Biodiesel Purification Using Micro and Ultrafiltration Membranes

7232019 Biodiesel Purification Using Micro and Ultrafiltration Membranes

httpslidepdfcomreaderfullbiodiesel-purification-using-micro-and-ultrafiltration-membranes 16

Biodiesel puri1047297cation using micro and ultra1047297ltration membranes

Magno Joseacute Alves Suellen Mendonccedila Nascimento Iara Gomes Pereira Maria Inecircs MartinsVicelma Luiz Cardoso Miria Reis

Universidade Federal de Uberlacircndia Faculdade de Engenharia Quiacutemica Av Joatildeo Naves de Aacutevila 2121 38400-902 Uberlacircndia MG Brazil

a r t i c l e i n f o

Article history

Received 21 May 2012Accepted 26 February 2013

Available online 30 March 2013

KeywordsBiodiesel

Puri1047297cation

Membrane

a b s t r a c t

Biodiesel is an environmental-friendly fuel that can replace petroleum diesel However after trans-

esteri1047297cation reaction of vegetable oils the obtained crude biodiesel must be puri1047297ed The commonlyapplied puri1047297cation step is water washing This step is a concern in biodiesel production since large

quantities of clean water are used generating a wastewater stream to be further treated Here we pro-pose the application of micro and ultra1047297ltration processes to purify crude biodiesel Crude biodiesel was

1047297ltrated in a dead-end process at different transmembrane pressures and using membranes of differentpore sizes Flux results showed that greater transmembrane pressures as well as greater pore sizes

enable greater 1047298uxes Density viscosity and acid values of puri1047297ed biodiesel (washed and 1047297ltrated) are inaccordance to the international legislation for biodiesel quality Both processes (water washing and

membrane separation) were able to reduce the amount of soap detected in crude biodiesel However theproposed micro1047297ltration membranes were not ef 1047297cient as the washing method to reduce the free

glycerol content The ultra1047297ltration membrane of 30 kDa was also not able to produce a puri1047297ed biodieselaccording to the international legislation for free glycerol content Between the analyzed membranes the

glycerol content limit (less than 002 wt) was achieved only with the ultra1047297ltration membrane of 10 kDa Water addition in the crude biodiesel improved the glycerol removal by membrane 1047297ltration The

obtained results showed that the membrane separation process is a suitable alternative for biodiesel

puri1047297

cation 2013 Elsevier Ltd All rights reserved

1 Introduction

Energetic and environmental issues have encouraged thedevelopment of alternative fuel sources Biodiesel is a potential fuelfor diesel engines since it is obtained of renewable sources andcombustion emissions for biodiesel are lower than for petroleum

diesel [1] Biodiesel can be derived from vegetable oils animal fatsor recycled greases Choice of the raw material to be used in bio-diesel production is both a process chemistry decision and an

economic decision [1] In Brazil soybean oil is largely applied forbiodiesel production [2]

Biodiesel is commonly produced by the transesteri1047297cation re-action In this reaction a triglyceride reacts with an alcohol of shortchain (methanolor ethanol) in the presence of a catalyst to produce

a mixture of fatty esters (biodiesel) and glycerol Although the 31mole ratio between methanol and oil is required extra alcohol isadded to the reactor in order to drive the reaction closer to higheryields Using vegetable oils as a feedstock base catalyst systems are

mainly used The most commonly used catalyst materials for con-verting triglycerides to biodiesel are sodium hydroxide potassium

hydroxide and sodium methoxide [3] Typical catalyst loadingsrange from 03 to about 15 [1] The operating reactor tempera-ture is usually about 60 C although temperatures from 25 C to85 C have been reported [1] After the reaction the reactionmixture is allowed to settle in a decanter to give a separation of

ester and glycerol phases Alcohol is removed from both the glyc-erol and ester stream using an evaporator or a 1047298ash unit After these

steps the ester phase still contains impurities such as freedispersed glycerol particles soap and trace amounts of residualcatalyst and mono di and triglycerides This crude biodiesel mustbe treated in order to attempt standard speci1047297cations that de1047297nethe quality of biodiesel (eg ASTM D6751 [4] and EN 14214 [5])

The conventional puri1047297cation process of the ester phase is waterwashing being applied to remove the residual glycerol base cata-lyst and any soap formed during the reaction [6] However thisprocess generates a large amount of highly polluting wastewater

causing environmental disposal problemsMembrane technology can be applied for biodiesel puri1047297cation

in order to avoid the water washing step Atadashi et al [6] stated Corresponding author

E-mail addresses miriafequfubr miriareishotmailcom (M Reis)

Contents lists available at SciVerse ScienceDirect

Renewable Energy

j o u r n a l h o m e p a g e w w w e l s e v i e r c o m l o c a t e r e n e n e

0960-1481$ e see front matter 2013 Elsevier Ltd All rights reserved

httpdxdoiorg101016jrenene201302035

Renewable Energy 58 (2013) 15e20



that the introduction of membrane technology can minimize thedif 1047297culties encountered in the separation and puri1047297cation of bio-

diesel However this technology needs to be thoroughly exploredand exploited to determine its potential applications for the sepa-ration and puri1047297cation of the biodiesel product mixture

The principle of membrane separation of ester and free glycerolis depicted in Fig 1 Glycerol molecules must be associated withother ones in order to increase the particle size In this way theester phase could be get in the permeate side while glycerol and

other impurities are retained in the feed side [56]Some scienti1047297c papers reported the application of a membrane

reactor system to shift the reaction equilibrium to the product side

Cao et al [7] observed that the glycerin content in the producedbiodiesel was signi1047297cantly lower than that produced via a con-ventional batch transesteri1047297cation reaction Cao et al [8] investi-gated the effect of membrane pore size on the performance of a

membrane reactor for biodiesel production Baroutian et al [9]showed that a TiO2Al2O3 membrane reactor was able to produce

a biodiesel with characteristics according to the ASTM standardlimits Cheng et al [10] simulated a membrane reactor integratedwith a prereactor and showed that this system can be used to

separate the unreacted emulsi1047297ed oil from the product stream

He et al [11] compared membrane extraction and traditionalextraction methods for biodiesel puri1047297cation In the membranemethod a hollow 1047297ber membrane (1 m long 1 mm diameter 1047298ow

rate 05 mLmin operating pressure 01 MPa) was used to purifycrude biodiesel Two types of hollow 1047297ber membranes polysulfoneand polyacrylonitrile which are hydrophilic and hydrophobicrespectively were used According to the obtained results He et al

[11] concluded that membrane process caused less ester loss thanwashing or solvent extraction methods The polysulfone membranewas more ef 1047297cient than the polyacrylonitrile one However Heet al [11] did not compare the glycerin removal

Cheng et al [12] evaluated the membrane separation processusing a ceramic membrane combined a with liquideliquid extrac-tion process for the continuous cross 1047298ow rejection of triglycerides

Wang et al [13] investigated re1047297ning of biodiesel by ceramicmembrane separation with different pore size membranes and atdifferent temperatures and transmembrane pressures According toWang et al [13] the glycerin removal was greater by the membrane

process than by the water washing processSaleh et al [14] investigated the effects of soap methanol and

water on glycerol particle size in biodiesel puri1047297cation concludingthat the addition of small amounts of water improved the removal

of glycerol from FAME Gomes et al [15] showed that the waterconcentration to be added to the mixture plays an important role inglycerol separation as well as in the permeate1047298ux according to the

proposed glycerol separation mechanism using a ceramicmembrane

In this work we propose the comparison of micro and ultra1047297l-tration membranes for biodiesel puri1047297cation The trade-off be-

tween permeate 1047298ux and free glycerol removal was investigatedBesides the effect of water addition was analyzed in order to ach-ieve higher free glycerol removal

2 Materials and methods

21 Biodiesel synthesis

Biodiesel was produced using re1047297ned soybean oil and methanol(999 purity Vetec Brazil) as reactants and potassium hydroxide(KOH reagent grade Vetec Brazil) as a catalyst The trans-esteri1047297cation reaction was carried out in a 2 L three-neck round-

bottomed 1047298ask 1047297tted with a thermometer to control the reactiontemperature a re1047298ux condenser to prevent methanol loss bycooling water and a mechanical stirrer to keep the reaction underconstant agitation The 1047298ask was supported on a heating mantle tocontrol the reaction temperature at 60 C The oil was fed into the

1047298ask and preheated before catalyst (KOH) and methanol additionThe catalyst was previously dissolved into methanol until completedissolution This solution was also preheated at 60 C Methanoloilmolar ratio was 41 the reaction time was 1 h and the amount of catalyst in relation to the oil mass was 075 wt These conditions

arewell established in the literature for a satisfactory ester yield [6]The obtained product was transferred to a rotary evaporator

under 600 mmHg vacuum at 90 C for 60 min for methanol andwater removals This mixture was then placed on a separator funnel

and allowed to settle for 12 h and the bottom glycerol-rich layerwas removed A total of 4 runs were performed to generate suf 1047297-cient quantities of ester-rich phase (called as crude biodiesel) forthe puri1047297cation experiments

The crude ester phase was washed with hot distilled water(50 C) at a 11 mass ratio under mild agitation as suggested by Heet al [11] until that the pH of the water washing was neutral This

condition was reached with three washing steps

22 Filtration process to purify crude biodiesel

Besides water washing puri1047297cation method the crude biodiesel

was also puri1047297ed by membrane 1047297ltration using 1047298at polymericmembranes Mixed cellulose ester micro1047297ltration membranes of 022 and 030 mm pore size (Millipore Ireland) and poly(ether-sulfone) ultra1047297ltration membranes of 10 and 30 kDa nominal

Fig 1 Scheme for biodiesel (FAME) puri1047297

cation by the membrane separation process

MJ Alves et al Renewable Energy 58 (2013) 15e 2016



MWCO (GE Osmonics USA) were evaluated in this work Only newmembranes were used in the experiments

The micro1047297ltration experiments were carried out at twodifferent transmembrane pressures 1 and 2 bar The ultra1047297ltrationtests were performed at 4 bar of transmembrane pressure for bothevaluated ultra1047297ltration membranes These pressures were chosen

based on preliminary tests in which suitable biodiesel 1047298uxes wereobserved

The 1047297ltrations were carried out in a semi-batch module (Fig 2)using membranes with 1047297ltration radius of 45 mm A volume of

500 mL of biodiesel was fed into the membrane module for eachexperiment The pressure was adjusted with N2 gas and monitoredin a manometer The permeate 1047298ux was monitored through the

1047297ltration time Micro and ultra1047297ltrations were carried out during 10and 60 min respectively These times were 1047297xed based on thevolume of crude biodiesel fed in the 1047297ltration module

Besides crude biodiesel 1047297ltrations additional tests were carried

out by the adding of low quantities of water to the crude biodieselbefore the 1047297ltration Deionized water was added to the biodieselsample at concentrations of 01 and 02 wt as suggested by Salehet al [16] Deionized water was mixed with the crude biodiesel

using a magnetic stirrer for 1 h at ambient temperature prior to the

1047297ltration run

23 Chemical analysis

Soybean oil and crude washed and 1047297ltrated biodiesel sampleswere analyzed for free glycerol content density at 20 C kinematic

viscosity at 40 C acid value saponi1047297cation value amount of soapand water content

Kinematic viscosity density and acid value were determinedaccording to ASTM D445 [17] D1298 [18] and D664 [19] respec-

tively The acid number is a direct measure of free fatty acids inbiodiesel It is measured in terms of the quantity of KOH required toneutralize the sample

Amount of soap was measured following a modi1047297ed version of

AOCS method Cc 17e

79 [20] soap in oil Saponi1047297

cation value was

measured according to AOCS Of 1047297cial Method Cd 3e25 [21] The

saponi1047297cation value represents milligrams of KOH required tosaponify 1 g of fat or oil Water content was measured according tothe EN ISO 12937 [22] by Karl Fischer coulometric titration

(Metrohm)Free glycerol content was measured by the volumetric method

described by AOCS methodology for the analysis of free glycerol inoils and fats (Ca 14e56 [23]) Free glycerol refers to the amount of

glycerol that is left in the 1047297nished biodiesel Glycerol is insoluble inbiodiesel so almost all of the glycerol is easily removed by settlingSome glycerol may remain either as suspended droplets or a verysmall amount that is dissolved in the biodiesel and it is known as

free glycerolAlthough the volumetric method for free glycerol content is

accurate for this determination [24] the chromatography methoddescribed in ASTM-D6584 [25] was employed to verify free glycerol

percent in some biodiesel samples An Agilent 7890A gas chro-matography (GC) with a 1047298ame ionization detector (FID) and with aDB-5HT capillary column (JampW Scienti1047297c) capillary column of 15 mlength 032 mm ID 01 mm 1047297lm thickness with (5 phenyl)-

methylpolysiloxane was usedThe yield of biodiesel was calculated as presented in Equation

(1) [26]

YieldethTHORN frac14

mbiodiesel

mraw oil

100 (1)

where mbiodiesel is the quantity of crude biodiesel obtained after thetransesteri1047297cation reaction and mraw oil is the quantity of soybean

oil used as feedstock

3 Results and discussion

31 Transesteri 1047297cation reaction and water washing puri 1047297cation

The used soybean oil had a density of 915 kg m3 at 25 C ki-

nematic viscosity of 293 mm2 s1 at 40 C acid value of 017 mgKOH g1 and saponi1047297cation value of 16212 mgKOH g1 Theseresults show that this feedstock is appropriate to obtain high esteryields According to Freedman et al [27] the feedstock must present

an acid value less than 1 to obtain maximum ester formation bytransesteri1047297cation of vegetable oils Sharma and Singh [28]reviewed the literature and stated that the acid value of the feed-stock has to be reduced to less than 2 mg KOH g1 for alkaline

transesteri1047297cationAccording to Equation (1) the product yield was 93 similar to

the result reported by Sharma and Singh [28]After the transesteri1047297cation reaction and the settling process to

separate ester and glycerin phases the obtained crude biodieselwas characterized (Table 1) Crude biodiesel was washed with

water and the characteristics of the washed biodiesel are alsopresented in Table 1

Filtration

module

Magnetic stirrer

Manometer

Permeate

collection

N2 gas tank

Digital balance

Fig 2 Schematic diagram of 1047297ltration module

Table 1

Characterization of crude and washed biodiesel

Parameter Biodiesel sample

Crude Washed

Density (kg m3) 880 880

Kinematic viscosity (mm2 s1) 50 50

Water content (ppm) 5254 10262

Acid value (mgKOH g1) 008 014

Saponi1047297cation value (mgKOH g1) 1915 1792

Amount of soap (gsoap g1sample)a 26 103 n d

Free glycerol ( wtwt) 0029 0007

n d frac14 not detecteda

As potassium oleate

MJ Alves et al Renewable Energy 58 (2013) 15e 20 17



Transesteri1047297cation reaction reduced the feedstock oil densityand viscosity as expected Water washing process did not change

density and viscosity values of crude biodieselAccording to EN 14214 the limit for water content in fatty acid

methyl esters is 500 ppm As shown in Table 1 the water washing

process increased the water content and the puri1047297ed biodiesel hasmore water than the limit allowed by the legislation He et al [11]observed that water washing can increase the water content if wa-ter is added at 20 C Gonzalo et al [29] reported the values of watercontent in puri1047297ed biodieselsamples ranging from 800 to 1000 ppm

Moreover Gonzalo et al [29] also observed that this water contentincreases after the water washing process This behavior can beassociated to the interaction between mono and diglycerides andwater since water solubility in ester is very small Mono and di-

glycerides molecules left from an incomplete reaction can act as anemulsi1047297er allowing the water to be mixed with the biodiesel

The acid values of crude and washed biodiesel are smaller than

the acid value of soybean oil Usually for a base catalyzed processthe acid value after production will be low since the base catalystwill strip the available free fatty acids The alkali catalyst also servesas a caustic stripper and removes the free fat acids by converting

them into soap that is removed during washing The acid value of

crude biodiesel is smaller than the acid value of washed biodiesel

In this case the presence of alkali catalyst in crude biodieseldiminished the quantity of base (KOH) that was necessary toneutralize the available free fatty acids The catalyst was removedby the washing process and then the acid value increased Soap was

removed by the washing process and the amount of soap decreasedafter the washing process

The water washing process was able to achieve the limitimposed by ASTM D6751 (USA) [4] and EN 14214 (Europe) [5] for

free glycerol content Except for the water content all the otheranalyzed parameters of the washed biodiesel are in accordance tothe limits imposed by the legislation

32 Membrane separation process

Crude biodiesel was1047297ltered throughout micro and ultra1047297ltrationmembranes Fig 3 presents the obtained 1047298ux of biodiesel throughthe micro1047297ltration membranes at 1 and 2 bar A 1047298ux decline is

observed in the1047297rst 2 min ofoperation forthemembrane of022mm(Fig 3a) Fig 3b shows that for the 030 mm membrane steady de-clines are observed for1 and 5 min at 1 and 2 bar of transmembranepressures respectively The stabilized 1047298ux is greater at2 bar than at

1 bar showing that greater transmembrane pressure enables

greater 1047298uxes within the analyzed pressure range Moreover the1047298ux obtained is greater with the more open membrane

Fig 4 presents the permeate 1047298ux throughout the ultra1047297ltration

membranes (10 and 20 kDa MWCO) at the transmembrane pres-sure of 4 bar Besides the higher transmembrane pressure the 1047298uxwith ultra1047297ltration membranes was smaller than with the micro-

1047297ltration ones and a less pronounced 1047298ux decline was observed in

this case The membrane with higher cutoff presented higher1047298uxes

Table 2 presents the observed 1047297nal 1047298ux for each evaluatedmembrane Othman [30] evaluated nano1047297ltration polymeric

membranes for biodiesel 1047297ltration and the higher observed 1047298uxwas approximately 51 kg h1 m2 Saleh et al [31] proposed theapplication of ceramic membranes for biodiesel puri1047297cation and

observed stabilized 1047298uxes around 40 and 30 kg h1 m2 formicro and ultra1047297ltration processes respectively Wang et al [13]used a ceramic micro1047297ltration membrane of 01 mm pore size at15 bar of transmembrane pressure for biodiesel puri1047297cation andobserved a stabilized 1047298ux of about 300 kg h1 m2 Mah et al [32]

also used 1047298at polymeric membrane of 30 kDa for dead-end

Fig 4 Permeate 1047298

ux of biodiesel throughout ultra1047297

ltration membranes

Fig 3 Permeate 1047298ux of biodiesel at 1 and 2 bar of transmembrane pressures

throughout micro1047297

ltration membranes of 022 mm (a) and 030 mm (b) pore size




1047297ltration of synthetic mixtures containing glycerol oleic acid and

palm oil Mah et al [32] observed 1047297nal 1047298uxes ranging from 349 to828 kg h1 m2 depending on the composition of the feed mix-tures Several aspects can in1047298uence the observed 1047298ux throughoutthe membrane as the membrane material and its pore size theoperation mode and the feed composition According to the

observed 1047298uxes the membranes proposed in this work are apromising alternative for biodiesel puri1047297cation

The physico-chemical characterization of permeate samplesshowed that the 1047297ltration process did not affect the density and the

viscosity of crude biodiesel These results show that the membranewas not able to remove catalyst excess andor free acid content of crude biodiesel since the acid value of crude biodiesel did notchange after the 1047297ltration Table 3 presents the amount of soap and

the free glycerol content measured in 1047297ltrate biodiesel samples

Fig 5 presents the percentage reductions related to the parametervalues of crude biodiesel

Only the ultra1047297ltration membrane of 30 kDa (4 bar) was not able

to reduce the amount of soap and free glycerol content detected incrude biodiesel sample And additional test was carried out withthis membrane at a smaller transmembrane pressure (3 bar) Thisreduction in the transmembrane pressure value increases the

performance of the 30 kDa membrane for biodiesel puri1047297cationHowever this membrane did not show promising values for bio-diesel puri1047297cation probably related to the more open pore size (in

relation to the 10 kDa membrane) and to the higher appliedtransmembrane pressure

Fig 5 shows how the removal of soap is related to the freeglycerol removal Higher soap removals lead to higher free glycerol

removals Wang et al [13] stated that the size of reversed micelleformed by the soap and free glycerol with the mean size of 221 mm(analyzed by zeta potential analyzer) was larger than that of bio-diesel and was easier to be removed the membrane separation

Saleh et al [14] showed that the presence of water increases glyc-erin removal by the membrane separation process

The transmembrane pressure applied in the micro1047297ltration ex-periments did not affect the biodiesel quality Regarding to free glyc-

erol content as presented in Table 3 only the ultra1047297ltrationmembrane of 10 kDawasable toreducethe glycerol contentaccordingto the international legislation limit for biodiesel (less than 002 wt)

This result was con1047297rmed by chromatography analysis Table 4

presents the results obtained by chromatography analyzes of crude washed and permeate samples This result shows that theultra1047297ltration process with the 10 kDa membrane was able toreduce the glycerol content to the desired level (less than 002 wt)

33 Water addition

Further 1047297ltrations were carried out using the membrane of

10 kDa and adding water to the crude biodiesel sample prior to the

1047297ltration Fig 6 presents 1047298ux results for 1047297ltrations of the sampleswith and without water addition throughout the 10 kDa ultra1047297l-tration membrane According to these results (Fig 6) the water

addition decreases the observed stabilized 1047298ux Gomes et al [15]evaluated the addition of acidi1047297ed water to crude biodiesel sam-ple at 20 wt Theseauthors observed a sharp drop in the 1047298uxand asmaller stabilized 1047298ux for the sample with water addition

The decrease in the 1047298ux is probably associated with higher re-movals Table 5 presents free glycerol and water concentrations inthe permeate at some 1047297ltration times For these samples free

glycerol content was measured by gas chromatographyWater addition improved the glycerol removal since glycerol andwater (completely soluble) formed an immiscible phase with theFAME phase [14] Themolecules of water joinedto glycerol andthese

larger molecules were unable to pass through the membrane poresAftersome 1047297ltration time the glycerolconcentrationin the permeateincreased as the water concentration decreased This increase in the

glycerol content in the permeate as a function of the1047297ltration time isprobably related to the dead-end operation mode The accumulationof glycerol particles near to the membrane surface caused theirpermeation at longer 1047297ltration times Mah et al [32] reported the

cake formation in dead-end 1047297ltrations of synthetic mixtures of palmoil with glycerin

Addition of water at higher concentration (02 wt) improved theglycerol removal by the membrane at the end of the 1047297ltration time

Lower water concentration was measured in the permeate for thesample with water addition at 02 wt showing that this added waterwas effectively used to be joined to the glycerol molecules Saleh et al[16] showed thata polyacrylonitrile(PAN) membrane witha molecularweight cutoff of 100 kDa was able to reduce the glycerol content in

biodiesel obtained from canola oil The authors applied a

Table 2

Final 1047298ux throughout micro and ultra1047297ltration membranes

Membrane pore size 022 mm 030 mm 10 kDa 30 kDa

Pressure (bar) 1 2 1 2 4 4

Final 1047298ux (kg h1 m2) 109 253 536 923 55 120

Table 3

Characterization of 1047297ltrate biodiesel samples

Membrane and pressure Parameter

Amount of soap

(103 gsoap g1sample)a

Free glycerol

( wtwt)

022 mm (1 bar) 13 0022

022 mm (2 bar) 13 0025

03 mm (1 bar) 16 0026

03 mm (2 bar) 16 0026

10 kDa (4 bar) 10 0020

30 kDa (4 bar) 27 0031

30 kDa (3 bar) 24 0029

a

As potassium oleate

Fig 5 Reductions for amount of soap and free glycerol content in puri1047297ed biodiesel

samples

Table 4

Free glycerol content in biodiesel samples determined by gas chromatography

analysis


Crude Washed Filtrated (10 kPa 4 bar)

Free glycerol ( wtwt) 0049 0011 0019




transmembrane pressureof 552 kPa However according to the results

showed by Saleh et al [16] the glycerol content in the permeated

achievedthe limitof less than 02wtonly when pure water was addedto the feed solution Saheh et al [14] showed that small quantities of water have a great effect in removing glycerol from biodiesel

4 Conclusions

This work evaluated the application of micro and ultra1047297ltration

membranes for biodiesel puri1047297cation Micro1047297ltration membranespresented higher 1047298uxes but the permeate characteristics did notattempt the international legislation regarding to free glycerolcontent The ultra1047297ltration membrane of 30 kDa was not able to

produce a puri1047297ed biodiesel according to the international legis-lation parameters Between the analyzed membranes the glycerolcontent level (less than 002 wt) was achieved only with the

membrane of 10 kDa Water addition in the biodiesel sampleimproved the glycerol removal This membrane (10 kDa) also pre-sented a suitable permeate 1047298ux showing that the membrane sep-aration process is a suitable alternative for biodiesel puri1047297cation

Acknowledgments

The research work was funded by VALE SA and ConselhoNacional de Desenvolvimento Cientiacute1047297co e Tecnoloacutegico (CNPQ)

References

[1] Basha SA Gopal KR Jebaraj S A review on biodiesel production combustionemissions and performance Renew Sustain Energy Rev 2009131628e34

[2] Nogueira LAH Does biodiesel make sense Energy 2011363659e66[3] Cheng JJ Timilsina GR Status and barriers of advanced biofuel technologies a

review Renew Energy 2011363541e9[4] ASTM D6751 Standard speci1047297cation for biodiesel fuel blend stock (B100) for

middle distillate fuels 2012[5] EN 14214 The pure biodiesel standard 2008[6] Atadashi IM Aroua MK Aziz AA Biodiesel separation and puri1047297cation a re-

view Renew Energy 201136437e43[7] Cao PG Dube MA Tremblay AY High-purity fatty acid methyl ester produc-

tion from canola soybean palm and yellow grease lipids by means of amembrane reactor Biomass Bioenergy 2008321028e36

[8] Cao PG Tremblay AY Dube MA Morse K Effect of membrane pore size on theperformance of a membrane reactor for biodiesel production Ind Eng ChemRes 20074652e8

[9] Baroutian S Aroua MK Aziz ARA Sulaiman NMN TiO2Al2O3 membranereactor equipped with a methanol recovery unit to produce palm oil biodieselInt J Energy Res 201236120e9

[10] Cheng LH Yen SY Chen ZS Chen JH Modeling and simulation of biodieselproduction using a membrane reactor integrated with a prereactor Chem EngSci 20126981e92

[11] He HY Guo X Zhu SL Comparison of membrane extraction with traditionalextraction methods for biodiesel production J Am Oil Chem Soc 200683457e60

[12] Cheng LH Cheng YF Yen SY Chen JH Ultra1047297ltration of triglyceride from

biodiesel using the phase diagram of oil-FAME-MeOH J Membr Sci 2009330156e65[13] Wang Y Wang XG Liu YF Ou SY Tan YL Tang SZ Re1047297ning of biodiesel by

ceramic membrane separation Fuel Process Technol 200990422e7[14] Saleh J Dube MA Tremblay AY Effect of soap methanol and water on

glycerol particle size in biodiesel puri1047297cation Energy Fuel 2010246179e86

[15] Gomes MCS Arroyo PA Pereira NC Biodiesel production from degummedsoybean oil and glycerol removal using ceramic membrane J Membr Sci2011378453e61

[16] Saleh J Tremblay AY Dube MA Glycerol removal from biodiesel usingmembrane separation technology Fuel 2010892260e6

[17] ASTM D445 Standard test method for kinematic viscosity of transparent andopaque liquids (and calculation of dynamic viscosity) 2006

[18] ASTM D1298 Standard test method for density relative density (speci1047297cgravity) or API gravity of crude petroleum and liquid petroleum products byhydrometer method 2003

[19] ASTM D664 Standard test method for acid number of petroleum products bypotentiometric titration 2006

[20] Knothe G Analytical methods used in the production and fuel qualityassessment of biodiesel Trans ASAE 200144193e200

[21] AOCS Of 1047297cial method Cd 3-25 saponi1047297cation value 2003[22] EN ISO 12937 Petroleum products determination of water coulometric Karl

Fisher titration method 2000[23] AOCS Of 1047297cial method Ca14-56 total free and combined glycerol iodometric-

periodic acid method 1997[24] Monteiro MR Ambrozin ARP Liao LM Ferreira AG Critical review on

analytical methods for biodiesel characterization Talanta 200877593e605

[25] ASTM D6584 Test method for determination of free and total glycerin in B-100 biddies methyl esters by gas chromatography 2000

[26] Leung DYC Guo Y Transesteri1047297cation of neat and used frying oil optimizationfor biodiesel production Fuel Process Technol 200687883e90

[27] Freedman B Pryde EH Mounts TL Variables affecting the yields of fatty estersfrom transesteri1047297ed vegetable-oils J Am Oil Chem Soc 1984611638e43

[28] Sharma YC Singh B Development of biodiesel current scenario RenewSustain Energy Rev 2009131646e51

[29] Gonzalo A Garcia M Sanchez JL Arauzo J Pena JA Water cleaning of bio-diesel Effect of catalyst concentration water amount and washing temper-ature on biodiesel obtained from rapeseed oil and used oil Ind Eng Chem Res2010494436e43

[30] Othman R Mohammad AW Ismail M Salimon J Application of polymericsolvent resistant nano1047297ltration membranes for biodiesel production J MembrSci 2010348287e97

[31] Saleh J Dube MA Tremblay AY Separation of glycerol from FAME usingceramic membranes Fuel Process Technol 2011921305e10

[32] Mah SK Leo CP Wu TY Chai SP A feasibility investigation on ultra1047297ltration of palm oil and oleic acid removal from glycerin solutions 1047298ux decline foulingpattern rejection and membrane characterizations J Membr Sci 2012389245e56

Fig 6 Permeate 1047298uxes throughout the ultra1047297ltration membrane of 10 kDa with water

addition to the crude biodiesel

Table 5

Free glycerol and watercontents in biodiesel permeate samples with water addition

for the 10 kDa membrane at 4 bar

Filtration

time (min)

Sample crude biodiesel thorn

01 wt of water


02 wt of water

Free glycerol

( wtwt)

Water

(ppm)

Free glycerol

( wtwt)

Water

(ppm)

10 0002 157717 0007 10010840 0006 136236 0007 93776

60 0010 98790 0009 91028




that the introduction of membrane technology can minimize thedif 1047297culties encountered in the separation and puri1047297cation of bio-

diesel However this technology needs to be thoroughly exploredand exploited to determine its potential applications for the sepa-ration and puri1047297cation of the biodiesel product mixture

The principle of membrane separation of ester and free glycerolis depicted in Fig 1 Glycerol molecules must be associated withother ones in order to increase the particle size In this way theester phase could be get in the permeate side while glycerol and

other impurities are retained in the feed side [56]Some scienti1047297c papers reported the application of a membrane

reactor system to shift the reaction equilibrium to the product side

Cao et al [7] observed that the glycerin content in the producedbiodiesel was signi1047297cantly lower than that produced via a con-ventional batch transesteri1047297cation reaction Cao et al [8] investi-gated the effect of membrane pore size on the performance of a

membrane reactor for biodiesel production Baroutian et al [9]showed that a TiO2Al2O3 membrane reactor was able to produce

a biodiesel with characteristics according to the ASTM standardlimits Cheng et al [10] simulated a membrane reactor integratedwith a prereactor and showed that this system can be used to

separate the unreacted emulsi1047297ed oil from the product stream

He et al [11] compared membrane extraction and traditionalextraction methods for biodiesel puri1047297cation In the membranemethod a hollow 1047297ber membrane (1 m long 1 mm diameter 1047298ow

rate 05 mLmin operating pressure 01 MPa) was used to purifycrude biodiesel Two types of hollow 1047297ber membranes polysulfoneand polyacrylonitrile which are hydrophilic and hydrophobicrespectively were used According to the obtained results He et al

[11] concluded that membrane process caused less ester loss thanwashing or solvent extraction methods The polysulfone membranewas more ef 1047297cient than the polyacrylonitrile one However Heet al [11] did not compare the glycerin removal

Cheng et al [12] evaluated the membrane separation processusing a ceramic membrane combined a with liquideliquid extrac-tion process for the continuous cross 1047298ow rejection of triglycerides

Wang et al [13] investigated re1047297ning of biodiesel by ceramicmembrane separation with different pore size membranes and atdifferent temperatures and transmembrane pressures According toWang et al [13] the glycerin removal was greater by the membrane

process than by the water washing processSaleh et al [14] investigated the effects of soap methanol and

water on glycerol particle size in biodiesel puri1047297cation concludingthat the addition of small amounts of water improved the removal

of glycerol from FAME Gomes et al [15] showed that the waterconcentration to be added to the mixture plays an important role inglycerol separation as well as in the permeate1047298ux according to the

proposed glycerol separation mechanism using a ceramicmembrane

In this work we propose the comparison of micro and ultra1047297l-tration membranes for biodiesel puri1047297cation The trade-off be-

tween permeate 1047298ux and free glycerol removal was investigatedBesides the effect of water addition was analyzed in order to ach-ieve higher free glycerol removal

2 Materials and methods

21 Biodiesel synthesis

Biodiesel was produced using re1047297ned soybean oil and methanol(999 purity Vetec Brazil) as reactants and potassium hydroxide(KOH reagent grade Vetec Brazil) as a catalyst The trans-esteri1047297cation reaction was carried out in a 2 L three-neck round-

bottomed 1047298ask 1047297tted with a thermometer to control the reactiontemperature a re1047298ux condenser to prevent methanol loss bycooling water and a mechanical stirrer to keep the reaction underconstant agitation The 1047298ask was supported on a heating mantle tocontrol the reaction temperature at 60 C The oil was fed into the

1047298ask and preheated before catalyst (KOH) and methanol additionThe catalyst was previously dissolved into methanol until completedissolution This solution was also preheated at 60 C Methanoloilmolar ratio was 41 the reaction time was 1 h and the amount of catalyst in relation to the oil mass was 075 wt These conditions

arewell established in the literature for a satisfactory ester yield [6]The obtained product was transferred to a rotary evaporator

under 600 mmHg vacuum at 90 C for 60 min for methanol andwater removals This mixture was then placed on a separator funnel

and allowed to settle for 12 h and the bottom glycerol-rich layerwas removed A total of 4 runs were performed to generate suf 1047297-cient quantities of ester-rich phase (called as crude biodiesel) forthe puri1047297cation experiments

The crude ester phase was washed with hot distilled water(50 C) at a 11 mass ratio under mild agitation as suggested by Heet al [11] until that the pH of the water washing was neutral This

condition was reached with three washing steps

22 Filtration process to purify crude biodiesel

Besides water washing puri1047297cation method the crude biodiesel

was also puri1047297ed by membrane 1047297ltration using 1047298at polymericmembranes Mixed cellulose ester micro1047297ltration membranes of 022 and 030 mm pore size (Millipore Ireland) and poly(ether-sulfone) ultra1047297ltration membranes of 10 and 30 kDa nominal

Fig 1 Scheme for biodiesel (FAME) puri1047297

cation by the membrane separation process













1047297ltration run







AOCS method Cc 17e


cation value was










(1) [26]


mbiodiesel

mraw oil

100 (1)












Filtration

module

Magnetic stirrer

Manometer

Permeate

collection

N2 gas tank

Digital balance


Table 1



Crude Washed









As potassium oleate

































ltration membranes

























33 Water addition













Table 2




Final 1047298ux (kg h1 m2) 109 253 536 923 55 120

Table 3



Amount of soap


Free glycerol

( wtwt)

022 mm (1 bar) 13 0022

022 mm (2 bar) 13 0025

03 mm (1 bar) 16 0026

03 mm (2 bar) 16 0026

10 kDa (4 bar) 10 0020

30 kDa (4 bar) 27 0031

30 kDa (3 bar) 24 0029

a

As potassium oleate


samples

Table 4


analysis










4 Conclusions





Acknowledgments


References



































Table 5



Filtration

time (min)


01 wt of water


02 wt of water

Free glycerol

( wtwt)

Water

(ppm)

Free glycerol

( wtwt)

Water

(ppm)

10 0002 157717 0007 10010840 0006 136236 0007 93776

60 0010 98790 0009 91028













1047297ltration run







AOCS method Cc 17e


cation value was










(1) [26]


mbiodiesel

mraw oil

100 (1)












Filtration

module

Magnetic stirrer

Manometer

Permeate

collection

N2 gas tank

Digital balance


Table 1



Crude Washed









As potassium oleate

































ltration membranes

























33 Water addition













Table 2




Final 1047298ux (kg h1 m2) 109 253 536 923 55 120

Table 3



Amount of soap


Free glycerol

( wtwt)

022 mm (1 bar) 13 0022

022 mm (2 bar) 13 0025

03 mm (1 bar) 16 0026

03 mm (2 bar) 16 0026

10 kDa (4 bar) 10 0020

30 kDa (4 bar) 27 0031

30 kDa (3 bar) 24 0029

a

As potassium oleate


samples

Table 4


analysis










4 Conclusions





Acknowledgments


References



































Table 5



Filtration

time (min)


01 wt of water


02 wt of water

Free glycerol

( wtwt)

Water

(ppm)

Free glycerol

( wtwt)

Water

(ppm)

10 0002 157717 0007 10010840 0006 136236 0007 93776

60 0010 98790 0009 91028

































ltration membranes

























33 Water addition













Table 2




Final 1047298ux (kg h1 m2) 109 253 536 923 55 120

Table 3



Amount of soap


Free glycerol

( wtwt)

022 mm (1 bar) 13 0022

022 mm (2 bar) 13 0025

03 mm (1 bar) 16 0026

03 mm (2 bar) 16 0026

10 kDa (4 bar) 10 0020

30 kDa (4 bar) 27 0031

30 kDa (3 bar) 24 0029

a

As potassium oleate


samples

Table 4


analysis










4 Conclusions





Acknowledgments


References



































Table 5



Filtration

time (min)


01 wt of water


02 wt of water

Free glycerol

( wtwt)

Water

(ppm)

Free glycerol

( wtwt)

Water

(ppm)

10 0002 157717 0007 10010840 0006 136236 0007 93776

60 0010 98790 0009 91028






















33 Water addition













Table 2




Final 1047298ux (kg h1 m2) 109 253 536 923 55 120

Table 3



Amount of soap


Free glycerol

( wtwt)

022 mm (1 bar) 13 0022

022 mm (2 bar) 13 0025

03 mm (1 bar) 16 0026

03 mm (2 bar) 16 0026

10 kDa (4 bar) 10 0020

30 kDa (4 bar) 27 0031

30 kDa (3 bar) 24 0029

a

As potassium oleate


samples

Table 4


analysis










4 Conclusions





Acknowledgments


References



































Table 5



Filtration

time (min)


01 wt of water


02 wt of water

Free glycerol

( wtwt)

Water

(ppm)

Free glycerol

( wtwt)

Water

(ppm)

10 0002 157717 0007 10010840 0006 136236 0007 93776

60 0010 98790 0009 91028







4 Conclusions





Acknowledgments


References



































Table 5



Filtration

time (min)


01 wt of water


02 wt of water

Free glycerol

( wtwt)

Water

(ppm)

Free glycerol

( wtwt)

Water

(ppm)

10 0002 157717 0007 10010840 0006 136236 0007 93776

60 0010 98790 0009 91028


Biodiesel Purification Using Micro and Ultrafiltration Membranes

Documents

Transcript of Biodiesel Purification Using Micro and Ultrafiltration Membranes