Article ID Journal Published Year Pages File Type
151064 Chemical Engineering Journal 2011 10 Pages PDF
Abstract

The BiLangmuir and Redlich–Peterson models as well as their extended equations were tested for the modeling of one- and two-component adsorption equilibrium of Co(II) and Ni(II) ions on EDTA- and DTPA-modified silica gel. An approach consisting in initialization of parameter values and non-linear parameter estimation by minimization of two objective functions (MPSD and ERRSQ) was proposed to assure that equilibrium parameters obtained related to the global minimum. A usage of the experimentally obtained value of maximum adsorption capacity as an initial guess made an iteration procedure well-posed and independent of the Ki guess values. None of the parameters obtained for one-component systems satisfactorily helped in prediction of the two-component adsorption equilibrium. The application of the extended BiLangmuir model identified the coexistence of low- and high-energy active sites on EDTA/DTPA-silica gel that showed an unequal ability for Co(II) and Ni(II) adsorption.

• EDTA- and DTPA-silica gel were good adsorbents for Co(II) and Ni(II). • Affinity of the surface groups toward Ni(II) was clearly higher than toward Co(II). • BiLangmuir model and its extended form described the adsorption data well. • Initial guesses, error function, and the amount of fixed parameters affected the simulations. • Parameters from one-component modeling could not be used to predict the two-component behavior.

Related Topics
Physical Sciences and Engineering Chemical Engineering Chemical Engineering (General)
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