Intraparticle Diffusion Equation Research Articles

Kinetics studies on the adsorption behaviour of Basic Blue 9 dye on macroporous ion exchanger resins

AbstractAmong various types of adsorbents used in the treatment of wastewaters impurified with dyes, the ion exchange resins still have an important place. The aims of this paper are: to evaluate the influence of contact time on the dye adsorption from aqueous solutions on Purolite macroporous ion exchange resins for strong acid (C-145) and for weak acid (C-107E), to understand the mechanisms that govern dye removal and to find an appropriate kinetic model to describe the process. In order to investigate the mechanism of adsorption and the potential rate controlling steps, pseuso-first- and second-order equations, the intraparticle diffusion equation and the Elovich equation have been used to test experimental data. The kinetics of the adsorption process of Basic Blue 9 dye onto Purolite ion exchanges follows a pseudo-second- order rather than pseudo-first- order model, and both the film and the intraparticle diffusion mechanisms are involved in the adsorption processes, and may be the rate determining st...

Removal of copper ions from aqueous solution by adlai shell (Coix lacryma-jobi L.) adsorbents

Adlai shell (Coix lacryma-jobi L.) adsorbents (ASA) were used to remove copper ions from aqueous solutions under batch conditions. The effect of physical and chemical modification of ASA on Cu(II) removal was evaluated. Results showed that the high coefficients of determination for the pseudo-second order (R2>0.9999) and for the intraparticle diffusion (R2>0.9843) equations indicate that the rate-determining step is a combination of pore diffusion and chemisorption at low Cu(II) concentration and boundary layer, pore diffusion and chemisorption at high Cu(II) concentration. At 298K and 100mgL−1 Cu(II), the computed qe and k2 values were 17.2mgg−1 and 0.012gmg−1min−1, respectively. The Freundlich model (R2>0.9636) adequately describes the experimental data indicating heterogeneous adsorption. Overall, the results of the study demonstrate the potential of adlai shell adsorbents for the removal of heavy metals from aqueous solutions.

Adsorption behaviors of acid dye by amphoteric chitosan/gelatin composite microspheres

The use of amphoteric chitosan/gelatin composite microspheres (CGMSs) has been studied as an adsorbent for the removal of Acid Red 337 (AR337) from wastewater. The adsorbent was characterized by using several methods such as scanning electron microscopy and atomic force microscope (AFM). The kinetic study was performed based on pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. It was shown that the adsorption process could be described by the pseudo-second-order equation, suggesting that the adsorption process is presumably a chemisorption. Freundlich, Langmuir, Dubinin–Radushkevich isotherms were used to analyze the adsorption equilibrium and the isotherm constants were evaluated at different temperatures. According to the Langmuir model, CGMS adsorbent exhibited the highest AR337 dye uptake capacities of 748.50 mg/g. The values of equilibrium parameter (0 < RL <0.08) clearly exhibit that the adsorption of AR337 dye onto CGMSs is very favorable. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) have been calculated. The adsorption process of AR337 dye onto CGMSs was found to be spontaneous and endothermic. Furthermore, the data from regeneration efficiencies for six cycles provided evidence of the high reusability of the CGMSs in the treatment of dye wastewater.

One-pot hydrothermal synthesis of thrust spherical Mg–Al layered double hydroxides/MnO2 and adsorption for Pb(II) from aqueous solutions

In this study, Mg–Al layered double hydroxides/MnO2(Mg–Al LDHs/MnO2) was synthesized by one-pot hydrothermal method, and their use for removal of Pb(II) from aqueous solutions. The produced composite was characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). A series of experimental parameters including adsorbent dose, initial pH and contact time on Pb(II) uptake was evaluated. The results showed that the morphology of as-fabricated sample was thrust spherical structure. The removal efficiency of Pb(II) reached up to 96.73% when 0.05g MgAlLDHs/MnO2 was added in 50mL Pb(II) solutions which the concentration was 50mg/L at the condition of the pH4 and 25°C. Adsorption kinetic data were modeled using the pseudo-first-order, pseudo-second-order and intraparticle diffusion equations and its rate constants were evaluated. The adsorption process followed the pseudo-second-order reaction kinetics, suggesting that it was presumably chemisorption.

Investigation of Strontium (II) Sorption Kinetic and Thermodynamic onto Straw-derived Biochar

Biochars have attracted much research attention recently because of their potential applications in many environmental areas. In this study, rice straw-derived biochars produced at different pyrolysis temperatures (550–750°C) were used as adsorbents for the removal of strontium (II) under different experimental conditions of time, pH, and temperature. Sr(II) sorption equilibrium occurs after 30 min and its sorption maximum achieved at pH 6. The kinetic data obtained were analyzed to predict the constant rate of sorption using three common kinetic models: pseudo-first-order, pseudo-second-order equation, and intraparticle diffusion equation. The pseudo-second-order model was suitable for describing the sorption kinetics for the removal of Sr(II) from aqueous solution onto straw-derived biochar. Sorption of Sr(II) onto biochar was endothermic. Biochar has the highest Sr(II) sorption capacity in comparison to other adsorbents.

Zinc Oxide Nanoparticles Loaded on Activated Carbon and Its Application for Adsorption Removal of Uric Acid

The work was devoted to the study of uric acid (UA) adsorption onto zinc oxide nanoparticles loaded on activated carbon (ZnO-NP-AC). This nontoxic and cheap material with high efficiency in a routine manner was synthesized in our laboratory and its surface properties such as surface area, pore volume and functional groups were characterized with different techniques such FT-IR, SEM, and BET analysis. Then, the its utilization for the removal of UA was investigated by optimization of the effects of variables such as solution pH, initial UA concentration, amount of adsorbent, temperature, and adsorption time. Fitting the equilibrium data to conventional isotherm models (Langmuir, Freundlich, and Tempkin) according to correlation coefficient and error analysis show the priority of the Langmuir model in term of higher correlation coefficient (0.995) and high adsorption capacity (345.8 mg g−1) for data elucidation. The favorable adsorption data suggest its suitability for the fast and economic UA removal (more than 90% in time less than 15 min) using small amount of nanoparticle (<0.012 g). The result of removal of UA at various time was investigated and experimental data was analyzed by four kinetic models including pseudo first and second order Elovich and the intraparticle diffusion equations and subsequently their respective parameters such as rate constants, equilibrium adsorption capacities, and correlation coefficients were investigated and based on well known criterion their applicability was judged. The result show that adsorption of UA onto proposed adsorbent at all conditions such as versatile adsorbent dosage and initial UA concentrations sufficiently described by the pseudo second-order equation in addition to interparticle diffusion model.

Application of activated carbon derived from waste Delonix regia seed pods for the adsorption of acid dyes: kinetic and equilibrium studies

Activated carbon prepared from Delonix regia (DR) seed pod has been used as adsorbent for the removal of anionic dyes from aqueous solution. Three anionic textile dyes (C.I. Acid Blue 15, C.I. Acid Red 114, C.I. Acid Violet 17) and one dye mixture were used as model compounds. The capacity of DR to adsorb anionic dyes from aqueous dye solution was evaluated at different contact times, dosage, pH, and initial adsorbent concentration. Results show that the highest dye removal (>95%) was obtained at pH 2 for the adsorption of all the selected dyes. Four isotherms (Langmuir, Freundlich, Temkin, and Redlich–Peterson) were used to fit the equilibrium data. The adsorption equilibrium showed that the Langmuir equation represented best fit of the experimental data than others. The adsorption isotherm indicates that the adsorption capacities are 151.51, 113.63, and 129.87 mg dye per gram of DR for AR-114, AV-17, and AB-15 Acid dyes, respectively. In order to investigate the mechanism of adsorption and rate-controlling steps, pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich equations have been used to test the experimental data. The adsorption kinetics was found to follow pseudo-second-order kinetics with correlation coefficients greater than 0.99. It was found that at the higher initial acid dye concentration, intraparticle diffusion is becoming significant rate-controlling step.

Study of Fluorescent Dyeing Process and Influence of Mixture Dyes on High-visibility

In this paper, we present the results of an investigation and analysis of an experimental study of fluorescent disperse dyes used for dyeing polyester fabrics to high-visibility colors. This paper describes the results of spectrophotometric color measurements for yellow luminous, red luminous and orange luminous fluorescent dyes and their matching with the requirements of the EN 471 standard. The results of this study showed that the adsorption isotherms of polyester dyeing with fluorescent disperse luminous dyes follow the Nernst equation; the Nernst constants were determined and interpreted. The adsorption kinetics of fluorescent disperse dyes on polyester is studied by using the peudo-first-order model, the pseudo-second-order equation and the intraparticle diffusion equation. The results show that pseudo-second-order models fit well the experimental data with higher average regression coefficients (R2&gt; 0.98). They also show that high-visibility is influenced by the dye concentration, and that the dye mixtures can affect the high-visibility.

Convenient synthesis of micron-sized macroporous polymers with dents on their surfaces and excellent adsorption performance for λ-cyhalothrin

Macroporous poly(methyl methacrylate) (MPMMA) microspheres with more than a dozen dents on their surfaces were synthesized by Pickering emulsion polymerization. In this method, sulfonated polystyrene (SP) particles were used as stabilizers to establish a stable oil-in-water emulsion. Then, the system was fabricated by radical polymerization in the presence of the functional and polymeric monomers in the oil phase. The as-prepared MPMMA polymers were named “dandelion-pollen”-like microspheres, the diameter of numerous MPMMA microspheres was about from 7μm to 9μm and the size of numerous dents on the MPMMA surface was ranged from 0.96μm to 1.94μm. May be the formation of dents increased the surface area and binding sites, a favorable adsorption for λ-cyhalothrin was shown in the subsequent adsorption process. The kinetic properties of MPMMA were well described by the pseudo-second-order and intraparticle diffusion equations, which indicating that the chemical process could be the rate-limiting step in the adsorption process for λ-cyhalothrin. The equilibrium adsorption capacity of MPMMA were 241.12μmolg−1, 222.67μmolg−1, 164.62μmolg−1 at 298K, 308K, 318K, respectively. The Freundlich isotherm model gave a better fit to the experimental data that indicating multilevel molecular adsorption for λ-cyhalothrin. The dynamic equilibrium adsorption capacity of MPMMA and regenerative MPMMA were 30.79mgg−1 and 36.76mgg−1, respectively. Moreover, the dynamic adsorption curve was in good agreement with the Thomas model, which predicted that the performance of flow column was conformed to the assumptions of the model. At the end of four regeneration recycles, the adsorption capacity remained at 95% of the initial value, which implied that MPMMA particles had good regeneration capacity.

Comparison study on the adsorption performance of methylene blue and congo red on Cu-BTC

AbstractCu-BTC, one of the metal–organic frameworks (MOFs), has been applied to remove the cationic dye methylene blue (MB) and anionic dye methyl orange (CR) from contaminated water. Liquid phase adsorption experiments were conducted and the maximum adsorptive capacity was determined. Various conditions were evaluated, including initial dye concentration, contact time, solution pH, and temperature. The Langmuir and Freundlich adsorption models were used to describe the equilibrium isotherm and isotherm constant calculation. It was found that the Cu-BTC adsorption capacities of MB and CR are much higher than those of the other types of MOFs and adsorbents. Maximum equilibrium adsorption capacities of 143.27 and 877.19 mg/g for MB and CR were achieved. Three simplified kinetic models including pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations were used to investigate the adsorption process. The pseudo-second-order equation was followed for adsorption of MB and CR on Cu-BTC. Te...

Adsorption Kinetics of Lignite Activated Carbon in Treating Coal Gasification Wastewater

Lignite activated carbon was provided through lignite which is treated specially. The adsorption capacity and mechanism of COD from Coal gasification wastewater by lignite activated carbon have been studied.The adsorption capacities of lignite activated carbon at different times were obtained by concentration of COD in the remainder solution. Three simplified kinetic models: pseudo-first-order, pseudo-second-order, intraparticle diffusion equations were adopted to examine the mechanism of the adsorption process. The results showed that the adsorption can be expressed by the pseudo-second-order model. The adsorption balance capacity was obtained as 50.8mg·g-1 (298K), and the adsorption balance capacity decreased with increasing of temperature, which showed that the adsorption process was exothermic. The adsorption activation energy (Ea) was calculated as 5.76kJ·mol-1, and it showed that the adsorption process was Physical adsorption. This study explored new treatment channels for lignite comprehensive utilization..

Removal of congo red from aqueous solution by its sorption onto the metal organic framework MIL-100(Fe): equilibrium, kinetic and thermodynamic studies

AbstractIn this study, an iron based metal organic framework (MIL-100(Fe)) with high surface area and large pore volume has been synthesized by the hydrothermal method and its capability as an efficient sorbent for congo red (CR) removal from aqueous samples has been evaluated. The metal organic framework sorbent was characterized by Fourier transform infrared spectroscopy, scanning tunneling microscopy, thermogravimetric analysis/differential thermal analysis, and X-ray diffraction methods. The sorption capacity of the sorbent for CR was maximized through systematic studies of different factors which affect its sorption, such as contact time, initial concentration, sorbent dosage, pH and temperature. Sorption kinetic was studied in detail by four kinetic models, the pseudo-first-order and second-order equations, the Elovich equation and the intraparticle diffusion equation. The results indicate that the mechanism of the sorption process followed Elovich and pseudo-second-order kinetic. Sorption equilibri...

Equilibrium Modeling and Kinetic Studies on the Adsorption of Basic Dye by A low-Cost Adsorbent: Sugarcane Bagasse

This study was carried out to examine the effectiveness of sugarcane bagasse, an agricultural waste available in bulky quantity in Malaysia, to remove basic dye (e.g., methylene blue) from aqueous solution by adsorption. Batch mode experiments were carried out to study the effects of shaking speed, contact time, adsorbent dosage, and pH. Furthermore, equilibrium adsorption isotherms and kinetics were investigated. In the optimum operation condition, about 96.9 and 95.5 removal percentage of colour was obtained at 200 rpm shaking speed, 6 hr contact time and 0.2 g AC dosage. The experimental data were analyzed by the Langmuir, and Freundlich models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm. The kinetic data has been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model with R 2 > 0.99. Consequently, the adsorption of MB onto the AC driven from sugarcane bagasse has a great potential to be used textile waste water treatment.

Adsorption of Ni (II) from Wastewater using Low Cost Activated Carbon Prepared from Prosopis Juliflora- A Kinetics and Equilibrium Studies

The optimum parameters affecting the adsorption of Ni(II) using Prosopis Juliflora bark carbon (PJBC) were determined. The adsorption of Ni(II) was strongly dependent on pH, temperature and initial adsorbate concentration. The equilibrium adsorption data follows Langmuir and Freundlich isotherms. The optimum pH for Ni(II) ions removal was found out to be 5.5. The equilibrium data shows the exothermic nature of adsorption. Kinetic studies shows pseudo second order and intra-particle diffusion equations successfully describe the adsorption process.

Fabrication of porous ZrO2 hollow sphere and its adsorption performance to Congo red in water

Hollow and solid ZrO2 microspheres with mesoporous structures were prepared by a hydrothermal method using zirconium oxychloride and urea as precursors. The as-prepared samples were characterized by X-ray diffraction, scanning and transmission electron microscopy and nitrogen adsorption–desorption isotherms. Adsorption performance of the as-prepared samples toward Congo red (CR) aqueous solutions was investigated and discussed. The pore structure analyses indicated that the prepared ZrO2 hollow and solid microspheres contained bimodal porous organization: small mesopores (ca. 2nm) and large mesopores and macropores (ca. 40–70nm). The CR equilibrium adsorption data of the as-prepared samples were fitted using Langmuir and Freundlich equations, indicating that the Langmuir equation exhibited the better correlation of the experimental data. The CR adsorption capacities were determined by the Langmuir equation and found to be 59.5, 21.4 and 4.8mgg−1 for the ZrO2 hollow, solid microsphere and reagent samples, respectively. Adsorption data were further modeled by the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations. The results suggested that pseudo-second-order kinetic and intra-particle diffusion equations could better describe the kinetics of CR adsorption. The prepared ZrO2 hollow microsphere was found to be good adsorbent for the CR removal from water due to its high specific surface areas and bimodal porous structures.

Adsorption of Methylene Blue from Aqueous Solution by Crosslinked Chitosan/Bentonite Composite

This article reports the application of a crosslinked chitosan/bentonite composite as adsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solution. Batch experiments were conducted to study the effects of contact time, initial concentration of adsorbate (50–200 mg L−1), temperature (298–313 K), agitation speed (90–150 rpm), and pH (2–10) on adsorption. The equilibrium experimental data were analyzed by the Freundlich and Langmuir models. The kinetic data obtained with different initial concentration and temperature were analyzed using a pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. Maximum adsorption capacity (Q m) was calculated at different temperatures (298, 308, and 313 K) as 95.24, 97.09, and 142.86 mg g−1, respectively. The results showed that this novel adsorbent had a high adsorption capacity, making it suitable for use in the treatment MB-enriched wastewater.

Magnetic particles precipitated onto wheat husk for removal of methyl blue from aqueous solution

Magnetic particles prepared via co-precipitation and impregnated onto wheat husk (MN-WH) were used for the removal of methyl blue (MB) from aqueous solution. Experiments were conducted in a batch mode for optimization regarding pH, contact time, adsorbent dose, initial dye concentrations, and temperature. Maximum adsorption (98%) was achieved at pH 5. The adsorption data were fitted into pseudo-first, pseudo-second, intraparticle diffusion, and Elovich equation revealing that adsorption followed pseudo-second-order kinetics. The four most common isotherm models, i.e. the Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R), were used to evaluate the data, with the best fit to a Langmuir isotherm (R2 = 0.996), followed by a Freundlich isotherm (R2 = 0.995), indicating monolayer adsorption of MB on the surface of MN-WH. Thermodynamic parameters calculated from the Van't Hoff equation revealed that the adsorption is exothermic (ΔHº = −19.7 kJ mol−1).

Adsorption isotherm, kinetic modeling and thermodynamics of crystal violet dye on coconut husk-based activated carbon

The present study shows that the H2SO4-modified coconut husk derived activated carbon powder (CHACP) can be used as a potential adsorbent for the removal of crystal violet (CV, basic dye) from aqueous solutions. Experiments were carried out as a function of contact time, concentration, pH, mass dosage, and temperature, the equilibrium was attained in 60 min. The amount of dye uptake (mg/g) was found to increase with increase in dye concentration, pH, temperature, and contact time. The kinetics of CV on to the adsorbent can be described well by pseudo-second order > Elovich > pseudo-first order > intra-particle diffusion equation. The applicability of the isotherm’s model for the present data follows the order: Freundlich > Temkin > Langmuir. Based on the calculated thermodynamic parameters such as enthalpy (ΔH°), entropy (ΔS°), activation energy (Ea), sticking probability (S*), and Gibbs free energy changes (ΔG°), it is noticeable that the sorption of CV dye onto CHACP was a spontaneous and endothermic process. The morphological and chemical characteristics of the adsorbent were established by scanning electron microscopy and Fourier transform infrared spectroscopy.

Biosorption of uranium by immobilized cells of Rhodotorula glutinis

Biosorption of uranium ions from diluted solution (≤40 mg L−1) onto immobilized cells of Rhodotorula glutinis was investigated in a batch system. Equilibrium, kinetic and thermodynamic studies were conducted by considering the effect of initial uranium concentration, contact time and temperature. Non-linear forms of Langmuir, Freundlich and Sips isotherm models were used to fit the equilibrium data, Sips model was designated as the best one. Kinetic data were simulated by non-linear pseudo-first-order, pseudo-second-order and intra-particle diffusion equations. Pseudo-first-order kinetic equation described the experimental data better than pseudo-second-order equation and intra-particle diffusion equation can fit the kinetic data with two independent curves. Thermodynamic parameters, including ∆H 0, ∆G 0 and ∆S 0, were evaluated, the sorption process was determined to be spontaneous and endothermic. Uranium sorption from pure uranium solutions and uranium pit wastewater by immobilized biomass and blank beads, as well as the regeneration results indicated that immobilized R. glutinis can be use to recovery uranium from uranium pit wastewater.

Synthesis of a new chelating resin bearing amidoxime group for adsorption of Cu(II), Ni(II) and Pb(II) by batch and fixed-bed column methods

A new amidoxime chelating resin (PAO-AM) was synthesized from the functionalization of poly(acrylamide-co-N,N′-methylenebisacrylamide) (CPM) supported acrylonitrile group (CPM-EA-AN) with hydroxylamine under alkaline conditions. The CPM-EA-AN was prepared by treatment of CPM with ethylenediamine; the amino group in CPM-EA was reacted with acrylonitrile to give CPM-EA-AN. The resulting chelating resin was characterized with FTIR spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), water regain and Brunauer–Emmett–Teller (BET). Batch experiments were performed to study the effects of solution pH, metal ions concentration, contact time and adsorption temperature on metal ion adsorption. It was found that PAO-AM showed high affinity toward Cu(II), Ni(II) and Pb(II) ions. The maximum adsorption capacities were found to be 2.3, 1.94 and 1.14mmol/g resin for Cu(II), Ni(II) and Pb(II), respectively. The adsorption isotherms were analyzed using the Langmuir, Freundlich and Temkin isotherms. The adsorption isotherms were better fitted by the Langmuir equation. The kinetics data were analyzed by pseudo-first order, pseudo-second order, and intra-particle diffusion equations. The results showed that the adsorption process could be described by pseudo-second-order kinetic model. Thermodynamic parameters revealed the spontaneity of adsorption process and higher temperatures favor the adsorption process. Additionally, the adsorption performance of (PAO-AM) toward Cu(II), Ni(II) and Pb(II) using fixed bed column method was investigated. Regeneration of chelating resin loaded with metal ions was effectively performed and the resin could be used repetitively for 5 times with a small decrease in adsorption capacity.