UNIVERSITI PUTRA MALAYSIA

FIROOZEH DANAFAR

FK 2011 5

FLUIDIZED BED CHEMICAL VAPOR DEPOSITION SYNTHESIS OF CARBON NANOTUBES AND ITS APPLICATION FOR CELLULASE IMMOBILIZATION

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FLUIDIZED BED CHEMICAL VAPOR DEPOSITION SYNTHESIS OF

CARBON NANOTUBES AND ITS APPLICATION FOR CELLULASE

IMMOBILIZATION

By

FIROOZEH DANAFAR

This thesis Submitted to the School of Graduate Studies, Universiti Putra

Malaysia, in Fulfillment of the Requirements for the Degree of Doctor of

Philosophy

December 2010

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfillment

of the requirement for the degree of Doctor of Philosophy

FLUIDIZED BED CHEMICAL VAPOR DEPOSITION SYNTHESIS OF

CARBON NANOTUBES AND ITS APPLICATION FOR CELLULASE

IMMOBILIZATION

By

FIROOZEH DANAFAR

December 2010

Chair: Professor Fakhru’l-Razi Ahmadun, PhD

Faculty: Engineering

Over the past decade, Carbon Nanotubes (CNTs) have evolved into one of the most

important material under investigation, as they can be used in various applications,

due to their excellent unique characteristics. If the CNTs are ever to fulfill their

promise as an engineering material, commercial production will be required. Recent

advances on Chemical Vapor Deposition (CVD) synthesis of CNTs have shown that

fluidized bed reactors have a great potential for commercial production of this

valuable material. However, Fluidized Bed Chemical Vapor Deposition (FBCVD) is

still in its infancy and further studies and innovations are needed.

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Accordingly, the first objective of this study was to develop a FBCVD process for

the synthesis of CNT using ethanol (as a carbon source) in the presence of iron and

cobalt catalysts supported on alumina. At this stage, attempts were made to find the

best value for ethanol flow rate and amount of catalytic particles. The second

objective was to investigate the inherent characteristics of catalytic particles, namely,

composition and particle size range on FBCVD synthesis of CNT. The maximum

carbon deposition efficiency obtained from the experiments was 85%. The deposited

carbon was estimated to contain CNTs with a purity of approximately 98% based on

thermogravimetric analysis. This result was achieved when 5 g catalytic particles

comprising iron: cobalt, with weight percentage of 2:1% and particles size of 10-20

μm were fed into the reactor and the operating parameters including ethanol flow

rate, temperature and time of the reaction were set at 2 Sccm, 600 ºC and 30 min,

respectively.

In addition to the FBCVD synthesis of CNTs, the possibility of cellulase

immobilization on carriers consist of CNT was investigated. A circular-shaped flake

nanocomposite made of chitosan-CNTs with a uniform diameter of about 4 mm was

fabricated and examined for cellulase immobilization. Physical adsorption of

cellulase on carriers composed of chitosan-CNTs revealed that the activity of the

immobilized cellulase on the chitosan-CNTs supports is about 3.25 U/g, which is

fairly higher than the activity of the immobilized enzyme on the pure chitosan

carriers (~ 2 U/g). The activity of the immobilized cellulase on chitosan-CNT

carriers was estimated approximately 65% of the free cellulase activity (5.4 U/g),

while it was only 40% for enzyme immobilized on pure chitosan supports. Moreover,

the immobilized cellulase on the chitosan-CNTs carriers had almost 70% of the fresh

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enzyme activity after using it three times. They also retained about 85% of the initial

activity after two weeks storage at 4 ºC.

In this dissertation, a selective FBCVD process for gram scale production of CNT

was developed. Besides that, it was shown that the characteristics of the catalytic

particles, composition and particle size range, have significant impacts not only on

the process efficiency but also on the product selectivity and its morphology. In

further attempts, the feasibility of using CNT for cellulase immobilization was

investigated. Results indicated significant improvement on the physical adsorption of

cellulase when the carriers composed of CNT was used. The enzyme reusability and

storage ability were also improved when CNT was present in the carriers.

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Abstrak tesis yang dikemukakan kepada Senat Universii Putra Malaysia sebagai

memenuhi keperluan ijazah Doktor Falsafah

TURUS TERBENDALIR PEMENDAPAN WAP KIMIA SINTESIS

KARBON NANO TIUB DAN UNTUK APLIKASI IMOBILISI SELLULASE

Oleh

FIROOZEH DANAFAR

Disember 2010

Pengerusi: Profesor Fakhru’l-Razi Ahmadun, PhD

Fakulti: Kejuruteraan

Penyelidikan berkenaan karbon tiub nano (CNT) telah berkembang sejak sedekad

lalu sehingga menjadi antara penyelidikan utama disebabkan oleh ciri-cirinya yang

unik yang sesuai untuk pelbagai aplikasi. Untuk menjadikannya sebagai bahan

kejuruteraan, penghasilannya dalam jumlah komersil adalah sangat perlu. Kemajuan

terkini dalam sintesis CNT melalui kaedah pemendapan wap kimia (CVD)

menunjukkan bahawa turus terbendalir mempunyai potensi yang besar dalam

menghasilkan CNT pada skala komersil. Walaubagaimanapun turus terbendalir

pemendapan wap kimia (FBCVD) masih lagi baru dan memerlukan kajian dan

inovasi yang mendalam.

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Dalam usaha untuk membina kaedah yang tidak mahal dan berkesan untuk

pengeluaran besaran CNT, satu proses telah di rekabentuk berdasarkan FBCVD

menggunakan methanol dan pemangkin yang mempunyai komposisi besi-kobalt

disokong alumina. Hasilnya CNT terhasil dalam kuantiti gram dan bebas dari karbon

amorf. Rekabentuk baru ini juga mempunyai pelbagai kelebihan seperti ringkas,

murah, kebolehkawalan, dan mudah di skala besarkan menyebabkan ianya sesuai

untuk pengeluaran skala komersil.

Lanjutan itu, kesan keadaan zarah pemangkin keatas FBCVD terutamanya komposisi

logam dan size zarah telah dikaji menggunakan perlbagai teknik. Hasil menunjukkan

bahawa julat size zarah pemangkin dan strukturnya mempunyai kesan yang besar

kepada keberkesanan FBCVD. Oleh itu, sifat zarah pemangkin, seperti struktur dan

saiz liang, dan taburan zarah nano logam perlu diubah untuk mendapatkan kualiti dan

kuantiti CNT yang dikehendaki. Selepas mengambil kira semua hasil, CNT

dihasilkan daripada 2 Sccm etanol dialirkan ke atas 5 g zarah pemangkin

mengandungi 1-2 peratus berat besi-kobalt dan size zarah dibawah 20 μm, pada suhu

600 ºC selama 30 minit. Dalam keadaan tersebut keberkesanan proses ialah 85% dari

segi karbon terhasil yang mengandungi 98% CNT.

Lanjutan kepada sinthesis CNT dalam FBCVD, aplikasi CNT yang terhasil dalam

bidang bioteknologi telah diselidik. Secara ringkas, empingan komposit nano terdiri

daripada chitosan dan CNT telah dihasilkan dan diselidik untuk aplikasi imobilasi

selulase. Selulase memangkin dalam penghasilan pelbagai polimer asli yang

mengandungi selulosa. Enzim ini mempunyai pelbagai aplikasi komersil seperti

ubahsuai fabrik, kertas dan pulpa, makanan, dan industri farmaseutikal. Lebih dari

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itu, wujud potensi yang besar dalam bidang pengeluaran bahanapi bio daripada sisa

biomass. Penjerapan fizikal selulase oleh empingan Chitosan-CNT menunjukkan

peningkatan dalam kitar semula enzim dan kemampuan penyimpanan enzim

berbanding dengan Chitosan asli. Hasil menunjukkan immobilisasi selulase

menggunakan empingan Chitosan-CNT masih mampu menghasilkan 70% aktiviti

dari kadar aktiviti permulaan enzim selepas digunakan sebanyak tiga kali. Ia juga

masih menunjukkan 85% kadar aktiviti selepas disimpan dua minggu pada suhu 4ºC.

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ACKNOWLEDGEMENT

In the Name of Allah, Most Gracious, Most Merciful, all praise and thanks are due to

Allah, and peace and blessings be upon His Messenger. I would like to express the

most sincere appreciation to those who made this work possible; supervisory

members, Friends and Family.

Firstly, I would like to thank my supervisor Professor Dr Fakhru’l-Razi Ahmadun for

the many useful advice and discussions, for his constant encouragement, guidance,

support and patience all the way through my study work. Equally the appreciation

extends to the supervisory committee members Professor Mohd Ali Hassan and Dr

Dayang Radiah Awang Biak and Dr Mohd Amran Mohd Salleh for providing me the

opportunity to complete my studies under their valuable guidance.

I would also like to acknowledge the Chemical Engineering Department of Universiti

Putra Malaysia for providing the numerous facilities and support for this research

work.

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I certify that a Thesis Examination Committee has met on 3 December 2011 to

conduct the final examination of Firoozeh Danafar on her PhD thesis entitled

“Fluidized Bed Chemical Vapor Deposition Synthesis of Carbon Nanotubes and its

Application for Cellulase Immobilization” in accordance with the Universities and

University College Act 1971 and Constitution of the Universiti Putra Malaysia

[P.U.(A)106] 15 March 1998. The committee recommends that the student be

awarded the Doctor of Philosophy.

Member of the Thesis Examination Committee were as follows:

Mohd Halim Shah Ismail, PhD

Senior Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Chairman)

Suraya binti Abdul Rashid, PhD

Senior Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Internal Examiner)

Norhafizah binti Abdullah, PhD

Associate Professor

Faculty of Engineering

Universiti Putra Malaysia

(Internal Examiner)

Said Salah Eldin Hamed Elnashaie, PhD

Professor

Pennsylvania State University at Harrisburg

United State of America

(External Examiner)

NORITA OMAR, PhD

Associate Professor and Deputy Dean

School of Graduate Student

Universiti Putra Malaysia

Date

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfillment of the requirement for degree of Doctor of Philosophy. The

members of Supervisory Committee were as follows:

Fakhru’l-Razi Ahmadun, PhD

Professor

Faculty of Engineering

Universiti Putra Malaysia

(Chairman)

Mohammad Ali Hassan, PhD

Professor

Faculty of Biotechnology and Bimolecular Science

Universiti Putra Malaysia

(Member)

Mohammad Amran Mohd Salleh, PhD

Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Member)

Dayang Radiah Awang Biak, PhD

Lecturer

Faculty of Engineering

Universiti Putra Malaysia

(Member)

HASANAH MOHD GHAZALI, PhD

Professor and Dean

School of Graduate Studies

Universiti Putra Malaysia

Date: 12 May 2011

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which

have been duly acknowledged. I also declare that it has not been previously, and is

not concurrently submitted for any other degree at Universiti Putra Malaysia or at

any other institution.

FIROOZEH DANAFAR

Date: 3 December 2010

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TABLE OF CONTENT

Page

ABSTRACT ii

ABSTRAK v

ACKNOWLEDGEMENT viii

APPROVAL ix

DECLARATION xi

LIST OF TABLES xv

LIST OF FIGURES xvi

LIST OF ABBREVIATION xx

CHAPTER

1. INTRODUCTION 1

1.1. General Background 1

1.2. Problem statement 4

1.3. Aim and objectives 5

1.4. Thesis Scope 5

1.5. Thesis Layout 8

2. LITERATURE REVIEW 10

2.1. Introduction 10

2.2. Carbon nanotubes 10

2.3. Carbon nanotubes Synthesis by Chemical Vapor Deposition 13

2.3.1. Catalyst 15

2.3.2. Temperature 20

2.3.3. Carbon feedstock 24

2.3.4. Carrier gas 27

2.3.5. Reaction time and space velocity 31

2.4. Chemical vapor deposition Synthesis of carbon nanotubes 33

using Fluidized bed technique

2.5. Characterization of Carbon Nanotubes 49

2.6. Carbon nanotubes application in Cellulase immobilization 54

2.6.1. Introduction 54

2.6.2. Cellulase 55

2.6.3. Immobilization method 58

2.6.4. Chitosan a promising support for enzyme immobilization 61

2.6.5. Cellulase Immobilization 63

2.6.6. Immobilizing biomolecule using CNT 65

2.7. Summary 66

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3. MATERIALS AND METHODS 70

3.1. Introduction 70

3.2. Fluidized bed chemical vapor deposition synthesis of 71

carbon nanotubes

3.2.1. Reactor 72

3.2.2. Catalytic particles preparation 74

3.2.3. Fluidization parameters determination 75

3.2.4. The process conditions for FBCVD synthesis of CNTs 76

3.3. Characterization techniques 83

3.3.1. Scanning electron microscopy 83

3.3.2. Transition electron microscopy 84

3.3.3. X-ray diffractometry 85

3.3.4. Nitogen adsorption-desorption analysis 87

3.3.5. Thermogravimetric analysis 87

3.3.6. Carbon deposition efficiency calculation 88

3.3.7. Catalyst activity calculation 88

3.3.7 Deposited carbon produced per mole of ethanol 89

3.4 A new CNTs application for cellulase immobilization 89

3.4.1 Carrier preparation 89

3.4.2 Enzyme Immobilization 93

3.4.3 Determination of Cellulase activity 94

3.4.3.1 Total reducing sugar analysis (DNS method) 96

3.5 Summary 96

4. RESULTS AND DISCUSSIONS 98

4.1. Introduction 98

4.2. Initial experiments towards FBCVD synthesis of CNT 99

4.2.1. Determination of process parameters 99

4.2.2. Process Improvement 115

4.3. Introducing a new application for Carbon nanotubes 157

4.4. Summary 163

5. CONCLUSION AND RECOMMENDATIONS 166

FOR FUTURE RESEARCH

5.1. Conclusion 166

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5.2. Recommendations 167

REFERENCES 168

LIST OF PUBLICATIONS 188

APPENDIX 189

BIODATA OF STUDENT 195