Component Sorption Research Articles

Copper(II) and lead(II) removal from aqueous solution in fixed-bed columns by manganese oxide coated zeolite

The ability of manganese oxide coated zeolite (MOCZ) to adsorb copper and lead ions in single- (non-competitive) and binary- (competitive) component sorption systems was studied in fixed-bed column. The experiments were applied to quantify particle size, bed length, influent flow rate and influent metal concentration on breakthrough time during the removal of copper and lead ions from aqueous solutions using MOCZ column. Results of fixed-bed adsorption showed that the breakthrough time appeared to increase with increase of the bed length and decrease of influent metal concentration, but decreased with increase of the flow rate. The Thomas model was applied to adsorption of copper and lead ions at bed length, MOCZ particle size, different flow rate and different initial concentration to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The model was found suitable for describing the adsorption process of the dynamic behavior of the MOCZ column. The total adsorbed quantities, equilibrium uptakes and total removal percents of Cu(II) and Pb(II) related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different conditions. The results suggested that MOCZ could be used as an adsorbent for an efficient removal of copper and lead ions from aqueous solution. The removal of metal ion was decreased when other additional heavy metal ion was added, but the total saturation capacity of MOCZ for copper and lead ions was not significantly decreased. This competitive adsorption also showed that adsorption of lead ions was decreased insignificantly when copper ions was added to the influent, whereas a dramatic decrease was observed on the adsorption of copper ions by the presence of lead ions. The removal of copper and lead ion by MOCZ columns followed the descending order: Pb(II) > Cu(II). The adsorbed copper and lead ions were easily desorbed from MOCZ with 0.5 mol l −1 HNO 3 solution.

Removal of copper(II) and lead(II) from aqueous solution by manganese oxide coated sand: II. Equilibrium study and competitive adsorption

The adsorption equilibrium of MOCS and the Cu(II) and Pb(II) ions removal capacity by MOCS in single-(non-competitive) and binary-(competitive) component sorption systems from aqueous solutions were investigated. The equilibrium data were analyzed using the Langmuir, Freundlich, Temkin and Redlich–Peterson isotherms. The characteristic parameters for each isotherm were determined. The Langmuir and Redlich–Peterson isotherms provided the best correlation for both Cu(II) and Pb(II) onto MOCS. From the Langmuir isotherms, maximum adsorption capacities of MOCS towards Cu(II) and Pb(II) are determined at different temperature. The maximum adsorption capacity of Cu(II) and Pb(II) per gram MOCS in single component sorption systems were from 5.91 and 7.71μmol to 7.56 and 9.22μmol for the temperature range of 288–318K, respectively. The order of affinity based on a weight uptake by MOCS was as follows: Pb(II)>Cu(II). The same behavior was observed during competitive adsorption that is in the case of adsorption from their binary solution. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for Cu(II) and Pb(II) sorption on MOCS were also determined from the temperature dependence. This competitive adsorption showed that the uptake of each metal was considerably reduced with an increasing concentration of the other, the adsorption of Cu(II) being more strongly influenced by Pb(II) than vice versa due to the higher affinity of MOCS for the latter.

Influence of sucrose and water content on molecular mobilityin starch‐based glasses as assessed through structureand secondary relaxation

Molecular mobility is known to be a key parameter in controlling the physical properties of materials and thus their quality and performance. Beyond glass transition related changes, attention should be called to the impact of local motions remaining in the glassy state. Gelatinized waxy maize starch at different sucrose contents (0-20% solids) was equilibrated between 0 and 14% water and sorption isotherms determined at 25 degrees C. The effect of water and sucrose content on the molecular mobility of glassy starch was investigated by differential scanning calorimetry through enthalpy relaxation studies and dynamical mechanical thermal analysis. The existence of sucrose-starch interactions was suggested by the sorption isotherms not following the expected additivity of the single component sorption curves. Contrary to the glass transition or associated alpha relaxation, water and sucrose affected differently the secondary relaxations. Indeed, the beta relaxation observed around -15 degrees C was shifted to lower temperature upon increasing hydration, and to higher temperature when sucrose content increased, suggesting a hindering of these local motions. Enthalpy relaxation of the ternary mixtures was studied following aging up to 668 h at Tg -15 degrees C. Ternary mixtures exhibited an enthalpy relaxation upon aging lower than starch alone as a sign of lower polymer mobility in the presence of small molecules, contrary to the free volume theory. Relaxation kinetics were characterized with the Cowie-Ferguson model and compared to literature data. The extent of the enthalpy relaxation appeared to be controlled by the distance between the aging temperature and the beta relaxation temperature.

Diffusion of Alkane Mixtures in Zeolites: Validating the Maxwell−Stefan Formulation Using MD Simulations

Molecular dynamics (MD) simulations have been carried out for pure components, binary, ternary, and quaternary mixtures containing methane, ethane, propane, and n-butane in FAU zeolite at 300 K for a range of molecular loadings Theta, approaching saturation limits. The n-dimensional matrix of Maxwell-Stefan (M-S) diffusivities [Delta], defined by (N) = -rho[Delta][Gamma](nabla Theta), was determined along with the self-diffusivities, D(i)(,self). Additionally, configurational-bias Monte Carlo (CBMC) simulations were carried out to obtain the pure component sorption isotherms and the saturation capacities Theta(i)(,sat). From the information on Delta(ij), D(i)(,self), and Theta(i)(,sat), the various M-S diffusivities were determined: (1) component D(i), reflecting the interactions of the species i with the zeolite, self-exchange D(ii), and (2) binary exchange D(ij). The obtained data underline the major advantage of the M-S formulation that at a given occupancy, theta = Sigma(N)(n)(i=l)Theta(j)/Theta(j)(,sat) within the zeolite, the D(i) has nearly the same value for species i whether this species is present on its own or in a mixture with other species. The same advantage holds, too, for the self-exchange D(ii); the value at a given occupancy, theta, is the same whether determined from pure component, binary, or ternary mixture data. For all binary and ternary mixtures studied, it was verified that the binary exchange coefficient D(ij) can be interpolated from the corresponding values of the self-exchange parameters D(ii) and D(jj) using a generalization of the interpolation formula developed earlier (Skoulidas et al., Langmuir, 2003, 19, 7977). We also demonstrate that if the occupancy dependence of the pure component parameters D(i) and D(ii) are modeled properly, this information is sufficient to provide very good estimates of the matrix [Delta] for mixtures with 2, 3, or 4 components over the entire range of loadings. Simulations of mixture diffusion of alkanes in MFI and LTA confirm that the above-mentioned advantages of the M-S formulation also hold for these zeolite topologies.

A kinetic study of metal complex dye sorption onto pine sawdust

The removal of metal complex dyes, Metal Complex Blue (MCB) and Metal Complex Yellow (MCY), from aqueous solutions by pine sawdust has been studied in single component sorption systems. The aim of this study was to understand the mechanisms that govern metal complex dyes removal and find a appropriate model for the kinetics of removal in a batch reactor. In order to investigate the mechanism of sorption and potential rate controlling steps, pseuso first- and second-order equations, intraparticle diffusion equation and the Elovich equation have been used to test experimental data. Kinetic analysis of the four models has been carried out for system variables—particle size and mass of sawdust, pH and initial dye concentration. The rate constants for the four models have been determined and the correlation coefficients have been calculated in order to assess which model provides the best fit predicted data with experimental results. Both pseudo second-order equation and the Elovich equation provide the best fit to experimental data.

The dynamics of moisture migration in packaged multi-component food systems II: analytical solutions and comparison to experimental moisture transfer rate results

The previously proposed kinetic theory of moisture migration in packaged multi-component systems is developed further and tested against experimental data. Two simplified analytical solutions suitable for implementation without special purpose software have been found. The first solution concerns the case where the moisture exchange of one component is rate limiting. The other solution describes the situation where all components are characterized by the same moisture uptake dynamics (response function). The numerical calculations using the full theory as well as the solution assuming same sorption dynamics of all components are shown to be in accordance with experimental data for the moisture transfer in closed systems containing binary or ternary mixtures of raisins, roasted almonds, peanuts and banana chips. The calculations show that the headspace water activity is distinctly different from the water activities of the components at any time indicating that no single component sorption process is rate limiting. The implications of the theory are that the information of dynamics of moisture sorption of the individual food components under constant humidity conditions can be utilized in simple expressions for the time development of component moisture contents with the possibility of making shelf life calculations on any combinations of the food components.

Sorption kinetics for the removal of copper and zinc from effluents using bone char

Abstract The removal of copper and zinc ions from aqueous effluents by bone char has been studied in single component sorption systems. The sorption capacity of bone char for copper and zinc is 0.75 and 0.53 mmol per g bone char, respectively. The values indicate that bone char is a suitable sorbent for the two metal ions. The equilibrium isotherms are best described by a Langmuir–Freundlich (L–F) type isotherm equation. The kinetics of sorption of the two metal ions have been analyzed by two kinetic models, namely, the Lagergren pseudo first-order model and the Elovich kinetic model. Kinetic analysis of the two models has been carried out for system variables — initial metal ion concentration and mass of bone char. The rate constants for the two models have been determined and the correlation coefficients have been calculated in order to assess which model provides the best fit predicted data with experimental results. The Elovich equation provides the best fit to experimental data.

Pure and binary component sorption equilibria of light hydrocarbons in the zeolite silicalite from grand canonical Monte Carlo simulations

Results of grand canonical Monte Carlo (GCMC) simulations of methane, ethane, propane and their binary mixtures in the zeolite silicalite are presented. The simulations show good agreement with experimentally obtained isotherms and isosteric heats. The binary simulations agree well with predictions made using the Ideal Adsorbed Solution (IAS) theory. This indicates that these light hydrocarbons behave ideally within the silicalite pores, in agreement with previous experiments [J.A. Dunne, M. Rao, S. Sircar, R.J. Gorte, A.L. Myers, Langmuir 13 (1997) 4333–4341]. All three species prefer to locate within the channel regions of silicalite, occupying the spacious but energetically unfavorable intersection regions only at the highest pressures.

Time-Dependent Permeance of Gas Mixtures through Zeolite Membranes

The time-dependent permeation behavior of binary gas mixtures through a ZSM-5 zeolite membrane was studied. Although steady-state permeation rates were indistinguishable for CO(2) and N(2) or for cis- and trans-2-butene in binary mixtures, differences in the rate of approach to steady state allowed component distinction. In "normal" systems, one component is initially enriched in the permeate following application of a pulse of analyte gas to the membrane, and then disappears more quickly upon termination of the pulse. Mixtures of cis- and trans-2-butene exhibit qualitatively different behavior; the permeate is enriched in cis-2-butene during both the leading and trailing edges of a sample pulse (though not at steady state). These differences in permeation behavior reflect different balances among multiple transport mechanisms through the zeolite membrane, thought to reflect a combination of selective component sorption and intracrystalline diffusion; in the case of cis- and trans-2-butene, these two factors oppose one another. It is known that this mechanistic complexity can engender synergistic effects, wherein the presence of one component can affect the permeation of another. These may limit applicability to true "unknowns", but resulting complications should be less problematic in well-defined process applications.

Sorption and Transport of Species in Silicalite Study of Binary Systems Containing Iodine

Sorption of iodine from both the vapour phase and iodine solutions in organic solvents on large Silicalite-1 crystals was investigated. The single component sorption of iodine and sorption from binary mixtures under co-diffusion conditions led to a uniform colouring of the crystals. Under counter-diffusion conditions with crystals saturated initially with vapour of a selected solvent, the sorption kinetics of iodine was 2 or 3 orders of magnitude slower as compared with the corresponding co-diffusion experiment. Colouring of crystals was always, at least in its initial stage, non-uniform with visualized pyramids at crystal basal planes. This finding together with the nature of outer and inner crystal morphology suggests that our Silicalite-1 crystals are 90°-intergrowths which have only pore mouth openings of sinusoidal channels in the crystal surface. The process of crystal colouring under counter-diffusion conditions seems to proceed via diffusion along the boundaries of crystal sections.

Performance of PDMS and organofunctionalised PDMS membranes for the pervaporative recovery of organics from aqueous streams

Modified polysiloxane membranes containing different organofunctional side chains were produced and tested for the recovery of various organic contaminants from aqueous sterams, using the process of pervaporation. Four separate organic components, phenol, chloroform, pyridine and methylisobutylketone (MIBK), each representative of an industrially significant family of chemicals, were chosen for evaluation. In each case significant performance enhancements, over that achieved with an unfunctionalised poly(dimethylsiloxane) membrane, were realise. Phenol transport is significantly facilitated by the incorporation of basic groups into the membrane structure. This is thought to be due to a weak acid-base interaction, increasing phenol sorption into the membrane. For pyridine, chloroform and MIBK separations from water, selectivity towards the organic component is greatly enhanced by the incorporation of long chain alkyl groups. A dual effect of the increased organic content of the membrane leading to increased organic component sorption and reduced water sorption is thought to be responsible. The effect of varying the three process parameters, feed concentration, membrane cross-linking density and membrane functional loading, were investigated. Some flux coupling effects were apparent, particularly affecting the transport of water with changing organic component concentration. Changing the cross-linking density of the membrane was found to have negligible effect across the range studied. An optimal functional loading generally close to 10% exists.

Modeling Sorption Transport In Rooms And Sorption Filtration Systems For Building Air Quality Analysis

Adsorption, desorption and chemisorption are known to impact the dispersal of volatile organic and chemically reactive compounds in buildings. These same three processes may be used to advantage to control the levels of these compounds indoors using building sorption filtration devices. To add to the understanding of these processes, to provide the means to predict the impact of these processes on human exposure and to provide the tools needed to design gaseous filtration systems to mitigate the exposure to these compounds, a general approach to modeling the dynamics of these processes is presented. Equations are presented to account for the elemental advection, diffusion, sorption, and chemical transport steps affecting single component sorption dynamics in rooms and sorption filtration systems. These element equations are based on general principles and formulated in terms of fundamental physical parameters that may be determined using standard procedures. Models to predict room and sorption filtration system dynamics are formulated using assemblages of these element equations and a series of simplified models of these systems are derived. Initial applications to model single-component sorption transport in rooms and sorption filtration systems indicate that the approach has the potential to provide accurate predictions providing the sorption and chemical characteristics of the sorbate-sorbent system being considered are well-characterized. This potential is, however, compromised by the lack (or present uncertainty) of fundamental data relating to sorption equilibrium, porous diffusion, surface chemistry, and boundary layer mass transport

Quaternary, ternary, binary, and pure component sorption on zeolites. 2. Light alkanes on Linde 5A and 13X zeolites at moderate to high pressures

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuaternary, ternary, binary, and pure component sorption on zeolites. 2. Light alkanes on Linde 5A and 13X zeolites at moderate to high pressuresK. F. Loughlin, M. A. Hasanain, and H. B. Abdul-RehmanCite this: Ind. Eng. Chem. Res. 1990, 29, 7, 1535–1546Publication Date (Print):July 1, 1990Publication History Published online1 May 2002Published inissue 1 July 1990https://doi.org/10.1021/ie00103a064RIGHTS & PERMISSIONSArticle Views410Altmetric-Citations61LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Quaternary, ternary, binary, and pure component sorption on zeolites. 1. Light alkanes on Linde S-115 silicalite at moderate to high pressures

Pure component and multicomponent equilibrium adsorption data are reported for the adsorption of the light n-alkanes on Linde 5A and 13X pellets in the temperature range 275-350K and at pressures up to 1.732 MPa but primarily at a pressure of 345 kPa. The intrinsic Henry constants and heats of adsorption are extracted from the data using virial isotherm techniques. The experimental K 0 values for 13X are in excellent agreement with theoretical quantum mechanical calculations. For zeolite 5A, predictions of theoretical pure component, binary, and ternary profiles employing the Ruthven isotherm using intrinsic Henry constants are satisfactory. For 13X zeolite, profile predictions using the Ruthven isotherm require that the intrinsic Henry constant be increased by on average 212% to adequately fit the data. This increase is attributed to the increase in the heat of sorption with loading for these systems

Solid-state voltammetry and polymer electrolyte plasticization as a basis for an electrochemical gas chromatographic detector

A new type of electrochemical gas chromatographic (ECGC) detector is described. The detector consists of a film of polymer electrolyte, PEO{sub 16}/LiCF{sub 3}SO{sub 3}, coating a microelectrode-based electrochemical cell and in contact with the effluent stream of a gas chromatograph. The PEO{sub 16}/LiCF{sub 3}SO{sub 3} polymer acts as an ionically conducting but physically rigid medium. Currents passed at the microelectrode/polymer interface depend on reactions of electroactive solutes dissolved in and diffusing through the polymer phase. These currents respond to the presence of sample components in the gas phase through their sorption into, and plasticization of, the PEO polymer phase. The polymer plasticization results in larger diffusion coefficients for the electroactive solutes and, consequently, larger microelectrode currents. Several forms of electrochemical potential control are examined as are the effects of chosen electroactive probe, probe concentration, polymer film thickness, and gaseous sample concentration and sorption. Faster detector responses are obtained with thin PEO{sub 16}/LiCF{sub 3}SO{sub 3} films and faster diffusing electroactive probes. The detector responds linearly to small quantities of sample but exponentially to large sample concentrations. The detector is unusual in that it is most sensitive to later-eluting components of a sample mixture; this effect results from the connection between themore » degree of sample component sorption or partition into the polymer electrolyte and the resulting degree of polymer plasticization and transport rate enhancement.« less

Multicomponent gas sorption in glassy polymers

AbstractGlassy polymers are nonequilibrium solids whose properties may change slowly due to time‐dependent variation in the excess volume and enthalpy functions of these materials. Measurable changes in the gas sorption behavior of samples exposed to different time–temperature histories below the polymer's glass transition temperature can be explained primarily in terms of differences between the excess volume of different samples. A simple physical and mathematical model will be described which relates excess sorption in glasses, compared to rubbery polymers, to sorption into excess volume frozen into the quenched matrix. The model will be explained for pure component gases and then generalized to treat multicomponent sorption data for the CO2/C2H4 and CO2/N2O systems in poly(methyl methacrylate). The rather complex mixed gas behavior can be predicted quantitatively using only pure component sorption data in conjunction with the generalized model for multicomponent gases. The model, based on the concept of competition of sorbing penetrants for the excess volume present in the glass, is successful for the two systems described above for total pressures up to 300 psia.

Pure and mixed gas sorption of carbon dioxide and ethylene in poly(methyl methacrylate)

The sorption of CO 2, C 2 H 4 and mixtures of these gases in poly(methyl methacrylate) at 35°C has been characterized at pressures up to 6.5 atm. The pure gas sorption isotherms exhibit significant concave curvature to the pressure axis and are described well by the dual mode sorption model. The mixed gas sorption data indicate that significant decrements in the solubility of each component in the mixture occur relative to the pure component case at equivalent partial pressures. This phenomenon is predicted accurately by the dual mode sorption model, which accounts for competition between mixture components for sorption in the polymer. The model requires only pure component sorption parameters to describe the mixture behaviour over the full range of composition. The mixture data reveal that the model should be formulated in terms of the gas phase fugacity rather than the partial pressures of the gases at high pressures where non-ideal gas mixture behavior may occur. Deviations between mixed gas sorption data and model predictions based on pure component dual mode parameters are small (± 2.1%) and probably negligible for most purposes for the pressure range studied.

A sorption theory for gas mixtures

AbstractFrom kinetic theory, an equation has been developed for the multilayer sorption of each of two competing gases or vapors onto sites on or within a sorbing material. The thermodynamic characteristics of sorption in the first layer are assumed to differ from those of the second and higher layers, which are all assumed to be identical, as in the Brunauer, Emmett and Teller (B.E.T.) Model. However, in contrast to the B.E.T. Model, these outer layers are not taken to be identical to bulk liquid. The model gives a closed form solution involving seven constants of which five can be obtained from the corresponding pure component sorption. The version of this equation for single gas sorption has three constants and differs from the classical B.E.T. equation, by having the extra constant. The Langmuir and B.E.T. equations are in fact limiting forms of this single gas equation. Examples are given which show excellent fits to experimental, sigmoidal isotherms from the literature up to about 95 percent of the saturation pressure, whereas the B.E.T. generally deviates above 40–50 percent of saturation. The equation can also be partitioned to give important information regarding the distribution of the sorbed molecules, and gives values for the ‘bound’ first layer content and for the ‘mobile’ higher layer sorbed fraction at equilibrium for any relative pressure.