a review - Acta Technica Corviniensis

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Table (1):-Constant values of Langmuir equation and the equation for each media. Media q max b R 2 Equation PAC 3.4843 0.994 0.85 q e =3.4843*0.994C f / (1+0.994C f ) Karab 37.037 3.448 0.626 q e =37.037*3.448C f / Rice husks 136 24.39 0.0413 0.508 Corncobs 12.5 4.417 0.374 (1+3.448C f ) q e =24.39*0.0413C f / (1+0.0413C f ) q e =12.5*0.4.417C f / (1+4.417C f ) Freundlich model Figures (12), (13), (14) and (15) illustrate the plotting of Log q e vs. Log C f for rice husks, karab, corncobs and PAC, respectively. These Figures show a straight line (Freundlich adsorption isotherm) which means that the equilibrium data is correlated well with Freundlich equation. Figure (12):- Plot of Log q e vs. Log C f for determination of Freundlich constant for rice husks. Figure (13):- Plot of Log q e vs. Log C f for determination of Freundlich constant for karab. Figure (14):- Plot of Log q e vs. Log C f for determination of Freundlich constant for corncobs. ACTA TECHNICA CORVINIENSIS – Bulletin of Engineering Figure (15):- Plot of Log q e vs. Log C f for determination of Freundlich constant for PAC. The constants for Freundlich equation were calculated from the slope and intercept of the straight line, as tabulated in Table (2). Table (2):- Constant values of Freundlich equation and the equation for each media. Media K f 1/n R 2 Equation PAC 0.18 1.087 0.927 1.087 q e =0.18C f Karab 0.202 1.285 0.946 1.285 q e =0.202C f Rice husks 1.3 0.748 0.92 0.748 q e =1.3C f Corncobs 0.144 1.307 0.9 1.307 q e =0.144C f Multiple correlation The degree of relationship existing between three or more variables is called a multiple correlation. A regression equation is an equation for estimating a dependent variable, say X 1 , from the independent variables X 1 , X 2 , X 3 , … and is called a regression equation of X 1 on X 2 , X 3 , …. In functional notation, this sometimes is written briefly as X 1 =F(X 2 , X 3 , …) read “X 1 is a function of X 2 , X 3 , and so on” [Spiegel,1979]. In batch experiments, the removal efficiency of Cd(II) (sorption process) affected by many factors, therefore, it can be simulated with the regression equation by application the Excel program. The Cd(II) uptake capacity has an optimum value for each factor. The optimum value for each factor was found and put in the equation to find the correlation coefficient of it. The effect of particle size diameter can be neglected, because there was no optimum value for Cd(II) uptake capacity. Table (3) shows the relationships between the Cd(II) uptake capacity and their affected factors with determination coefficient of the equation for each media. Table (3):- The best equation for Cd(II) uptake capacity and its correlation coefficient for each media Media R 2 Equation 3.05 0.92 1.22 0.25 x1 x3 x4 x -6 5 PAC 0.984 y = 1.7 * 10 0. 58 x 1.72 0.28 x1 x3 x -4 4 Karab 0.946 y = 2.24 * 10 0. 54 x 1.16 0.27 x1 x3 x -4 4 Rice husks 0.951 y = 8.71* 10 0. 72 x 2.6 0.52 x1 x3 x -5 4 Corncobs 0.932 y = 1.59 * 10 0. 41 x 2 2013. Fascicule 2 [April–June] 2 2 2 x 1.16 0.26 5 x 1.07 0.29 5 x 1.24 0.23 5
ACTA TECHNICA CORVINIENSIS – Bulletin of Engineering Table (3):- The best equation for Cd(II) uptake capacity and its correlation coefficient for each media (continue) y practical y theortical Media (mgCd (II)/g) (mgCd (II)/g) adsorbent adsorbent PAC 3.35 2.632 Karab 3.84 3.373 Rice husks 4.31 3.941 Corncobs 3.49 2.892 Where: y: Cd (II) uptake capacity (mg Cd(II)/g adsorbent), X 1 :pH, X 2 : dosage adsorbent (mg), X 3 : contact time (min), X 4 : initial concentration (mg/L), X 5 : stirring speed (rpm), y practical : Cd (II) uptake capacity (mg Cd(II)/g adsorbent) calculated from batch tests and y theoretical : Cd (II) uptake capacity (mg Cd(II)/g adsorbent) calculated from the equation by multiple correlation. Continuous tests In column tests, a series of experimental breakthrough curves were plotted for adsorption of a single component system. The experiments included studying the effect of flow rate (Q) and the effect of the height of the adsorbate bed (H). The effect of flow rate Four column experiments were carried out at different flow rates (influents) (1, 3, 5 and 7 L/h) and at constant initial conditions: pH 5.5, rice husks particle size (0.425-1.4 mm), bed height (20 cm) and initial cadmium concentration (100 ppm). Data of effluent concentrations (C f ) vs. time of these experiments were plotted in Figures (16) and (17). It is clear from these figures that as the flow rate increases, the time of breakthrough point decreases. This is because that the residence time of solute in the bed decreases as the flow rate increases and there is not enough time for adsorption equilibrium to be reached, which results in lower bed utilization, and the absorbent solution leaves the column before equilibrium. more loading of metal ions onto the rice husks particles surfaces and then quicker saturation of rice husks adsorbent. The rate of Cd(II) uptake is clearly shown in the slopes of the linear portions of the relations in this figure. Figure (17):- Uptake curves for different flow rates The effect of bed height Rice husks bed height effect was examined by carrying out three experiments at different heights (H = 10, 20 and 30 cm) of weights (W = 56, 84 and 121 g), respectively. Other initial conditions were kept constants, flow rate (Q = 3 L/h), pH 5.5, particle size (0.425-1.4 mm) and average cadmium ion concentration (C i = 100 ppm). Figure (18) shown that the time required to reach the equilibrium state increases as the bed height increases. This can be attributed to the presence of more available sites of the removal in the media when increasing the bed height and, therefore, the time required reaching the equilibrium state increases. Figure (16):- Breakthrough curves of Cd(II) sorption for different flow rates Figure (17) illustrates the effect of flow rate on the rate of uptake by plotting the accumulative Cd(II) uptakes (q ac ) vs. time of column operation. From this figure, it can be seen that the accumulative uptake, at a certain time, increases when the flow rate increases, because the increase in flow rate means Figure (18):- Breakthrough curves of Cd(II) biosorption for different bed heights Besides, the accumulative Cd(II) uptakes (q ac ) for the rice husks vs. time of column operation were plotted as in Figure (18). From this figure, it can be seen that the time to saturation increases when the rice husks height increases, because using extra amount of rice husks results in extra surfaces for sorption, long flow paths and more contact time between the cadmium solution and rice husks particles. 2013. Fascicule 2 [April–June] 137
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ACTA TECHNICA CORVINIENSIS - BULLET
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ACTA TECHNICA CORVINIENSIS - Bullet
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offset or angled extensions from su
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There are two process trees at crea
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ROLE OF METAMODELING Detailed resea
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economy, packaging and knock limita
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satisfy constraints. This technique
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metamodel driven conceptual design
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[90.] Jian Deng, 2006, Structural r
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The wire movement is reported to th
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Figure 5 presents the cross-recepta
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RESULTS AND DISCUSSION. Electrochem
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REFERENCES [1.] Velisek, J.; Cejpek
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October 2008 (6.200 BAR) Figure 1.
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Figure 5. High pressure connection
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FD max = (σ1,h,BHF ,μ,t,n,K fm ,r
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Table 2: Ranges of variables select
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which solves the problem of mobile
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Figure 5. Diagram illustrating the
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CONCLUSIONS Based on the discussed
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market and competitive price. This
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[4.] RAJŇÁK, Milan a kol.: Cenov
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temporary organizational Project Po
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projects belong to the Project Port
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problem”, European Journal of Ope
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Figure 3. EBM process The applicati
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The benefits of registration to ISO
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assumed ratio of 12 ) has been made
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REFERENCES [1] Budzik G., Kozik B.,
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MHD effects on impulsively started
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The concentration distribution is f
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