Optimization of kinetic data for two‐stage batch adsorption of Pb(II) ions onto tripolyphosphate‐modified kaolinite clay

BACKGROUND: Most adsorption studies consider only the adsorption of pollutants onto low cost adsorbents without considering how equilibrium and kinetic data can be optimized for the proper design of adsorption systems. This study considers the optimization of kinetic data obtained for the removal of Pb(II) from aqueous solution by a tripolyphosphate modified kaolinite clay adsorbent. RESULTS: Modification of kaolinite clay with pentasodium tripolyphosphate increases its cation adsorption capacity (CEC) and specific surface area (SSA) from 7.81 to 78.9 meq (100 g)^?1 and 10.56 to 13.2 m² g^?1 respectively. X‐ray diffraction patterns for both unmodified and tripolyphosphate‐modified kaolinite clay suggest the modification is effective on the surface of the clay mineral. Kinetic data from the batch adsorption of Pb(II) onto the tripolyphosphate‐modified kaolinite clay adsorbent were optimized to a two‐stage batch adsorption of Pb(II) using the pseudo‐second‐order kinetic model. Mathematical model equations were developed to predict the minimum operating time for the adsorption of Pb(II). Results obtained suggest that increasing temperature and decreasing percentage Pb(II) removal by the adsorbent enhanced operating time of the adsorption process. The use of two‐stage batch adsorption reduces contact time to 6.7 min from 300 min in the single‐stage batch adsorption process for the adsorption of 2.5 m³ of 500 mg L^?1 Pb(II) under the same operating conditions. CONCLUSION: Results show the potential of a tripolyphosphate‐modified kaolinite clay for the adsorption of Pb(II) from aqueous solution and the improved efficiency of a two‐stage batch adsorption process for the adsorption of Pb(II) even at increased temperature. Copyright © 2009 Society of Chemical Industry     

Removal of Basic Blue 3 by sorption onto a weak acid acrylic resin

A weak acid acrylic resin was used as an adsorbent for the investigation of Basic Blue 3 (BB3) adsorption kinetics, isotherms, and thermodynamic parameters. Batch adsorption studies were carried out to evaluate the effect of pH, contact time, initial concentration (28–100 mg/g), adsorbent dose (0.05–0.3 g), and temperature (290–323 K) on the removal of BB3. The adsorption equilibrium data were analyzed by the Langmuir, Temkin, and Freundlich isotherm models, with the best fitting being the first one. The adsorption capacity (Q_o) increased with increasing initial dye concentration, adsorbent dose, and temperature; the highest maximum Q_o (59.53 mg/g) was obtained at 323 K. Pseudo‐first‐order and pseudo‐second‐order kinetic models and intraparticle diffusion models were used to analyze the kinetic data; good agreement between the experimental and calculated amounts of dye adsorbed at equilibrium were obtained for the pseudo‐second‐order kinetic models for the entire investigated concentrations domain. Various thermodynamic parameters, such as standard enthalpy of adsorption (ΔH^o = 88.817 kJ/mol), standard entropy of adsorption (ΔS^o = 0.307 kJ mol^?1 K^?1), and Gibbs free energy (ΔG^o < 0, for all temperatures investigated), were evaluated and revealed that the adsorption process was endothermic and favorable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of poly (acrylic acid) containing core‐shell type resin for removal of basic dyes

BACKGROUND: A core‐shell type carboxylic acid modified resin was prepared and dye sorption characteristics of the resin were investigated. The resulting grafted resin material has been shown to be an efficient sorbent for removal of basic dyes from water as a result of the carboxylic acid group's affinity towards basic dye molecules. RESULTS: The resin was characterized using Fourier transform infrared spectroscopy (FT‐IR) and titrimetric methods. The basic dyes (methylene blue and crystal violet) were removed by contacting the swollen resin with aqueous dye solutions at room temperature. The adsorption capacities of resin were determined by colorimetric analysis of the residual dye content in the adsorption medium, which gave capacities for methylene blue and crystal violet of 300 and 250 mg g^?1 resin, respectively. The prepared resin is also able to remove basic dyes completely from dilute aqueous dye solutions. Batch kinetic sorption experiments determined that a pseudo‐second‐order rate kinetic model was applicable. CONCLUSION: Flexibility of the polymer side chains is expected to provide pseudo‐homogeneous reaction conditions and easy accessibility of the functional groups involved. The adsorbents are expected to have the advantage of mobility of the grafted chains in the removal of basic dyes from aqueous mixtures. The resin has potential as an adsorbent for removal of basic dyes for use over a wide pH range. Copyright © 2011 Society of Chemical Industry     

Defluoridation performance and mechanism of nano‐scale aluminum oxide hydroxide in aqueous solution

BACKGROUND: The present study has concentrated on investigating the fluoride removal potential of nano‐scale aluminum oxide hydroxide (nano‐AlOOH). A series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The different parameters investigated include the effect of contact time, initial fluoride concentration, adsorbent dose, pH of the solution and co‐existing anions. RESULTS: Most of the adsorption took place during the first 30 min and kinetic and equilibrium adsorption data show that the process obeys a pseudo‐second‐order kinetic equation and the Langmuir adsorption model. The fluoride removal efficiency is greater than 90% between pH 6 and 8 and decreases as pH values increase to 11. The presence of SO₄^2? or PO₄^3? in aqueous solution was found to reduce the fluoride uptake. Desorption studies showed that the fluoride can easily be desorbed at pH 13. CONCLUSION: Nano‐AlOOH possesses a maximum fluoride capacity of 3259 mg F^? kg^?1, which is comparable with that of activated alumina. Maximum adsorption occurred at around pH 7, which makes nano‐AlOOH a potential adsorbent for drinking water treatment. Copyright © 2009 Society of Chemical Industry     

Study on quaternary ammonium modified tentacle‐type cellulose beads and its adsorption for

A novel anion exchange resin based on cellulose has been prepared to adsorb for the urgent demand of silver and the high toxicity of metal‐cyanide complexes. Quaternary ammonium groups were grafted onto cellulose beads as main active sites in tentacle‐type through a series of chemical reactions. The substitution degree of each reaction was determined to be about 0.854, 2.125, and 2.899 mmol g^?1, respectively. The resin exhibited excellent spherical shape with microporous structure by the observation of optical microscopy and scanning electron microscope. Moreover, the adsorption experiments demonstrated the adsorption was fast in alkaline condition. Fitting the data into isotherm and kinetic models gave the conclusion that the adsorption behavior matched better with Langmuir model and pseudo‐second‐order kinetic in initial time followed pseudo‐first‐order kinetic model in later phase. The equilibrium adsorption capacity was determined to be 3.016 mmol g^?1. With the advantages of high capacity, short equilibrium time, and alkaline resistance, the resin would be considered to a top‐priority adsorbent for the separation of . © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40987.     

Adsorption and heat‐energy‐aid desorption of cationic dye on a new thermo‐sensitive adsorbent: Methyl cellulose/calcium alginate beads

The adsorption and heat‐energy‐aid desorption of methylene blue (MB) on a thermo‐sensitive adsorbent of methyl cellulose/calcium alginate beads (MC/CABs) has been studied. The addition of methyl cellulose intensified the desorption ability of adsorbent, and boosted the difference of adsorption capacity of adsorbent between low temperature and high temperature. At the mass ratio of methyl cellulose to sodium alginate of 2:1, the difference of adsorption capacity of MC/CABs between 20 and 60°C reached 20.48 mg g^?1. The effects of temperature, time and initial MB concentration on adsorption performance were investigated in detail. The MB adsorption on MC/CABs followed the pseudo‐second‐order kinetic model. The equilibrium data was fitted well with Langmuir isotherm. The maximum adsorption capacity of 336.70 mg g^?1 exhibited MC/CABs had a good adsorption capability. Thermodynamic analyses showed high temperature was not favorable to MB adsorption, and MC/CABs had a distinct superiority in desorption of adsorbate with heat‐energy‐aid. Lastly, the possible mechanisms involving in adsorption and heat‐energy‐aid desorption were presented. POLYM. ENG. SCI., 56:1382–1389, 2016. © 2016 Society of Plastics Engineers     

Feldspar/titanium dioxide/chitosan as a biophotocatalyst hybrid for the removal of organic dyes from aquatic phases

Feldspar/titanium dioxide/chitosan hybrid, a photoactive biocompatible adsorbent for anionic dyes, was synthesized, characterized, and successfully tested. The adsorbent characterization, pH role, adsorbent dose effect, equilibrium data, kinetic plats, and thermodynamic parameters are reported. The point of zero charge for the hybrid was measured to be 8.3, and the most favorable pH range for the adsorption process was found to be below this pH value. The adsorption equilibrium study demonstrated that the Freundlich model was best fitted to the experimental data. Without UV light exposure, the prepared adsorbent adsorbed 72 mg of Acid Black 1 (AB1)/g of sorbent (86% removal) from a 100‐mL solution with an initial dye concentration of 50 mg/L, whereas UV irradiation resulted in an increase in the elimination of AB1 dye (97% removal). The kinetic data was depicted well by the pseudo‐second‐order model. The thermodynamic parameters indicated that the reaction between the hybrid and the dye was exothermic and also spontaneous at lower temperatures. In the batch desorption process, several aqueous solutions adjusted to different pH values were tested, and the best desorption performance (90% desorption) was achieved at pH 11. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40247.     

Arsenic adsorption from contaminated water on Fe(III)‐coordinated amino‐functionalized poly(glycidylmethacrylate)‐grafted TiO2‐densified cellulose

BACKGROUND: The main aim of this study is to determine the sorptive potential of a novel anion exchanger, Fe(III)‐coordinated amino‐functionalized poly(glycidylmethacrylate)‐grafted TiO₂‐densified cellulose (AM‐Fe‐PGDC) for arsenic(V) removal from aqueous solutions by batch technique. RESULTS: The adsorbent was characterized using infrared spectroscopy, powder X‐ray diffraction, scanning electron microscopy, thermogravimetry and potentiometric titrations. The effective pH for removal was 6.0. The adsorption rate was influenced by initial metal ion concentration and contact time. The equilibrium was achieved within 1.5 h and follows a pseudo‐second‐order kinetic model. The adsorption capacity for As(V) calculated using the Langmuir isotherm equation was 105.47 mg g^?1. The AM‐Fe‐PGDC developed was used to remove As(V) from simulated groundwater. Regeneration experiments were attempted for four cycles using 0.1 mol L^?1 NaCl solution. CONCLUSION: It was found that AM‐Fe‐PGDC is very efficient for the removal of As(V) from aqueous solutions. © 2012 Society of Chemical Industry     

Kinetics,Thermodynamics, and Isothermic Evaluation in Sorption Study of Hazardous Dye Using Sodium Dodecylsulfate Physically Impregnated in Polyester‐Type Polyurethane Foam

Use of polyester‐type polyurethane foam (PUF) is an effective adsorbent for the removal of hazardous dye: crystal violet (CV) from an aqueous solution. In this adsorption study, the formation of hydrophobic ion pair (opposite charge attraction) between the charged species, i.e., cationic (basic) dye CV and anionic surfactant sodium dodecylsulfate (SDS) sorbed onto PUF. Chemical calculations were performed using quantum simulation to understand ion‐pair formation for CV–SDS at the semiempirical PM6 level. Adsorption studies were performed using 200 mg cylindrical PUF with an overhead stirrer in solutions containing varying compositions of the dye–surfactant mixture. The equilibrium thermodynamics and kinetics of the adsorption process were studies by measuring CV dye removal as a function of time and temperature. Results show that the formation of the dye–surfactant ion pair is necessary for effective adsorption onto PUF. Various adsorption isotherms, viz., Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (DRK), Harkin‐Jura, and several kinetic models, viz., pseudo‐first order, pseudo‐second order, Elovich, and Intraparticle diffusion were used to fit the spectrophotometric result. The equilibrium adsorption data fit to the Langmuir isotherm gives the maximum adsorption of PUF as 33.39 mg g^?1 from 200 mL 5.0 × 10^?5 mol L^?1 CV solution at 298.15 K. The kinetics study showed that the overall adsorption process follows pseudo‐second‐order kinetics. The Morris–Weber model suggests that an intraparticle diffusion process is active in controlling the adsorption rate. The Freundlich, Temkin, DRK adsorption isotherms showed that solute dye transfers from solution to the PUF adsorbent surface through physical adsorption. The Langmuir and Harkin‐Jura adsorption isotherms suggest that the adsorbent surface is homogeneous in nature. The thermodynamic data showed that the adsorption process is spontaneous and endothermic with a positive enthalpy change and a negative change in Gibb's energy.     

Application of polypyrrole coated onto wood sawdust for the removal of carmoisine dye from aqueous solutions

In this research, the removal of carmoisine dye from aqueous solutions using polypyrrole coated onto sawdust (PPy/SD) has been investigated. The sorption experiments were performed using both batch and column systems. The effects of some important parameters such as pH, initial concentration, sorbent dosage, exposure time, and temperature on uptake of carmoisine dye were investigated. Based on the data obtained in batch system, it was found that maximum adsorption is occurred under acidic conditions. Complete removal was observed when a dye solution with the initial concentration of 100 mg L^?1 was treated by 1.0 g of the used adsorbent (PPy/SD) at pH value of 4 and room temperature. However, higher sorption was observed at elevated temperature. According to the kinetics study, it was found that the experimental data fitted very well the pseudo‐second‐order kinetic model (k₂ = 0.184 g mg^?1 min^?1). It was found that polypyrrole chemically coated on SD is an efficient system for the removal of carmoisine dye from aqueous solutions. Desorption of the dye‐loaded column was also possible by using dilute NaOH solution with high efficiency (～ 80%). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhanced adsorption of Acid Red 88 by an excellent adsorbent prepared from alunite

BACKGROUND: Calcination significantly increased the adsorption performance of alunite for Acid Red 88. RESULTS: The adsorption properties of calcined alunite for Acid Red 88 were investigated. pH, adsorbent dosage, contact time and ionic strength were found to influence the adsorption. Temperature did not significantly affect the process. Kinetic data obey a pseudo‐second‐order model, while intraparticle diffusion is not the only rate‐limiting step. The Langmuir isotherm well described the equilibrium data. The monolayer adsorption capacity of calcined alunite was found to be 832.81 mg g^?1. It was successfully used for the removal of dye in continuous mode at a flow rate of 4.0 mL min^?1. Co‐anions affected the adsorption capacity of calcined alunite but the presence of other organic compounds in the same medium did not significantly change the adsorption performance. Reusability studies showed that the calcined alunite can be reused four times. Electrostatic interaction, ion‐exchange and complexation were found to be effective mechanisms for the adsorption of Acid Red 88 by calcined alunite. CONCLUSION: This study demonstrated that calcined alunite has excellent adsorption performance and might be a very good adsorbent for Acid Red 88 as an abundant, economical and practical material. © 2012 Society of Chemical Industry     

Adsorption and desorption characteristics of zinc on ash particles derived from oil palm waste

Solid waste such as palm fibre and shell produced by the palm oil industry is used by palm oil mills as boiler fuel to produce steam for electricity generation. The ash produced after combustion creates a disposal problem for the palm oil industry. This study explored the potential of oil palm ash as an adsorbent material for removal and recovery of zinc ions from aqueous solutions. The equilibrium uptake of zinc was found to increase with solution pH in the range 3–6, yielding a maximum adsorption capacity of 0.163 mmol g^?1 of ash at a pH of 6. The affinity constant of oil palm ash was found to greatly exceed that of a commercial ion exchange resin, suggesting that oil palm ash may find potential application in treating dilute zinc‐containing waste streams. Four isotherm models were used to fit the constant pH equilibrium isotherms obtained at four different pH values. The entire data set was successfully simulated using two of the isotherm models: a Langmuir model with pH‐dependent parameters and an extended Langmuir–Freundlich model with pH‐independent parameters. The rates of adsorption and desorption for zinc were measured using a stirred‐batch contactor. The contact time required to reach apparent adsorption equilibrium was found to decrease with increasing adsorbent dosage. Both the rate and the extent of zinc desorption were affected by the pH of the desorbing solution. The adsorption and desorption rates were consistent with simple first‐order rate models. © 2002 Society of Chemical Industry     

Poly(methacrylic acid)‐modified chitosan for enhancement adsorption of water‐soluble cationic dyes

The preparation of poly(methacrylic acid)‐modified chitosan microspheres and its application for the removal of cationic dyes, methylene blue (MB) and malachite green (MG), in aqueous solution in a batch system were described. The modified chitosan was characterized using SEM, FTIR, and XPS analyses. The effects of the pH of the solution, contact time, and initial dye concentration were studied. The adsorption capacities of the microspheres for the two cationic dyes increased significantly after the modification because a large number of carboxyl groups were introduced. The equilibrium process was better described by the Langmuir than the Freundlich isotherm. According to the Langmuir equation, the maximum adsorption capacities were 1000.0 and 523.6 mg g^?1 for MB and MG, respectively. Kinetic studies showed better correlation coefficients for a pseudo‐second‐order kinetic model, confirming that the sorption rate was controlled by a chemisorption process. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Biosorption of phenolic compounds from aqueous solutions onto chitosan–abrus precatorius blended beads

BACKGROUND: This research focuses on understanding the biosorption process and developing a cost‐effective technology for the treatment of water contaminated with phenolic compounds (phenol, 2‐chlorophenol and 4‐chlorophenol), which are discharged into the aquatic environment from a variety of sources and are highly toxic. In order to remove phenolic compounds from water, a new biobased sorbent is developed, blending chitosan with abrus precatorius, both naturally occurring biopolymers. The resulting chitosan–abrus precatorius blended beads (CS/Ab) were characterized by Brunauer, Emmett and Teller (BET) analysis, Fourier Transform Infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques under batch equilibrium and column flow experimental conditions. The binding capacity of the biosorbent was investigated as a function of initial pH, contact time, initial concentration of adsorbate and dosage of adsorbent. RESULTS: The percentage removal of phenol, 2‐CP and 4‐CP increased with increasing adsorbent dose, while the adsorption capacity at equilibrium, q_e (mg g^?1) (amount of phenol, 2‐CP and 4‐CP loaded per unit weight of adsorbent) decreased. The equilibrium time was found to be 240 min for full equilibration of all adsorbates. Adsorption kinetic and isotherm studies showed that the pseudo‐first‐order model and the Langmuir isotherm were the best choices to describe the adsorption behaviors. The maximum monolayer adsorption capacity of phenol, 2‐CP and 4‐CP on to the (CS/Ab) beads was found to be 156 mg g^?1, 204 mg g^?1 and 278 mg g^?1, respectively. CONCLUSION: The experimental results suggested that (CS/Ab) blended beads are effective in the removal of phenolic compounds from aqueous medium. Copyright © 2009 Society of Chemical Industry     

Influence of synthesis conditions on the production of molecularly imprinted polymers for the selective recovery of isovaleric acid from anaerobic effluents

Two molecularly imprinted polymers (MIPs) – poly(methacrylic acid‐co‐TRIM) (TRIM, trimethylolpropanetrimethacrylate) and poly(acylamide‐co‐TRIM) – were synthesized in different solvents for the selective recovery of isovaleric acid (template) generated during the anaerobic digestion process. The chemical and structural characterizations of the synthetic adsorbent were carried out by Fourier transform infrared spectroscopy, TGA and porosimetry through N₂ adsorption–desorption isotherms. The selective and adsorptive performances of the imprinted polymers were evaluated by kinetic, isothermal, thermodynamic and selectivity studies and by adsorbent reuse experiments. The poly(methacrylic acid‐co‐TRIM) synthesized with dimethyl sulfoxide:chloroform presented higher selectivity and adsorption capacity for isovaleric acid in the presence of six volatile fatty acids. The kinetic results were well adjusted to the pseudo‐nth order and intraparticle diffusion models, leading to k values of 10^?4 and 6 × 10^?5 for the best synthesis of MIPs and not‐imprinted polymers, respectively. Moreover, the Sips model best described the adsorption isotherm and generated a maximum adsorption capacity of ca 209 mg g^?1 (at 25 °C). Cycles of MIP use–desorption–reuse indicated that the selective adsorbent performed better than commercial adsorbents, losing less than 3% of adsorption capacity after three cycles. © 2018 Society of Chemical Industry     

Kinetic and Statistical Studies of Adsorptive Desulfurization of Diesel Fuel on Commercial Activated Carbons

Diesel fuel desulfurization by different commercial activated carbons was studied in a batch adsorber. Experiments, carried out to determine the sulfur adsorption dependency on time, were used to perform kinetic characterization and to screen the best performing activated carbon. The equilibrium characterization of the adsorption process was also performed. The statistical study of the process was undertaken by way of a two‐level one‐half fractional factorial experimental design with five process parameters. Individual parameters and their interaction effects on sulfur adsorption were determined and a statistical model of the process was developed. Chemviron Carbon SOLCARBTM C3 was found to be the most efficient adsorbent. The kinetic pseudo‐second order model and Freundlich isotherm are shown to exhibit the best fits of experimental data. The lowest achieved sulfur concentration in treated diesel fuel was 9.1 mg kg^–1.     

Activated carbon derived from macadamia nut shells: an effective adsorbent for phenol removal

In this study, activated carbon based on the waste macadamia nut shells (MAC) was investigated for potential use as an adsorbent for phenol removal. The pseudo second-order kinetic model best described the adsorption process. The extent of the phenol adsorption was affected by the pH solution and the adsorbent dosage. Equilibrium data fitted well to the Langmuir model with a maximum adsorption capacity of 341 mg g^?1. The calculated thermodynamic parameters suggested that the phenol adsorption onto MAC was physisorptive, spontaneous and exothermic in nature. Phenol desorption from loaded adsorbent was achieved by using 0.1 mol L^?1 NaOH, ethanol (100 %) and deionized water.     

Lignocellulosic jute fiber as a bioadsorbent for the removal of azo dye from its aqueous solution: Batch and column studies

The feasibility of the use of jute fiber for the adsorption of azo dye from an aqueous solution was evaluated with batch and fixed‐bed column studies. The batch studies illustrated that dye uptake was highly dependent on different process variables, namely, the pH, initial dye concentration of the solution, adsorbent dosage, contact time, ionic strength, and temperature. The exothermic and spontaneous nature of adsorption was revealed from thermodynamic study. The equilibrium adsorption data were highly consistent with the Langmuir isotherm and yielded an R² value of 0.999. Kinetic studies divulged that the adsorption followed a pseudo‐second‐order model with regard to the intraparticle diffusion. In the column studies, the total amount of adsorbed dye and the adsorption capacity decreased with increasing flow rate and increased with increasing bed height and initial dye concentration. Also, the breakthrough time and exhaustion time increased with increasing bed depth but decreased with increasing flow rate and influent dye concentration. The column performances were predicted by the application of the bed‐depth service time model and Thomas model to the experimental data. The virgin and dye‐adsorbed jute fiber was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The investigation suggested that jute fiber could be applied as a promising low‐cost adsorbent for dye removal. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel batch reactor design for the adsorption of arsenate on chitosan

BACKGROUND: The sorption of arsenate, a poison of acute toxicity found in natural waters, onto chitosan, a biosorbent derived from waste seafood shells has been studied. A batch adsorber design model was developed to determine how much chitosan adsorbent is required to reduce the arsenate concentration in solutions to the WHO standard of 10 µg L^?1. RESULTS: A series of batch kinetic experiments has been carried out at different initial pH values. The initial arsenate sorption appears to be completed after 30 min, however, a steady reversible reaction takes place resulting in the desorption of arsenate over 48 h. These phenomena in the batch kinetic data have been correlated simultaneously using the newly developed pseudo‐first order reversible model. Two batch reactor design models have been developed and compared. The first model is a conventional approach based on the equilibrium isotherm capacity equation. A second batch adsorption reactor design is based on the principle of contacting time required, t_max, for the chitosan to achieve its maximum adsorption capacity, q_max. The practical outcome from the second batch adsorber model results in a saving in adsorbent mass per batch of approximately 39.4%, 96.2% and 92.3% chitosan adsorbent at pH conditions of 3.5, 4.0 and 5.0, respectively. CONCLUSION: The adsorbent cost and handling costs are reduced in the second batch adsorber model. There is also a significant savings in the batch turnaround time required in the batch adsorber design when the design is based on the maximum adsorption capacity rather than the equilibrium adsorption capacity. Copyright © 2010 Society of Chemical Industry     

Removal of water‐soluble azo dye by the magnetic material MnFe2O4

Magnetic ferrite material, MnFe₂O₄, as a novel adsorbent was prepared and characterized. Adsorption tests indicated that it is an excellent adsorbent for the removal of the azo dye Acid Red B (ARB) from water. After adsorbing ARB and recovery by the magnetic separation method, it can be regenerated by Fenton's reagent. The pseudo‐first‐order and second‐order kinetic models were used to describe the kinetic data and the rate constants were evaluated. The adsorption capacity was highly affected by the pH of the solution, and pH 3.8 was optimal. After regeneration, the adsorption capacity of MnFe₂O₄ increased significantly, which was the result of a decrease in average pore diameter, an increase in surface area of the adsorbent and the adsorption of ferric hydroxide produced in the regeneration reaction. The adsorption can be described with the Langmuir model and the maximum adsorption capacity for ARB was 53.8 mg g^?1 adsorbent. FTIR study for ARB on MnFe₂O₄ indicated that the adsorption of ARB occurred via the azo group and the sulfonic group of the dye through the formation of a complex with the adsorbent surface. Copyright © 2004 Society of Chemical Industry