Modelling of Organophilic and Hydrophilic Pervaporations for Separation of Ethyl Acetate – water Mixture

Abstract

Pervaporation is a separation method that is considered as green technology because of its low energy consumption. The mechanism of component separation in a liquid mixture by pervaporation is complex but it can be explained with the solution-diffusion mechanism. The work is motivated by an industrial separation problem, that is, ethyl acetate removal from aqueous mixture. To complete this goal hybrid organophilic/hydrophilic pervaporation of ethyl acetate/water mixture through commercially available Sulzer PERVAP™ 4060 and 1510 membranes are investigated to obtain information about the removal of ethyl acetate. Our experimental data are evaluated with the pervaporation model of our improvement (Valentínyi et al., 2013) and it is found that the model can be applied also for both cases. The hybrid separation process is rigorously modelled in professional flowsheet environment, and optimized with the dynamic programming optimization method. The objective function is product purity of 99.0, 99.5 m/m% in water and ethyl acetate content and the total annual cost is also determined. It can be determined, this hybrid separation should be become the alternative of distillation if the energy prices are too high.

Introduction

Pervaporation (PV) is a chemical unit operation where the liquid mixture to be separated is vaporized at low pressure on the downstream/permeate side of the membranes and the separation of the mixtures takes place by preferential sorption and diffusion of the desired component through the membrane (Valentínyi et al., 2013). A solution to achieve the difference in the partial pressures is to maintain a low vapour pressure using a vacuum pump on the permeate side (Van Baelen et al., 2005). Pervaporation shows good features such as special separation effect, no-extra material addition and energy-saving which are difficult to obtain by other conventional methods (Szabados et al., 2018). Depending on the permeating component two main areas of pervaporation can be identified: hydrophilic (HPV) and organophilic pervaporation (OPV) (Heintz and Stephan, 1994a, Heintz and Stephan, 1994b).

The aim of this work is to examine the ethyl acetate (EtAc) - water separation with pervaporation. The organophilic-hydrophilic pervaporation process is modelled and optimized for the separation of a binary mixture. EtAc forms heteroazeotrope with water (Gmehling et al., 1978), therefore this mixture cannot be separated with conventional distillation (Waltermann et al., 2017). Basically, the problem and the aims must be defined, that is, 5 m/m% ethyl acetate-water mixture with a feed flow of 1000 kg/h should be separated. The product purity of 99.0 and 99.5 m/m% should be achieved both for water and ethyl acetate.