and Their Application in Pervaporation

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UNlVERSm SAINS MALAYSIA

Laporan Akhir Projek Penyelidikan Jangka Pendek

Development of Carbon Nanotubes Supported Ionic Liquid Membrane (SILM)

and Their Application in Pervaporation

Process

by

Assoc. Prof. Dr. Tan Soon Huat

Assoc. Prof. Dr. Sharif Hussein Sharif Zein

2015

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m o CN

Z3

Separation ^purification Reuieius, 43:62-88, 2014 Taylor &Francis

DDI: 10.1080/15422119.2012.716134

^A Review on the Use and Stability of Supported Liquid Membranes

in the Pervaporation Process

YIT THAI ONG, KIAN FEI YEE, YOKE KOOI CHENG,

and SOON HUAT TAN

SchoolofChemicalEngineering, EngineeringCampus, Universiti Sains Malaysia,

Pulau Pinang, Malaysia

In recent decades, pervaporation has been one of the most studied membrane separation processes and has undergone substantial 22 progress and excitingbreakthroughsdue to itseffectiveness in sepa-

^ rating azeotropic mixtures and its low energy consumption. Often,

•§ pervaporation processes are operated using a solid membrane.

M However, the inherent limitations of solid membranes prompted S the use ofsupported liquid membranes (SLMs), which are formed

I by immobilizing the liquid membrane with a porous supporting w membrane. The idea of using a SIM in pervaporation is attractive '% because the rate of molecular diffusion in liquid is much higher

§ than that in a solid membrane. This short article reviews the role of SLMs as a pervaporation membrane. The effects of operating parameters on the pervaporation performance of SLMs as well as concerns on the stability of SLMs and methods to improve its sta bilityare discussed. At the end of this article, wepropose the use of carbon nanotubes (CNTs) in SLMs and perform an evaluation of the commercial value ofSLMs.

>>

a>

"S

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KEYWORDS Pervaporation, supported liquid membrane, carbon

nanotubes

Received 24 February 2012, Accepted 23 July 2012

Addresscorrespondence to Soon Huat Tan, School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300, Nibong Tebal, SPS, Pulau Pinang, Malaysia. E-mail: chshtan@eng.usm.my

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Review RSC Advances

Table 1 Specific surface area, average pore diameter and type of porosity for the various transesterification catalysts Catalyst

SWCNTs MWCNTs

Activated carbon (AC)

CaO SrO BaO

VOP £

MgO

Mg9Ali thoroughly washed

K/BaO Li/BaO Na/BaO

Li/CaO (with 1.25 wt% of Li) Na/CaO (with 1.25 wt% of Na) K/CaO(with 1.25 wt% of K) Ca0/Zr02 (Ca to Zr ratio of 0.25) • CaO/ZiOz (Ca to Zr ratio of 0.5) WOj/ZrOz (powder)

WOj/ZrOz (pellet) CaHOa

CaMnOa CazFcjOs CaZrOa CaCeOa CaCOz Cazl^a]

Y-AI2O3 NaOH/y-AlzOa Na/y-AlzOj Na/NaOH/y-AlzOa K2CO3/AI2O3

SBA-15

SBA-CaO (with 14 wt% of CaO) SBA-15/MgO

MCM-41/MgO KlT-6/MgO

Mg(pH)2-4MgC03

S0/~/Sn02 SO4 /SnOz^SiOz SG^^'/SnOz-AlzOs Tungstated zirconia (WZ) Sulfated zirconia (SZ) AmberlysM5

Nation NR50

Supported phosphoric acid (SPA) Titanosilicate (ETS-10)

Zeolite HP Eggshell

Golden apple snail shell

Meretrix venus shell Waste mud crab shell Calcined waste fish scale

Cesium-exchanged NaCsX zeolites Hydrotalcite

Specificsurface area (m^ g~') Average pore diameter (A) Porosity'® ^Reference

400-900 ^— Microporous ⁹⁰

200-400 ^— Mesoporous 90

700-1200 ^— Microporous 90

8.1-21.0 44.00-85.91 Mesoporous" 69,92,93

1.05-11.0 135.60 Mesoporous" 69,94

4.0 123.80 Mesoporous" 69

2-4 ^— ^— 95

96 ± 4 ^— ^— ⁹³

96.0 ^— ^— ¹³

6.1 50.20 Mesoporous" ⁹⁶

12.5 167.17 Mesoporous" 92

18.7 203.79 Mesoporous" 92

57.0 130.00 Mesoporous" 98

40.0 110.00 Mesoporous" ⁹⁸

4.9 ^— ^— 99

1.5 ^— ^— 99

0.71 ^— ^— 99

1.8 ^— ^— 99

2.9 ^— ^— ⁹⁹

0.6 ± 0.1 ^— ^— ⁹³

62.6 ^— ^— 100

143.1 134.30 Mesoporous" 101

120.7 137.80 Mesoporous" ¹⁰¹

97.7 148.20 Mesoporous" ¹⁰¹

83.2 155.00 Mesoporous" 101

118.0 130.20 Mesoporous" 96

413 4.20 Microporous" 57

7.4 5.40 Microporous" 57

252.0 37.60 Mesoporous" ¹⁰²

391.0 27.00 Mesoporous" ¹⁰²

112.0 46.80 Mesoporous" 102

20 ± 0.5 ^— ^— ⁹³

6.77 164.00 Mesoporous" 19

13.90 137.00 Mesoporous" 19

14.04 132.00 Mesoporous" 19

68.0-89.2 ^— ^— 103

134.4 ± 5.3 ^— ^— ⁷⁰

37.8 ± 2.6 ^— ^— ⁷⁰

0.02 — — 70

2.6 ± 0.1 ^— ^— ⁷⁰

440.8 ± 11.8 ^— Microporous 70

620.0 ^— ^— 70

1.1 ^— ^— ¹⁷

0.9 ^— ^— ¹⁷

0.5 ^— ^— 17

13.0 ^— ^— 16

39.0 ^— ^— 18

450 ^— ^— 104

160 — — 104

1based on the definition stated by Kohn and FrSba, 2003.'^

3.2 Excellent catalyst stability

Unlike other conventional transesterification catalysts, which

are prepared by precipitation or impregnation methods, CNTs can be tuned to be catalytically active via functionalisation

with specific functional gjroups onto their surfaces.®^'®'* It has been reported that the leaching problem under liquid-phase

reaction conditions occurs because the active species are not

covalently bonded to the solid support.^®' CNTs appear to be

the perfect candidate to serve as a catalyst support for

transesterification/esterification because the functional

groups or active species can be chemically modified to covalently bond to the CNTs.®® Covalent bonds between the active species and CNTs are strong bonds that will not easily rupture under the reaction temperature;®®® therefore; the leaching of the active species®"®'®®® into the reaction medium can be prevented. Experimental studies wherein no leaching problem occurred during a reaction with covalently modified

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