Hemijska industrija 2012 Volume 66, Issue 4, Pages: 497-503
https://doi.org/10.2298/HEMIND111114003B
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Isotherms for the adsorption of Cu(II) onto lignin: Comparison of linear and non-linear methods
Brdar Mirjana M. (Faculty of Technology, Novi Sad)
Takači Aleksandar A. (Faculty of Technology, Novi Sad)
Šćiban Marina B. (Faculty of Technology, Novi Sad)
Rakić Dušan Z. (Faculty of Technology, Novi Sad)
Equilibrium studies were carried out for the adsorption of Cu(II) onto Kraft
lignin as an adsorbent. The experimental data were fitted to the Freundlich,
Langmuir and Redlich-Peterson isotherms by linear and non-linear method.
Comparison of linear and non-linear regression method was given in selecting
the optimum isotherm for the experimental data. The coefficient of
correlation r2 and Chi-square test χ2 was used to select the best linear
theoretical isotherm. The best linear model is Redlich-Peterson isotherm
model, where r2=0,985 and χ2=0,02. In order to predict the error ERRSQ,
HYBRD, MPSD, ARE and EABS were used. Moreover, by minimizing these error
functions the optimal values of parameters and also the optimum isotherm was
found. The Redlich-Peterson isotherm was found to be the best representative
for adsorption of Cu(II) on the adsorbent in the cases when ERRSQ, HYBRD,
MPSD functions were used. There coefficients of determination are 0.986,
0.985, 0.984, respectively and Chi-square is 0.02 in all cases. Freundlich
isotherms which were obtained by minimization of the ERRSQ, HYBRD, MPSD, ARE
and EABS function showed very good agreement with experimental data. In all
cases the coefficients of determination are greater than 0.91. Besides, it
was observed that non-linear isotherm models were better for representation
of equilibrium data than linearized models.
Keywords: Adsorption isotherm, linear and non-linear methods, Cu(II), lignin