3.7. Equilibrium isotherms Langmuir isotherm proposed by Langmuir, (1918) with some limitations Dąbrowski, (2001) expressed as: (4)
Where qm (mg g–1) is the maximum amount of the metal ion per unit weight of adsorbent, ‘qe’ is equilibrium adsorption capacity (mg g–1), ‘Ce’ is the equilibrium concentration of the adsorbate (mg L–1), and b is a constant which reveals the affinity of binding sites (L mg-1). From the plots between (Ce/qe ) and Ce the slope (1/qm ) and the intercept (1/ qmb) can be calculated. The Langmuir constant used to calculate the suitability of the adsorbent to adsorbate by using dimensionless factor RL by: (5)
0 1 designated un-favorable and RL = 1 be a sign of linear and RL = 0 point out as irreversible adsorption. Adsorption constants and correlation coefficients were shown in table 1. Ce / qe vs Ce plot yielded a straight line with R2 (0.991) indicated the sorption data could be well represented by the Langmuir model (Fig. 5c). The …show more content…
The coefficient of determination for this case is 0.998 and the values of nf and Kf (table 1) are found to be 1.2804 (g/L) and 0.2032 {(mg g–1)(mg L–1)n} at 323 K (Fig. 5d). The values of high correlation coefficients indicated that the Pb (II) sorption data were very well represented by Freundlich model. The Freundlich constant nf was greater than 1, at all temperatures studied as well as initial Pb (II) concentrations representing that adsorption intensity was high and reflecting the favorable sorption. Further, PVA–SA–J. rubens matrix, PVA–SA–nZnO–J. rubens matrix and Pb(II) loaded PVA–SA–nZnO–J. rubens matrix images were depicted in figure 6 (a), (b) and (c) respectively. The schematic diagram of uptake mechanism on PVA–SA–nZnO–J. rubens matrix was shown in figure 6
Where qm (mg g–1) is the maximum amount of the metal ion per unit weight of adsorbent, ‘qe’ is equilibrium adsorption capacity (mg g–1), ‘Ce’ is the equilibrium concentration of the adsorbate (mg L–1), and b is a constant which reveals the affinity of binding sites (L mg-1). From the plots between (Ce/qe ) and Ce the slope (1/qm ) and the intercept (1/ qmb) can be calculated. The Langmuir constant used to calculate the suitability of the adsorbent to adsorbate by using dimensionless factor RL by: (5)
0 1 designated un-favorable and RL = 1 be a sign of linear and RL = 0 point out as irreversible adsorption. Adsorption constants and correlation coefficients were shown in table 1. Ce / qe vs Ce plot yielded a straight line with R2 (0.991) indicated the sorption data could be well represented by the Langmuir model (Fig. 5c). The …show more content…
The coefficient of determination for this case is 0.998 and the values of nf and Kf (table 1) are found to be 1.2804 (g/L) and 0.2032 {(mg g–1)(mg L–1)n} at 323 K (Fig. 5d). The values of high correlation coefficients indicated that the Pb (II) sorption data were very well represented by Freundlich model. The Freundlich constant nf was greater than 1, at all temperatures studied as well as initial Pb (II) concentrations representing that adsorption intensity was high and reflecting the favorable sorption. Further, PVA–SA–J. rubens matrix, PVA–SA–nZnO–J. rubens matrix and Pb(II) loaded PVA–SA–nZnO–J. rubens matrix images were depicted in figure 6 (a), (b) and (c) respectively. The schematic diagram of uptake mechanism on PVA–SA–nZnO–J. rubens matrix was shown in figure 6