Sorption Capacity Of Sorbent Research Articles

SELECTIVE SORBENTS BASED ON DIAMINODICYCLOHEXYLCROWN ETHERS

Macromolecules with crown ether groups are a fundamentally new type of sorbents whose active centers are ligands that retain electrical neutrality in the process of simultaneous binding of cations, anions, or organic compounds. The purpose of this work is to create new selective sorbents based on diaminodicyclohexylcrown ethers and to study their complexing properties with respect to alkali metal ions. Methodology. To study the composition and properties of the products of the synthesis of crown ether-containing sorbents, chemical and physicochemical methods of analysis were used: infrared spectroscopy, atomic absorption spectrophotometry. Results and discussion. Chemical grafting of cycloaliphatic crown ethers onto a macroporous chloromethylated copolymer of styrene and divinylbenzene has been carried out. Under the chosen conditions, when using diaminodicyclohexyl-18-crown-6, polycrown ethers were obtained with a content of crown ether grains of 1.42 mmol/g, when using diaminodicyclohexyl-24-crown-8, the content of macrocyclic groups was 1.24 mmol/g. The extraction of alkali metals under static conditions by grafted sorbents based on various macrocycles has been studied. The high values of the distribution coefficients of alkali metals (Na+, K+, Cs+) by the synthesized sorbents in an acidic medium are shown. The following selectivity series were found for the sorbent with diaminodicyclohexyl-18-crown-6 fragments: K+ ˃ Cs + ˃ Na+, and for the sorbent with diaminodicyclohexyl-24-crown-8 fragments: Cs+ ˃ K+ ˃ Na+ metals. Conclusion. The efficiency of extracting metal ions from aqueous solutions containing Crown esters is affected by the presence of amino groups. It is known that the amino group promotes the formation of a polymer that swells in water. It was noted that the use of sorbents based on polymers that swell in water when metal salts are removed from the aqueous medium leads to an increase in the sorption capacity of sorbents by facilitating the access of metal ions in water to the active areas of the immobilized sorbent.

Сорбционно-десорбционные свойства нанокомпозита оксид графена/полигидрохинон при извлечении редкоземельного элемента Sm (III) из уксусно-ацетатных буферных систем

The paper describes the extraction of the rare earth element Sm3+ from aqueous buffer systems by a graphene-based nanostructured composite, modified using an organic polymer – polyhydroquinone. The authors determined the important parameters of the sorption-desorption of Sm3+ ions on a new nanocomposite “graphene oxide/polyhydroquinone” during a batch test, such as: initial concentration, the sorbent weight, pH of the solution, sorption rate constants, maximum sorption capacity of the nanocomposite, percentage sorption and desorption, entropy and enthalpy of the Sm3+ extraction process. The kinetic, isothermal and thermodynamic dependences allowed to propose of the Sm3+ ions adsorption mechanisms. The kinetic data were processed by pseudo-first- and second-order, Elovich and intraparticle diffusion models, and adsorption isotherms — using the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich equations. As a result of kinetic studies, the contact time of the samarium adsorption was determined — 15 min, while the sorption capacity was 100 mg·g–1. It was found that the absorption of Sm3+ ions proceeds by a mixed diffusion mechanism and limited by the interaction “samarium ions : sorbent functional groups”. According to the Langmuir model, the maximum sorbent sorption capacity was 333.3 mg·g–1. Thus, the high efficiency of the developed graphene oxide/polyhydroquinone nanocomposite for purification of aqueous media from rare earth elements was confirmed.

Optimization of dose calculation of modified magnetite during sorption purification of water from copper ions to create environmentally friendly technology

Due to the growth of man-caused pollution, there is a need to use modern methods of water purification. It is advisable to use sorption methods for the extraction of heavy metals, which are considered to be particularly dangerous. It is established that sorbents based on magnetite are quite effective in the extraction of copper ions. It is shown that the sorption capacity of magnetite-based sorbents towards copper ions depends on the ratio of concentrations of Fe2+ and Fe3+ ions in the reaction mixture, and increases with increasing this indicator from 1/2 to 2. The sorption capacity of the sorbent towards copper ions increases by 4.4 times. It is shown that the efficiency of copper ions removal onto magnetite increases for sorbent modified with sodium sulfide. The proposed scheme provides the possibility of sorption treatment of large volumes of water from copper ions to the norms for the discharge of wastewater into fishery reservoirs. Post-productional magnetite is dehydrated and supplied to metallurgical enterprises for processing. The developed technology of water purification from copper ions is environmentally safe and energy efficient.

Research of mechanisms of transformation and removal of antibiotics from wine by sorbents of different nature

On the basis of own research, the authors experimentally confirmed the reliability of the hypothesis expressed in the scientific literature about the possibility of effective removal of nisin and natamycin from wines and wine materials. New knowledge has been obtained about the possible mechanisms of sorption of nisin and natamycin through the use of sorbents of various nature. Comparative experimental data on the interaction of sorbents with antibiotics in wines are presented. In this work, experimental data are presented that indicate different efficiency of antibiotic removal during wine processing, which is due to the structure and properties of sorbents. It has been shown that the sorption capacity of sorbents for natamycin and nisin decreases in the series: activated carbon, bentonite, and colloidal silicon dioxide. Mathematical models have been obtained for decontamination of antibiotics from wine production using sorbents of various nature.

Investigation of sorption capacity of dye-affinity sorbents in the process of purification of factor VIII coagulation

Background. Chromatographic methods, in particular affinity chromatography, are the most effective in obtaining highly purified preparations of plasma proteins. The active triazine and vinyl sulfone dyes are the special group of ligands for affinity chromatograph. We found that the dye-affinity sorbents bind non-target to factor VIII (FVIII) proteins in the previous stages of the study. The sorption capacity of the affinity sorbent is defined as the maximum amount of sample (protein) that can bind to the column under certain conditions. Determining the adsorption limit or limiting capacity of the sorbent makes it possible to identify the feasibility of its use to extract a certain type of protein.
 Objective. To study the sorption capacity of various dye-ligand affinity sorbents in the process of purification of FVIII.
 Materials and methods. We used next sorbents: Diasorb-Procion Blue HB, Diasorb-Procion Gelb M4R and Diasorb-Procion Blue MXR. The cryoprecipitate was initial material. The total protein concentration was determined by the Bradford method, the activity of factors VIII – one-stage clotting method.
 Results and discussion. Sorption of non-target proteins and FVIII activity were investigated after preparation of a number of dilutions of the initial solution of cryoprecipitate. Different concentrations of protein were applied per 1 cm3 of sorbent to select the optimal concentration and do not to oversaturate the column: I – 19.74±0.20 mg of protein/ml; II – 7.94±0.05 mg of protein/ml; III – 3.97±0.05 mg of protein/ml; IV – 1.96±0.04 mg of protein/ml. The maximum sorption capacity among the studied sorbents was 14.62±0.04 mg of protein / 1 cm3 for of sorbent Diasorb-Procion Blue HB. It was found that to achieve maximum purification of FVIII (highest specific activity), the optimal concentration of protein to 1 ml of sorbent should be in the range of 4-8 mg of protein / 1 cm3 of sorbent. The highest degree of purification for these sorbents was 19.65 times at an initial protein concentration of about 4 mg protein/ml (p≤0.01).
 Conclusions. The sorption capacity of sorbents was calculated. It was demonstrated that the maximum sorption capacity is approximately 15 (14.62±0.04) mg of protein / 1 cm3 of sorbent.

The technology of producing sorbents from linseed flax shive

Flax processing waste, flax shive is of great importance for producing sorbents from non-wooden materials in Russia. There are more than 700 thousand hectares of linseed flax crops in the country. Linseed flax shive had been burned everywhere until recently as there was no technology of its processing. The waste disposal problem in the linseed flax cultivation regions could be solved by introducing new flax waste recycling and linen producing technologies developed by scientists of the Federal Research Center for Bast Fiber Crops. In 2015-2018 some studies were carried out in research laboratories and on the experi-mental plant of the center as well as on flax-sowing farms of the Udmurt Republic, Rostov region and Krasnodar territory. The research has shown that linseed shive contains 49-51% of cellulose and 23-27% of lignin, on which the sorption capacity of the material depends. The values of flax waste sorbent sorption capacity by the effective sorption of ions in relation to heavy metals are 85-91 %, to oil products - from 3.9 to 17.3 mg/g, to iodine and methylene blue - 222 and 220 mg/g, respectively. These values don’t concede the sorbents from wood and can replace the use of the latter. The developed technology of obtaining sorbent from flax allows to organize the production directly on flax-sowing farms and flax factories applying raw materials ready to use.

Exhaust gas purification process using fly ash-based sorbents

A fly ash-based sorbents has been designed for NO2 capture and separation from exhaust gases at room temperature. NO2 adsorbents-Na-X, SBA-15, MCM-41 were prepared by synthesizing from fly ash and modifying with polyethylene glycol (PEG). The sorption capacity of sorbents have been evaluated for NO2 removal from the simulated gas streams in a thermogravimetric analyzer TGA/DSC1at 25 °C under atmospheric pressure.The results show that the highest sorption capacity characterized zeolite Na-X-(FA) 44.7 mg NO2 g-1 sorbent. After impregnation with PEG, the sorption capacity of SBA-15(FA) increased from 1.6 mg NO2g−1 to 3.2 mg NO2g−1, while for Na-X(FA) and MCM-41(FA) dropped after impregnation with PEG. In addition, the spent sorbent can be regenerated easily and completely by heating to 100 °C.With this study the present study may open a new window for developing high-performance fly ash-based sorbents for NO2 removal from exhaust gases.

SORPTION OF CERIUM(III) IONS ONTO CHELATING POLYMERIC SORBENT

In a present paper methods of concentration of Ce(III) from aqueous solutions onto synthetic polymer adsorbent. The sorption-photometric determination of the microquantities of cerium ions by new polymeric chelating sorbent, modified with dithizone has been studied. Sorption process was carried out under static conditions. Optimal characteristics of the sorption process: influence of pH, time of contact, effect of the initial concentration of metal, influence of ionic strength were studied. pH for extracting Ce is 5; the residence time is 210 min. Optimal ionic strength was achieved at a value of μ =0.6. The sorption capacity of the sorbent and the percentage recovery were determined from the difference in the initial and final concentrations of cerium(III) in the solution. The sorbability of cerium(III) ions was 91.38%, sorption capacity of sorbent with respect to cerium ions is 682.85 mg∙g-1. At the final stage, a desorption process was carried out using different (organic and mineral) acids with the same concentrations (0.5, 1.0, 1.5, and 2.0 M). 1M HCl has the highest eluting ability with respect to cerium (III) ions. Sorbent modified with dithizone based on a styrene-maleic anhydride (SMA) copolymer is proposed as synthetic sorbent with the best analytical properties (high sorption capacity, residence time 3 h with respect to cerium ions). Multiple use of the regenerated sorbent for concentration is possible. The developed techniques can be used to determine Ce(III) in standard samples, soil and tap water.

Solid-phase concentration of calcium ions with mineral sorbents in creation of anti-icing materials

The results of an experimental study of calcium ion adsorption processes carried out on various mineral sorbents of natural origin are presented. The sorption properties of the selected objects were studied and the possibility of their use as combined anti-icing materials was evaluated. In the work were investigated technological indicators of the quality of sorbents - the pH of the zero-charge point, the sorption capacity of sorbents and the optimum pH interval to determine the sorption activity of mineral raw materials on calcium ion. Analysis of the adsorption isotherms of calcium ions by the mineral sorbents studied makes it possible to note that the adsorption equilibrium on the clay is established more rapidly than on the opal of the marl type and marl. At the same time, the maximum absorption capacity of clay and marl has close values, which is related to the structure of the sorbent surface and the mineral composition of the materials. Opal of the marl type has a more developed surface, which is illustrated by a much higher absorption capacity and is confirmed by the values of the specific surface area. The obtained experimental data were processed using Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich models. When describing the adsorption equilibrium of calcium ions on mineral sorbents, the Freyndlich isotherm is a more rigorous model, which indicates the presence of a large number of active centers and their exponential distribution on the surface of sorbents. The quantitative characteristics of the adsorption capacity of sorbents, found by adsorption models, made it possible to identify the optimum conditions of processes, establish a relationship between the values of the sorption of calcium ions by their structure and the porosity of the materials. It has been established that opal of marl type is the most effective carrier for producing anti-icing materials.
 For citation:
 Dzhigola L.A., Syutova E.A. Solid-phase concentration of calcium ions with mineral sorbents in creation of anti-icing materials. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 98-104

OPERATING CHARACTERISTICS OF ADSORPTIVE REGENERATOR OF LOW-POTENTIAL HEAT AND MOISTURE BASED ON COMPOSITE SORBENTS ‘SILICA GEL – SODIUM SULPHATE’ AND ‘SILICA GEL – SODIUM ACETATE’ SYNTHESIZED BY SOL – GEL METHOD

The operating characteristics adsorptive regenerator of low-potential heat and moisture based on composite sorbents ‘silica gel – sodium sulphate’ and ‘silica gel – sodium acetate’ synthesized by sol – gel method are studied. Sorption heat regenerator operating and environmental test results are shown. Flows switch-over time is observed to depend on airflow rate and temperature differential between warm and cold ends of regenerator in steady-state conditions. Time dependences of absolute and relative humidity on the warm and cold regenerator ends are shown to be of periodic nature when both of sorbent used. Time dependences of temperature are observed to be periodic nature on warm and cold ends of regenerator and between holders with sorbent. Amplitude of time dependences of absolute and relative humidity and temperature for ‘silica gel – sodium acetate’ are stated to be less than observed when composite ‘silica gel – sodium sulphate’ used. Correspondence of temperature and humidity time dependences and sorbent sorption capacity is shown. Correlation between heat-regeneration-coefficient-dimensionless temperature differential and moisture-regeneration coefficients-dimensionless humidity differential dependences is approximated with fair accuracy for engineering calculation by linear polynomials of degree 2. Similarity of polynomials described both of dependences is shown to result from close interrelation between heat and mass transfer processes. These coefficients are shown to be capable of task-oriented variation in sufficient wide ranges by changing of half-cycle time, sorbent granules sizes and its amount. The investigation results can be used for development energy-efficient ventilation systems for residential and storage premises.

Fabrication and Characterization of Zinc Oxide Nanoparticles for the Preconcentration of Lead(II) in Milk and Water with Detection by Flame Atomic Absorption Spectrometry

ABSTRACTA method is reported for the immobilization of iminodiacetic acid on zinc oxide nanoparticles modified by N-[2-aminoethyl]-3 aminopropyltrimethoxysilane. The nanosorbent was characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and scanning electron microscopy. The preconcentration and determination of trace Pb(II) were characterized in environmental water and milk. The optimum pH for sorption of the metal was 7. The sorption capacity of sorbent was 51 mg g−1. A high recovery of Pb(II) ions was obtained from 81 to 100% with 0.5 M nitric acid as the elution solvent. The reported nanosorbent provided high accessibility of active chelating sites in the modified zinc oxide nanoparticles. The equilibrium adsorption of Pb(II) by this sorbent were characterized by Langmuir, Freundlich, Temkin, and Redlich-Peterson models.

CO2 Sorption by Hydrotalcite-Like Compounds in Dry and Wet Conditions

Abstract A pre-combustion removal option, coupling water–gas shift and CO2 capture is the well-known sorption-enhanced water–gas shift (SEWGS): the removal of CO2 produced by WGS reaction, shifting the thermodynamic equilibrium, enhances H2 production. Among the different CO2 sorbents, hydrotalcite-like compounds work at the required intermediate temperature (T = 200–400°C). Using low supersaturation method, three different sorbents were synthesized. Sieved fractions were impregnated with 20%w/w K2CO3 and then dried and subjected to thermal treatment. Sample characterization was performed by means of FT-IR spectroscopy, XRD analysis and TG-DTA analysis. Sample analysis was carried out after synthesis, thermal treatment (calcination) and after fixed bed reactor capture tests. Sorption and desorption tests were performed in a fixed bed microreactor, under cyclic conditions, at temperature level of T = 350°C and P = 5 bar in dry and wet condition. The amount of CO2 captured by the sorbent in each test was quantified by means of a first order with dead time flow distribution model applied to the experimental system. Sorption capacity of sorbents in dry conditions increases of 30% with respect to previous atmospheric pressure results obtained in fluidized bed. These sorbents seem to be good candidates to be used as a bi-functional sorbent-catalyst for SEWGS.

Amine-impregnated millimeter-sized spherical silica foams with hierarchical mesoporous–macroporous structure for CO2 capture

Abstract Millimeter-sized spherical silica foam supports with hierarchical mesoporous–macroporous structure were prepared using agar addition, foaming, and drop-in-oil method, and they were modified with polyethyleneimine (PEI) by a wet impregnation process for CO 2 capture. CO 2 sorption capacity of the millimeter-sized spherical sorbents increased as amount of PEI impregnation increased. However, the CO 2 sorption capacity of the sorbent with 70 wt% PEI impregnation loading did not show steady increase, and the maximum CO 2 sorption capacity decreased. This was attributed to the channels (i.e., small macropores) in the sorbents being clogged by the amine that remained after the mesopores had been filled up, which decreased the inward diffusion of CO 2 molecules and eventually reduced the accessibility of CO 2 molecules to the activated sites. Furthermore, the CO 2 sorption capacity of the mm-sized sorbents was shown to increase due to the bimodal macropore structure (small and large). Among the studied sorbents, SSF-PEI60 (at 56.5 wt% PEI loading) exhibited the highest CO 2 sorption capacity of 188.3 mg g −1 of sorbent, corresponding to 333.2 mg g −1 of PEI. The CO 2 sorption capacity of the spherical sorbents reported in this study does not supersede those of the particle-type sorbents reported in previous studies under the same experimental conditions. Nevertheless, these spherical sorbents are bulk-type sorbents with the best performance in terms of CO 2 capture capacity per gram of PEI among all bulk-type sorbents reported so far. Sorption stability was confirmed through 100 cycles of CO 2 sorption–desorption.

Sorption of gelatin as a protein marker on a porous substrate of birch bark bast

The applicability of sorbent made from birch bark bast as a porous substrate to the immobilization of enzymes (catalytic proteins) was studied using the sorption of gelatin as an example. The effects of pH, temperature, and the nature and concentration of supporting electrolytes (NaCl, KCl, CaCl2, and MgCl2) on the sorption of gelatin from model solutions were studied. The electrostatic interaction of gelatin with the sorbent surface prevents the adsorption of acidic and alkaline solutions. The sorption capacities of sorbent made from birch bark bast were determined at different gelatin concentrations in a model solution. The maximum sorption capacity for gelatin with the minimum time required to reach equilibrium was observed at pH 4.5.

CHARACTERIZATION OF SORBENT PRODUCED THROUGH IMMOBILIZATION OF HUMIC ACID ON CHITOSAN USING GLUTARALDEHYDE AS CROSS-LINKING AGENT AND Pb(II) ION AS ACTIVE SITE PROTECTOR

Sorbent produced through immobilization of humic acid (HA) on chitosan using glutaraldehyde as cross-linking agent and Pb(II) ions as active site protector has been characterized. Active sorption site of HA was protected by reacting HA with Pb(II) ion, and the protected-HA was then activated by glutaraldehyde, crosslinked onto chitosan, and deprotected by 0.1 M disodium ethylenediamine tetra-acetic acid (Na2EDTA). The protected-crosslinking method enhanced the content of immobilized-HA and its chemical stability. Based on the FTIR spectra, crosslinking of HA on chitosan probably occurred through a chemical reaction. The sorption capacity of sorbent still remains unchanged after the second regeneration, but some of HA start to be soluble. The latter shows that cross-linking reaction between HA and chitosan is through formation an unstable product. The effectiveness of sorbent regeneration can also be identified by the XRD pattern.

A brown coal-based sorbent for water treatment for removal of humic substances: Optimization of the sorbent manufacturing process

A two-factor mathematical model has been proposed for the preparation of a lignite sorbent designed for the removal of humic substances from water purification. It has been shown that this model adequately describes the dependence of the sorption capacity of the sorbent on the preparation conditions, the temperature and time of the heat treatment process. Based on the proposed model, optimal conditions for the manufacture of the lignite sorbent that ensures the maximum extraction of humic substances from water. By means of the experimental-statistical analysis method, the dependence of the sorption capacity of the polydisperse sorbent on the particle size was found. It has been shown that these models can effectively predict the properties of a brown coal sorbent.

Water hyacinth biomass (WHB) for the biosorption of hexavalent chromium: Optimization of process parameters

Water hyacinth (Eichhornia crassipes) biomass has been used for many years for the remediation of heavy metals. The present study successfully utilizes the dried powdered biomass of the aerial part (stem and leaves) of water hyacinth for biosorption of hexavalent chromium. The effect of various parameters (viz. pH, initial metal ion concentration and temperature) on the removal of Cr(VI) was studied by conducting only 15 sets of sorption runs using Box-Behnken Design (BBD). The pH had a negative and temperature and concentration had positive effects on uptake of chromium. The predicted results (obtained using an empirical linear polynomial model) were found to be in good agreement (R2 = 99.8%) with the experimental results. The predicted maximum removal of Cr(VI) (91.5181 mg/g) can be achieved at pH 2.0, initial metal ion concentration 300 mg/L, and temperature 40 °C. The sorption capacity of sorbent was also calculated using a Langmuir sorption isotherm model and was found to be 101 mg/g at 40 °C and pH 2.0.

Solid phase extraction of Cd(II) using mesoporous organosilicas and determination by FAAS

A simple and reproducible method for the rapid extraction and determination of trace amounts of Cd(II) ions using mesoporous organo-silicas mesoporous silica and atomic absorption spectrometry is presented. Common coexisting ions did not interfere with the separation and determination. The preconcentration factor was 100 (1 ml elution volume) for a 100 ml sample volume. The limit of detection of the proposed method is 0.7 ng L−1. The maximum sorption capacity of sorbent under optimum conditions has been found to be 5 mg of Cd per gram of sorbent. The relative standard deviation under optimum conditions was 3.0% (n = 10). Accuracy and application of the method was estimated by using test samples of natural and synthetic water spiked with different amounts of Cd(II) ion. Key words: Preconcentration, Cd(II), mesoporous organo-silica, solid phase extraction, flame atomic absorption spectrometry (FAAS).

Recovery of 137Cs and 90Sr from wastewater by sorption on finely dispersed minerals under static conditions

The natural minerals clinoptilolite and tripoli were used for sorption treatment of liquid radioactive waste (LRW) to remove 137Cs and 90Sr. The efficiency of sorption recovery of these radionuclides with finely dispersed mineral sorbents under static conditions was studied in relation to the sorption time, pH, size of mineral granules, sorbent amount, salt content and chemical composition of solutions, and number of successive sorption steps. The distribution coefficient of radionuclides between the sorbent and aqueous phase and the sorption capacity of sorbents for radionuclides were determined. It was found that treatment of real salt-containing LRW from the Leipunskii Institute of Energy Physics, State Scientific Center of the Russian Federation, with the natural sorbents decreased their activity by 2–3 orders of magnitude owing to recovery of 137Cs and 90Sr.

A physicochemical study of the sorption of lead: Correlations in a series of chelating polymer sorbents

The sorption properties of chelating polymer sorbents (CPSs), the derivatives of poly(styrene-2-oxy-azo-2′-oxybenzene), with respect to the lead ion are studied. The parameters of the sorption processes—optimum conditions of sorption (acidity, temperature, and time), the sorption capacities of sorbents, the possibility of desorption, and the stability constants of the chelated polymers—are determined. Quantitative correlations between p K′OH of the functional analytical group (FAG) of the sorbent and σ o + p(p) for ortho-and para-substituents, between p K′OH and pH50 for the formation of chelate complexes of lead, between p K′OH and the stability of lead complexes (logβ), and between σ o + p(p) and pH50 for the formation of chelate complexes of lead are established with the aim of studying regularities of the influence of the structure and acid-base properties of FAGs on parameters of chemisorption of Pb2+. It is shown that the established correlations provide a means for quantitatively predicting physicochemical parameters of sorbents and the process of sorption of lead with the aim of targeted synthesis of CPSs and their use in the chemistry of polymer compounds and in the process of concentrating.