Modelo y Simulacion De Separacion De Butanol a Partir De Una Solucion Acuosa Utilizando Una Pervaporacion

Journal of Membrane Science 280 (2006) 278–283

Modeling and simulation of butanol separation from aqueous solutions using pervaporation
E. El-Zanati a,∗ , E. Abdel-Hakim a , O. El-Ardi a , M. Fahmy b
a

National Research Centre, Cairo, Egypt b Cairo University, Cairo, Egypt

Received 17 October 2005; received in revised form 8 January 2006; accepted 15 January 2006 Available online 21February 2006

Abstract A study was conducted to separate butanol from an aqueous solution using pervaporation. A specially designed and manufactured cell was used to separate the butanol from butanol/water solutions of different butanol concentrations (6-8-11-16-20-50) g/l. A 250 cm3 butanol mixture at 33 ◦ C was used to feed the cell, while the pressure of permeation side was about ∼0 bar.Results revealed that butanol concentration changes non-linearly during the first 3 h, and then proceeds linearly. The percentage of butanol removal increases with increasing feed concentration. The permeability of the used membrane was determined experimentally. A resistance in series model was used to simulate the pervaporation step. The butanol concentration in the feed during the pervaporationstep was predicted by using the developed model. There is a fair agreement between butanol concentration in feeding tank of pervaporation cell both experimentally and predicted from the developed model. © 2006 Elsevier B.V. All rights reserved.
Keywords: Pervaporation; Influencing parameters; Butanol; Membrane separation; Modeling and simulation

1. Introduction During the past decade, severalstudies have focused on the integration of the product recovery step of alcoholic fermentation, with the objective of developing a low cost alcohol production process. Alcohol recovery by membrane technology was found to lead to a decrease in energy compared with the conventional distillation method, and, thus, an overall reduction in processing costs [1]. Investigations have focused on thedevelopment of a suitable recovery method for butanol, including pervaporation, perstraction, stripping, adsorption and extraction. In these studies, attention is paid to the selectivity and the capacity of the recovery methods. In most cases the operational characteristics of the combined process have been assessed [11]. The pervaporation technology is a membrane-based process that removes volatileorganic compounds, e.g. alcohol, from aqueous matrices. The cross-flow pervaporation technology uses an organophilic membrane, which is permeable to the butanol [5]. The present article is aiming at studying the influencing

parameters of the pervaporation technology for butanol separation, and also to develop a mathematical model describing this process. 2. Background The main factor in acetonebutanol (AB) fermentation systems is the elimination of the main inhibiting factors. Butanol inhibits the micro-organism at low concentrations of (4–6 g/l) and halts their growth completely at concentrations of approximately 20 g/l. This results in a low productivity, a low yield and a high cost of separation using conventional separation methods. Less expensive methods have been proposed andreported [3,14,2,13,9]. 3. Pervaporation Pervaporation—a promising technique has been reported to produce butanol and acetone from AB fermentation [4]. This technique was used to extract in situ the produced butanol, it leads to greater glucose consumption (more than 70 g/l) and higher butanol production (more than 14–16 g/l) [8]. Five technologies for in situ product recovery are evaluated based onthe

∗

Corresponding author. Tel.: +20 2 3853714; fax: +20 2 3834496. E-mail address: eelzanati@gmx.net (E. El-Zanati).

0376-7388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2006.01.029

E. El-Zanati et al. / Journal of Membrane Science 280 (2006) 278–283 Table 1 Energy requirements in the integrated processes Recovery method Stripping Adsorption...