Sorption of aromatic compounds in water using polymer sorbents containing amino groups

Porous organic sorbents containing primary amino groups and crosslinked with divinylbenzene or ethyleneglycol dimethacrylate were used for the recovery of various organic pollutants from aqueous solutions. The kinetics of sorption of these solutes is dependent on the specific area and the average pore radius of the sorbent. Physical sorption and chemical interaction of the acid solutes with the amino functions are both involved in the sorption process. The variation of the sorption capacity with the specific area of the solute depends on the nature of the solute. Experiments with mixtures of organic solutes show that the sorption of a given solute may be increased or decreased by the presence of another one. The capacity is increased during cycles of using and regenerating the sorbent. © 1994 John Wiley & Sons, Inc.     

Dynamic interfacial tension minima in finite systems

A physical model is presented to explain the dramatic interfacial tension minima that may sometimes occur during the equilibration of a surface-active solute between two liquid phases. The effects of bulk phase mass transfer resistances, interfacial sorption kinetics, and finite phase volumes are included. Adsorption and desorption barriers are treated both by linear and Langmuir kinetics. Dynamic interfacial tension minima are predicted whenever the solute mass transfer resistance is higher and/or a large desorption barrier exists in the phase towards which transfer is occurring. Experimental dynamic tension minima for acidic organic phases contacting an alkaline aqueous phase can be rationalized by the existence of desorption barriers. The relevance of such tension minima to interfacial turbulence, spontaneous emulsification, and enhanced oil recovery is discussed.     

Quantitative Analysis of High Temperature Toxic Metal Sorption Rates Using Aerosol Fractionation

The airborne emission of toxic metals, such as lead, arsenic, and cadmium, from coal-fired boilers and incinerators is a major problem. These metals, which are considered to be semivolatile, are vaporized in the flame and subsequently form submicron particles. Since submicron particles are difficult to remove, one strategy to prevent emission is to inhibit ultra-fine particle formation within the combustor. Recent work has demonstrated that the sorbents such as kaolinite and lime are able to capture semivolatile metal vapors at high temperatures, thus preventing nucleation and condensation at lower temperatures. However, to develop practical scale technology, the rate of metal sorption by sorbents must be quantified. In this paper, an aerosol size fractionation approach is proposed to determine the extent of metal vapor-sorbent interactions above the metal dew point. The applicability of this methodology is illustrated by determining the rate of capture of cadmium by powdered, kaolinite sorbent at high combustion temperatures. An estimate of the rate of reaction was found to be 0.8 10⁹cm³ gas/mol sorbent s. A simple competitive reaction model was constructed to investigate the competition between sodium and cadmium vapor sorption on a dispersed kaolinite substrate. Previous work had demonstrated that the presence of sodium hindered the sorption of cadmium by kaolinite. Results of the competition model suggest that sodium not only competes for available sorbent but also inhibits the sorption of cadmium when both metals are present.     

INTERIONIC AND INTERMOLECULAR INTERACTIONS IN ION-EXCHANGE AND SORPTION SYSTEMS INVOLVING PHYSIOLOGICALLY ACTIVE SUBSTANCE

ABSTRACT

This paper reviews the results obtained by studying the sorption of physiologically active substances (PAS) of different types such as, amino acids, nucleotides and melanoidins on ion exchangers and non-ionogenic sorbents. The review is mainly focused upon die mechanisms of interaction of PAS molecules in the sorbent phase. The contribution of ion-ionic, ion-molecular and intermolecular interactions to the overall sorption effect is discussed. The results of studying ion-exchange isothermal supersaturation of amino acid solutions on anion exchangers are reported and discussed. The mechanisms of aging of ion-exchange materials in the course of recovery of PAS from fermentation broths and hydrolysates are proposed.     

Sorption properties toward substituted phenolic derivatives in water using macroporous polyamines containing β-cyclodextrin

Macroporous polyamines containing β-cyclodextrin (β-CD) are used for the recovery of various organic pollutants from aqueous solutions. Several insoluble polyamines with various degrees of β-CD were prepared. Studies concerning the sorption kinetics, the effect of pollutant concentration, pH of the solutions, and β-CD content are presented here. The results of sorption experiments show that these sorbents exhibit high sorption capacities toward substituted phenolic derivatives. The mechanism of sorption is both physical adsorption in the resin polymer network through acid–base interactions, ion exchange, and hydrogen bonding due to the amino groups and the formation of an inclusion complex due to the β-CD molecules through host–guest interactions, and hydrophobic interactions such as guest–guest interactions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2903–2910, 1999     

G/O/W微分散体系实现甲酸/三辛胺-正辛醇体系萃取分离

以络合萃取法实现了稀溶液中甲酸的富集。确定了高分配系数的萃取体系。根据传质基本方程建立了传质模型,计算并分析了油/水体系中的传质过程,确定传质控制步骤为甲酸自水相至水/油界面的传质。计算了分散尺寸对体系传质性能的影响,结果表明,由于水/油相比高,体系的传质系数低,界面积小,以油/水微分散乳液实现萃取过程,传质效率仍不高。引入惰性气体,并构建气/油/水体系,计算并分析了气/油/水体系中的传质过程并优化了气相加入量,结果表明,气相的加入可以有效促进传质过程。设计了双重膜分散设备,制备了微米尺度的气/油/水双重乳液,并以此实现了稀溶液中甲酸的高效富集。     

Extraction of formic acid with G/O/W microdispersion system

The enrichment of formic acid in dilute solution was achieved by complex extraction method. An extraction system with high partition coefficient was determined. The continuum model was then applied for describing mass transfer process and predicting the mass transfer characteristics in O/W system. The rate-limiting step was determined to be mass transfer of formic acid in aqueous phase, by comparison of mass transfer rates between extractant in organic phase and solute in aqueous phase. The effect of dispersion size of organic droplets on mass transfer characteristics in O/W systems was determined, indicating inefficient extraction process with low mass transfer coefficients and surficial area in O/W systems. Inert gas was introduced into extraction system and a G/O/W system was developed. The calculation of mass transfer performance in G/O/W system indicates the addition of microbubbles effectively enhances the mass transfer process. Also, suitable volumetric fraction of inert gas was optimized. According to the calculation, a double-membrane-dispersion-device was designed, with which G/O/W double emulsion was prepared and effective enrichment of formic acid from its dilute solution was realized.     

Composite Fe3O4/Humic Acid Magnetic Sorbent and its Sorption Ability for Chlorophenols and some other Aromatic Compounds

A composite magnetic sorbent with a relatively high content of humic substances (above 35% of organic carbon) was prepared by co-precipitation of Fe²⁺/Fe³⁺ salts with commercially available alkaline humate concentrate. Magnetite (Fe₃O₄) was identified as the main crystalline phase bearing the magnetic properties of the sorbent. Scanning electron microscope (SEM) images revealed the presence of uniform sub-micron structures on the surface of the sorbent grains. Due to the presence of humic substances, the sorbent exhibited good sorption ability towards low-polarity organic pollutants, namely chlorophenols. The sorption efficiency increased in the order of 4-mono- < 2,4-di- < 2,4,5-trichlorophenol in accordance with growing hydrophobicity of these compounds, confirming a hydrophobic nature of the interactions involved in the sorption process. Similar trends were found in the desorption study utilizing water and methanol as leachants. Some polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene, fluoranthene, pyrene) were also retained on the sorbent. The chemical composition as well as the main physical characteristics (surface area, phase composition) of the sorbent remained virtually unchanged during the sorption process. The sorbent retained its magnetic properties during the sorption of organic substances from aqueous solutions, which provides an opportunity for its regeneration.     

Copper Sorption from Aqueous Solutions by Plasma Modified Polyacrylonitrile Beads

Summary The adsorption of Cu(II) ions from aqueous solutions on acrylonitrile(AN) copolymer sorbents has been studied. Porous sorbents from acrylonitrile copolymer-90.6% acrylonitrile (AN), 8.1% methylmethacrylate (MMA) and 1.4% 2-acrylamido-methylpropensylfonic acid (AMPSA) have been prepared and modified by ammonia, air and ethylenediamine plasma. Fourteen types of sorbents have been obtained changing plasma agent and plasma vacuum. The Cu(II) ions uptake has been studied and the sorbent with best sorption characteristics determined. The best sorption uptake has been achieved for the modified sorbent obtained at ethylenediamine plasma modification under 5 Pa plasma vacuum (PAN1-1.20 mgeq/g). Effect of sorbents regeneration after different elution cycles has also been investigated . The sorbents showed high effectiveness of regeneration towards Cu(II) ions, which was above 50% after the IV cycle of elution.     

Penetration-sorption of cotton fibers measured by immersed weight

Weight of cotton immersed in an aqueous solution (various concentrations of NaOH) was explored as a basis for assessing penetration and sorption of the solute. The overall effects of swelling are indicated. Penetration and sorption phenomena can be identified with supplementary information, but they cannot yet be quantified. This methodology supplements and complements gel filtration as a means of measuring interactions between solutes in aqueous solution and cellulose fibers.     

Preconcentration and determination of Cu (II) from aqueous samples using functionalized sawdust and comparison with synthetic functionalized sorbents

The efficiency of indigenous functionalized sorbent (sawdust functionalized with polyaniline) was compared with synthetic functionalized sorbents (Dowex functionalized with 8-hydroxyquinoline (Dowex-8HQ) and α-nitroso-β-naphthol (Dowex-αNβN)) for preconcentration and determination of Cu (II) from aqueous samples. The synthetic functionalized sorbents and indigenous functionalized sorbent were characterized using FTIR. Different parameters like pH, equilibration time and sample volume were investigated for maximum sorption of Cu (II). Isotherm studies showed that the sorption data fitted well into Langmuir isotherm for the sawdust functionalized with polyaniline. Freundlich isotherm was followed for Dowex-8HQ and Dowex-αNβN. Four types of kinetic equations were applied to the data, and it was observed that sorption of Cu (II) followed second-order kinetics. Thermodynamically, the sorption of Cu (II) on these three sorbents was found to be exothermic and spontaneous. For maximum recovery of Cu (II) from loaded sorbents, different parameters like shaking time, eluent type, concentration and volume were investigated, and 89% Cu (II) was recovered from loaded sawdust functionalized with polyaniline and Dowex-8HQ. The interference studies showed the selectivity of sawdust functionalized with polyaniline for Cu (II) in comparison to synthetic functionalized sorbents. Thus, Cu (II) can be easily removed from aqueous samples in the presence of foreign ions.     

Détermination des caractéristiques diffusionnelles de transfert d'un solute gazeux adsorbable au sein d'un milieu poreux. Application au cas de la vapeur d'eau au sein du bois de hêtre

An experimental method is proposed to characterize the diffusional transfer of adsorbable gaseous solute medium in a porous medium. Three types of experimental measurements are used to successively access to the solute apparent diffusivity in the gas phase, in the adsorbed phase and to check whether the hypothesis of the thermodynamic equilibrium between the gas phase solute and the adsorbed solute is verified during the transient transfer process. This methodology is applied to a longitudinal section of a beech wood sample for the water transfer in the wood hygroscopic domain.     

Adsorption of chlorinated hydrocarbons from aqueous solutions by wetted and non-wetted synthetic sorbents: dynamics

In the present investigation the dynamics of the adsorption of several chlorinated hydrocarbons onto wetted and non-wetted synthetic sorbents was studied. A single particle model was developed to describe the adsorption behavior. The values of the mass transfer coefficient, needed to describe the experimental results, were found to be considerably less than those predicted from theory. The difference between measured and expected mass transfer coefficient was found to increase with non-ideality of the solute and to depend on type of sorbent. Apparently, the rate of mass transfer does not only depend on hydrodynamics but also on possible interaction between solute, solvent and sorbent.     

Computational Simulation of Mass Transfer in Molecular Separation Using Microporous Polymeric Membranes

Computational simulation was conducted to predict mass‐transfer phenomenon in the molecular separation of solute using microporous membrane contactors. Both diffusional and convectional mass‐transfer mechanisms were considered. The membrane system was a hollow‐fiber contactor in which an aqueous phase containing an organic compound was contacted with an organic phase for extractive separation of the solute. Benzoic acid was used as the solute. The main focus was on understanding the mass transfer of solute in the process. The concentration equation for the solute was solved numerically using a computational fluid dynamics approach. It was found that the model can predict the solute transport from the aqueous phase to the organic phase and can be used as a predictive model for process understanding.     

Reactivity stabilization and capacity study of fabricated alumina and zirconia-supported CaO-based sorbents for high-temperature CO2 capture in a fixed-bed reactor

Calcium looping process is a promising approach for CO₂ capture from the flue gas of fossil fuel power plants and the cement industry. Even though the advantages of calcium-based sorbents are low cost and high uptake capacity, they suffer from low durability during cycles. Modified sorbents were fabricated by adding alumina and zirconia and the mixture of alumina and zirconia to calcium oxide via the co-precipitation method. The performance of synthesized sorbents in terms of stability and CO₂ capture capacity were evaluated using a fixed bed reactor in various CO₂ sorption/desorption cycles. The sorbents were fabricated by a co-precipitation methodology using 10% binders (alumina and/or silica). X-ray diffraction (XRD), BET/BJH, and scanning electron microscopy (SEM) were conducted for characterization of synthesized sorbents. CaO-10% ZrO₂ showed the best performance among the fabricated sorbents in terms of stability during 5 cycles and CO₂ capacity (14 mmol CO₂/g sorbent). The formation of CaZrO₃ with a perovskite structure and high-temperature resistance could be attributed to well performance of zirconia-supported sorbent. On the other hand, no sign of aluminum zirconate formation was approved in XRD analysis for the fabricated sorbent using mixed binders of zirconia and alumina to enhance its stability during cycles.     

Sorption-enhanced water gas shift reaction by sodium-promoted calcium oxides

The water gas shift reaction was evaluated in the presence of novel carbon dioxide (CO₂) capture sorbents, both alone and with catalyst, at moderate reaction conditions (i.e., 300-600 °C and 1-11.2 atm). Experimental results showed significant improvements to carbon monoxide (CO) conversions and production of hydrogen (H₂) when CO₂ sorbents are incorporated into the water gas shift reaction. Results suggested that the performance of the sorbent is linked to the presence of a Ca(OH)₂ phase within the sorbent. Promoting calcium oxide (CaO) sorbents with sodium hydroxide (NaOH) as well as pre-treating the CaO sorbent with steam appeared to lead to formation of Ca(OH)₂, which improved CO₂ sorption capacity and WGS performance. Results suggest that an optimum amount of NaOH exists as too much leads to a lower capture capacity of the resultant sorbent. During capture, the NaOH-promoted sorbents displayed a high capture efficiency (nearly 100%) at temperatures of 300-600 °C. Results also suggest that the CaO sorbents possess catalytic properties which may augment the WGS reactivity even post-breakthrough. Furthermore, promotion of CaO by NaOH significantly reduces the regeneration temperature of the former.     

一种吸附式空气取水装置的性能实验

基于大气中水的吸附与解吸循环,设计出吸附式空气取水装置,并对其进行了实验研究。该装置主要由太阳能集热器、吸附床和冷凝器等组成。晚上吸附剂吸附空气中的水,白天由太阳能提供热量进行解吸。实验制备了硅胶（SC）-CaCl₂、SC-LiCl、活性炭纤维毡（ACF）-CaCl₂、ACF-LiCl 4种新型复合吸附剂,并对其进行了实验测试。结果表明：由ACF制备的复合吸附剂性能比由SC制备的复合吸附剂性能要好;ACF-LiCl的吸附与解吸性能最好,在吸附床出口温度为90℃时,解吸6 h的产水率是0.412 kg水·（kg吸附剂）^-1。     

Adsorption of Nonpolar Solutes onto Neutral Polymeric Sorbents

Abstract

Model nonpolar solutes were chosen to examine adsorption onto neutral polymeric sorbents. When n-hexane was used as the solvent hydrogen bonding appeared to play a predominant role in adsorption. Hydrogen bonds were presumably established between the carboxylic ester groups of the sorbent and either the -OH or -NH groups of the solutes. These results suggest that the specificity of hydrogen bonding can be exploited to selectively adsorb solutes from nonpolar solvents. When water was used as the solvent, adsorption increased with decreasing solute polarity; while hydrogen bonding between the solute and sorbent appeared to be less important. These results suggest that hydrophobic interactions play a major role in adsorption from aqueaous solutions, and thus the selectivity of adsorption may be limited by the nonspecific nature of hydrophobic interactions.     

Removal of sulfide ions from aqueous solutions using carbon- and silicon-containing sorbents

Sulfide ions are among the most common pollutants in natural waters. Sulfide sorption methods are widely used in the waste water treatment practice. The most promising sorbents for removing sulfide ions are porous carbon materials. In the present study we researched sorption capacity of the carbon- and silicon-containing samples of rice and buckwheat processing wastes, as well as the activated carbon, carbon fiber, chitosan and natural silicates toward the sulfide ions in aqueous solutions. It was found that the most effective sorbent from the studied ones is the carbon fiber Aktilen B (99%) and from plant wastes – carbonaceous sorbents obtained from rice straw (77–98%) and buckwheat (94%). We studied the physico-chemical and structural properties of the carbonaceous sorbent based on rice straw and it was found that this sample is amorphous and has a predominant microporous structure. At the concentration of sulfide ions ranging from 140 to 800?µg?l^?1, the studied sorbent reduces the amount of sulfide ions to 0.4–1.4 of the maximum permissible concentration and can be used for treating natural and post-treating waste waters.     

Bestimmung der sorptionsisothermen lösungsmittelfeuchter sorbentien nach der durchströmungsmethodeDetermination of sorption isotherms of solvent wetted sorbents by the through flowing method

The sorption isotherm is defined as the equilibrium moisture content of a sorbent as a function of the relative humidity at constant temperature. It is a measure for the hygroscopic behavior of the sorbent. In this work a simple and reliable method for the determination of sorption isotherms of solvent wetted sorbents is described. The sorption isotherm is determined by passing a nitrogen stream with a given relative humidity through a U-tube filled with the sorbent (through flowing method). The sorption isotherms of gas concrete, brick and clay for the sorbates isopropyl alcohol and water at 20 °C were measured. The reliability of the method was tested by comparing it with two other methods.