in preparation of theranostic radiopharmaceuticals. This radioisotope was produced in a no-carrier-added form by irradiation of enriched 186W target via 186W(p, n) 186Re reaction in a pelletron. A facile radiochemical separation procedure based on selective solvent extraction in methylethyl ketone medium followed by column chromatography using mesoporous alumina sorbent has been developed to obtain 186Re in a form suitable for radiopharmaceutical preparation. This approach is expected to promote widespread utilization of this radioisotope for the benefit of cancer patients.

Dispersive micro solid phase extraction of busulfan from plasma samples using novel mesoporous sorbent prior to determination by HPLC-MS/MS

Determination of busulfan concentration in patients undergoing bone marrow transplantation is necessary in order to reduce toxic effects and/or graft rejection due to unadjusted dose exposure. A new extraction method namely dispersive micro solid phase extraction (DMSPE) based on mesoporous sorbent was used for cleaning-up the plasma samples. DMSPE coupling with liquid chromatography with tandem mass spectrometry (LC–MS/MS) was implemented for the determination of busulfan dosage in plasma samples. The linear range was found from 10 to 2000 ng/ml. The precision and accuracy were found better than 15% according to Food and drug Administration (FDA) guideline. This method was successfully used to determine the busulfan in patients administrated busulfan as part of the preparative regimen for bone marrow transplantation.

Synthesis of highly efficient asphalt-based carbon for adsorption of polycyclic aromatic hydrocarbons and diesel from emulsified aqueous phase

This work reports the syntheses of an inexpensive and efficient asphalt-derived mesoporous carbon (AdMC) as an adsorbent. The adsorbent was activated with potassium hydroxide to increase its surface area and then characterized by SEM–EDS, FT-IR, and BET. The adsorption properties of AdMC were evaluated for the adsorptive removal of eleven Poly Aromatic Hydrocarbons (PAHs) and diesel from water samples. The prepared AdMC showed very high surface areas and high micropore volumes equal to 2316 m2/g and 1.2 cm3/g, respectively. Various experimental conditions influencing the adsorption capacity of eleven PAHs and diesel were investigated. At high concentrations, PAHs and diesel solubility in water is very low. Hence, samples were emulsified with a surfactant, and then maximum adsorption capacity was investigated. Adsorption profile of individual PAHs was examined using gas chromatography/mass spectrometry analysis followed by liquid–liquid extraction. Total hydrocarbon removal was studied using a total organic analyzer. Asphalt-derived mesoporous sorbent showed an extreme ability to remove PAHs and diesel (average adsorption capacity of 166 mg/g for individual PAHs and diesel (maximum capacity of 1600 mg/g). The experimental results fitted the Langmuir model with a correlation efficiency of 0.9853. The results obtained for both adsorbents also matched to pseudo-second-order kinetics, suggesting that the adsorption of PAHs and diesel is chemical, monolayer, and homogeneous process.

Synthesis and characterization of a sulfonic species-based mesoporous sorbent for the pre-concentration of nine personal care products in wastewater and swimming pool water

A mesoporous material functionalized with sulfonic moieties has been synthesized by co-condensation. The functionalized material was characterized and then employed for the solid phase extraction of nine personal care products (UV filters and parabens) in effluent wastewater and swimming pool water. UV filters and parabens were analyzed by ultra performance liquid chromatography coupled to tandem mass spectrometry. Validation parameters (linearity, matrix effect, limit of quantitation, trueness and precision) were established according to the EURACHEM Guide using a blank effluent wastewater sample. The new sorbent enabled the selective extraction of the target analytes from the rest of matrix components, with low matrix effect (ME ≤ |20%|) for all analytes, the exception being isopropylparaben with a ME = −27%. The effect of the co-extracted components from the effluent water sample in the recovery study was evaluated using external calibration curves (using standard solutions) and the standard addition method. Similar results were obtained using both methodologies and, according to the validation guide requirements, slightly better results were obtained using the standard addition methodology (75.0−99.6%) compared to external calibration (66.7−115.2%). The quantitation limits ranged between 0.5 and 5.0 ng L−1 in wastewater. Two types of real samples (effluent wastewater and swimming pool water) were pre-concentrated using the optimized methodology. Four parabens (methylparaben, propylparaben, benzylparaben and butylparaben) and two UV filters (4-hydroxybenzophenone and 4,4´-dihydroxybenzophenone) were found in the effluent water sample at ng L−1 concentration levels. In addition, the same four parabens and 4,4´-dihydroxybenzophenone were detected in the swimming pool water at slightly lower concentrations than those found in wastewater.

Frontal Dynamics of the Sorption of Molecules by Mesoporous Materials of the MCM-41 Type

The sorption of molecules by MCM-41 nanostructured mesoporous sorbents under dynamic conditions is considered. A model of the dynamics of sorption of molecules that considers characteristic features of transport in sorbents, and the kinetic parameter of the ratio between the equilibrium concentrations of dissolved molecules in a solution and the phase of the adsorbent, is presented. The effect the ratio between the rates and characteristic time of the diffusion processes of sorbates in a liquid and a solid body has on the patterns of sorption is shown. The role of the nature of the adsorbent and mobile phase in contact with it is noted, and the effect the solubility and difference between the energy of interaction between the adsorbate and the solvent and adsorbent have on the change in kinetic parameter K and the width of the sorption front is considered as well. The conditions of the change in the width of the sorption front depending on the size of grains and concentration of impurity molecules in the liquid are specified. Limiting cases of the kinetics of adsorption of impurity molecules from solutions are considered.