Sorption of mixture of MEK and DMF using activated carbon

Abstract

In our study characteristics of adsorption and desorption of mixture of methyl ethyl ketone and dimethyl formamide which have considerable difference in their relative affinities to solid adsorbent of activated carbon were investigated. Two mathematical models for the adsorption of a mixture by Hsieh et al.$^{(16)}$ and Miura et al.$^{(14)}$ were used to analyze characteristics of adsorption system. According to the experimental results obtained from single component equilibrium state, both MEK and DMF were well fitted to Langmuir type isotherms. These adsorption equilibrium coefficients were compared with those of binary component adsorption. They agreed well with each other and as a result it seemed that the adsorption equilibrium coefficients of Langmuir isotherms could describe the degree of mutual competition. The adsorption equilibrium coefficients as function of temperature were expressed as follows; $a_{MEK} = 0.425 T^{-0.5} exp(3389.8/T)$ $a_{DMF} = 0.322 T^{-0.5} exp(2398.1/T)$ $b_{MEK} = 0.383 T^{-0.5} exp(5307.9/T)$ $b_{DMF} = 0.319 T^{-0.5} exp(2398.1/T)$ According to the breakthrough curves in binary system, it was noticed that concentration of MEK at the exit, which had lower affinity, became larger than that at the entrance and reached a maximum value. This maximum concentration obtained analytically using the approximation of constant pattern and linear driving force was compared with the experimental results. Mass transfer coefficients were estimated from optimization of theoretical solution with experimental results, that is, minimization of square sum of the difference between them. Used optimization technique was conjugate gradient method. All parameters, adsorption equilibrium coefficients and mass transfer coefficients, were not dependent on concentration but on temperature as expected, which means that the introduced models are suitable. Chromatographic method was used to investigate the effects of concentration, column temperatur...