Fig. 4. Adsorption isotherms of Pb2+ onto FeAA at different temperatures.
it was smoother after the reaction in the FBR had proceeded for
3 months. Moreover, Fig. 3b and d shows details of the original
activated alumina grain support with a typical sheet-like structure
and the surface of the FeAA with fine granular structure.
The specific surface areas of the original activated alumina grain
support and FeAA are 127 and 170 m2 g−1, respectively.
3.2. Adsorption isotherm
Fig. 4 shows the adsorption isotherms of Pb2+ on FeAA at
288, 308 and 318 K. Equilibrium data can be analyzed using
commonly known adsorption isotherms, which provide the basis
for the design of adsorption systems. The most widely used
isotherm equation for modelling of the adsorption data is the
Langmuir equation, which is valid for monolayer sorption onto
a surface with a finite number of identical sites and is given by
Eq. (2).
qe = KLqmCe
1 + KLCe
, (2)
where KL is the adsorption equilibrium constant including the
affinity of binding sites (mM−1), qm the maximum adsorption
capacity (mmol g−1) and qe is the amount of sorbed Pb2+ at equilibrium
(mmol g−1). It represents a practical limiting adsorption
capacity when the surface is fully covered with Pb2+. qm and
KL can be determined from the linear plot of Ce/qe versus Ce
[27,28].
The Freundlich model is an empirical equation based on
sorption on a heterogenous surface. It is given as:
qe = KFC1/n
e , (3)
where KF and n are the Freundlich constants related to the
adsorption capacity and adsorption intensity, respectively. The
Freundlich equation can be linearized by taking logarithms and
constants can be determined [28].
Linear plots of Ce/qe versus Ce and ln qe versus lnCe are
shown in Fig. 5a and b. For each isotherm in Fig. 5a, the values
of qm and KL were calculated from experimental data through
Fig. 4. Adsorption isotherms of Pb2+ onto FeAA at different temperatures.it was smoother after the reaction in the FBR had proceeded for3 months. Moreover, Fig. 3b and d shows details of the originalactivated alumina grain support with a typical sheet-like structureand the surface of the FeAA with fine granular structure.The specific surface areas of the original activated alumina grainsupport and FeAA are 127 and 170 m2 g−1, respectively.3.2. Adsorption isothermFig. 4 shows the adsorption isotherms of Pb2+ on FeAA at288, 308 and 318 K. Equilibrium data can be analyzed usingcommonly known adsorption isotherms, which provide the basisfor the design of adsorption systems. The most widely usedisotherm equation for modelling of the adsorption data is theLangmuir equation, which is valid for monolayer sorption ontoa surface with a finite number of identical sites and is given byEq. (2).qe = KLqmCe1 + KLCe, (2)where KL is the adsorption equilibrium constant including theaffinity of binding sites (mM−1), qm the maximum adsorptioncapacity (mmol g−1) and qe is the amount of sorbed Pb2+ at equilibrium(mmol g−1). It represents a practical limiting adsorptioncapacity when the surface is fully covered with Pb2+. qm andKL can be determined from the linear plot of Ce/qe versus Ce[27,28].The Freundlich model is an empirical equation based onsorption on a heterogenous surface. It is given as:qe = KFC1/ne , (3)where KF and n are the Freundlich constants related to theadsorption capacity and adsorption intensity, respectively. TheFreundlich equation can be linearized by taking logarithms andconstants can be determined [28].Linear plots of Ce/qe versus Ce and ln qe versus lnCe areshown in Fig. 5a and b. For each isotherm in Fig. 5a, the valuesof qm and KL were calculated from experimental data through
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