Sorption of metal ions from aqueous solution using bone char

The sorption of cadmium, copper and zinc from aqueous solutions onto bone char has been studied in both single and binary multicomponent systems. Equilibrium experimental studies have been performed to determine the sorption capacity of bone char for each metal ion. The isotherm results have been analysed using single and multi-component equilibrium models. The rate of sorption of the metal ions onto bone char has been studied using an agitated batch adsorber. The concentration versus time decay curves have been measured and a number of mass transfer models have been developed and tested based on diffusion controlled sorption. The results of the equilibrium and rate studies are presented and discussed in the paper. The possible mechanisms of metal sorption are also discussed. Finally a series of fixed bed column studies have been performed and analysed using a diffusion mass transport model. The experimental results show a displacement effect for the binary metal ion breakthrough curves. (C) 2005 Elsevier Ltd. All rights reserved

Sorption of cadmium, copper, and zinc ions onto bone char using Crank diffusion model

The rates of adsorption of cadmium, copper and zinc ions onto bone char have been studied in three single component systems using an agitated batch adsorber. The effects of initial metal ion solution concentration and bone char mass have been studied. The capacities of the three metals on bone char are 0.477, 0.709 and 0.505 mmol g(-1) for cadmium, copper and zinc respectively which are much higher than most other adsorbents reported in the literature for these three metals. In order to model the experimental concentration decay curves, a film-surface diffusion equation proposed by Crank (1979) has been solved. The model results correlate the experimental better than a previously applied film-pore diffusion model. However, the results indicate that the surface diffusion coefficient was a variable function of initial metal ion concentration. The surface diffusivities vary from 3.00 x 10(-9) to 8.80 x 10(-9) cm(2) s(-1), 2.11 x 10(-9) cm(2) s(-1) to 5.4 x 10(-9) cm(2) s(-1) and 3.10 x 10(-9) to 8.49 x 10(-9) cm(2) s(-1) for cadmium, copper and zinc respectively, for metal ion solution concentrations of 2.10-5.40 mmol dm(-3). (C) 2005 Elsevier Ltd. All rights reserved

Film-surface diffusion during the adsorption of acid dyes onto activated carbon

A mass transport model has been developed and applied to the adsorption of three acid dyes onto activated carbon in three single component systems. The mass transfer model is based on two rate controlling mass transfer steps, namely external film mass transfer and homogeneous solid-phase surface diffusion (HSD). Almost all previous film-HSD models have been based on numerical solutions to the diffusion equation using orthogonal collocation or Crank-Nicolson finite difference solutions. However, in the present model a semi-analytical solution to the solid surface diffusion equation is presented, yielding a sophisticated solution of the differential equations. The solutions provide a good correlation between the experimental concentration-time decay curves by incorporating the Langmuir equilibrium isotherm to describe the solid phase surface dye concentrations. However, the surface diffusivities show a dependence on the carbon particle surface coverage and these diffusivities have been correlated using a Darken relationship. (C) 2004 Society of Chemical Industry

Langmuir isotherm models applied to the multicomponent sorption of acid dyes from effluent onto activated carbon

The adsorption of three acidic dyes, Acid Blue 80 (AB80), Acid Red 114 (AR114), and Acid Yellow 117 (AY117) onto activated carbon, Filtrasorb 400, has been studied. Three single-component and three binary, AB80 + AR114, AB80 + AY117, and AR114 + AY117, isotherms were determined. Four models for predicting the multicomponent equilibrium sorption isotherms have been compared in order to determine which is the best; fit model to predict or correlate binary adsorption data. These were an extended Langmuir isotherm, a simplified model based on single-component equilibrium factors, a modified extended Langmuir isotherm with a constant interaction factor, and a modified extended Langmuir isotherm incorporating a surface coverage dependent interaction factor

Single and multicomponent equilibrium studies for the adsorption of acidic dyes on carbon from effluents

The ability of activated carbon to adsorb three acidic dyes, namely, Acid Blue 80 (AB80), Acid Red 114 (AR114), and Acid Yellow (AY117), from wastewater has been studied at 20degreesC. The three single-component systems and the three binary equilibrium systems have been measured experimentally. The three single component isotherms were analyzed using the Langmuir, Freundlich, Redlich-Peterson, and Sips equations. The Redlich-Peterson equation gave the lowest errors using the sum of the squares of the errors closely followed by the Sips and Langmuir equations; the Freundlich fits were significantly worse. The three bisolute experimental equilibrium sets of data were analyzed by incorporating the previous four single-component isotherm equations into the ideal adsorbed solution theory (IAST). The solution methods for each of the four isotherm equations are presented in the paper, and the predicted results for the three bisolute systems, using the four isotherm equations, are compared. For the three bisolute systems (AB80 + AR114, AB80 + AY117, and AR114 + AY117), the Redlich-Peterson isotherm gives the best correlation with the experimental isotherm data

Sorption of acid dyes from effluents using activated carbon

The sorption of three acid dyes, namely, Acid Red 114, Polar Yellow and Polar Blue RAWL, onto activated carbon, has been studied. Equilibrium isotherms have been measured for three single component systems (AB, AR, AY) and one binary component system (AB + AY). The isotherms were determined by shaking 0.05 g activated carbon, particle size range 500-710 mu m, with 0.05 dm(3) dye solution of initial concentrations from 10 to 250 mg/dm(3). A constant temperature agitating 400-rpm shaking water bath was used and the temperature maintained at 20 +/- 2 degrees C. A contact time of 21 days was required to achieve equilibrium Analysis of data has been carried out in two stages. (a) In single component analysis, the experimental isotherm data were analysed using Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich equations for each individual dye. The monolayer adsorption capacities are 101.0 mg Acid Red per g carbon, 100.9 mg Acid Blue per g carbon and 128.8 mg Acid Yellow per g carbon. (b) In multicomponent analysis, one binary system has been analysed using an extended form of the Langmuir equation. The correlation between theoretical data and experimental data only had limited success due to competitive and interactive effects between the dyes and dye-surface interactions. (C) 1999 Elsevier Science B.V. All rights reserved

Film-pore diffusion models - analytical and numerical solutions

The sorption of acid dyes from aqueous effluents onto activated carbon has been studied. The effects of initial dye concentration and activated carbon mass on the rate of Acid Blue 80 and Acid Yellow 117 removal have been investigated. Three mass transport models based on film and pore diffusion control have been applied to model the experimental concentration decay curves. The models are compared on the basis of the solid-phase loading capacity using various assumptions since the assignment of an appropriate solid-phase loading has been the subject of several papers on this topic and no comparisons have been provided on the effectiveness of each approach. The equilibrium solid-phase concentration is assumed: (i) incorporating a time-dependent solid-phase concentration Y-e,Y-t,Y- (ii) equal to the intersection point of the equilibrium isotherm and the operating line and (iii) the point on the equilibrium isotherm where the liquid-phase concentration equals the initial concentration in the film-pore diffusion model. (C) 2003 Elsevier Ltd. All rights reserved

Empirical multicomponent equilibrium and film-pore model for the sorption of copper, cadmium and zinc onto bone char

The adsorption of three metal ions onto bone char has been studied in both equilibrium and kinetic systems. An empirical Langmuir-type equation has been proposed to correlate the experimental equilibrium data for multicomponent systems. The sorption equilibrium of three metal ions, namely, cadmium (II) ion, zinc (II) ion and copper (II) ion in the three binary and one ternary systems is well correlated by the Langmuir-type equation. For the batch kinetic studies, a multicomponent film-pore diffusion model was developed by incorporating this empirical Langmuir-type equation into a single component film-pore diffusion model and was used to correlate the multicomponent batch kinetic data. The multicomponent film-pore diffusion model shows some deviation from the experimental data for the sorption of cadmium ions in Cd-Cu, Cd-Zn and Cd-Cu-Zn systems. However, overall this model gives a good correlation of the experimental data for three binary and one ternary systems

An empirical study on patients' acceptance and resistance towards electronic health record sharing system : a case study of Hong Kong

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Film and intraparticle mass transfer during the adsorption of metal ions onto bone char

The sorption of three metal ions, namely, copper, cadmium, and zinc, onto bone char has been studied in terms of equilibrium and rate studies. Equilibrium studies have been analyzed using the Langmuir isotherm equation and the maximum sorption capacities for the metals were 0.477, 0.709, and 0.505 mmol g(-1) bone char for cadmium, copper, and zinc ions, respectively. The kinetic experimental data were used to analyze the effect of external film boundary layer and intraparticle mass transfer resistance on the sorption process and its significance. Four methods of determining the external film transport coefficient were developed and tested; three utilized experimental data to obtain the coefficient and the fourth method was completely empirical. The three experimentally based models give very similar results and consequently similar values of the deviation error values, whereas the error values for the empirical correlation were greater than these three values. The results also demonstrated that the methods for determining the film coefficient could be integrated into more complex diffusion-transport models such as film-intraparticle diffusion processes. (C) 2004 Elsevier Inc. All rights reserved