Multicomponent Isotherm Research Articles

Mono/competitive adsorption of Arsenic(III) and Nickel(II) using modified green tea waste

Adsorption capability of the modified green tea waste (MGTW) for Arsenic (III) (As(III)) and Nickel (II) (Ni(II)) from aqueous solution in single and binary system was assessed. The MGTW before and after adsorption was characterized. Moreover, the effect of pH in single and binary component system was studied, a maximum sorption was achieved at about pH 3 for As(III) and pH 7 for Ni(II). Increasing ionic strength could enhance both As(III) and Ni(II) adsorption. Langmuir isotherm could describe As(III) adsorption better while Ni(II) adsorption conformed well to Freundlich. Meanwhile, the maximum adsorption capacity for As(III) and Ni(II) was estimated as 0.4212 and 0.3116 mg/g, respectively. Besides, the adsorption kinetic data of both As(III) and Ni(II) followed well by the pseudo-second-order kinetic. In the binary component system, the presence of As(III) and Ni(II) exerted inhibitory action on the adsorption of each other. At the same time, the extended Langmuir (ELMI) and the extended Freundlich (EFMI) multicomponent isotherm models were found to fit the adsorption data of As(III) and Ni(II) well, respectively, in the competitive adsorption system. This work could provide some effective data about the usage of modified green tea waste for metal removal.

Multicomponent isotherm for biosorption of Zn(II), CO(II) and Cd(II) from ternary mixture onto pretreated dried Aspergillus niger biomass

In the present study, multicomponent competitive biosorption of heavy metal from aqueous solution onto pretreated dried Aspergillus niger in batch system was investigated. The adsorption data were fitted to the multicomponent Langmuir, Freundlich, Temkin and Sips equations. We used the genetic algorithm of biosorption in ternary mixture to evaluate the potential effects of each metal in the removal of other metals. In order to take both mechanisms of the cell-surface binding and intra-particle diffusion into account, an alternative model was investigated by combining the pseudo-second-order kinetics model and the intra-particle diffusion model. A model describing the process of biosorption by a single-stage batch design was developed and verified based on the Temkin isotherm model. Fundamentally, the outlook from these observations of the experiments that the pretreated dried biomass is a suitable absorbent for the removal of significant amounts of the heavy metal from the effluents of industrial wastewater is promising.

Modeling mono- and multi-component adsorption of cobalt(II), copper(II), and nickel(II) metal ions from aqueous solution onto a new carboxylated sugarcane bagasse. Part I: Batch adsorption study

A new carboxylated-functionalized sugarcane bagasse (STA) was prepared through the esterification of sugarcane bagasse with trimellitic anhydride. The optimized synthesis conditions yield STA with a percent weight gain of 73.9% and the number of carboxylic acid groups accounted for 3.78mmol/g. STA was characterized by FTIR, elemental analysis, TGA, PZC, and SEM. Adsorption kinetics followed a pseudo-second-order model. The adsorption rate constant showed the following order: k2,Ni2+>k2,Cu2+>k2,Co2+. Four mono- and multi-component isotherm models were used to model the adsorption systems. Monocomponent experimental data were fitted to Langmuir and Sips models; whereas, multicomponent data were fitted to modified extended Langmuir and P-factor models. The maximum adsorption capacities (Qmax,mono) obtained from the Langmuir model were 1.140, 1.197, and 1.563mmol/g for Co2+, Cu2+, and Ni2+, respectively. The competitive studies demonstrated that the multicomponent adsorption capacity (Qmax,multi) was smaller than Qmax,mono, as a result of the interaction between the metal ions. Desorption studies showed that all metal ions could be fully desorbed from STA.

The significance of a second adsorption phase with weakly adsorbed species for the calculation of the surface concentrations of a mixture: methanol–DME and methanol–ethene adsorption in SAPO-34

With the calorimetric (adsorption heat versus coverage) curve also measured together with the adsorption isotherm, the simultaneous use of both curves showed that there were two phases of adsorption in the adsorption of methanol, dimethyl ether, ethene and propane in SAPO-34. The dual-site Langmuir equation gave good fits to the adsorption data to support the interpretation that a second (type 2) adsorption phase occurred in the high-pressure region in addition to a first (type 1) adsorption phase on the acid sites at lower pressures. Adsorption experiments and calculations using binary gas mixtures showed that due to the existence of two types of adsorption, the multicomponent Langmuir isotherm equation (Langmuir competitive adsorption model) calculated incorrect surface concentrations when the concentrations were high. In contrast, the ideal adsorbed solution theory (IAST) calculated correct surface concentrations in the adsorption of mixtures.

Simultaneous adsorption of Cr(VI) and phenol onto tea waste biomass from binary mixture: Multicomponent adsorption, thermodynamic and kinetic study

During this investigation simultaneous removal of Cr(VI) and phenol using tea waste biomass is studied in a batch reactor. The influences of process parameters such as pH, adsorbent quantity, contact time, initial concentration on the percentage removal have been studied. The optimal pH condition for the adsorption of Cr(VI) was found acidic while that for phenol was basic but at pH 7 both phenol and Cr(VI) were adsorbed to maximum extent simultaneously onto the surface of tea waste biomass. At an optimum pH 7, temp 30°C, adsorbent dose 15gL−1, 99.19% of 100mgL−1 Cr(VI) and 95.07% of 50mgL−1 phenol were removed. The equilibrium was reached after 12h for Cr(VI) and 24h for phenol. The maximum adsorption capacity of tea waste biomass, according to extended Langmuir isotherm model was 199.523 and 9.487mgg−1 for Cr(VI) and phenol, respectively. Multicomponent adsorption isotherms such as non modified competitive Langmuir, modified competitive Langmuir, extended Langmuir, extended Freundlich, competitive non modified Redlich Peterson and competitive modified Redlich Peterson model were used to study the equilibrium process at the initial concentration range of 100–450mgL−1 of Cr(VI) and 50–225mgL−1 of phenol. The experimental results demonstrated that both Cr(VI) and phenol were well described by pseudo second order model. Thermodynamic study depicted that adsorption of phenol onto tea waste biomass was spontaneous and exothermic while for Cr(VI) was endothermic in nature.

Simultaneous removal of Cr(VI) and phenol from binary solution using Bacillus sp. immobilized onto tea waste biomass

In this investigation, simultaneous Cr(VI) reduction and phenol degradation from contaminated water using Bacillus sp. immobilized onto the surface of tea waste biomass have been studied in a batch reactor. It was observed that Bacillus sp. utilized phenol as a carbon source for Cr(VI) reduction. Optimal conditions were achieved at a biomass dosage of 15g/L with an initial concentration of 100mg/L of Cr(VI) and 50mg/L of phenol. The maximum uptake capacity of Cr(VI) and phenol onto tea waste biomass surface was 741.389mg/g and 7.761mg/g, respectively. The equilibrium condition was reached after 27h for phenol and 48h for Cr(VI). Multicomponent isotherm models were used to determine the adsorption mechanism for both Cr(VI) reduction and phenol degradation. Non-modified competitive Redlich–Peterson was found to be the best fit for Cr(VI) sorption while extended Langmuir was followed in the case of phenol degradation. Moreover, the experimental results revealed that both Cr(VI) and phenol were well described by the pseudo second-order model.

Single and binary adsorption of Cd (II) and Zn (II) ions from aqueous solutions onto bottom ash

Bottom ash, a waste obtained from coal-burning power plant, was used as a low cost adsorbent for the removal of Cd (II) and Zn (II) ions from single and binary systems in batch experiments. The results of adsorption capacity showed that bottom ash could be considered as a potential adsorbent. The uptake of Zn (II) ion was greater than that of Cd (II) ion. For single adsorption, based on the correlation coefficient (R2) values, both Langmuir and Freundlich isotherms suitably described the adsorption equilibrium data in the initial metal ion concentration range of 10–50 mg/L. The multicomponent isotherms, including the extended Langmuir and IAST-Freundlich isotherms, were used to predict the binary adsorption of Cd (II) and Zn (II) ions. Furthermore, the appropriate multicomponent isotherm was investigated by minimizing the average relative error (ARE) function. It should be confirmed that the extended Langmuir isotherm fitted the binary adsorption equilibrium data satisfactorily.

Modeling the biosorption of basic dyes from binary mixtures

The biosorption of basic dyes, methylene blue and rhodamine B, from binary aqueous solutions onto cypress cone chips, was analyzed through mathematical modeling. This study aimed at introducing a novel model to predict the dynamic binary sorption of the dyes. It consisted of a modified Langmuir multicomponent isotherm coupled with a linear driving force model. Experimental data from recent studies using the untreated and alkaline-treated biosorbent was used to determine the model parameters, and the breakthrough predictions are in good agreement with the experimental results. Useful information on the effects of bed length and feed concentration on the breakthrough time and mass transfer length was obtained. This can guide the design and optimization of the biosorbent column.

Modeling Langmuir isotherms with the Gillespie stochastic algorithm

The overall goal of this work is to develop a robust modeling approach that is capable of simulating single and multicomponent isotherms for biological molecules interacting with a variety of adsorbents. Provided the ratio between the forward and reverse adsorption/desorption constants is known, the Gillespie stochastic algorithm has been shown to be effective in modeling isotherms consistent with the Langmuir theory and uptake curves that fall outside this traditional approach. We have used this method to model protein adsorption on ion-exchange adsorbents, hydrophobic interactive adsorbents and ice crystals. In our latest efforts we have applied the Gillespie approach to simulate binary and ternary isotherms from the literature involving gas–solid adsorption applications. In each case the model is consistent with the experimental results presented.

Synthesis of butyl acrylate in a fixed‐bed adsorptive reactor over Amberlyst 15

The butyl acrylate synthesis from the esterification reaction of acrylic acid with 1‐butanol in a fixed‐bed adsorptive reactor packed with Amberlyst 15 ion exchange resin was evaluated. Adsorption experiments were carried out with nonreactive pairs at two temperatures (323 and 363 K). The experimental results were used to obtain multicomponent adsorption equilibrium isotherms of Langmuir type. Reactive adsorption experiments using different feed molar ratios and flow rates were performed, at 363 K, and used to validate a mathematical model developed to describe the dynamic behavior of the fixed‐bed adsorptive reactor for the butyl acrylate synthesis. Due to the simultaneous reaction and separation steps, it was possible to obtain a butyl acrylate maximum concentration 38% higher than the equilibrium concentration (for an equimolar reactants ratio solution as feed at a flow rate of 0.9 mL min−1 and 363 K) showing that sorption‐enhanced reaction technologies are very promising for butyl acrylate synthesis. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1263–1274, 2015

Three column intermittent simulated moving bed chromatography: 3. Cascade operation for center-cut separations

A general design methodology for chromatographic three fraction separation by application of the three column intermittent simulated moving bed (3C-ISMB) cascade is proposed and experimentally validated by studying the purification of an intermediately retained stereoisomer of nadolol, from an equimolar mixture of its four stereoisomers. The theoretical part shows that the 3C-ISMB cascade can be easily designed by applying Triangle Theory. Moreover, a re-scaling approach for the second stage is proposed so as to account for the fact that the feed flow rates to stage 2 are generally higher as compared to stage 1 due to dilution in the latter. Scaling the columns of the second stage accordingly enables to run both stages under optimal conditions with respect to switching time and step ratio, which is an important advantage as compared to integrated ternary processes. The experimental part starts with studying the linear adsorption behavior of nadolol in heptane/ethanol/DEA on Chiralpak AD for varying ratios of heptane and ethanol. Based on that, a solvent composition of Hept/EtOH/DEA 30/70/0.3 (v/v/v) is selected and the competitive multi-component Langmuir isotherm of the quaternary mixture is determined by frontal analysis. The resulting isotherm parameters are used to design several first stage experiments aiming at removal of the most retained component. The resulting ternary intermediate product is reprocessed in several second stage experiments studying various configurations. Finally, the dilution of the intermediate product with Hept/DEA yielding a solvent composition of Hept/EtOH/DEA 60/40/0.3 (v/v/v) is examined showing that the resulting increase in retention is beneficial for final product purities. Moreover, the reduction in viscosity compensates for the dilution as it enables higher flow rates. Dilution of the intermediate product is hence the best option, yielding highest overall cascade productivity (2.10gl−1h−1) and highest product purity (97.8%) requiring a specific solvent consumption of 12l/g of product.

Development of a new compositional model with multi-component sorption isotherm and slip flow in tight gas reservoirs

Natural gas in unconventional gas reservoirs typically contains multiple gas components. Existing models incorporate either the unique flow mechanisms in tight and shale gas reservoirs (slip flow) or multi-component sorption isotherm without combining them. In this work, we developed a compositional flow code incorporating slip flow and multi-component sorption using the extended Langmuir isotherm (EL). The model was discretized using finite volume method based on unstructured Perpendicular Bisection (PEBI) grids for their local orthogonality and flexibility in handling irregular shaped domain. The code was verified using ECLIPSE-CBM for multi-component sorption and using ECLIPSE with modified transmissibility for slip flow calculation. The model was further validated by reproducing the pressure build up data during well shut-in period in a tight gas reservoir in Xinjiang, China.The developed code was used to understand and quantify the importance of multi-component EL isotherm and slip flow. The evolution of the bottom-hole pressure (BHP), sorption volume, and gas composition was also simulated under various reservoir conditions including different initial gas compositions, sorption capacities, and reservoir sizes. The deviations caused by representing shale gas as pure methane using single-component Langmuir isotherm can reach as much as 90% for BHP and 45% for sorbed volume if the initial methane composition was 80%. The predicted produced gas composition with the EL isotherm showed a unique constant composition (CC) stage before the gas flow reached the domain boundary, indicating the potential use of gas composition as another type of data to infer reservoir boundary and flow regimes. The developed code offers a powerful tool to understand gas flow and sorption, as well as an analyzing tool to identify reservoir boundary and flow regimes compared to traditional well test method, which requires expensive measurements of BHP.

Microwaves initiated synthesis of activated carbon-based composite hydrogel for simultaneous removal of copper(II) ions and direct red 80 dye: A multi-component adsorption system

We present a novel microwave initiated preparation of polyacrylamide/activated carbon hydrogel (PAAm-FAc) in this article and characterized by FT-IR, pHzpc and Boehm titration. The adsorbent was assessed for competitive adsorption of copper(II) and direct red 80 from a binary mixture in a single-staged batch process as a function of volume of binary mixture/mass of adsorbent (V0/M0) ratio at varying orders of second pollutant concentration. A competitive, multi-component Langmuir isotherm was used to express the adsorption process and the model was applied for calculating adsorbed or equilibrium individual pollutant concentration (Cad,eq,i or Ceq,i) at a fixed V0/M0 ratio for a combination of pollutants in a batch reactor. The data obtained indicated that the decrease of V0/M0 ratio with the addition of second pollutant influenced the amount of copper or direct red 80 removed. The prepared adsorbent is efficient and useful in multi-component adsorption system.

Biosorption of Cr(VI) and Ni(II) onto Hydrilla verticillata dried biomass

In the present study Hydrilla verticillata dried biomass was modified by Fenton reagent and its technical feasibility for removal of Cr6+ and Ni2+ ions from wastewater were investigated. Fenton modification process was optimized by varying pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio. For Fenton modification process the optimum values of pH, biosorbent dose, contact time, and Fe2+/H2O2 ratio were 4, 70gL−1, 70min and 0.04 w/w, respectively. The modified biosorbent was characterized by using SEM-EDX, FT-IR and Malvern particle size analyzer. SEM-EDX analysis revealed the enhancement in weight percent of Cr6+ (47.38%) and Ni2+ (41.26%) ions on the surface of Fenton modified dried biomass of Hydrilla verticillata (FMB) after biosorption. Maximum biosorption of Cr6+ and Ni2+ ions were observed to be 29.43 and 48.72mgg−1 for raw biomass and 107.64 and 106.12mgg−1 for Fenton modified biomass respectively. Experimental data were modeled using single and multi-component isotherm models. For single-metal component, the Freundlich isotherm model fits the data better than the Langmuir isotherm model. In case of binary-metal solution the experimental data show good agreement with multi-component Freundlich isotherm model. The enhancement in the overall biosorption capacity after the Fenton modification was observed which follows the sequence: Cr6+>Ni2+. The biosorption process followed the pseudo-second order kinetics. The equilibrium data suggest the involvement of chemisorption mechanism. Positive values of enthalpy and negative values of Gibbs free energy obtained during thermodynamic study revealed that the biosorption process was endothermic and spontaneous in nature.

Model Analysis of Equilibrium Adsorption Isotherms of Pure N2, O2, and Their Binary Mixtures on LiLSX Zeolite

Three analytical adsorption isotherm models for energetically homogeneous (Langmuir) and heterogeneous (Toth, Sircar) adsorbents were tested for describing recently measured pure gas isotherm data for adsorption of N2 and O2 on pelletized LiLSX zeolite at three different temperatures and in the pressure range of 0–6 atm. Estimated binary gas isotherms for this system by these models and the Ideal Adsorbed Solution Theory (IAST) were compared with the corresponding experimental data. All three models describe the pure gas isotherms reasonably well, but the model that accounts for the differences in the degrees of adsorbent heterogeneity of the components of a mixture (Sircar) provided better correlation between experimental and estimated binary selectivities than the other models and IAST under various conditions of pressure, temperature, and gas composition. Predictions of multicomponent isotherm data by models must be extensively tested experimentally, since their ability to describe pure gas isotherms d...

Equilibrium biosorption studies of wastewater U(VI), Cu(II) and Ni(II) by the brown alga Cystoseira indica in single, binary and ternary metal systems

Biosorption of U(VI), Cu(II) and Ni(II) onto Cystoseira indica was investigated in single, binary and ternary metal systems. The single-ion biosorption results showed that the affinity order of metal ions on C. indica was Cu(II) > Ni(II) > U(VI) and the mechanism of metal ions biosorption on this biomass was physisorption. The binary and ternary biosorption data were interpreted using the multicomponent isotherms. Competitive biosorption results showed that the metal biosorption decreased with increasing the concentrations of other metal ions and an antagonistic effect was observed in binary and ternary systems. Also, the inhibitory effect increased with increasing the initial metal ions concentrations.

Analysis of synergistic and antagonistic adsorption of heavy metals and acid blue 25 on activated carbon from ternary systems

This article reports the antagonistic and synergistic adsorption involved in the multicomponent removal of acid blue 25 dye (AB25) and heavy metal ions (Zn2+, Ni2+, Cd2+) from ternary systems using an activated carbon modified with wastes of egg shell. Adsorption experiments were performed in ternary mixtures: Zn2+–Ni2+–AB25, Ni2+–Cd2+–AB25 and Zn2+–Cd2+–AB25 where Taguchi experimental designs have been used to study the adsorbent performance and to identify the antagonistic and synergistic adsorption caused by the simultaneous presence of these water pollutants. Results indicated that these systems might show both competitive and synergistic adsorption. Dye AB25 enhanced the removal of these metallic species and reduced the competitive adsorption between the metal ions present in multicomponent solution especially for Cd2+. This synergistic adsorption caused by AB25 depends on the concentrations of dye and heavy metals, and the improvement of metal adsorption is also dependent on the metal ion. This improvement of the adsorption capacity of activated carbon could be caused mainly by the ion exchange between the heavy metals and the ion Na+ from the auxochrome functional group of the dye molecule. Traditional multicomponent isotherm models and a model based on the response surface methodology have been employed and compared in the modeling of multicomponent adsorption data. This study provides new experimental data and new findings on the multicomponent adsorption of water pollutants using activated carbon.

Analysis and modeling of multicomponent sorption of heavy metals on chicken feathers using Taguchi’s experimental designs and artificial neural networks

In this study, we have used an integrated approach based on Taguchi’s experimental designs and artificial neural networks (ANNs) for the analysis and modeling of the simultaneous removal of cadmium (Cd2+), nickel (Ni2+), and lead (Pb2+) ions from ternary aqueous solutions using chicken feathers. Our results indicated that the multicomponent sorption of these heavy metals on chicken feathers is a complex antagonistic process. Specifically, chicken feathers showed a strong preference for the removal of Pb2+ ions in multicomponent solutions and the presence of these ions affected significantly the multicomponent removal of Cd2+ and Ni2+. This antagonistic sorption effect is more significant at pH 5 and the sorption preference of chicken feathers during heavy metal removal depends on the solution pH. Results of X-ray absorption near edge structure suggested that sulfide and carboxylic groups of chicken feathers appear to play a relevant role for the removal of heavy metal ions using this biomass. On the other hand, the desorption process using diluted acidic solutions is effective for the recovery of both Pb2+ and Cd2+ from metal-loaded chicken feathers indicating the feasibility of sorbent regeneration. Finally, ANNs model offers a better performance and more advantages for modeling the sorption of heavy metals in multicomponent solutions than those obtained using Langmuir- and Sips-type multicomponent isotherm equations. This ANNs model is capable of modeling and predicting the sorbent performance at different conditions of pH. In summary, the application of Taguchi’s experimental designs and ANNs models is promising for data analysis and modeling of multicomponent pollutant removal for wastewater and water treatment.

Two metal biosorption of chromium and copper by Ca-loaded Laminaria japonica biomass

Cu and Cr sorption capacities of Ca-loaded Laminaria japonica biomass were studied using an equilibrium methodology and evaluation of the sorption performance, and modeling in a two-metal system was carried out with a modified multi-component Langmuir isotherm. The maximum Cu and Cr uptakes calculated from the Langmuir isotherm were 1.59 mmol/g (10.1 wt.%) and 1.81 mmol/g (9.4 wt.%) at pH 4.5, respectively. The desorption efficiency of the Cr-sorbed L. japonica was approximately 5% for 8 h in the 0.1 N HNO3 solution, while that of Cu-sorbed L. japonica was more than 99% in the 0.1 N HNO3 solution. The modified Langmuir model gave the following affinity correlated coefficients: 1.12 for Cu and 7.31 for Cr at pH 4.5. The interference of Cr with Cu biosorptive uptake was assessed by ‘cutting’ the three dimensional uptake isotherm surfaces at constant second-metal final concentrations. Equimolar final equilibrium concentrations of Cu and Cr of 1 mM at pH 4.5 reduced Cu and Cr uptakes by 75.5 and 11.0%, respectively.

Experimental Study of the Competitive Adsorption of HNO3 and H2O on Surfaces by Using Brewster Angle Cavity Ring-Down Spectroscopy in the 295–345 nm Region

The competitive adsorption of HNO3 and H2O from the gas phase onto fused silica surfaces is investigated. Brewster angle cavity ring-down spectroscopy is used to measure absorption of a laser probe beam by the HNO3/H2O coadsorbed on fused silica surfaces as a function of the mixture pressure. The laser absorption measurements were made in the 295-345 nm region. Langmuir adsorption constants for nitric acid and water were found to be 107 ± 17 and 562 ± 21 Torr(-1), respectively. A method has been developed for calculating absorption by HNO3 and H2O codeposited on the surface as a function of the HNO3/H2O mixture pressure using multicomponent Langmuir adsorption isotherms and absorption cross-sections at a given wavelength for surface-adsorbed HNO3 and H2O. The validity of this treatment has been evaluated both as a function of wavelength and as a function of mixing ratio.