See discussions, stats, and author profiles for this publication at: https://www.researchgate.

net/publication/262384265

Pervaporation of ethanol produced from banana waste

Article in Waste Management · August 2014

DOI: 10.1016/j.wasman.2014.04.013

CITATIONS READS

33 180

7 authors, including:

Roger Hoel Bello Poliana Linzmeyer

Universidade do Estado do Amazonas Universidade da Região de Joinville (Univille)
14 PUBLICATIONS 74 CITATIONS 5 PUBLICATIONS 37 CITATIONS

SEE PROFILE SEE PROFILE

Noeli Sellin Sandra Medeiros

Universidade da Região de Joinville (Univille) Universidade da Região de Joinville (Univille)
32 PUBLICATIONS 291 CITATIONS 10 PUBLICATIONS 70 CITATIONS

SEE PROFILE SEE PROFILE

Some of the authors of this publication are also working on these related projects:

Toughening mechanisms on epoxy nanocomposites View project

Polymer-derived ceramic membranes View project

All content following this page was uploaded by Roger Hoel Bello on 18 March 2019.

The user has requested enhancement of the downloaded file.

 Waste Management 34 (2014) 1501–1509

Contents lists available at ScienceDirect

Waste Management
journal homepage: www.elsevier.com/locate/wasman

Pervaporation of ethanol produced from banana waste

Roger Hoel Bello a, Poliana Linzmeyer b, Cláudia Maria Bueno Franco b, Ozair Souza a,b,c, Noeli Sellin a,b,c,
Sandra Helena Westrupp Medeiros a,b,c, Cintia Marangoni d,⇑
a
Chemical Engineering Department, University of Joinville Region (UNIVILLE), Joinville, SC, Brazil
b
Sanitary and Ambient Engineering Department, University of Joinville Region (UNIVILLE), Joinville, SC, Brazil
c
Masters Program in Process Engineering, University of Joinville Region (UNIVILLE), Joinville, SC, Brazil
d
Federal University of Santa Catarina (UFSC), Campus Blumenau, Blumenau, SC, Brazil

a r t i c l e i n f o a b s t r a c t

Article history: Banana waste has the potential to produce ethanol with a low-cost and sustainable production method.
Received 19 December 2013 The present work seeks to evaluate the separation of ethanol produced from banana waste (rejected fruit)
Accepted 10 April 2014 using pervaporation with different operating conditions. Tests were carried out with model solutions and
Available online 16 May 2014
broth with commercial hollow hydrophobic polydimethylsiloxane membranes. It was observed that
pervaporation performance for ethanol/water binary mixtures was strongly dependent on the feed
Keywords: concentration and operating temperature with ethanol concentrations of 1–10%; that an increase of feed
Banana waste
flow rate can enhance the permeation rate of ethanol with the water remaining at almost the same value;
Bioethanol
Biofuel
that water and ethanol fluxes was increased with the temperature increase; and that the higher effect in
Lignocellulosic residue flux increase was observed when the vapor pressure in the permeate stream was close to the ethanol
Pervaporation vapor pressure. Better results were obtained with fermentation broth than with model solutions,
Polydimethylsiloxane membrane indicated by the permeance and membrane selectivity. This could be attributed to by-products present
in the multicomponent mixtures, facilitating the ethanol permeability. By-products analyses show that
the presence of lactic acid increased the hydrophilicity of the membrane. Based on this, we believe that
pervaporation with hollow membrane of ethanol produced from banana waste is indeed a technology
with the potential to be applied.
Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction and South America (Hammond et al., 1996). In countries like India,
all kind of banana waste is considered an important urban waste
One of the bases for the economic development of Brazil is because the fruit is used in all religious functions, festivals and in
agriculture, and in certain states, such as Santa Catarina, banana temples (Chanakya and Sreesha, 2011). According to Graefe et al.
is widely cultivated as a commercial crop. Banana is one of the (2011), around 20–40% of the bananas produced do not meet
most consumed fruits in the world and it is commercially grown export standards or even the quality demands of spot markets. In
in about 120 countries. Currently, Brazil is the second largest Brazil, particularly in the southern regions, it is estimated that
producer (preceded by India) and is responsible for 7.5% of world for every 100 kg of harvested fruit, 46 kg are not used (EMBRAPA,
production (about 7.2 million tons per annum, according to the 2006). Further, Souza et al. (2010) indicate that for every ton of
Center of Socioeconomics and Agricultural Planning for the State bananas produced approximately 3 tons of pseudostem, 160 kg
of Santa Catarina). The State of Santa Catarina has approximately of stems, 480 kg of leaves and 440 kg of skins are generated.
six thousand producers, being the fourth largest banana growing Fernandes et al. (2013) found that less than 10% of available bio-
region in Brazil, with 663,892 tonnes of bunches of bananas mass as waste (440 million tons) is designated to some application.
produced per annum (ABIB, 2011). Thus, an established commercial use for such residues, as well as
Commercial banana production generates a large proportion of generating extra remuneration for regional farmers, would help
waste; there are reports of 30% waste in Australia (Clarke et al., to reduce environmental pollution. Alternative uses for these dis-
2008) and Malaysia (Tock et al., 2010), and 25–50% in Central cards have to be explored, and in this regard processing to produce
ethanol is seen to have potential from both an environmental as
⇑ Corresponding author. Address: Rua Pomerode, 710 Salto do Norte, Blumenau, well as an economic point of view.
SC 89065-300, Brazil. Tel.: +55 48 3721-6308. Many countries are investing in the development and use of
E-mail address: ci.marangoni@gmail.com (C. Marangoni). biofuels as a way of reducing environmental impacts and ethanol

http://dx.doi.org/10.1016/j.wasman.2014.04.013
0956-053X/Ó 2014 Elsevier Ltd. All rights reserved.
1502 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509

is one of the fuels that can be produced from various raw materials based separation technologies normally fulfill the criteria for sus-
(España-Gamboa et al., 2011). The use of agricultural or agro- tainability and energy efficiency (Korelskiy et al., 2013). In addition
industrial waste is an interesting option in this context. Biofuel to reducing the inhibition of ethanol in the production stage due to
has been produced on a large scale in Brazil for three decades using the possibility of its simultaneous use with fermentation
sugarcane as feedstock (Soccol et al., 2010), however there are (Lewandowska and Kujawski, 2007), this procedure could replace
many criticisms of the practice and an ongoing debate about the a concentration step that is required for recovery because of the
ethical issue of using food (or land available for the cultivation of presence of alcohol in small quantities in the broth (Nomura
food) as an energy source (Sarkar et al., 2012; Swana et al., et al., 2002). As shown by Chovau et al. (2011), the composition
2011). Lignocellulosic material does not play an intrinsic role in of the fermentation broth influences the separation, and the use
the food chain and this is a fundamental aspect that makes it an of different substrates leads to the need to reevaluate the process,
attractive alternative for ethanol production. Besides, the cost even if it is already well established. Also, in multicomponent
and availability of the feedstock are crucial and can contribute systems, the diffusivity of one component is influenced by the
65–70% to the total ethanol production costs (Kazi et al., 2010). presence of others. The use of lignocellulosic biomass will not only
In this sense, the substitution of biomass wastes for raw materials affect feedstock pretreatment and fermentation process of the
such as cane sugar, starch and corn for ethanol production is an ethanol production but also the downstream processing
alternative that has shown promising results (Dermibas, 2011; (Gaykawad et al., 2013).
Mabee et al., 2011). Examples of this residual biomass include In pervaporation, a liquid mixture is fed through a membrane.
bagasse sugar cane, corn straw and fiber, wheat and rice straw, The mixture components permeate selectively through the mem-
eucalyptus wood and crop wastes from commercial cultivation of brane and vaporize on the other side of the membrane where
fruits such as bananas, grapes and apples (Rivas-Cantu et al., 2013). low pressure is maintained. By this means, there is a selective
Technologies for the conversion of biomass to ethanol are removal of organic compounds from dilute aqueous solutions.
also under various stages of development. The use of these There are several studies regarding ethanol pervaporation and they
lignocellulosic residues requires some separation of cellulose and relate mainly to the use of different membranes. Specifically the
hemicellulose from lignin, followed by hydrolysis of sugars, and pervaporation of ethanol from lignocellulosic residues is reported
this bioconversion has been extensively studied using the different by Gaykawad et al. (2013) with barley straw and willow wood
types of wastes. The potential yield of ethanol from lignocellulosics using commercial polydimethylsiloxane (PDMS) membranes.
varies significantly between feedstocks, so many applications in Zhang et al. (2012) studied the membrane fouling in pervaporation
alcoholic fermentation are reported in the literature with different of ethanol from food waste after a flocculation–filtration pretreat-
wastes. Specifically in the case of ethanol from bananas, the few ment. Aroujalian and Raisi (2009) study the effects of various oper-
studies that have been published involve the use of the fruit, leaves ating parameters such as feed temperature, permeate side
and other waste such as the pseudostem. Tewari et al. (1986) pressure, and Reynolds number (volumetric flow rate) on the total
reported the suitability of banana peel for alcohol fermentation. flux, and ethanol selectivity of a porous membrane-based pervap-
Hammond et al. (1996) presented ethanol yield (on a dry weight oration process with 2% aqueous ethanol solutions, simulating an
basis) from ripe bananas as higher than from most other agricul- ethanol content from lignocellulosic residues. O’Brien et al.
tural commodities. Velásquez-Arredondo et al. (2010) investigated (2004) related an efficient system of coupled fermentation and
the acid hydrolysis of banana pulp and fruit and the enzymatic pervaporation for ethanol from corn fiber hydrolisates.
hydrolysis of flower stalk and banana skin, and the results obtained Studies of pervaporation in ethanol production hitherto have
demonstrated a positive energy balance for the four production not used banana waste as a substrate for ethanol production. Thus
routes evaluated. The study by Graefe et al. (2011) presents results the aim of this research is to evaluate if pervaporation can be used
of a case study in Costa Rica and Ecuador which found that consid- in the production of ethanol from banana and to investigate the
erable amounts of ethanol could be produced from banana effects of operating variables and of lignocellulosic biomass fer-
bunches that do not meet quality standards, as well as from which mentation by-products on membrane performance for the recov-
are partly left to rot in the fields. Oberoi et al. (2011) also demon- ery of ethanol by using pervaporation.
strated that banana peel could serve as an ideal substrate for the
production of ethanol through simultaneous saccharification and
2. Materials and methods
fermentation. Hossain et al. (2011) evaluated bioethanol from
rotten banana and concluded that this can be used in motor
To investigate the membrane behavior, first model solutions of
vehicle engines, producing low emissions, and thus it can be used
ethanol/water were separated in pervaporation experiments to
as an environmental recycling process for waste management.
characterize ethanol transfer across the hollow polydimethylsilox-
Arumugam and Manikandan (2011) explore the potential applica-
ane (PDMS) membrane and these results provided the reference for
tion of pulp and banana peel wastes in bioethanol production using
the broth experiments.
dilute acid pretreatment followed by enzymatic hydrolysis.
In the first case, feed conditions (flow rate, temperature, ethanol
Gonçalves Filho et al. (2013) evaluate the same techniques with
composition) and permeate pressure were modified. Also, the time
banana tree pseudostem.
necessary to reach steady state was determined. Then, tests were
Although the lignocellulosic material shows positive results, it
performed with the fermentation broth produced using banana
still requires more research to be exploited on an industrial scale.
fruit waste as a substrate varying the ethanol feed mass fraction
Great efforts are being undertaken to improve ethanol productivity
and feed flow rate. The presence of some byproducts was also
and reduce the overall production costs. According to Gaykawad
studied.
et al. (2013), one of the ways to achieve these goals is to modify
the configuration of the process and perform process integration.
Traditionally, the recovery of ethanol by distillation is a challenge 2.1. Membrane
because of the high costs and energy expenditure required (Vane,
2008). Toward this end, membrane separation processes such as The pervaporation unit used consisted of a removable perme-
pervaporation have been used. The great interest in these pro- ation module made of polyvinyl chloride (PVC) of 0.2 m internal
cesses is mainly because of features such as cost-effectiveness, diameter containing 50 dense hollow polydimethylsiloxane
high energy efficiency and environmental friendliness. Membrane (PDMS) membranes (di = 0.6 mm and de = 1 mm), 0.25 m in length,
 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509 1503

covering an area of 0.04 m2. This is a hydrophobic commercial Table 2

membrane, with the membrane and module built by a Brazilian Operating conditions used in the experiments with fermentation broth.

company (PAM-Membranas Selectivas). Experiments with fermentation Operating conditions

broth
Effect of feed flow rate Feed flow rate: 5.5  106 and
2.2. Fermentation
22.2  106 m3 s1
Feed mass fraction: 3 wt%
To obtain the feed from the process of pervaporation, 0.002 m3 Feed temperature: 295 K
of fermentation broth was produced, as described by Schulz Variation of feed weight Feed flow rate: 5.5  106 m3 s1
(2010). Rejected banana fruit (Musa cavendishii) was used as ligno- fraction Feed mass fraction: 2, 2.5 and 3 wt%
cellulosic material (500 g L1 wet mass) and 20% (v/v) of inoculum Feed temperature: 295 K
(Saccharomyces cerevisiae). After a period of 10 h of fermentation,
different ethanol mass fractions were obtained in broths for per-
vaporation tests. The total volume of the broth was centrifuged Eqs. (1)–(5), respectively (Pereira et al., 2006; Gaykawad et al.,
at 3800 min1 (3018g) for 1200 s in a refrigerated centrifuge and 2013; Sun et al., 2013):
then stored at 277 K.
yi =yj
ai ¼ ð1Þ
xi =xj
2.3. Pervaporation

The fermentation broth/standard solution was supplied with

W
J tot ¼ ð2Þ
the aid of a gear pump from a reservoir positioned upstream from At
the membrane. A vacuum pump coupled to the permeate side
J i ¼ J tot yi ð3Þ
of the assembly provided the pressure drop for vaporization of
ethanol. The permeate vapor was directed to a condensation bath
yi
refrigerated with liquid nitrogen. The liquid retentate was bi ¼ ð4Þ
xi
recirculated to the feed tank.
A summary of the operating conditions tested is presented in
PSI ¼ J tot ðai  1Þ ð5Þ
Table 1 for the standard mixture and in Table 2 for the fermenta-
tion broth. All experiments were carried out with condensation where yi and yj are the weight fractions of ethanol and water in the
temperature of 77 K and permeate pressure lower than 667 Pa. permeate, respectively, and xi and xj are the weight fractions of eth-
The tests were carried out in duplicate, and the results presented anol and water in the feed, W is the mass (g) of the permeate, A is
here were consistent with the average of the same. Feed and the effective area (m2) of the membrane, and t is the time interval
permeate samples (upon reaching the steady-state condition), (h) for pervaporation.
were collected for 1–2 during each test to quantify the concentra- The membrane flux was determined gravimetrically using a
tions of ethanol with a gas chromatograph (GC, Agilent model balance with an accuracy of 104 g by weighing the mass of perme-
6890, coupled with autosampler: Agilent model 7683) using a ate obtained during the collecting time. The enrichment factor rep-
Hewlett–Packard HP-1 column with a length of 50 m, an external resents the membrane capacity of concentrating the component i
diameter of 0.32 mm, a stationary phase composed of 100% (Pereira et al., 2006) and is an interesting parameter to evaluate
polydimethylsiloxane and a film thickness of 1.05 lm. the process for multicomponent mixtures.
Temperature dependency of the flux was analyzed using an
2.4. Parameters from the process evaluation Arrhenius-type equation:
 
Ea
The performance of the process of pervaporation has been lnðJ i Þ ¼ J io exp  ð6Þ
RT
expressed in terms of separation factor of the membrane (ai), the
total permeate flux (Jtot), the ethanol permeate flux (Ji), enrichment where Ji is the partial flux of the compound, Jio is the pre-exponen-
factor (bi) and pervaporation separation index (PSI) according to tial factor of the flux, R is the gas constant (J mol1 K1), T is the
temperature (K) and Ea is the apparent activation energy (KJ mol1).
Permeance was estimated according to Eq. (9), based on the
Table 1
molar flux of each component – ji (obtained from Eqs. (7) and
Operating conditions used in the experiments with the model solutions.
(8)), and the selectivity of the membrane was calculated from
Experiments with model Operating conditions the ratio between permeances (Eq. (10)).
solutions
mi
Effect of ethanol feed weight Feed flow rate: 5.5  106 m3 s1 J im ¼ J tot yi ð7Þ
fraction mt
Feed weight fraction: 1–12 wt%
Feed temperature: 295 K J im v Gi
Effect of feed flow rate Feed flow rate: 5.5  106 and ji ¼ ð8Þ
22.2  106 m3 s1 mi
Feed weight fraction: 10 wt%
Feed temperature: 295 K Pi ji
Effect of feed temperature Feed flow rate: 5.5  106 m3 s1 ¼ ð9Þ
l ðxi ci Poi  yi Pp Þ
Feed weight fraction: 3 wt%
Feed temperature: 295, 300 and 303 K
Effect of permeate pressure Feed flow rate: 5.5  106 m3 s1 Pi=l
Feed weight fraction: 3 wt% ai=j ¼ ð10Þ
Pj=l
Feed temperature: 295 K
Permeate pressure: <600, 2600 and
with mi and mt being the molecular weight of the component I and
6000 Pa
the mixture, respectively, tGi is the molar volume of gas, cI is the
1504 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509

activity coefficient for each component, Poi is the vapor pressure and
Pp is the total pressure in the permeate side.
Reynolds number was calculated according to Schnabel et al.
(1998). It was considered an aqueous solution, and because of this,
viscosity and density used was the values described by the authors
with temperature of 298 K (25 °C).

3. Results and discussion

3.1. Experiments with model fermentation broths

3.1.1. Effect of ethanol feed weight fraction

Chovau et al. (2013) reported that the fermentation of lignocel-
lulosic wastes produces, on average, 3–6 wt% of ethanol. Hence we
analyzed the results for total and partial fluxes and separation and
enrichment factors, as illustrated in Figs. 1 and 2, respectively, with
an ethanol weight fraction range from 1% to 5% (values expected
for a second-generation biomass) and then compared them with Fig. 2. Effect of ethanol content in feed on separation (j) and enrichment (d)
factors.
9%, 10% and 12% (values related or even superior to first-generation
biomass).
Increasing alcohol concentration increases permeation fluxes of side chain mobility increases. Consequently, small-sized water
the mixture of ethanol and water resulting in higher total flux cluster can permeate easily through the membrane-free volume.
(Fig. 1). In fact increasing the amount of the component that has However, Van Baelen et al. (2004) reported that this behavior
major affinity with the membrane in the feed stream leads to an can be attributed to a dragging effect. In both cases, the final result
increase in the flux of these components in the permeate as is a decrease in separation factor. This also was observed by Zhou
reported in literature (Ortiz et al., 2002; Sommer and Melin, et al. (2011), Lai et al. (2012), Lee et al. (2012), who also analyzed
2005; Wu et al., 2005; Zereshki et al., 2011). A higher ethanol con- pervaporation of alcohols in dilute mixtures with hollow poly-
centration in the feed produces a higher ethanol flux. Dobrak et al. dimethylsiloxane membrane.
(2010) reported similar results with polydimethylsiloxane com-
posite membranes, where the permeate flux through the mem-
3.1.2. Effect of feed flow rate
brane increased with increasing concentration of ethanol in the
Table 3 compares the values for the average total and ethanol
feed, due to the swelling effects.
permeate mass fluxes, separation and enrichment factor of the
The ethanol flux demonstrated an increase even with ethanol
polydimethylsiloxane membrane obtained in pervaporation of
concentrations less than 5 wt% in the feed, but this increase is even
10 wt% of alcoholic mixtures when the feed flow rate was varied.
greater at higher concentrations. As reported by Pereira et al.
As expected, ethanol and total flux increased with feed flow rate
(2006), the permeate flux of an organic dilute feed solution is gen-
as shown in Table 3 due to a decrease of concentration polariza-
erally a linear function of concentration, and the water flux
tion. These results are in agreement with other research, even
remains constant (dependent on the concentration of the organic
when different membranes were used (Jiraratananon et al., 2002;
component). This behavior is observed in this study when ethanol
Zereshki et al., 2011). As the ethanol is the component having
content in the feed is less than 5 wt%.
the greatest affinity with the polydimethylsiloxane membrane, a
However, water flux increases more than alcohol, resulting in a
reduction of concentration polarization means that ethanol con-
separation factor reduction as observed in Fig. 2. According to
centration near the membrane surface was close to the ethanol
Mohammadi et al. (2005), this is a result of an enhanced diffusion
concentration in the bulk. As observed in relation to the partial flux
of water into the membrane by the fact that increasing alcohol con-
of ethanol, an increase of feed flow rate can enhance the perme-
centration increases membrane-free volume and simultaneously
ation rate of ethanol with the water remaining at almost the same
value. This behavior is in agreement with studies considering
the effect of Reynolds number in pervaporation of organic com-
pounds (Liang et al., 2004) In fact, the lower flux was observed at
the lowest value of the Reynolds number (feed flow = 5.5  106
m3 s1 – Reynolds number: 18.47; feed flow = 22.2  106 m3 s1 –
Reynolds number = 73.90).
The increase of feed flow rate enables better penetration of eth-
anol into the membrane as the driving force of ethanol increases.
As consequence, the hydrophobic properties of the membrane also
increase, and the process will be more selective for ethanol, as indi-
cated by the separation factor that showed an increase around 30%.
Li et al. (2004) also reported that with increasing flow rate both
total flux and separation factor increase, using a similar membrane
(polydimethylsiloxane supported by cellulose acetate) for a model
solution with 5 wt% ethanol. The authors show values for the
separation factor very close to that indicated in Table 4, with
the same feed flow rate. Finally, an increase of PSI with feed flow
rate indicated that better results will be obtained for the pervapo-
Fig. 1. Effect of ethanol content in feed on total (j), ethanol (d) and (N) water ration system with higher flow rates, as observed in other works
fluxes. (Jiraratananon et al., 2002).
 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509 1505

Table 3
Results obtained for pervaporation experiments with model solutions (10 wt% ethanol) and flow rates of 5.5 and 22.2  106 m3 s1.

Flow rate (m3 s1) Total flux (g m2 h1) Ethanol flux (g m2 h1) Separation factor Enrichment factor PSI
6
5.5  10 8.07 3.34 6.32 4.13 43.07
22.2  106 8.22 3.92 8.26 4.72 61.05

The improvement in ethanol content in permeate, which occurs temperature increased. These results are in agreement with the
because of the effect of reduced concentration polarization at study by Shepherd et al. (2002) that used the same membrane to
higher flow rates that reduces the transport resistance in the liquid separate aroma compounds. Thus the separation factor increases
boundary layer, results in a mass fraction of ethanol in permeate of with the increase of temperature. Similar results are presented
41.27 wt% with 5.55  106 m3 s1 and 47.24 wt% with 22.2  by Dobrak et al. (2010).
106 m3 s1. This is an interesting result when compared with
the conventional ethanol recovery method, which is distillation. 3.1.4. Effect of permeate pressure
Standard purification involves a first distillation column, the ‘beer Three variations of permeate pressure were investigated in the
column’, where the top product consists of 37–40 wt% of ethanol pervaporation system: 6000, 2600 and less than 600 Pa. The results
(Chovau et al., 2013). The ethanol content observed was similar, obtained for the mass flow of permeate with respect to the differ-
indicating the potential of pervaporation as a concentration ent applied pressures in the process of pervaporation are shown in
method for further distillation. Table 5. Pereira et al. (2006) describe how when the permeate
pressure grows, the chemical potential gradient across the mem-
3.1.3. Effect of feed temperature brane is reduced and, as a consequence, a reduction in transmem-
The effect of the temperature on the total and partial fluxes for brane flux is observed. The same result was obtained in this work,
3 wt% ethanol/water mixture is presented in Fig. 3. with the higher effect observed when the vapor pressure in the
As related in other works (Li et al., 2004; Mohammadi et al., permeate stream was close to the ethanol vapor pressure.
2005; Dobrak et al., 2010; Luis et al., 2013) increasing temperature The results presented in Table 5 show a decrease of 64% at a
causes an increase in the total permeate flux due to the increase of pressure of 2660 Pa and 95% at 6000 Pa in relation to a maximum
diffusion rate of individual permeating molecules by the free of 5.85 g m2 h1 were obtained for the permeate flux at the sys-
volumes produced because of the thermal motions of polymer tem operating with a permeate pressure less than 600 Pa.
chains. As related by Pereira et al. (2006), a higher temperature Jiraratananon et al. (2002) found that in ethanol–water mixtures,
stimulates the driving force due to an increase in vapor pressure as permeate pressure increases, the driving force for permeation
and the activity coefficient of the permeating species (and their of the ethanol molecules decreases, which results in a decrease
chemical potentials) as temperature grows. Fig. 3 illustrates that in the mass flow of the permeate.
when temperature feed was tested from 295 to 300 K, total flux
was increased by a factor of 1.18, water flux by 1.14 and ethanol 3.2. Experiments with fermentation broth
flux by 1.5. This can also be observed from Fig. 4 which illustrates
the effect of feed temperature in separation factor. Different effects 3.2.1. Effect of feed flow rate
were related in the literature, with some studies demonstrating Tests were performed with the fermentation broth that con-
that the separation factor increases when temperature is increas- tained about 3 wt% ethanol by weight in the feed mixture, and
ing and others showing the contrary. According to Zereshki et al. the results were compared with those obtained using the standard
(2011), the main reason for the separation factor to be affected solution at the same ethanol weight fraction. The results are sum-
by temperature is because the diffusion and solubility of penetrat- marized in Table 6.
ing components changes significantly with temperature, but also It was observed that all of the parameters increased for the per-
depends on many factors such as different organics, different vaporation of the broth at low flow rates compared with the model
membrane-preparation method, and different supports of compos- solutions. For the specific case of the ethanol produced from the
ite membranes and so on.
The total and partial permeation flux is plotted in logarithmic
scale as a function of the reciprocal temperature in Fig. 5 and
results show that an Arrhenius type relationship exists between
the fluxes and feed temperature, i.e. fluxes decrease with decreas-
ing temperature. These results are in agreement with the literature
(Zhou et al., 2011; Lai et al., 2012; Lee et al., 2012).
The apparent activation energy could be calculated from the
slope of the corresponding curve and Eq. (6) and the value is
summarized in Table 4.
The higher apparent activation energy value for ethanol flux
indicates that it was more affected than water flux as the

Table 4
Apparent activation energy for ethanol and water per-
meation estimated from experiments with ethanol
(3 wt%) and water mixtures.

Apparent activation energy (KJ mol1) Value

Ethanol 83.23
Water 62.64 Fig. 3. Temperature dependency on the total (j), ethanol (d) and water (N) fluxes
for 3 wt% ethanol/water mixture.
1506 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509

enrichment factor, since this parameter relates to the separation

ability by the ratio of permeate and feed weight fractions. A reduc-
tion twice was observed. Also, when comparing the pervaporation
of fermentation broth between different flow rates, all parameters
decrease with the increase of feed flow. In these cases, the effect
observed in the enrichment factor was more pronounced.

3.2.2. Variation of feed weight fraction

Tests were performed with the fermentation broth of varying
ethanol by weight in the feed mixture, and the results were com-
pared with those obtained using the standard solution at the same
ethanol weight fraction. Figs. 6–8 show the comparison of results
obtained with the model mixture and fermentation broth for total
flux, separation and enrichment factors and pervaporation index,
respectively. The results of the parameters presented demon-
strated an increase that was observed with the pervaporation of
fermentation broth. The comparison between model solutions
and broth shows similar results, i.e., when the feed ethanol weight
Fig. 4. Effect of feed temperature in separation factor for 3 wt% ethanol/water fraction is increased, we observed an increase of flux, decrease of
mixture.
enrichment and separation factor (consequently an increasing of
permeate ethanol weight fraction). More interesting, however, is
the increase in pervaporation index (Fig. 8), which indicates that
the pervaporation of the fermentation broth obtained from banana
residue with PDMS membrane has a more pronounced increase
with the increase of feed ethanol weight fraction than does the
model solution.
Figs. 9 and 10 show the comparison of results obtained with
model mixture and fermentation broth for permeance and selectiv-
ity, respectively. According to Luis et al. (2013), these parameters
enable better observation of the process efficiency once the effect
of the driving force and operating conditions is eliminated when
the parameters are calculated. Fig. 9 shows better results for broth
pervaporation, and an increase of both ethanol and water flux as
the feed ethanol weight fraction is increased, as observed in
Fig. 6. However, the permeance analysis shows clearly that the eth-
anol flux increase has a major effect on the total flux increase,
especially for fermentation broth. This indicates that by-products
present in the multicomponent mixtures could be facilitating the
ethanol permeability, and no coupling flux is observed. In fact,
by-products of fermentation, such as carboxylic acids, aldehydes,
Fig. 5. Arrhenius plot of total (j), water (N) and ethanol (d) fluxes vs. temperature alcohols and other salts, may influence the separation process,
for ethanol (3 wt%) and water mixtures.
especially at lower ethanol feed mass fractions and flow rates. No
glucose was observed in the broth used for the separation, when
lignocellulosic banana waste, with 5.5x106 m3 s1 of flow rate, an analyzed via high-performance liquid chromatography. Glucose
increase of about 28% in the enrichment factor was obtained, as has been shown to affect the performance of pervaporation, as
well as a 3.5 times increase in ethanol flux, which resulted in a per- reported by Chovau et al. (2011).
vaporation index (PSI) double that achieved with the standard In testing for selectivity, as observed before and with model
mixture (62.18 vs. 29.11). One important analysis consists of the solutions, the membrane shows more affinity for water, mainly
enrichment factor. This parameter remained almost the same, indi- at higher feed ethanol weight fractions. However, is important to
cating a possibility that there is no flux coupling mechanism. notice that a value of selectivity equal to 1 represents the perfor-
Shepherd et al. (2002) reported the same results using the similar mance of a membrane with no intrinsic membrane selectivity,
membrane and studying multicomponent model mixtures. achieving the same separation as simple evaporation of the liquid
For the flow rate of 22.2  106 m3 s1, contrary observations into the vapor phase (Luis et al., 2013). In this work, selectivity
were made. All performance parameters decrease for fermentation shows values greater than 1, and higher for fermentation broth
broth compared with model solutions. This can be a result of the than for model solutions, which indicates that the effect of the
presence of by-product that at this flow rate has an influence on membrane is to enrich the permeate with ethanol.
the ethanol diffusion mechanism. As the flux was reduced by a
factor of 0.25 and the separation factor was reduced by a factor 3.2.3. Influence of by-products
of 0.43, it was concluded that the ethanol pervaporation was Table 7 presents the average values of the by-products of the
minimized. This behavior could be supported by the results of broth in the feed analyzed by HPLC. The results for the centrifuged
broth were compared with those for the standard mixture to deter-
Table 5 mine the influence of by-products on the permeate flux, the
Effect of permeate pressure in total permeate flux for 3 wt% ethanol/water mixtures. enrichment factor and the concentration of the permeate.
Pressure (Pa) <600 2660 6000 According to Table 7, the glycerol concentration in the fermen-
tation broth in the present study was 1.67% by weight. Chovau
Total flux (g m2 h1) 5.85 2.1 0.3
et al. (2011) have reported that the presence of glycerol in low con-
 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509 1507

Table 6
Comparison of the pervaporation carried out at different feed flow rates with ethanol/water model solutions and fermentation broth with 3 wt% of ethanol.

Experiment Total flux (g m2 h1) Ethanol flux (g m2 h1) Enrichment factor Separation factor PSI
6 3 1
Flow rate 5.5  10 m s
Ethanol/water 3.58 0.37 7.56 8.31 29.71
Broth 5.85 1.06 8.88 10.63 62.18

Flow rate 22.2  106 m3 s1

Ethanol/water 4.80 0.41 6.51 7.06 33.91
Broth 3.60 0.30 3.73 3.97 14.29

Fig. 6. Comparison of the effect of ethanol content in feed on total flux for model
solutions (j) and fermentation broth (h). Fig. 8. Comparison of the effect of ethanol content in feed in pervaporation index
(PSI) for model solutions (j) and fermentation broth (h).

Fig. 7. Comparison of the effect of ethanol content in feed on separation (j) and Fig. 9. Comparison of the effect of ethanol content in feed on permeance of ethanol
enrichment (d) factors for model solutions (closed symbols) and fermentation (d) and water (N) for model solutions (closed symbols) and fermentation broth
broth (open symbols). (open symbols).

centrations does not significantly affect the permeate flux param- observed for the pervaporation index than for the standard mix-
eter or the coefficient of enrichment. In addition, the effect of car- ture. We believe that the observed increase in the pervaporation
boxylic acids on the process of pervaporation was studied, and the index was due to the presence of lactic acid in the broth. As a result
presence of lactic acid at a concentration of 10.9 mmol L1 was of the low concentration of this acid observed in the fermentation
observed to increase both permeate and water flux; however, the broth at 0.75 mmol L1, a decrease was not observed in the enrich-
coefficient of enrichment was reduced to 12.2%. ment factor of ethanol, as reported in the work of Chovau et al.
As previously discussed, in tests where a flow rate of (2011). Thus, because the polydimethylsiloxane membrane is
5.5  106 m3 s1 was used, a comparison of the pervaporation of hydrophobic, the presence of lactic acid increased the hydrophilic-
the fermentation broth and that of the standard mixture of ethanol ity of the membrane, which increased the flow of water, whereas
and water indicates that the best results are achieved with the the increase in the flow of ethanol can be attributed to the effect
fermentation broth. Furthermore, in the specific case of ethanol of membrane fouling. Bowen et al. (2007) have confirmed these
produced from lignocellulosic banana waste, greater values were statements in their studies.
1508 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509

solutions. The process efficiency was evaluated by permeance and

selectivity, showing that ethanol flux increase has a major effect on
the total flux increase, especially for fermentation broth. In fact, in
the specific case of ethanol produced from lignocellulosic banana
waste, greater values were observed for the pervaporation index
than for the standard mixture. This could due to by-products pres-
ent in the multicomponent mixtures facilitating the ethanol per-
meability. By-products analysis show that the presence of lactic
acid increased the hydrophilicity of the membrane, which
increased the flow of water, whereas the increase in the flow of
ethanol can be attributed to the effect of membrane fouling.
Thus, it can be concluded that the pervaporation of ethanol pro-
duced from banana waste is indeed a technology with the potential
to be applied. The results showed a very interesting performance,
highlighting the better separation efficiency for fermentation broth
in relation to model solutions.

Fig. 10. Comparison of the effect of ethanol content in feed on selectivity for model
Acknowledgements
solutions (j) and fermentation broth (h).
The authors acknowledge the support received from the Uni-
versidade da Região de Joinville – Univille as well as all of the
Table 7 resources that allowed for the preparation of this work, and
By-products of the fermentation broth that may affect the process of pervaporation. acknowledge the financial support that was received in the form
Byproduct Average concentration (g L1)
of research grants.

Lactic acid 0.068

Acetic acid NDª
References
Glucose ND
Glycerol 1.67 ABIB – Associação Brasileira Indústrias Biomassa Brasil Biomassa E Energia
Renovável. Inventário Residual Brasil – Wood Pellets - Briquete – Energia,
a 2011. E-book. <http://pt.calameo.com/read/000200968cc3a949579a0>.
Not detected.
(accessed 27.02.12).
Aroujalian, A., Raisi, A., 2009. Pervaporation as a means of recovering ethanol from
lignocellulosic bioconversions. Desalination 247, 509–517.
Finally, in all experiments the flux values obtained (5 g m2 h1) Arumugam, R., Manikandan, M., 2011. Fermentation of pretreated hydrolyzates of
banana and mango fruit wastes for ethanol production. Asian J. Exp. Biol. Sci. 2,
were inferior to those described in the literature, such as those
246–256.
mentioned in work by Molina et al. (2002), who obtained Bowen, T.C., Meier, R.G., Vane, L.M., 2007. Stability of MFI zeolite-filled PDMS
500 g m2 h1 at a concentration of 15% (wt) under similar operat- membranes during pervaporative ethanol recovery from aqueous mixtures
ing conditions. This discrepancy indicates the need for optimization containing acetic acid. J. Membr. Sci. 298, 117–125.
Clarke, W.P., Radnidge, P., Lai, T.E., Jensen, P.D., Hardin, M.T., 2008. Digestion of
of the operating conditions. However, the values obtained here are waste bananas to generate energy in Australia. Waste Manage. 28, 527–533.
consistent with the data provided by the membrane supplier. In this Chovau, S., Degrauwe, D., Van der Bruggen, B., 2013. Critical analysis of techno-
regard, the results are considered to be encouraging because the economic estimates for the production cost of lignocellulosic bio-ethanol.
Renewable Sustainable Energy Rev. 26, 307–321.
parameters show substantial increases in the recovery of ethanol Chovau, S., Gaykawad, S., Straathof, A.J.J., Van der Bruggen, B., 2011. Influence of
produced by fermentation using pervaporation compared with fermentation by-products on the purification of ethanol from water using
using the standard mixture. pervaporation. Bioresour. Technol. 102, 1669–1674.
Dermibas, A., 2011. Competitive liquid biofuels from biomass. Appl. Energy 88, 17–
28.
Dobrak, A., Figoli, A., Chovau, S., Galiano, F., Simone, S., Vankelecom, I.F.J., Drioli, E.,
4. Conclusions
Van der Bruggen, B., 2010. Performance of PDMS membranes in pervaporation:
effect of silicalite fillers and comparison with SBS membranes. J. Colloid
The use of the pervaporation process for the recovery of ethanol Interface Sci. 346, 254–264.
from fermentation broth produced from lignocellulosic banana EMBRAPA (2006) Empresa Brasileira de Pesquisa Agropecuária. Embrapa fruta
<http://www.jornalentreposto.com.br/anteriores/janeiro_2006/
waste demonstrated a very attractive alternative to classical meth- transporte.htm> June 2008. (accessed 13.08.12).
ods. When tests were carried out varying operational conditions España-Gamboa, E., Mijangos-Cortes, J., Barahona-Perez, L., Dominguez-Maldonado,
with model solutions, it was observed behaviors related to J., Hernández-Zarate, G., Alzate-Gaviria, L., 2011. Vinasses: characterization and
treatments. Waste Manage. Res. 29, 1235–1250.
reported in literature: a higher ethanol concentration in the feed Fernandes, E.R.K., Marangoni, C., Souza, O., Sellin, N., 2013. Thermochemical
produces a higher ethanol flux and decrease the separation factor; characterization of banana leaves as a potential energy source. Energy
an increase of feed flow rate can enhance the permeation rate of Convers. Manage. 75, 603–608.
Gaykawad, S.S., van der Wielen, L.A.M., Straathof, A.J.J., 2013. Effects of yeast-
ethanol with the water remaining at almost the same value; water originating polymeric compounds on ethanol pervaporation. Bioresour.
and ethanol fluxes was increased with the temperature increase; Technol. 116, 9–14.
and the higher effect in flux increase was observed when the vapor Graefe, S., Dufour, D., Giraldo, A., Muñoz, L.A., Mora, P., Solís, H., Garcés, H.,
Gonzalez, A., 2011. Energy and carbon footprints of ethanol production using
pressure in the permeate stream was close to the ethanol vapor banana and cooking banana discard: a case study from Costa Rica and Ecuador.
pressure. One interesting point was that the ethanol flux demon- Biomass Bioenergy 35, 2640–2649.
strated an increase even with ethanol concentrations less than Gonçalves Filho, L.C., Fischer, G.A.A., Sellin, N., Marangoni, C., Souza, O., 2013.
Hydrolysis of banana tree pseudostem and second-generation ethanol
5 wt% in the feed (concentration expected in second generation
production by saccharomyces cerevisae. Bioresour. Technol. 2, 65–69.
ethanol), but this increase is even greater at higher concentrations, Hammond, J.B., Egg, R., Diggins, D., Coble, C.G., 1996. Alcohol from bananas.
as expected. However, water flux increases more than alcohol, Bioresour. Technol. 56, 125–130.
resulting in a separation factor reduction. Hossain, A.B.M.S., Ahmed, S.A., Ahmed, M.A., Faris, M.A.A., Annuar, M.S.M., Hadeel,
M., Norah, H., 2011. Bioethanol fuel production from rotten banana as an
It was observed that all of the parameters increased for the per- environmental waste management and sustainable energy. Afr. J. Microbiol.
vaporation of the broth at low flow rates compared with the model Res. 5, 586–598.
 R.H. Bello et al. / Waste Management 34 (2014) 1501–1509 1509

Jiraratananon, R., Chanachai, A., Huang, R.Y.M., Uttapap, D., 2002. Pervaporation Schulz, M.A. 2010 Bioethanol production from banana cultivation waste: banana
dehydration of ethanol-water mixtures with chitosan/hydroxyethylcellulose peels and pulp. Dissertation. MSc in Process Engineering – UNIVILLE, Joinville,
(CS/HEC) composite membranes: I. Effect of operating conditions. J. Membr. Sci. SC. (In Portuguese).
195, 143–151. Shepherd, A., Habert, A.C., Borges, C.P., 2002. Hollow fibre modules for orange juice
Kazi, F.K., Fortman, J.A., Anex, R.P., Hsu, D.D., Aden, A., Dutta, A., Kothandaraman, G., aroma recovery using pervaporation. Desalination 148, 111–114.
2010. Techno-economic comparison of process technologies for biochemical Schnabel, S., Moulin, P., Nguyen, Q.T., Roizard, D., Aptel, P., 1998. Removal of volatile
ethanol production from corn stover. Fuel 89, S20–S28. organic components (VOCs) from water by pervaporation: separation
Korelskiy, D., Leppäajärvi, T., Zhou, H., Grahn, M., Tanskanen, J., Hedlund, J., 2013. improvement by Dean vortices. J. Membr. Sci. 142, 129–141.
High flux MFI membranes for pervaporation. J. Membr. Sci. 427, 381–389. Soccol, C.S., Vandenberghe, L.P.S., Medeiros, A.B.P., Karp, S.G., Buckeridge, M.,
Lai, C.-L., Fu, Y.-J., Chen, J.-T., An, Q.-F., Liao, K.-S., Fang, S.-C., Hu, C.-C., Lee, K.-R., Ramos, L.P., Pitarelo, A.P., Leitão, V.F., Gottschalk, L.M.F., Ferrara, M.A., Bon,
2012. Pervaporation separation of ethanol/water mixture by UV/O3-modified E.P.S., Moraes, L.M.P., Araújo, J.A., Torres, F.A.G., 2010. Bioethanol from
PDMS membranes. Sep. Purif. Technol. 100, 15–21. lignocelluloses: status and perspectives in Brazil. Bioresour. Technol. 101,
Lee, H.-J., Cho, E.J., Kim, Y.-G., Choi, I.S., Bae, H.-J., 2012. Pervaporative separation of 4820–4825.
bioethanol using a polydimethylsiloxane/polyetherimide composite hollow- Sommer, S., Melin, T., 2005. Influence of operation parameters on the separation of
fiber membrane. Bioresour. Technol. 109, 110–115. mixtures by pervaporation and vapor permeation with inorganic membranes.
Lewandowska, M., Kujawski, W., 2007. Ethanol production from lactose in a Part 1: dehydration of solvents. Chem. Eng. Sci. 60, 4509–4523.
fermentation/pervaporation system. J. Membr. Sci. 79, 430–437. Souza, O., Federizzi, M., Coelho, B., Wagner, T.M., Wisbeck, E., 2010. Biodegradação
Li, L., Xiao, Z., Tana, S., Pua, L., Zhang, Z., 2004. Composite PDMS membrane with de resíduos lignocelulósicos gerados na bananicultura e sua valorização para a
high flux for the separation of organics from water by pervaporation. J. Membr. produção de biogas. Revista Brasileira de Engenharia Agrícola e Ambiental 14,
Sci. 243, 177–187. 438–443 (in Portuguese).
Liang, L., Dickson, J.M., Jiang, J., Brook, M.A., 2004. Effect of low flow rate on Sun, D., Li, B.-B., Xu, Z.-L., 2013. Pervaporation of ethanol/water mixture by
pervaporation of 1,2-dichloroethane with novel polydimethylsiloxane organophilic nano-silica filled PDMS composite membranes. Desalination 322,
composite membranes. J. Membr. Sci. 231, 71–79. 159–166.
Luis, P., Degrève, J., Van der Bruggen, B., 2013. Separation of metanol-n-butyl Swana, J., Yang, Y., Behnam, M., Thompson, R., 2011. An analysis of net energy
acetate mixtures by pervaporation: potential of 10 commercial membranes. J. production and feedstock availability for biobutanol and bioethanol. Bioresour.
Membr. Sci. 429, 1–12. Technol. 102, 2112–2119.
Mabee, W.E., McFarlane, P.N., Saddler, J.N., 2011. Biomass availability for Tewari, H.K., Marwaha, S.S., Rupal, K., 1986. Ethanol from banana peels. Agric.
lignocellulosic ethanol production. Biomass Bioenergy 35, 4519–4529. Wastes 16, 135–146.
Mohammadi, T., Aroujalian, A., Bakhshia, A., 2005. Pervaporation of dilute alcoholic Tock, J.Y., Lai, C.L., Lee, K.T., Tan, K.T., Bhatia, S., 2010. Banana biomass as potential
mixtures using PDMS membrane. Chem. Eng. Sci. 60, 1875–1880. renewable energy resource: a Malaysian case study. Renewable Sustainable
Molina, J.M., Vatai, G., Bekassy-Molnar, E., 2002. Comparison of pervaporation of Energy Rev. 14, 798–805.
different alcohols from water on CMG-OM-010 and 1060-SULZER membranes. van Baelen, D., Reyniers, A., Van der Bruggen, B., Vandecasteele, C., Degreve, J., 2004.
Desalination 149, 89–94. Pervaporation of binary and ternary mixtures of water with methanol and/or
Nomura, M., Bin, T., Nakao, S., 2002. Selective ethanol extraction from fermentation ethanol. Separ. Sci. Technol. 39, 559–576.
broth using a silicalite membrane. Sep. Purif. Technol. 27, 56–69. Vane, L.M., 2008. Separation technologies for the recovery and dehydration of
Oberoi, H.S., Vadlani, P.V., Saida, L., Bansal, S., Hughes, J.D., 2011. Ethanol production alcohols from fermentation broths. Biofuels Bioprod. Biorefin. 2, 553–588.
from banana peels using statistically optimized simultaneous saccharification Velásquez-Arredondo, H.I., Ruiz-Colorado, A.A., De Oliveira Jr, S., 2010. Ethanol
and fermentation process. Waste Manage. 31, 1576–1584. production process from banana fruit and its lignocellulosic residues: energy
O’Brien, D.J., Senske, G.E., Kurantz, M.J., Craig Jr., J.C., 2004. Ethanol recovery from analysis. Energy 35, 3081–3087.
corn fiber hydrolysate fermentations by pervaporation. Bioresour. Technol. 92, Wu, Y., Xiao, Z., Huang, W., Zhong, Y., 2005. Mass transfer in pervaporation of active
15–19. fermentation broth with a composite PDMS membrane. Sep. Purif. Technol. 42,
Ortiz, I., Alonso, P., Urtiaga, A., 2002. Pervaporation of azeotropic mixtures ethanol/ 47–53.
ethyl tert-butyl ether: Influence of membrane conditioning and operation Zereshki, S., Figoli, A., Madaeni, S.S., Simone, S., Esmailinezhad, M., Drioli, E., 2011.
variables on pervaporation flux. Desalination 49, 67–72. Pervaporation separation of MeOH/MTBE mixtures with modified PEEK
Pereira, C.C., Ribeiro Jr., C.P., Nobrega, R., Borges, C.P., 2006. Pervaporative recovery membrane: effect of operating conditions. J. Membr. Sci. 371, 1–9.
of volatile aroma compounds from fruit juices. J. Membr. Sci. 274, 1–23. Zhang, W., Ma, H., Wang, Q., Zhao, F., Xiao, Z., 2012. Pretreatment technology for
Rivas-Cantu, R.C., Jones, K.D., Mills, P., 2013. A citrus waste-based biorefinery as a suspended solids and oil removal in an ethanol fermentation broth from food
source of renewable energy: technical advances and analysis of engineering waste separated by pervaporation process. Desalination 293, 112–117.
challenges. Waste Manage. Res. 31, 413–420. Zhou, H., Su, Y., Chen, X., Wan, Y., 2011. Separation of acetone, butanol and ethanol
Sarkar, N., Ghosh, S.K., Bannerjee, S., Aikat, K., 2012. Bioethanol production from (ABE) from dilute aqueous solutions by silicalite-1/PDMS hybrid pervaporation
agricultural wastes: an overview. Renewable Energy 37, 19–27. membranes. Sep. Purif. Technol. 79, 375–384.

View publication stats