Iraqi Journal of Chemical and Petroleum Engineering 

 Vol.14 No.4 (December 2013) 53- 70 

ISSN: 1997-4884 

 
 
 
 

Microfiltration Membranes for Separating Oil / Water Emulsion  

 
Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

Chemical Engineering Department – College of Engineering – University of Baghdad – Iraq 

 

Abstract 

   This research was aimed to study the efficiency of microfiltration membranes for 

the treatment of oily wastewater and the factors affecting the performance of the 

microfiltration membranes experimental work were includes operating the 

microfiltration process using polypropylene membrane (1 micron) and ceramic 

membrane (0.5 micron) constructed as candle; two methods of operation were 

examined: dead end and cross flow. The oil emulsion was prepared using two types of 

oils: vegetable oil and motor oil (classic oil 20W-50). The operating parameters 

studied are: feed oil concentration 50 – 800 mg/l, feed flow rate 10 – 40 l/h, and 

temperature 30 – 50 
o
C, for dead end and cross flow microfiltration. 

   It was found that water flux decreases with increasing operating time and feed oil 

concentration and increases with increasing operating temperature, feed flow rate and 

pore size of membrane. Also, it was found that rejection percentage of oil increases 

with increasing flow rate and rejection percentage decreases with increasing time, 

feed oil concentration, feed temperature and pore size of membrane for dead end and 

cross flow microfiltration. In cross flow microfiltration, reject concentration 

(concentrate) increases with increasing flow rate, feed concentration, time and feed 

temperature. The dead end filter has more flux compared to cross flow filter, while, in 

cross flow the oil rejection percentage is best than dead end. Flux for vegetable oil is 

more than motor oil but rejection percentage for vegetable oil is less than that for 

motor oil. The highest recovery ratio was found is 44.8% for cross flow process with 

recirculation of concentrating stream to feed vessel. The highest rejection percentage 

of oil was found is 98 % and 97.8 % for cross flow and dead ends respectively. 

 
Keywords: Membrane Separation; Microfiltration; Oil; Wastewater; Polypropylene 

Membranes; Ceramic Membrane 

 

Introduction 

   Petroleum refineries and 

petrochemical plants all generate oily 

wastewater to some extent, and the oils 

contained in those wastewaters can 

vary widely. Removal of oils from 

wastewater is normally one of the first 

steps in the treatment of wastewater 

and arguably, the most important 

treatment step (Thomas, 2007). In 

recent years, considerable attention has 

been focused on the discharge of oily 

wastewater and its impact on the 

environment. Pollution of water by 

oily hydrocarbons is especially harmful 

to the aquatic life, as it attenuates the 

light and perturbs the normal 

mechanism of oxygen transfer 

(Xianguo and Gyula, 2005, Nandi B.K 

2010). 

Iraqi Journal of Chemical and 
Petroleum Engineering 

 

University of Baghdad 
College of Engineering 



 Microfiltration Membranes for Separating Oil / Water Emulsion

54                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

   Typical oil concentrations from 

various industrial sources are: 

petroleum (10 – 7200 mg/l), Metals 

(100 – 5000 mg/l), food processing (14 

– 10550 mg/l), wool (3000 – 20000 

mg/l), textiles (20 – 12260 mg/l) and 

cooling and heating (7 – 1200 mg/l) 

(Syed, 2000). Iraqi requirements for 

the oil in the discharge water are 10 

mg/l (Jassim, 2008). Various types of 

technologies exist for treatment of oily 

waters. These methods are gravity 

separators, dissolved air flotation, 

coalescers, biological treatment and 

activated carbon adsorption (Shams, et 

al., 2007). 

Over the past several years, advances 

have been made in developing an 

industrial wastewater reclaim system 

for a separation process for oily 

industrial wastewater which is 

extremely effective and economical in 

recycling of aqueous parts washing 

solutions. This process is based on a 

membrane technology that has major 

technical and commercial advantages 

over other approaches that have been 

tried for this application (Mike and 

Ivan, 2008). Membrane separation 

technology has been around for many 

years. Initially, the use of membranes 

was isolated to a laboratory scale. 

However, improvements over the past 

twenty years have made it possible to 

use membranes on an industrial level. 

A membrane is simply a synthetic 

barrier, which prevents the transport of 

certain components based on various 

characteristics. Membranes are very 

diverse in their nature with the one 

unifying theme to separate. 

Membranes can be liquid or solid, 

homogeneous or heterogeneous and 

can range in thickness. They can be 

manufactured to be electrically neutral, 

positive, negative or bipolar. These 

different characteristics enable 

membranes to perform many different 

separations from reverse osmosis to 

microfiltration. Therefore pressure 

driven membrane processes such as 

microfiltration (MF), ultrafiltration 

(UF), nanofiltration (NF) and reverse 

osmosis (RO) are increasingly being 

applied for treating oily wastewater 

(Syed, 2000).  

Membranes have several advantages, 

among them: (Cheryan and 

Rajagopalan, 1998) 

 The technology is more widely 
applicable across a wide range of 

industries. 

 The membrane is a positive barrier 
to rejected components. Thus, the 

quality of the treated water is more 

uniform regardless of influent 

variations. These variations may 

decrease flux, but generally does 

not affect quality of its output. 

 No extraneous chemicals are 
needed, making subsequent oil 

recovery easier. 

 Membranes can be used in-process 
to allow recycling of selected waste 

streams within a plant. 

 Membrane equipment has a smaller 
foot print. 

 The plant can be highly automated 
and does not require highly skilled 

operators. 

   Microfiltration (MF) is filtration 

process that operation on a physical 

sieving separation process. It is best 

used for the removal of suspended 

solids, Giardia, Cryptosporidium and 

the reduction of turbidity. MF process 

require low trans membrane pressure 

(1–30 psi) to operate, and it is also 

used as a pretreatment to desalination 

technologies such as reverse osmosis, 

nanofiltration, and electrodialysis .MF 

membranes can operate in either cross 

flow separation or dead-end filtration. 

Cross flow separation is where only 

part of the feed stream is treated and 

the remainder of the water is passed 

through the membrane untreated. In 

dead-end separation, all of the feed 

water is treated. The microfiltration 

membrane can consist of various 



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             55 
 

materials like, for example, 

polysulfone, polypropylene, 

polyvinyldifluoride (PVDF), 

polyethersulfone (PES), ZrO2 and 

carbon (Peter, 2007). In this research 

study the efficiency of membrane 

separation process (MF) for oily 

wastewater treatment, and to achieve 

low content of oil in permeate and high 

permeate flux, effects of operating 

parameters such as oil concentration, 

temperature, feed flow rate, pore 

diameters of membranes, time, 

different types of membranes, different 

types of oils and methods of different 

operating (dead end and cross flow) in 

a microfiltration unit were studied. 

Simple filtration models have also 

been employed to help analyze the 

microfiltration membrane – fouling 

process. 

 

Membrane Fouling Models 

The permeation flux of particle-free 

water across a clean membrane can be 

described by Darcy’s law as: 

 

  
  

   
                                          …(1) 

 

Where J (m
3
 m

-2
 s

-1
) is the permeation 

flux, ∆p (pa) the Trans membrane 

pressure (TMP), μ (kg/m.sec) the 

absolute viscosity of the water, and Rm 

(m
-1

) the hydraulic resistance of the 

clean membrane (or clean membrane 

resistance). 

 

For suspension filtration, the 

permeation flux will always be lower 

than that given by Equation (1). Flux 

decline is a result of the increase of 

membrane resistance to the permeating 

flow, resulting from membrane fouling 

or particle deposition on or in the 

membrane. The mechanisms of 

membrane fouling usually include pore 

blocking, concentration polarization 

and cake formation. For 

microfiltration, the fouling by 

concentration polarization may be 

negligible due to the large size of the 

particles retained (Leow and Bai , 

2002). 

   Thus, the permeation flux through a 

microfiltration unit treating oily 

wastewater, can be given, by 

modifying Equation (1), as: (Leow and 

Bai, 2002) 

 

  
  

           
                            …(2) 

 

Where Rp (m
−1

) is the resistance due to 

pore blocking, and Rc (m
−1

) the 

resistance arising from cake formation. 

 

For microfiltration at a constant TMP, 

the initial permeate flux J0; will mainly 

depend on Rm as Rp and Rc are initially 

zero. With the proceeding of 

microfiltration operation, pore 

blocking and cake formation will cause 

Rp and Rc to increase, and change the 

relative significance of Rm, Rp, and Rc 

in Equation (2), and the microfiltration 

process can transfer from a membrane 

resistance to a pore blocking resistance 

or a cake resistance process. Based on 

this, generally four fouling 

mechanisms for porous membranes can 

be observed, these are (Subramanian 

and Raghavarao, 2001): 

a. Complete blocking model 
Complete blocking model assumes that 

particles arrive at the membrane and 

seal the membrane pores such that the 

particles are not superimposed upon 

the other. The blocked surface area is 

proportional to the permeate volume. 

b. Standard blocking model 
In standard blocking model, the 

particle diameter is much less than the 

pore diameter, thus, the particles can 

enter most pores, deposit on the pore 

walls, and thus reduce the pore 

volume. The decrease of pore volume 

is also proportional to the permeate 

volume. 

 



 Microfiltration Membranes for Separating Oil / Water Emulsion

56                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

c. Intermediate blocking model 
In intermediate blocking model, the 

number of blocked pores or surface is 

also assumed to be proportional to the 

permeate volume but it is less 

restrictive in such a way that not every 

particle necessarily blocks the pores 

and particles may settle on other 

particles. 

d. The cake filtration model 
The cake filtration model is used to 

explain for the case of large particles, 

which cannot enter most pores, and 

hence, deposit forms a cake on the 

membrane surface. 

   For microfiltration at a constant 

transmembrane pressure, the 

permeation fluxes under each of these 

case may be given as: 

a. Complete pore blocking model:           
 

                                       …(3) 
                                                      

b. Standard pore blocking model:                                                   
 

    (   
 

 
        

    )
  

        …(4) 

 

c. Intermediate pore blocking model:                                                
 

                
                       …(5) 

 

d. Cake filtration model:                                                       
 

                
                 …(6) 

 

   Where J0 depends on the 

transmembrane pressure, membrane 

resistance and viscosity of the filtrate 

and is expressed as J0 = ∆P/ μRm. The 

various K terms represent mass 

transfer coefficients for the associated 

filtration laws (Nandi et al., 2010). 

In the case of constant pressure 

filtration, the term (AJ0) is constant 

and the filtration laws can be 

simplified to: 

a. Complete pore blocking model:  
                                                   

                                        …(7) 

b. Standard pore blocking model:   
                                               

      ⁄        
   ⁄                    …(8) 

 

c. Intermediate pore blocking model:  
                                                   

   ⁄        ⁄                           …(9) 
 

d. Cake filtration model:    
                                                       

    ⁄        
 ⁄                      …(10) 

 

Where ks = (1/2) KsA
0.5

, ki = KiA, kc = 

2KcA
2
. 

 

Consequently plotting the left-hand 

side flux functions for each model 

against time are the tests to determine 

the more appropriate model and the 

means to obtain the mass transport 

parameters from the slope. Therefore, a 

plot of ln(J) vs. t, (1/J
0.5

) vs. t, (1/J) vs. 

t and (1/J
2
) vs. t shall be a straight line 

with slope of kb, ks, ki and kc, with y-

intercept of ln(J0), )/1(
5.0

0
J , (1/J0) and 

)/1(
2

0
J for complete pore blocking, 

standard pore blocking, intermediate 

pore blocking and cake filtration 

model, respectively. This is shown in 

figures 13 to 17.   The appropriate 

fitness and competence of various 

fouling models can be confirmed by 

comparing the values of coefficient of 

correlation (R
2
) obtained from the 

linear regression analysis (Peng and 

Tremblay, 2008). 

 

Oil Removal Efficiency 

Produced water treating equipment 

performance is commonly described in 

terms of its “oil removal efficiency.” 

This efficiency considers only the 

removal of dispersed oil and neglects 

the dissolved oil content. For example, 

if the equipment removes half of the 

dispersed oil contained in the influent 

produced water, it is said to have 50% 

oil removal efficiency. For a specific 

piece of equipment or an overall 



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             57 
 

system, the oil removal efficiency can 

be calculated using the following 

equation: 

 

    (   
  

  
)                   …(11)  

 

Where 

R % = oil removal efficiency, 

(rejection percentage) 

CP =dispersed oil concentration in the 

water outlet (effluent) stream, ppm. 

CF = dispersed oil concentration in the 

water inlet (influent) stream, ppm. 

             

Experimental 

Materials 

These filters have columnar filter 

element sealed within a pressure vessel 

to produce dry / wet cake. Figure 1 

show picture of Candle Filter.  

a) Ceramic filter: metal filter such as 
zirconium or titanium oxide over 

the support structure of an 

aluminum oxide tube. 

The specifications of the filter are as 

follow: 

 Absolute filtration to 0.5 micron 

 Removes algae ,rust ,sediment 
,suspended solids 

 Flow rate (liters) to 8 LPM  

 Pressure to 3 bar 

 Turbidity reduction  
b)   Polypropylene filter: 

Manufactured from pure 100% 

polypropylene. 

The specifications of the filter are as 

follow :( Made in China) 

 Designed for purity and chemical 
compatibility. 

 Spun fibers from a true gradient 
density from outer to inner surfaces. 

 Temperature Range: 4.4 
o
C to 62.8 

o
C 

 Dimensions: L = 25 cm and d = 6.5 
cm 

 Effective area: 0.051 m
2
 

 Absolute filtration to 1 micron 
                           

Experimental Procedure and 

Equipments 

Oil – Water emulsions were prepared 

by vigorous mixing of oil and water in 

the QVF glass vessel (30 l), using a 

stirrer (Janke and Kunkelkg, England, 

1 KA – Werk, RW 50 H, Staufen) at an 

agitation speed of 0 - 10000 rpm, 

Classic Oil 20W-50 and Edible 

Vegetable Oil was used for the 

preparation of the oil-water emulsions 

with oil concentration of 50, 400 and 

800 ppm. The physical and chemical 

properties of the oil are given in   

Table 1. 

   Feed solution was prepared in the 

QVF glass vessels by mixing with the 

oil (20W - 50) in 30 liter
 
of tap water, 

since stirring a mixture of small 

amount of oil in water made an 

emulsion which was stable during the 

experiment, no emulsifier was used.  

The out let valve of the feed vessel was 

open to let the emulsion fill the whole 

pipes of the system. The emulsion feed 

drawn from the feed vessel by means 

of a centrifugal pump to pass through 

filter (Polypropylene or Ceramic) to 

remove oil from oil – water emulsions. 

Permeate (filtered water) was collected 

every 30 minutes and volume of 

permeate during the interval was 

measured and recorded. The oil 

concentrations in the feed and 

permeate solutions were analyzed 

using UV spectrophotometer. The 

filtration flux was calculated by 

dividing the permeate volume by the 

product of effective membrane area 

and time.  

An experimental rig was constructed in 

the laboratory as shown schematically 

in Figure 2 and pictured in Figure 3. 

Experimental system consists of: 

1) Microfiltration Membrane: Two 
types of filters candle-

polypropylene (1 micron) and 

candle-ceramic (0.5 micron) are 

used to remove oil from wastewater.  



 Microfiltration Membranes for Separating Oil / Water Emulsion

58                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

2) Feed vessel: The QVF glass vessels 
with a capacity of 30 liters were 

used as feed vessel. 

3) Rotameters: Calibrated Rotameters 
is used to measure the volumetric 

flow rate of feed (O/W emulsions) 

inlet to membrane separation unit 

(range of 10 – 60 l/h). 

4) Pressure gauge: One pressure 
gauge is used in the feed (O/W 

emulsions) line to indicate the feed 

pressure (range of 0 – 2.5 bar). 

5) Heater: In order to maintain the 
temperature at a certain value, one 

submersible electrical coil (220 

Volt, 1000 Watt) and thermostat of 

range from 0 to 80 
o
C was used as a 

heating media. 

6) pH Meter: The pH value 
measurement was carried out by 

means of a bench pH meter with 

specification as following:       

(Type = SensoDirect pH200 , 

Range = 0 – 14 pH, Accuracy =  ± 

0.01 pH, Power requirements   = 

AC/DC 6V ) 

7) Digital Balance: A digital balance 
with 4 decimal points (Sartorius 

BP3015 max. 303 g, d = 0.1 mg) is 

used to measure the samples weight 

in experiments. 

8) Pump: Centrifugal pump was used 
to pump the feed (O/W emulsions) 

from vessel to membrane cell (54.5 

– 11.4 l/min, 3 – 13.7 m. H, 210 

Watt, Stuart Turner LTD. Henley on 

Thames Eng. (England)). 

9) Spectrophotometer: The   
concentration   of   oil   in   water   

was   measured   using 

spectrophotometer, with 

specification as following: ( Model 

= Genesys 10 UV, Wave length = 

1090 – 190 nm ,Power  = 50 / 60 

HZ     Made in U.S.A) 

 

Results and Discussion 

   In oily waste water treatment 

processes, oil concentration in 

emulsion often changes because of 

different input situations. 

 

Effect of Oil Concentration 
   In this process, higher concentration 

from the feed oil is produced the lower 

permeate flux. This is shown in Figure 

4. The feed oil concentration has a 

direct influence on adsorption of oil 

(fouling). Fouling is mainly due to 

adsorption of oil on the membrane 

structure, which modifies the critical 

surface tension and the wettability, as 

well as the effective pore diameter, 

resulting in reduced membrane 

permeability (Sama, 2011; 

Rajagopalan, 1998). The high oil 

concentration in feed increases the oil 

adsorption and causes easily great 

resistance for permeating water. 

Therefore, Figure 5 illustrates the 

permeate (or product) concentration of 

oil increased with the increase in feed 

concentration. The increase of oil 

concentration will decrease the 

rejection percentage and vice versa 

(according to Equation 11). As the feed 

concentration of oil increases, the 

reject concentration (or concentrate) 

will increase. This is shown in Figure 

6. Also, we can by increasing the 

operation time, the flux, oil rejection, 

and reject concentration will decreases. 

A similar observation was noticed in 

the experimental study of (Lawrence 

and Jiaping, 2011). The pressure and 

pH value for all experiments are 0.125 

bar and 8.2 respectively. 

 

Effect of Operating Temperature 

   In Figure 7, the permeate flux 

increased with an increase in the 

temperature. The higher temperature 

may lead to an enhancement of the 

activity of water molecules and a 

decline of the emulsion viscosity. 

Therefore, the rejection percentage of 

oil decreased with increase in 

operating temperature i.e. the oil 

concentration in product increased. 



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             59 
 

This is shown in Figure 8. The effect 

of temperature on the flux and 

permeate concentration explains the 

effect of temperature on reject 

concentration. Thus, the reject 

concentration increases with increasing 

temperature (see Figure 9). These 

results correspond with the results of 

the researcher (Sama, 2011; Lawrence, 

2011). 

 

Effect of Flow Rate 

   Flow rate is an important operation 

parameter for MF. High flow rate is 

used to reduce cake formation and/or 

concentration polarization. The 

convection to and diffusion away from 

the membrane surface determine the 

rate of build-up of fouling, the rate of 

convection to the membrane is a 

function of the permeate flux, and the 

diffusion away is linked to the degree 

of turbulence (Cheryan and 

Rajagopalan, 1998). According to this 

information we observe, the flux 

increased with an increase in feed flow 

rate. An increase in the cross-flow 

velocity will directly increase in oil 

rejection % and increase in the reject 

concentration. This is shown in Figures 

10 to 12. These results correspond with 

the results of the researcher (Samah, 

2013). 

 

The Filtration Models 

Figures 13 to 17 show application of 

Hermia's model (filtration models) for 

prediction and experimental data in 

dead end process. In most cases the 

models exhibit a reasonable agreement 

with experimental data giving linear 

correlations. The model correlations 

for each case are given in Figures 13 to 

17. The estimation of the flux at t = 0 

(J0), from the intercept, gives the 

following values, 187.73, 189.94, 

192.68 and 200.32 l/m
2
.h for the 

complete pore blocking, standard pore 

blocking, intermediate pore blocking 

and cake filtration models, 

respectively. These values are different 

from the initial experimental flux, 

measure at 196.07 l/m
2
.h. The best 

agreement with experimental data is 

given by the complete pore blocking 

model and came in second level, the 

standard model for polypropylene 

membrane (1 μm). These results 

correspond with the results of the 

researcher (Hasan, 2011; Erik, 1989). 

 

Conclusions 

The following conclusions could be 

drawn from this study: 

1. Microfiltration can be used for the 
treatment of oily wastewater.  

2. The flux decreases with increasing 
operating time and feed oil 

concentration. While, the flux of the 

membrane increases with increasing 

operating temperature, feed flow 

rate and pore size of membrane for 

dead end and cross flow. 

3. The oil rejection percent increases 
with increasing flow rate. While, the 

rejection percentage decreases with 

increasing time, feed oil 

concentration, feed temperature and 

pore size of membrane for dead end 

and cross flow. 

4. The reject concentration (or the 
concentrate) increases with 

increasing flow rate, feed 

concentration, time and feed 

temperature. 

5. In the dead end process the amount 
of flux is more than cross flow 

process. While, in the cross flow the 

oil rejection percentage is best than 

dead end. 

6. The amount of flux for Vegetable 
Oil more than oil 20W-50, but 

rejection percentage for Vegetable 

Oil is less than rejection percentage 

for oil 20W-50.  

7. The highest recovery ratio is 44.8% 
using cross flow process with 

recirculation of concentrate stream. 

8. In the microfiltration process, the 
highest rejection percentage of oil is 



 Microfiltration Membranes for Separating Oil / Water Emulsion

60                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

98% and 97.8% for cross flow and 

dead end respectively. 

Experimental results in this work were 

in excellent agreement with complete 

pore blocking model and the standard 

model.

 
Nomenclature 

Units Description Symbol 

pa Transmembrane Pressure P 
kg/m.sec Viscosity µ 

m
2 

Area A 

mg/l Feed Concentration CF 
mg/l Permeate Concentration CP 

kg .m/s
2 

Centrifugal Force F 

m
3
/m

2
.sec Permeation Flux J 

m
3
/m

2
.sec Initial Permeate Flux J0 

m/sec 
Mass Transfer Coefficient for Complete pore 

blocking model 
kb 

m/sec 
Mass Transfer Coefficient for Cake filtration 

model 
kc 

m/sec 
Mass Transfer Coefficient for Intermediate pore 

blocking model 
ki 

m/sec 
Mass Transfer Coefficient for Standard pore 

blocking model 
ks 

kg Mass of Particle m 

l/hr Feed Flow Rate Qfeed 
l/hr Permeate (or Product) Flow Rate Qpermeate 

m Distance from Central axis Rotation r 

 Rejection Percentage R % 

 Correlation of Coefficient R
2
 

m
-1

 Cake Resistance Rc 

m
-1

 Clean Membrane Resistance Rm 

m
-1

 Pore Blocking Resistance Rp 

h Time t 
o
C Temperature T 

rad/s Angular Velocity ω 

 
Abbreviation 

 
Description Symbol 

 Microfiltration MF 

 Oil-in-Water O/W 

 Water-in-Oil W/O 

 
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Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             61 
 

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Environment Protection 

Engineering , Vol. 31,No. 3-4. 

 

 

 
 



 Microfiltration Membranes for Separating Oil / Water Emulsion

62                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

Table 1, the Physical and Chemical Properties of Oil 

Classic Oil 20W-50 

Viscosity grade 20W-50 

Colour Amber 

Physical State Liquid at ambient temperature 

Odour Characteristic mineral oil 

Vapour Pressure Expected to be less than 0.5 Pa at 20 °C 

Initial Boiling Point Expected to be above 280 °C 

Solubility in Water Negligible 

Density 888 kg/m
3
 at 15 ºC. 

Flash Point 215 ºC 

Flammable Limits - Upper 1% (V/V) 

Flammable Limits - Lower 10% (V/V) 

Auto-Ignition Temperature Expected to be above 320ºC 

Kinematic Viscosity 157 mm
2
/s at 40 ºC 

Pour Point -27 ºC 

Vegetable Oil 

Density 985 kg/m
3
 

Viscosity 4.01×10
-2

 kg/m.sec 

Type ZER (Made in Turkey) 

 

 
 Fig. 1, Candle Filter 

 

 
 Fig. 2, Schematic Diagram of Microfiltration Process  



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             63 
 

Fig. 3, Picture Experimental System Consists 

 

 

 

 
 Fig. 4, Flux vs. Time at Different Oil Concentrations (Ceramic 0.5 µm, QF = 25 l/h, Oil 20W-

50 and T = 40°C) 

    

150

200

250

300

350

400

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

F
lu

x
, 

l/
m

2
h

Time, h

Cғ = 50 ppm

Cғ = 400 ppm

Cғ = 800 ppm



 Microfiltration Membranes for Separating Oil / Water Emulsion

64                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

 
Fig. 5, Oil Rejection % vs. Time at Different Oil Concentrations (Ceramic 0.5 µm, QF = 25 l/h, Oil 

20W-50 and T = 40°C) 

 

 

 

 
Fig. 6, Reject Concentration vs. Time at Different Oil Concentration (Ceramic 0.5 µm, QF = 25 l/h, Oil 

20W-50 and T = 40°C) 

 

 

 

 

 

50

55

60

65

70

75

80

85

90

95

100

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

O
il
 R

e
je

c
ti

o
n

 
%

Time, h

Cf = 50 ppm

Cf = 400 ppm

Cf = 800 ppm

0

200

400

600

800

1000

1200

1400

1600

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

R
e
je

c
t 

C
o
n

c
e
n

tr
a
ti

o
n

, 
p

p
m

Time, h

Cf = 50 ppm

Cf = 400 ppm

Cf = 800 ppm



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             65 
 

 
Fig. 7, Flux vs. Time at Different Feed Temperature (Ceramic 0.5 µm, QF = 25 l/h, Oil 20W-50 and CF 

= 400 ppm) 

 

 

 

 
 Fig. 8, Oil Rejection % vs. Time at Different Feed Temperature (Ceramic 0.5 µm, QF = 25 l/h, 

Oil 20W-50 and CF = 400 ppm) 

 

 

 

 

 

 

150

200

250

300

350

400

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

F
lu

x
, 

l/
m

2
h

Time, h

T = 30 ᴼC

T = 40 ᴼC

T = 50 ᴼC

60

70

80

90

100

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

O
il
 R

e
je

c
ti

o
n

  
%

Time, h

T = 30 ᴼC

T = 40 ᴼC

T = 50 ᴼC



 Microfiltration Membranes for Separating Oil / Water Emulsion

66                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

 
Fig. 9, Reject Concentrations vs. Time at Different Feed Temp. (Ceramic 0.5 µm, QF = 25 l/h, Oil 

20W-50 and CF = 400 ppm) 

 

 

 

 
Fig. 10, Flux vs. Time at Different Feed Flow Rate (Ceramic 0.5 µm, T = 40°C, Oil 20W-50 and CF = 

400 ppm) 

 

 

 

 

 

 

500

550

600

650

700

750

800

850

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

R
e
je

c
t 

C
o

n
c
e
n
tr

a
ti

o
n
, 

p
p
m

Time, h

T = 30 ᴼC

T = 40 ᴼC

T = 50 ᴼC

0

100

200

300

400

500

600

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

F
lu

x
, 

l/
m

2
h

Time, h

Qf = 15 l/h

Qf = 25 l/h

Qf = 40 l/h



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             67 
 

 
Fig. 11, Oil Rejection % vs. Time at Different Feed Flow Rate (Ceramic 0.5 µm, T = 40°C, Oil 20W-

50 and CF = 400 ppm) 

 

 

 

 
Fig. 12, Reject Concentration vs. Time at Different Feed Flow Rate (Ceramic 0.5 µm, CF = 400 ppm, 

Oil 20W-50 and T = 40°C) 

 

 

 

 

 

 

 

60

65

70

75

80

85

90

95

100

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

O
il
 R

e
je

c
ti

o
n
  

%

Time, h

Qf = 15 l/h

Qf = 25 l/h

Qf = 40 l/h

500

550

600

650

700

750

800

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

R
e
je

c
t 

C
o

n
c
e
n
tr

a
ti

o
n
, 

p
p
m

Time, h

Qf = 15 l/h

Qf = 25 l/h

Qf = 40 l/h



 Microfiltration Membranes for Separating Oil / Water Emulsion

68                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

 
Fig. 13, Complete Pore Blocking Model (CF = 400 ppm, T = 30°C and QF = 10 l/h) 

 

 

 

 
Fig. 14, Standard Pore Blocking Model (CF = 400 ppm, T = 30°C and QF = 10 l/h) 

 

 

 

 

 

 

ln(J) = -0.13(t) + 5.235

R² = 0.9864

4.80

4.85

4.90

4.95

5.00

5.05

5.10

5.15

5.20

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

ln
(J

, 
l/
m

²h
)

Time,h

(1/J0.5 ) = 0.534(t) + 7.2562

R² = 0.9826

7.4

7.8

8.2

8.6

9.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

J
 ¯

0
.5

  
 *

1
0

0

Time,h



Ahmed Faiq Al-Alawy and Samah Mohsin Al – Musawi 

 

-Available online at: www.iasj.net                 IJCPE Vol.14 No.4 (December 2013)                             69 
 

 
Fig. 15, Intermediate Pore Blocking Model (CF = 400 ppm, T = 30°C and QF = 10 l/h) 

 

 

 

 
Fig. 16, Cake Filtration Model (CF = 400 ppm, T = 30°C and QF = 10 l/h) 

 

 

 

(1/J) = 0.8789(t) + 5.1917

R² = 0.9778

5.5

6.0

6.5

7.0

7.5

8.0

8.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

(1
/J

) 
*
1

0
0

0

Time , h

(1/J2) = 1.197(t) + 2.4919

R² = 0.9653

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

J
 -

2
*

1
0

5

Time , h



 Microfiltration Membranes for Separating Oil / Water Emulsion

70                                    IJCPE Vol.14 No.4 (December 2013)          -Available online at: www.iasj.net 
 

 
Fig. 17, Comparison of Filtration Model Prediction with Experimental Data for Polypropylene 

Membrane (1 µm) 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

120

130

140

150

160

170

180

190

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

F
lu

x
, 

l/
m

2
h

Time , h

Experimental data

Complete blocking

Standar d blocking

Intermediate blocking

Cake filtrat ion