Kinetic modelling and mechanism of dye adsorption on unburned carbon

Wang, Shaobin; Li, Huiting

doi:10.1016/j.dyepig.2005.09.005

Cited by 174 publications

(85 citation statements)

References 20 publications

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“…The poor non-linearity of Boyd plots (Fig. 11) indicated the external mass transport with intraparticle diffusion controlled the rate-limiting process of adsorption, which is different from the conclusion drawn by Wang and Li (2005) on adsorption of dye on unburned carbon.…”

Section: Boyd Kineticscontrasting

confidence: 53%

Adsorption kinetics of fluoride on iron(III)-zirconium(IV) hybrid oxide

2007

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Fluoride occurs in some drinking water sources at levels that are hazardous to health. Tests were conducted to assess the ability of a mineral-based adsorbent to takeup fluoride ion. Consequently, in search of novel adsorbent media, crystalline and hydrous iron(III)-zirconium(IV) hybrid oxide (IZHO) was synthesized, and tested to determine its capacity and kinetics for fluoride adsorption. The Fourier Transform Infrared (FTIR) spectrum of IZHO indicated the presence of Fe-O-Zr linkage which showed hybrid nature of the synthetic oxide. The optimum pH range for fluoride adsorption was ranged between 4.0 and 7.0. The analyses of the isotherm equilibrium data using the Langmuir and the Redlich-Peterson model equations by linear and non-linear methods showed that the data fitted better with latter model than the former. Thermodynamic analysis showed spontaneous nature of fluoride adsorption, and that took place with the increase of entropy. The kinetic data obtained for fluoride adsorption on IZHO at pH 6.8 (±0.1) and room temperature (303 ± 2 K) described both the pseudo-first order and the reversible first-order equations equally well (r 2 = ∼0.98-0.99), and better than pseudo second order equation (r 2 = ∼0.96-0.98) for higher concentrations (12.5 and 25.0 mg/dm 3 ) of fluoride. The kinetics of fluoride adsorption on the mixed oxide took place with boundary layer diffusion. External mass transport with intra-particle diffusion phenomena governed the rate limiting process, which has been confirmed from the Boyd poor non-linear kinetic plots. Abbreviations C iThe initial concentration (mg/dm 3 ) of fluoride in solution C eThe concentration of fluoride (mg/dm 3 ) in solution at equilibrium C aThe concentration of fluoride (mg/dm 3 ) in solution at any time, t C bThe concentration of fluoride in solid phase (mg/g) at any time, t C a0 The initial concentration of fluoride in solution (mg/dm 3 ) C b0 The initial concentration of fluoride in adsorbent phase (mg/g) Cae The equilibrium concentration of solute in solution (mg/dm 3 ) q eThe adsorption capacity (mg/g) at equilibrium q mThe monolayer adsorption capacity (mg/g) q tThe adsorption capacity (mg/g) at any time, t B L The Langmuir adsorption equilibrium constant (dm 3 /mg) A L The Langmuir constant (dm 3 /g) A RP The Redlich-Peterson model isotherm constant (dm 3 /g) B RP The Redlich-Peterson model isotherm constant (dm 3 /mg) n RP n RP The Redlich-Peterson isotherm model exponent k 1 The pseudo-first order rate constant (time −1 ) k 2The pseudo-second order rate constant (mg/g time) t time (min) Xa The fractional conversion of solute k # (= k 1 + k 2 ) the overall rate constant (time −1 ) k 1The rate of forward reaction (time −1 ) k 2The rate of backward reaction (time −1 ) k B (= −k # ) the rate constant (time −1 ) of Bhattacharya and Venkobachar model kinetics 84Adsorption (2007) 13: [83][84][85][86][87][88][89][90][91][92][93][94]

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Section: Boyd Kineticscontrasting

confidence: 53%

Adsorption kinetics of fluoride on iron(III)-zirconium(IV) hybrid oxide

2007

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“…These are highly water-soluble and estimated that 10-20% of reactive dyes remain in the wastewater during the production process of these dyes and nearly 50% of reactive dyes may lost to the effluent during dyeing processes of cellulose fibers [3,4]. Moreover, the complex aromatic molecular structures of reactive dyes make them more stable and more difficult to biodegrade [5,6]. The majority of technologies presently employed for the decolorization of dyes in wastewater are based on either traditional physicochemical processes such as dilution, oxidation, adsorption, electrocoagulation and flocculation, chemical precipitation, ion exchange, reverse osmosis and ultra filtration [7,8], or biological process [9].…”

Section: Introductionmentioning

confidence: 99%

Adsorption Characteristics of Reactive Black 5 from Aqueous Solution onto Chitosan

Saha

Bhoumik

Karmaker

et al. 2011

CLEAN Soil Air Water

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Adsorption of reactive black 5 (RB5) from aqueous solution onto chitosan was investigated in a batch system. The effects of solution pH, initial dye concentration, and temperature were studied. Adsorption data obtained from different batch experiments were modeled using both pseudo first-and second-order kinetic equations. The equilibrium adsorption data were fitted to the Freundlich, Tempkin, and Langmuir isotherms over a dye concentration range of 45-100 mmol/L. The best results were achieved with the pseudo second-order kinetic and Langmuir isotherm equilibrium models, respectively. The equilibrium adsorption capacity (q e ) was increased with increasing the initial dye concentration and solution temperature, and decreasing solution pH. The chitosan flakes for the adsorption of the dye was regenerated efficiently through the alkaline solution and was then reused for dye removal. The activation energy (E a ) of sorption kinetics was estimated to be 13.88 kJ/mol. Thermodynamic parameters such as changes in free energy (DG), enthalpy (DH), and entropy (DS) were evaluated by applying the van't Hoff equation. The thermodynamics of reactive dye adsorption by chitosan indicates its spontaneous and endothermic nature.

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“…However, the complex aromatic molecular structures of dyes make them more stable and more difficult to biodegrade [1,2]. The extensive use of dyes in different kinds of industries often poses pollution problems in the form of colored wastewater discharged into environmental water bodies [3].…”

Section: Introductionmentioning

confidence: 99%

Removal of Brilliant Green Dye from Aqueous Solutions Using Home Made Activated Carbons

Calvete

Lima

Cardoso

et al. 2010

CLEAN Soil Air Water

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Activated carbon materials were prepared from the Brazilian pine-fruit shell (Araucaria angustifolia) by chemically activated carbon (CAC) and chemically and physically activated carbon (CPAC), and tested as adsorbents for the removal of brilliant green (BG) dye from aqueous effluents. The mixed activation process leads to increases in the specific surface area, average porous volume, and average porous diameter of the adsorbent CPAC when compared to CAC. The effects of shaking time, adsorbent dosage and pH on the adsorption capacity were studied. BG uptake was favorable at pH values ranging from 2.0 to 10.0 for both CAC and CPAC. The contact time required to obtain the equilibrium using CAC and CPAC as adsorbents was 4 h at 298 K, respectively. The fractionary-order kinetic model provided the best fit to experimental data compared with other models. Equilibrium data were better fit to the Sips and Redlich-Peterson isotherm models using CAC and CPAC as adsorbents. The enthalpy and entropy of adsorption of BG were obtained from adsorption experiments ranging from 298 to 323 K. IntroductionDyes are a kind of organic compound with a complex aromatic molecular structure that can bring bright and firm color to other substances. However, the complex aromatic molecular structures of dyes make them more stable and more difficult to biodegrade [1,2]. The extensive use of dyes in different kinds of industries often poses pollution problems in the form of colored wastewater discharged into environmental water bodies [3].The most efficient method for the removal of synthetic dyes from aqueous effluents is the adsorption procedure [4][5][6]. This process transfers the dye species from the water effluent to a solid phase thereby keeping the effluent volume to a minimum [7][8][9]. Subsequently, the adsorbent can be regenerated or stored in a dry place without direct contact with the environment [5][6][7][8][9].Activated carbon is the most employed adsorbent for toxic species removal from aqueous effluents because of well-developed pore structures and a high internal surface area that leads to its excellent adsorption properties [10,11]. Besides these physical characteristics, the adsorption capacity is also dependent on the source of organic material employed for the production of the activated carbon [10][11][12][13], as well as the experimental conditions employed in the activation processes [11].Activated carbon can be prepared using a variety of chemical [14] and physical [15] activation methods and in some cases using a combination of both types of methods [16]. Chemical activation is the process where the carbon precursor material is firstly treated with aqueous solutions of dehydrating agents such as H 3 PO 4 , ZnCl 2 , H 2 SO 4 , and KOH. Afterward, the carbon material is dried at 373-393 K to eliminate the water. In a subsequent step, the chemically treated carbon material is heated between 673 and 1073 K under nitrogen atmosphere [11,17]. The physical activation consists of a thermal treatment of previously carbonize...

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Kinetic modelling and mechanism of dye adsorption on unburned carbon

Cited by 174 publications

References 20 publications

Adsorption kinetics of fluoride on iron(III)-zirconium(IV) hybrid oxide

Adsorption kinetics of fluoride on iron(III)-zirconium(IV) hybrid oxide

Adsorption Characteristics of Reactive Black 5 from Aqueous Solution onto Chitosan

Removal of Brilliant Green Dye from Aqueous Solutions Using Home Made Activated Carbons

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