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Isotherms for the sorption of zinc and copper onto kaolinite: comparison of various error functions
Shahmohammadi-Kalalagh, Sh. & Babazadeh, H.
Abstract
In this research, the equilibrium sorption of
Zn(II) and Cu(II) by kaolinite was explained using the
Freundlich, Langmuir and Redlich–Peterson isotherms, via
both linear and non-linear regression analyses. In the case
of non-linear regression method, the best-fitting model was
evaluated using six different error functions, namely
coefficient of determination (r2), hybrid fractional error
function (HYBRID), Marquardt’s percent standard deviation
(MPSD), average relative error (ARE), sum of the
errors squared (SSE) and sum of the absolute errors
(EABS). The examination of error estimation methods
showed that the Langmuir model provides the best fit for
the experimental equilibrium data for both linear and nonlinear
regression analyses. The SSE function was found to
be a better option to minimize the error distribution
between the experimental equilibrium data and predicted
two-parameter isotherms. In the case of three-parameter
isotherm, HYBRID was found to be the best error function
to minimize the error distribution structure between
experimental equilibrium data and theoretical isotherms.
Non-linear method was found to be more appropriate
method for estimating the isotherm parameters.
Keywords
Adsorption; Freundlich; Langmuir; Redlich–Peterson; Regression analysis
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