ENHANCING PERFORMANCE OF PRODUCED WATER SEPARATION WITH POLYETHERSULFONE (PES) MEMBRANE

WITH MODIFICATION OF THERMAL ANNEALING TIME

Asri Wahyu Pradini, Yani Putri Armelia, Tutuk D. KusworoJurusan Teknik Kimia, Fakultas Teknik, Universitas Diponegoro

Jalan Prof. Soedarto, Tembalang, Semarang, 50239, Phone/Fax : (024) 7460058

AbstrackMembrane technology is an alternative of water treatment based on filtration that is being developed. The type of polymer that commonly used in the manufacture of membrane is polyethersulfone (PES). This study is purposed to determine the process of making and characterizing membranes, to investigate the effect of heating on the membrane’s morphology structure and performance, and also to investigate the stability of the polyethersulfone (PES) membrane for produced water treatment. The manufacturing of polyethersulfone (PES) membranes for this produced water treatment is used not-heating PES membrane and heating PES membranes with time variation of heating membrane. PES membrane heated at temperature of 180C for 15 and 25 seconds. Characterization membrane consists of flux and rejection measurement of produced water filtration, SEM and FTIR analysis. From the research that has been done, asymmetric PES membrane can be produced with dry / wet phase inversion method. With the heating and the longer the heating time, the membrane surface skin layer is smoother than the surface skin layer membrane without heating.

Keyword : asymmetric membran, polyethersulfone, produced water, heating time

1. Introduction

Produced water containing Total Dissolved Solid (TDS), oils and fats, as well as

organic and inorganic contaminants. Produced water treatment method using membranes is

expected to reduce the contaminant content effectively. Nanofiltration membranes that have a

very low pore sizes, between 0.5 nm – 2 nm can be used to filter dissolved solids with low

molecular weight effectively (Timmer, 2001).

Asymmetric membrane is one type of membrane that is often applied to water

treatment. Flux resulting from asymmetric membrane is higher than the symmetric membrane

because asymmetric membrane have dense layer on the surface membrane which is not

owned by a symmetric membrane (Khulbe, et al., 2008).

In a study of asymmetric membranes manufacture, polymer that can be used is

polyethersulfone (PES) (Idris, 2007; Lee, 2009; Safitri, 2013; Widyasmara, 2013).

Polyethersulfone used as polymers because it posesses excellent mechanical and film forming

properties as well as high thermal stability, which make it ideal material for membrane

preparation (Mansourpanah, 2010). Membrane stability and good membrane performance are

important factor in the membrane application. Therefore this study will examine the effect of

post-treatment in the form of heating to obtain optimal performance of polyethersulfone

(PES) membrane. Beside the influences of post treatment, will be tested the stability of

polyethersulfone (PES) membrane for the separation of produced water.

2. Materials and Method

2.1. Materials and Equipments

The materials that used in this study include : polyethersulfone (PES), n-

methylpyrrolidone (NMP), distilled water and produced water.

The tools that used in this study are beaker glass, measuring cylinder, erlenmeyer flask,

shaker, stirrer, pipette, stopwatch, turbidimeter, magnetic stirrer, glass plates, coagulation

bath, casting knife, tape, oven, SEM and FTIR equipment, and dead-end filtration cell.

2.2. Preparation Asymmetric Polyethersulfone (PES) Membrane

The dope solution preparation of polyethersulfone (PES) membrane conducted by

dissolving the polymer polyethersulfone (PES) 22.5 wt% in n-methylpyrrolidone (NMP)

solvent 77.5 wt% using magnetic stirrer for 24 hours until the solution is homogen.

Furthermore, let the solution for 1 day to remove air bubbles and the solution ready to be

printed using the phase inversion technique. To investigate the effect of heating, the

membrane is given post treatment by oven the membrane at 180C for 15 and 25 seconds.

2.3. Membrane Characterization

2.3.1. Flux and Rejection Measurement

Flux measurements on produced water filtration is conducted by measuring the volume

of produced water that collected during time interval of 15 minutes for one hour. Flux value

is calculated by comparing the volume of permeate per unit membrane area per unit time as

in the following equation.

J= VA . t

(2.1)

Determination of the coefficient of rejection is done by determining the concentration

before and after passing through the membrane as in the equation below.

R=(1−C p

C f) x100 % (2.2)

2.3.2. Scanning Electron Micoscopy (SEM)

Characterization membrane using SEM is used to know membrane morphology.

Through this analysis the cross section of the membrane is known in certain magnification.

2.3.3. Fourier Transform Infrared (FTIR)

Characterization membrane using FTIR is used to know the functional groups of

membrane that produced.

3. Result and Discussion

3.1. Performance of Polyethersulfone (PES) Membrane

3.1.1. Performance of Polyethersulfone (PES) Membrane against Flux

The result of flux measurement for produced water filtration on Polyethersulfone (PES)

membrane is presented in Fig. 1.

0.25 0.5 0.750000000000001 105

1015202530354045

PES

Time (Hour)

Flux

(L/j

hr.m

2.ba

r)

Fig. 1 Performance of PES membrane agains flux

Fig. 1 shows the membrane polyethersulfone (PES) membrane flux decreases with

time. Thus the passage of time, the value of the flux of a membrane is tend to fall. This is

happened because the longer the filtration time, the more fouling occurs in the membrane.

This fouling will be increased during the filtration until cover the pores of the membrane,

which make the performance membrane becomes more severe and as a result, decreasing the

amount of permeate. Since the permeate flux is directly proportional to the volume of

permeate at a certain time, then the decreasing the volume of the permeate makes the value of

flux membrane decreases (Chen et al., 2009; Henny et al., 2013).

3.1.2. Performance of Polyethersulfone (PES) Membrane against Rejection

Rejection value calculation is conducted using equation (2.2). The results of

measurements rejection of COD, turbidity, sulfide polyethersulfone (PES) membrane without

heating are presented in Table 1 and the results of measurements of TDS rejection and levels

of Ca2+ that is rejected by polyethersulfone (PES) membrane without heating are presented in

Fig. 2 – 3.

Table 1 Performance of PES membrane agains rejection of turbidity, COD and sulfide

Membran

e

Turbidity COD Sulfide

Initial

(NTU)

Final

(NTU)

%

Rejection

Initial

(ppm)

Final

(ppm

)

%

Rejection

Initial

(ppm)

Final

(ppm)

%

Rejection

PES 96,99 4,86 94,99 1288 592,3 54,01 6734 6413 4,76

Based on Table 1 can be seen that the overall rejection rate polyethersulfone (PES)

membrane at initial time (0.25 hours) is higher than the value of the final membrane rejection

(1 hour). This is happened because the membrane pore sizes smaller provide perfect filtering

effect on dead-end filtration process that resulted high levels of turbidity, COD and sulfide in

produced water (Darwis et al., 2004). These results are supported in accordance with the

image of surface section and cross section of PES membrane obtained through SEM analysis

in Figure 19.

0.25 0.5 0.750000000000004 10

5

10

15

20

25

30

35

40

PES

Time (Hour)

Ca2

+ R

ejec

tion

(%)

Fig. 2 Performance of PES membrane against Ca2+ rejection

0.25 0.5 0.750000000000004 10

10

20

30

40

50

60

PES

Time (Hour)

TD

S R

ejec

tion

(%)

Fig. 3 Performance of PES membrane against TDS rejection

Based on Fig. 2 – 3, it can be seen that the polyethersulfone (PES) membrane have a

increasing rejection rate. This phenomenon is contrary to the flux produced the PES

membrane in Fig. 1. Wenten (2002), stated one of the problems in the membrane process is

the value of flux and rejection that is inversely proportional. So when the value of the flux

decreased, the membrane rejection rate has increased as a phenomenon that occurs on the

studies conducted before. This occurs because during the passage of time, fouling will occurs

on the surface and inside the membrane. This make the particles and dissolved organic

components along the water difficult to penetrate the membrane, therefore increase the

percentage of rejection of dissolved and particulate organic components as a result the

membrane pores are becoming more narrow (Mulder, 1996; Mulyati 2008 and Kusworo et

al., 2013).

3.2. Effect of Heating on The Performance of Polyethersulfone (PES) Membrane

To determine the effect of heating on the performance of polyethersulfone (PES)

membrane is conducted by comparing the results of performance tests of PES membrane

without heating (control variables) with PES membrane that given the heat treatment

(independent variable). Heating is conducted at temperature 180C for 15 seconds and 25

seconds before the membrane is applied in produced water treatment.

Heat treatment PES membrane at a temperature of 180C for 15 seconds and 25 seconds

due to a temperature 180C is closer to PES glass transition temperature (Tg = 220C)

(Wibowo, 2010). Heating that approaching the glass transition temperatures will cause the

PES break the bonds between the polymer molecules into rubbery so that the membrane has a

thicker dense structure of skin layer (Zhou, 2005).

The result of heating effect on the performance on PES membrane is shown on two

parameter test, that are the value of flux produced and membrane rejection to turbidity, COD,

sulfide, Ca2+ and TDS.

3.2.1. Effect of Heating on The PES Membrane against Flux

From Table 2 and Fig. 4 can be seen that the value of polyethersulfone membrane flux

with heating is higher than polyethersulfone membrane flux without heating. Heat treatment

or annealling on the membrane will cause the polymer chain structure adjustment on the

membran suface and the membrane becomes more stable. The pore structure on the

membrane surface adjust the thermodynamic equilibrium that changed by the heat given

(Kim., et al 2004). The polymer chain structure adjustment cause morphological changes in

the membrane (Mulder, 1996; Mulyati 2008 and Siswanto, 2011).

Table 2 shows the increasing percentage of the value of the flux that occur in

polyethersulfone membrane given post treatment in various filtration time. Fig. 4 shows a

comparison of the flux phenomena that occur in the polyethersulfone (PES) membrane

without heating treatment and with heating treatment.

Table 2 Increasing percentage the value of PES membrane flux with heating against PES

membrane flux without heating in various filtration time

Time (hour)

Flux without

heating membrane

treatment

(L/hr.m2.bar)

Flux with heating

membrane treatment

(L/hr.m2.bar)

Increasing Flux

(%)

0,25 38,69091 115,0545 66,370,5 18,32727 27,49091 33,340,75 11,2 14,93333 25

1 6,618182 10,94545 39,53

0.25 0.5 0.750000000000001 10

20406080

100120140

PES without heat treatment PES with heat treatment

Time (Hour)

Flux

(L/h

r.m2.

bar)

Fig. 4 Effect of heating on PES membrane against flux

3.2.2. Effect of Heating on The PES Membrane against Rejection

Effect of heating on polyethersulfone (PES) membrane against rejection in this study is

conducted by comparing the value of turbidity, COD, sulfide, Ca2+ and TDS in initial n final

produced water filtration using membrane. Rejection calculation is performed using equation

(2.2). Result of calculation the value of rejection of turbidity, COD and sulfide from

polyethersulfone (PES) membrane filtration is presented in Table 3. While the result of

calculation Ca2+ and TDS rejection is shown in Fig. 5 – 6.

Table 3 Heating effect on polyethersulfone (PES) membrane against rejection of turbidity,

COD and sulfide

Membrane

Treatment

Turbidity COD Sulfide

Initial (NTU

)

Final (NTU

)

% Rejectio

n

Initial

(ppm)

Final (ppm

)

% Rejectio

n

Initial

(ppm)

Final (ppm

)

% Rejectio

n

Non-Treatment

96,99

4,86 94,99

1288

592,3 54,01

6734

6413 4,76

Annealing

Treatment4,56 95,30 532,3 58,67 5130 23,81

Table 3 shows the rejection of turbidity (NTU), COD and sulfide increased. NTU

rejection increased with the heat treatment given. It is caused by the narrowing of membrane

pore size that occurs along the heat treatment or thermal annealing (Kim et al., 2004). Heat

treatment causes the rearrangement of the membrane molecules (Myung, 1994). Heat

treatment can cause the narrowing of membrane pore size (Mulder, 1996). Turbidity value

represents the content of suspended solids contained in the feed (Chung, et al., 2005). More

denser the pore, will be more effective and stable to reject suspended solids that permeate

turbidity levels obtained were smaller.

COD rejection also increased for heat treatment. This is due to the membrane pores

become more dense due to heat treatment or thermal annealing (Kim et al., 2004). Heat

treatment will make the membrane pore size smaller and dense, causing greater rejection rate

(Siswanto, 2011). With the heat treatment, the rearrangement of the membrane molecules

becomes more dense and stable (Myeong, 1994). The more dense and stable of membrane

pore size, it will effectively hold contaminants in produced water. This makes the

contaminants level in permeate is less on higher heating temperature membrane treatment.

Obtained rejection of sulfide is increasing for heat treatment. The membrane efficiency

in contaminant removal is depend to contaminant concentration, it chemical properties,

membrane type and condition, as well as operating conditions. In this case, process of

nanofiltration membrane using polyethersulfone (PES) is effective to reject the sulfide so that

when given a heat treatment, S2- that got reject is increased.

Fig. 5 shows the heat treatment given to the polyethersulfone (PES) membrane result

the rejection rate of Ca2+ of polyethersulfone (PES) membrane increased significantly as heat

treatment given. Membrane that given heat treatment is more effective reduces Ca 2+ in

produced water. This is due to the membrane treatment with a higher heating temperature has

more dense pores and more stable (Kim et al., 2004). The same as the discussion about the

rejection polyethersulfone (PES) membrane before, heat treatment will cause the pores

become denser and stable so that rejection Ca2+ is increase.

0.25 0.5 0.75 10

10

20

30

40

50

60PES without heat treatment

Time (Hour)

Ca2

+ R

ejec

tion

(%)

Fig. 5 Effect of heating on PES membrane against Ca2+ rejection

Fig. 6 shows the heat treatment given to the polyethersulfone (PES) membrane result

the value of TDS rejection is increased significantly as heat treatment given. This is due to

the pores on the membrane surface is narrowed as the effect of thermal annealing on the

membrane (Kim et al., 2004). Membrane with more dense and stable membrane pores have

better filtering effect to turbidity so that the levels of turbidity in the permeate becomes less

(Darwis et al., 2004). These results are consistent with the image of membrane surface and

cross section that obtained using SEM analysis in Fig. 13 – 16.

0.25 0.5 0.750000000000001 10

10

20

30

40

50

60

70PES without heat treatment PES with heat treatment

Time (Hour)

TDS

Reje

ction

(%)

Fig. 6 Effect of heating on PES membrane against TDS rejection

3.3. Effect of Heating Time on The Performance of Polyethersulfone (PES) Membrane

In these discussions will be investigate on the effect of heating time variation on the

performance of polyethersulfone (PES) membrane. Before the membrane is applied to the

produced water treatment, each membrane is heated at 180C for 15 seconds and 25 seconds.

Then the result of characterization is compared and presented in a graph or table. Parameters

of characterization in this study are the flux and rejection of turbidity, COD, sulfide, Ca 2+ and

TDS

3.3.1. Effect of Heating Time on The PES Membrane against Flux

Figure 7 shows decreasing value of flux polyethersulfone (PES) membrane along the

heating time. This is due to the membrane pore size becomes more narrow as the effect of

heat treatment (Mulyati, 2008). Heat treatment will cause a rearrangement of the polymer

molecular chain in the membrane so the membrane pore becomes more dense and stable

(Myeong, 1994). Membranes with longer thermal annealing time will have denser pores thus

reducing the flux (Kim et al., 2004). These results are consistent with the image of membrane

surface and cross section that obtained using SEM analysis in Fig. 15 – 16.

0.25 0.5 0.750000000000001 10

20

40

60

80

100

120

140

PES 15 seconds PES 25 seconds

Time (Hour)

Flu

x(L

/hr.

m2.

bar)

Fig. 7 Effect of heating time on PES membrane against flux

3.3.2. Effect of Heating Time on The PES Membrane against Rejection

Table 4 shows the percentage of rejection of turbidity (NTU), COD and sulfide tend to

rise along the longer time of thermal annealing. The value of rejection turbidity percentage

from this study is increase along the longer time of heating. The turbidity value (NTU)

represents the content of suspended solids contained in the feed (Chung., Et al 2005). This is

caused by a narrowed pore size that occurs along heat treatment or thermal annealing (Kim et

al., 2004). Heat treatment causes the rearrangement of membrane molecules (Myeong, 1994).

Heat treatment can cause narrowing of the membrane pore size (Mulyati, 2008).

COD rejection values also increased more significantly in line with the longer heating

time. This is because the membrane pore more dense due to heat treatment or thermal

annealing (Kim et al., 2004). Heat treatment with higher temperatures makes the

rearrangement of membrane molecules becomes more dense and stable (Myeong, 1994).

Sulfide rejection values increase for more longer the heating time. The membrane

efficiency in contaminant removal is depend to contaminant concentration, it chemical

properties, membrane type and condition, as well as operating conditions. In this case,

process of nanofiltration membrane using polyethersulfone (PES) is effective to reject the

sulfide so that when given a heat treatment, S2- that got reject is increased.

Table 4 Effect of heating on PES membrane agains turbidity, COD and sulfide

Heatin

g Time

Turbidity COD Sulfide

Initial

(NTU

)

Final

(NTU

)

%

Rejectio

n

Initial

(ppm

)

Final

(ppm

)

%

Rejectio

n

Initial

(ppm

)

Final

(ppm

)

%

Rejectio

n

15

second

s

96,99 4,56 95,29 1288 532,3 58,67 6734 5130 23,81

25

second

s

4,26 95,61 512,3 60,23 4489 33,33

One of the parameters on the membran performance of produced water treatment is

rejection of Ca2+. Ca2+ rejection Measurement of is performed on produced water before and

during circulated through the membrane. It is performed by analysis the level Ca2+ that left in

permeat during time interval of 15 minutes for one hour on the application of dead-end

filtration. Percentage of rejection can be determined using equation 2.2.

Fig. 8 shows the rejection of the Ca2+ percentage is increases along more longer heating

time. This is due to the membrane pore becomes narrowed due to heat treatment (Mulyati,

2008). Heat treatment makes the rearrangement of membrane structural polymer chains so

that it can alter the morphology of the membrane (Budiyono et al., 2014). Membrane with a

longer heating time will have denser pores and more stable so its permeat will contain fewer

contaminants.

0.25 0.5 0.750000000000001 10

102030405060708090

PES 15 seconds PES 25 seconds

Time (Hour)

Ca2

+ R

ejec

tion

(%)

Fig. 8 Effect of heating time on PES membrane against Ca2+ rejection

The other membrane parameters performance on produced water treatment is TDS

rejection. Fig. 9 shows the TDS rejection percentage is increased along the variations in

heating time is longer. This case is happened because the membrane pore is narrowed as

effect of heat treatment (Mulyati, 2008). Heat treatment or thermal annealing causes

membrane molecules rearrangement becomes more dense and stable (Kim et al., 2004). The

more denser and stable the pore, filtering effect TDS becomes better so levels of TDS

permeate decrease significantly for membrane permeate with longer heating time.

0.25 0.5 0.750000000000001 10

10

20

30

40

50

60

70PES 15 seconds PES 25 seconds

Time (Hour)

TD

S R

ejec

tion

(%)

Fig. 9 Effect of heating time on PES membrane against TDS rejection

3.4. Stability of PES Membrane

After testing each character of flux and rejection membrane during the one hour, then

the study continue to test the membrane stability. Membrane stability test performed by

applying the membrane in produced water filtration for 4 hours and then see the value of flux

and rejection in 1 hour intervals. Flux test results shown in Fig. 10 while the result of

rejection of turbidity, COD, sulfide, Ca2+ and TDS is shown in Table 5 and Fig. 11-12.

Figure 10 shows that the polyethersulfone (PES) membrane flux decreases. Membrane

flux value is inversely proportional to a function of time, the more longer filtration operating

time (for 4 hours stability) then the value of the membrane flux tend to fall. The decreasing

flux value continues until steady state condition is reached. These phenomenon occur due to

fouling on the membrane surface which through with solution (Chen et al., 2009). This

results membrane flux decreases.

1 2 3 40

10

20

30

40

50

PES

Time (Hour)

Flu

x(L

/hr.

m2.

bar)

Fig. 10 Stability of PES membrane against flux

From Table 5 and Fig. 11-12 can be seen that polyethersulfone (PES) membrane has

increasing rejection rate along the length of time of stability filtration for 4 hours. This

phenomenon is contrary to the value of flux obtained on PES membrane which has been

discussed before. Wenten (2002), stated one of the problems in the process is the membrane

flux and rejection values are inversely proportional. So when the value of the flux decreased,

the membrane rejection rate has increased as a phenomenon that occurs on the research

conducted before. This is due to the fouling that occurs around the membrane surface that

affects the membrane pores so the membrane pores become narrow (Chen et al., 2009).

Membrane pore constriction causes increased rejection. The performance of membrane

stability for 4 hours result increasing rejection value higher than rejection value of dead-end

filtration for 1 hour.

Table 5 Stability of PES membrane against rejection of turbidity, COD and sulfide

MembraneTurbidity COD Sulfide

Initial (NTU)

Final (NTU)

% Rejeksi

Initial (ppm)

Final (ppm)

% Rejeksi

Initial (ppm)

Final (ppm)

% Rejeksi

PES 96,99 3,68 96,21 1288 445,7 65,40 6734 2245 66,67

1 2 3 40

20

40

60

80

100

PES

Time (Hour)

Ca2

+ R

ejec

tion

(%)

Fig. 11 Stability of PES membrane against Ca2+ rejection

1 2 3 40

102030405060708090

PES

Time (Hour)

TD

S R

ejec

tion

(%)

Fig. 12 Stability of PES membrane against TDS rejection

3.5. Characterization Polyethersulfone (PES) Membrane using Scanning Electron

Microscopy (SEM)

Fig. 13 – 16 shows the PES membrane has asymmetric shape because the membrane

cross-sectional form more than two layers. The layer that formed are the dense layer,

intermediate layer, and porous substructure. Asymmetric membranes are membranes with a

denser outer pore size with thickness between 0.1-0.5 µm, while the inside pore size has a

thickness between 50-200 lm. The technique of making membranes also supports the

formation of an asymmetric membrane. In this study, a membrane made by phase inversion

method, that is a process of changing the form of the polymer from a liquid into a solid phase

under controlled conditions (Ismail and Hassan, 2007; Mulder, 1996).

Fig. 15 – 16 shows the surface section of polyethersulfone (PES) membrane for heating

temperature 180°C and heating time for 25 seconds to have a smoother surface compared to

the membrane without heating and 15 seconds heating. In addition to a smoother surface,

pores or cavities that formed are smaller and denser. The cross section of the PES membrane

on Fig. 13, Fig. 15 – 16 shows the longer the heating time on polyethersulfone membrane

(PES) make the membrane morphology pore structure smaller and denser. The phenomenon

is the same as done by Idris and Zain (2006), who examined the effect of heating on the

polyethersulfone (PES) membrane at various temperature variables.

Heat treatment and heating time on the membrane cause the adjustment of the polymer

chain movement. When the polyethersulfone (PES) membrane is heated, the movement of

polymer chain molecules becomes easier thus affecting the morphology structure of the

membrane. In addition, heat treatment also decreases the free volume that formed in the

membrane manufacture, due to increasing molecular movement in the membrane. The less

amount of free volume in the membrane results the smaller pores or cavities, so the

membrane become more denser (Han and Bhattacharyya, 1994).

In Fig. 14, there are a lot of foulant accumulated on the surface of polyethersulfone

(PES) membrane after produced water filtration. This case because the fouling occurs on the

membrane. Fouling will increase along the length operation time so that it covers the pores of

the membrane (Chen et al., 2009; Henny et al., 2013). If Fig. 14 compared with Fig. 15 – 16,

it will show the decreasing amount of foulant accumulated on the membrane surface.

Polyethersulfone membranes that given heat treatment such as temperature 180C for 25

seconds (Fig. 16), the polarization is not as much as in Figure 14 – 15. Thus polyethersulfone

membrane in Figure 16 is good for produced water applications.

The smaller the pores or cavities are formed resulting permeation rate is low but the

selectivity of the membrane to reject contaminats in produced water increases. It has been

explained in the previous discussion about the decrasing value of flux and increasing values

of rejection in the polyethersulfone (PES) membrane without heat treatment, heating for 15

seconds and 25 seconds.

Fig. 13 Surface section (a) and cross section (b) of polyethersulfone (PES) membrane without

heating before filtration

Fig. 14 Surface section of polyethersulfone (PES) membrane after filtration

Fig. 15 Surface section (a) and cross section (b) of polyethersulfone (PES) membrane with

heating temperature 180C and heating time 15 seconds after filtration

Fig. 16 Surface section (a) and cross section (b) of polyethersulfone (PES) membrane with

heating temperature 180C and heating time 25 seconds after filtration

3.6. Characterization Polyethersulfone (PES) Membrane using Fourier Transform

Infrared (FTIR)

Characterization of PES membranes using FTIR is conducted to determine the

functional groups that present in the membrane. In Fig. 17 – 18 shows the result of FTIR

characterization of the PES membrane with variation heating temperature 180C and heating

time 15 seconds and 25 seconds.

Fig. 17 Characterization of polyethersulfone (PES) membrane using FTIR for heating

temperature 180C and heating time 15 seconds

Fig. 18 Characterization of polyethersulfone (PES) membrane using FTIR for heating

temperature 180C and heating time 15 seconds

Table 6 Functional group on polyethersulfone (PES) membrane for heating time180C and

heating time 15 seconds and 25 seconds

No.

Chemical compoundWavelength (cm-1)

15 detik 25 detik

1. O-H carboxylic acid 2500-2700 2500-2700

2. C-H alkane2850-2970 dan 1340-

1470-

3. C-H alkene3010-3095 dan 675-

9953010-3095 dan

675-995

4. C-H aromatic ring3010-3100 dan 690-

9003010-3100 dan

690-900

5.C-O alcohol/ether/carboxylic acid/

ester1050-1300 1050-1300

6. C-N amine/amide 1180-1360 1180-13607. C-N nitrile 2210-2280 2210-22808. C=C aromatic ring 1500-1600 1500-16009. C=C alkyne 2175,70 2173,7810. NO2 - 1300-1370

Fig. 17 – 18 show the polyethersulfone (PES) membrane has group of O-H carboxylic

acid , C-H alkanes, C-H alkenes, C-H aromatic ring, C-O alcohol/ether/carboxylic acid/ester,

C-N amine/amide, C-N nitrile, C=C aromatic ring, C=C alkyne, NO2.

Table 6 indicated the differences of wavelength sift of the chemical compounds that

contained in the polyethersulfone (PES) membrane for heating temperature 180C and

heating time 15 seconds and 25 seconds. Wavelength shift of the absorption area indicates the

provision of heat treatment and heating time give effect on the membrane morphology

sturcture and absorbtion area. It shows the amount of intensity that indicates the interaction

between water molecules and the presence of water content. Therefore, the smaller the area of

the absorption field shows the smaller interaction between water molecules in the membrane,

which means the lower water content presence in membrane. Heating that given to the

polyethersulfone (PES) membrane are post-treatment that conducted after the membrane is

formed. (Kusworo et al., 2008; Murphy and de Pinho, 1995).

4. Conclusion

Heat treatment on polyethersulfone (PES) membrane makes the pore shrinkage so

increase the rejection value and decrease the membrane flux. The length of heating time

towards the performance of polyethersulfone (PES) membrane affect the value of flux and

rejection, polymer chain molecular rearrangement so the membrane becomes more dense and

stable and give results decreasing flux value and increasing rejection value. The results of

SEM analysis of polyethersulfone (PES) membrane shows membrane pore shrinkage due to

heating. While the results of the FTIR analysis shows membrane polyether sulfone (PES) has

group of O-H carboxylic acid, C-H alkanes, C-H alkenes, C-H aromatic ring, C-O

alcohol/ether/carboxylic acid/ester, C-N amine/amide, C-N nitrile, C=C aromatic ring, C=C

alkyne, and NO2.

Acknowledgements

The acknowledgements give to Waste Treatment Laboratory for the contribution of this

study.

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