Physicochemical properties of aminopolystyrene- and 4-amino-N-azobenzenesulfonamide-based sorbents

The acid-base properties of the functional analytical groups of new synthetic polymer sorbents manufactured on the basis of macroporous polystyrene, their physicochemical properties, and the conditions of sorption of chromate anions were studied.     

Sorption of cadmium ions from aqueous solutions onto nanoporous modified carbon sorbents

Physicochemical properties of nanoporous modified carbon sorbents and sorption of cadmium ions (0.1–20 mg L^?1) onto them from nitrate solutions at pH 5–7 were studied. The acid-base nature of functional oxygen-containing groups on the carbon surface of the sorbents was determined. The ability to sorb cadmium ions depends on the kind of chemical modification of the sorbent surface.     

Effect of technique of applying layers of metal acetylacetonates on acid-base and chromatographic properties of sorbents

A series of chromatographic sorbents, which differ by way of applying modifying chelates of acetylacetone was obtained. The acid-base and chromatographic properties of sorbents with thermally and chemically grafted layers of metal acetylacetonates were investigated. It was shown that the modifi cation of the mineral sorbents with metal acetylacetonates leads to a change in the surface acidity, as well as to an increase in the polarity and selectivity with respect to different classes of compounds.     

Zirconium sorption by chelating polymer sorbents with an <Emphasis Type="Italic">o</Emphasis>,<Emphasis Type="Italic">o</Emphasis>′-dihydroxyazo analytical functional group

The complexing properties of new chelating polymer sorbents (CPSs) with an o, o′-dihydroxyazo functionality and zirconium sorption on these sorbents were studied. Quantitative correlations were found between pK′_OH of the analytical functional groups (AFGs) of sorbents and the stability of chelates (logβ) in order to understand the lows governing the effect of the structural features and acid-base properties of the AFGs on zirconium chemisorption parameters. These correlations make it possible to quantitatively predict the physicochemical parameters of sorbents and their chelates, synthesize them, and use CPSs for zirconium preconcentration in analyses of natural and industrial objects.     

Acid-base properties of the surface of chromatographic sorbents modified by metal acetylacetonates

The acid-base properties of metal acetylacetonates and chromatographic sorbents on the basis of Chromaton N with deposited combined stationary phases from polyethylene glycol (PEG 20M) and nickel(II) and iron(III) acetylacetonates have been investigated by means of pH measurement and Hammett indicator adsorption. The change of the acid-base state of the surface of Chromaton N depending on the nature of a metal of the modifying additive, the complex structure, and the deposition method has been demonstrated.     

Factors determining the catalytic properties of active carbons in some acid-base and redox reactions

The results of the authors’ investigation of the catalytic properties of active carbons in acid-base and redox reactions are summarized. The general principles of controlling the activity of carbon catalysts are described, the main factors in the catalytic processes occurring on these catalysts are revealed, and new ways of using the catalytic properties of carbon sorbents from various sources are considered. The article was translated by the authors. Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 4, pp. 643–648.     

Synthesis of new chelate ionites and some details of their metal ion interaction

The synthetic methods for chelate ionite groups with 8-quinolinol, 8-quinolinethiol and some other thiols, thioethers or thioamides were developed, their sorbing and acid-base properties being studied as well. The stability constants of complexes of metal ions with polymeric chelate groups were determined. A method to calculate the formation function of the complexes on the basis of potentiometric data was proposed. The experiments showed the synthesized sorbents to be applicable in the selective extraction of heavy metal ions from their solutions.     

Nitrate-Citrate Sol-Gel Synthesis of Hydrated Calcium Aluminate and Sorption Materials on Its Basis

Sol-gel technique was used to develop a method for synthesis of hydrated tricalcium aluminate Ca₃[Al(OH)₆]₂ and surface-layered gas-chromatographic sorbents on its basis. The materials obtained were examined by X-ray diffraction analysis, scanning electron microscopy, X-ray fluorescence microanalysis, adsorption porosimetry, and gas chromatography. It was found that cubic Ca₃[Al(OH)₆]₂ is the main phase in the surface layer of the sorption materials. The Hammett indicator method was used to examine the acid-base properties and the variation of the content of active centers between sorbents obtained in different ways. The chromatographic retention parameters were determined for test compounds, and the polarity and selectivity of the sorbents under study was evaluated. It was shown that Chromaton N-AW modified with hydrated calcium aluminate can be used, with addition of SE-30 stationary liquid phase, to separate complex mixtures of organic compounds.     

Chelating tendencies in the rows of polymeric sorbents and their copper(II) and lead(II) complexes

The physicochemical properties of chelating polymer sorbents (CPSs), derivatives of poly(styrene-2-hydroxy-〈1-azo-1′〉-2′-hydroxybenzene), are studied with respect to copper and lead ions. The following sorption parameters are determined: the optimum acidity, temperature, and duration; the sorption capacity of the sorbent (SCS); and stability constants of polychelates. Quantitative correlations are found between the dissociation constants (pK′ _a) of the analytical functional group (AFG) of the sorbent, and the pH₅₀ of chelation of the tested metals; between p K′ _a and the stability of the complexes (logβ); and between pK′_a and the charge of the oxygen atom of the complexing group (z); these correlations are intended for use in elucidating the effect of the structural features and acid-base properties of the AFG on the chemisorption parameters of copper(II) and lead(II). These correlations predict the physical-chemical properties of sorbents and the sorption parameters of trace elements for preconcentrating and separating them from biological, natural, and technical objects     

Main factors determining the catalytic properties of active carbons

The results of the authors' investigations into the catalytic properties of active carbons in acid-base and oxidation-reduction reactions, mostly obtained in recent years, are summarized. On the basis of previous and recent data the main factors affecting the course of the catalytic processes are identified, the general principles governing control of the catalytic activity of carbon catalysts are described, and new ways of using the catalytic properties of carbon sorbents from various sources are established.Institute of Sorption and Problems of Endoecology, Academy of Sciences of Ukraine, Kiev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 32, No. 6, pp. 336–344, November–December, 1996. Original article submitted March 22, 1996.     

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.     

A Study of the Zn-based Desulfurization Sorbents for H2S Removal in the IGCC

The various Zn-based sorbents were prepared by physical mixing method and co-precipitation method. The sulfur removing capacity and regeneration properties of the various sorbents were measured in fixed bed reactor at middle temperature condition (sulfidation process 480 °C, regeneration process 580 °C). The sulfur removing capacities of the sorbents were depended on the physical properties such as pore volume, surface area and particle size. The Zn-based sorbents prepared by co-precipitation method were higher pore volume, surface area and smaller particle size resulting in the higher capacities than those prepared by the physical mixing method. To improve the regeneration properties of the sorbents, the various promoters such as cobalt, iron, nickel and cerium were added to the sorbents. The promoters have various roles with the kind of promoter. The roles of promoters could be explained by heat effect and catalytic effect of the promoters. Also, the alloyed structure like spinel structure (ZnTi₂O₄) has been proposed to explain the superior regeneration properties compared to the single ZnO structure. In addition, the simultaneous removals of the H₂S and NH₃ over the Zn–Al-based sorbents were tested at 650 °C. So, the new process for simultaneous removal using the developed Zn-based sorbents could be proposed. The role of promoters, effect of hydrogen potential pressure and the deactivation mechanism including the sulfidation of metal oxide to metal sulfide were also discussed.     

铝基氧化铜干法烟气脱硫及再生研究

采用浸渍法制备了XP型和DS型两种铝基氧化铜脱硫剂，并利用制得的脱硫剂进行了烟气循环脱硫-再生实验，同时利用BET、XRD和EPMA等方法研究了载体性质对脱硫剂性能的影响以及脱硫剂的表面微观结构在脱硫和再生过程的变化。实验和分析表明，用于制备脱硫剂的载体应同时具备较大的比表面积和合适的孔结构，实验条件下制得的铝基氧化铜脱硫剂的脱硫效率可达90％，该脱硫剂在多次循环脱硫-再生过程中性能保持稳定。     

Utilization of Weak Acid-Base Interactions to Improve Separations in Normal Phase Liquid Preparative Chromatography

Abstract

Three 40 μm derivatized silicas, two aminoalkyl and one carboxyalkyl, have been compared to 40 μm silica gel for performance in normal phase preparative liquid chromatography. The three derivatives showed higher selectivity for compounds capable of hydrogen-bond formation or acid-base interactions. Retention times were related to the basicity of the amine bonded derivatives or the acidity of the carboxylic acid derivative and the pK values of the solutes. The advantages for each of the four sorbents for neutral, acidic and basic compounds have been described.     

Use of Adsorbents for Recovery of Acetic Acid from Aqueous Solutions Part III—Solvent Regeneration

Solvent leaching was investigated as a method of regeneration for activated carbons and polymer sorbents loaded with acetic acid by contact with aqueous solutions. Both batch-equilibration and fixed-bed experiments were employed. Methanol, methyl acetate, and acetone are suitable regeneration solvents for most activated carbons. Amoco GX-031 is an exception, giving incomplete regeneration. Methanol provides still more efficient regeneration for macroreticular styrene-divinylbenzenes adsorbents. Among basic sorbents, amine resins give incomplete regeneration by solvent leaching, as does a poly N oxide. Polybenzimidazole, a weaker base, gives higher recoveries of acetic acid when leached by solvents. Poly(4-vinylpyridine) is regenerated completely and efficiently by methanol, methyl acetate, and acetone in a fixed-bed geometry. It thus appears that an intermediate degree of basicity is desirable in a synthetic sorbent for acetic acid – strong enough to give the uptake benefits of acid-base interactions, but weak enough to be regenerable.     

New type of sorbents based on polyethers and some hydrophobic anions

New type of sorbent, based on the complexing properties of polyethyleneglycols, with high selectivity for Ba and Sr is described. The dependences of K_d on the initial concentration of HNO₃ for Ba, Sr, Eu, Ce, Cs and Na were studied. The capacity of two model sorbents for uptake of Cs and Sr is given. The properties of the sorbents are compared with those of the ammonium salts of heteropolyacids.     

Determination of standard isotherms of the sorption of some vapors with cellulose

Standard isotherms of the sorption of water, methanol, and benzene vapors on cellulose using a cellulose standard are determined. The standard, namely, mesoporous cellulose with specific surface of up to 350 m2/g, is obtained by the method of exchanging water in swollen cellulose with organic solvents. A comparison of the experimental sorption isotherm with the standard isotherm makes it possible to determine the specific surface of celluloses accessible a the given sorbate and, in combination with the Brunauer-Emmett-Teller adsorption equation, to characterize their surface properties. The identity of the sorption properties of the initial and dewatered (porous) celluloses relative to active vapors is shown, which evidences the assumed mechanism of swelling as the sorbent's division into morphological structures with the formation of new surface. A comparative analysis of the sorption properties of cellulose and silica, whose nature of active sorption centers is similar (weak acid hydroxyl groups), has been made. The affinity of the standard isotherms and close values of the cross-sectional area of different sorbates on both sorbents testify the similarity in their sorption behavior. Thus, the processes of sorption with rigid and swelling sorbents can be regarded in a unified context. Therefore, the adsorption models developed for rigid sorbents can be applied to cellulose sorbents to analyze their sorption properties.     

Mineral-carbon sorbents based on post-decarbonization lime and mixture of hydrocarbons

Summary An attempt was made to obtain mineral-carbon sorbents from waste products of petrochemical industry: lime from the decarbonization of river water to be used in technology and hydrocarbon wastes obtained in the treatment of industrial waste waters. The sorbents were prepared by thermal decomposition of mixtures of the mineral and carbon components. In order to optimize the preparation conditions, physicochemical studies were performed of both the mineral matrix and the mineral-carbon sorbents. Adsorption measurements involving nitrogen, water, and benzene as adsorbates were used for determining the parameters of porous structure of the obtained materials and their hydrophilic-hydrophobic properties. The properties influencing the sorptive properties of the organic compounds present in the petrochemical wastes were pointed out.     

Complex-Emulsion synthesis of organo-inorganic amphiphilic sorbents with specific affinity for glucose

Granular organo-inorganic amphiphilic sorbents with specific affinity for glucose were synthesized with the aim of developing selective hemosorbents for efferent therapy of hyperglycemia. The sorbents were prepared in oil/water/oil complex emulsions by copolymerization of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate on the surface of selenium nanoparticles stabilized with polyvinylpyrrolidone. The phases were stabilized with excess selenium/polyvinylpyrrolidone nanocomplexes. Optimum synthesis conditions ensuring formation of hybrid sorbents with the physicochemical properties required for performing efficient preparative hemosorption and plasma adsorption processes were found. The specific affinity for glucose was reached by modification of these sorbents via imprinting with template glucose molecules in the surface polymer layer and via introduction of boric acid as an affine ligand into the hybrid matrices.