BIOSORPTION OF Pb2+, Cd2+, & Ni2+ FROM WATERS BY ...
BIOSORPTION OF Pb2+, Cd2+, & Ni2+ FROM WATERS BY ...
BIOSORPTION OF Pb2+, Cd2+, & Ni2+ FROM WATERS BY ...
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where ce is the equilibirium concentration (mg/L), qe the amount of Pb 2+ , Cd 2+ , and<br />
Ni 2+ ions biosorbed (mg/g), cm is qe for a complete monolayer sorption capacity<br />
(mg/g), Ka is a sorption equilibrium constant (L/mg). The values of cm and Ka were<br />
determined from the intercept and the slope of 1/qe versus 1/ce; the linearized form of<br />
Langmuir equation 2.2.<br />
Freundlich isotherm model is based on the assumption of heterogeneous<br />
surfaces as well as multilayer sorption and also being the binding sites are not<br />
equivalent. It is expressed by the equation (Şeker, et al. 2008):<br />
q e = K f c e n<br />
The above equation can be rearranged to the following linear form:<br />
log q e = log K f + n log c e<br />
q e = c m exp(-kɛ 2 )<br />
ɛ = RT Ln (1 + 1/ce) The equation (5) can be rearranged to the following linear form:<br />
Ln q e = Ln c m - kɛ 2<br />
(2.3)<br />
(2.4)<br />
where Kf and n are isotherm constants, respectively. The values of Kf and n are<br />
calculated from the intercept and the slope of logqe versus logce; the linear form of<br />
Freundlich equation 2.4.<br />
Another isotherm model applied in this study is Dubinin-Radushkevich<br />
isotherm model. The basic principles of this model is the Polany’s adsorption<br />
potential theory and Dubinin’s minipore filling theory. Dubinin-Radushkevich<br />
isotherm model can be given by the equation (Shahwan, et al. 2005):<br />
where<br />
(2.5)<br />
(2.6)<br />
(2.7)<br />
where cm and k are the constants of Dubinin-Radushkevich isotherm<br />
model,respectively, the maximum adsorption capacity (mol/g) and the adsorption<br />
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