CHARACTERISTICS AND EFFICIENCY OF BLEACHING CLAYS IN THE PHYSICAL REFINING OF PALM OIL

Transcription

1 CHARACTERISTICS AND EFFICIENCY OF BLEACHING CLAYS IN THE PHYSICAL REFINING OF PALM OIL By NG SOOK KUEN Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirements for the Degree of Master March 2006

2 For my wonderful papa with love ii

3 Abstract of thesis presented to the Senate of Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science CHARACTERISTICS AND EFFICIENCY OF BLEACHING CLAYS IN THE PHYSICAL REFINING OF PALM OIL By NG SOOK KUEN March 2006 Chairman Faculty : Associate Professor Thomas Choong Shean Yaw, PhD : Engineering The physicochemical properties of the bleaching clays used in the physical refining of palm oil were characterized. The clays evaluated were acid-activated clays (Taiko Supreme 1B, Taiko PGEO and SBE Gold), mixed clays (Pure Flo) and natural clays (attapulgites like A4 and HRL 200). Electron micrographs of attapulgites displayed a spread of needle like lath on the surface while the acid activated clays mostly showed irregular flakes on the surface. The analysis of Freundlich isotherm was found to be more applicable than Langmuir isotherm in the adsorption isotherm data of pigments, carotene and chlorophyll on various types of bleaching clays. However, the adsorption of trace iron on the clays fitted the Langmuir model better than the Freundlich model. The results suggested that the high surface area in the acid-activated did not necessary possess better bleaching efficiency than other clays. Pure Flo, a neutral clay, is the best bleaching clay for adsorbing chlorophyll compared with other clays. This is contrary to the general belief that acid-activated clays is better in adsorbing chlorophyll. iii

4 Crude palm oil of poor quality was degummed, bleached and deodorized to evaluate the effectiveness of various bleaching clays using different dosages of 0.8% and 1.5%. The attapulgites are good in adsorbing chlorophyll but not good in adsorbing carotene. An attapulgite clay was heat-activated using different temperatures. The treated samples were tested in order to verify their capacity to bleach palm oil and were compared to the standard commercial bleaching clay. The mildly heat-treated attapulgite was superior to the other clays in adsorbing chlorophyll. The stepwise bleaching process and the single-step bleaching process was also compared between the acid-activated clay, attapulgite and silica. Silica was able to retain more carotene in both processes compared with the other two clays. However, the acid-activated clay was found to adsorb iron better in the stepwise process. iv

5 Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains CIRI-CIRI DAN KEBERKESANAN PELUNTUR BUMI DALAM PEMPROSESAN FIZIKAL MINYAK KELAPA SAWIT Oleh NG SOOK KUEN Mac 2006 Pengerusi Fakulti : Profesor Madya Thomas Choong Shean Yaw, PhD : Kejuruteraan Sifat kimia dan sifat fizik bagi peluntur bumi yang digunakan dalam pemprosesan minyak kelapa sawit telah diselidik.. Peluntur bumi yang dikaji merangkumi peluntur bumi berasid (Taiko Supreme 1B, Taiko PGEO and SBE Gold), peluntur bumi campuran (Pure Flo) dan peluntur bumi asli (attapulgites like A4 and HRL 200). Mikrograf elektron bagi attapulgite menunjukkan gumpalan berupa jarum pada permukaannya manakala kebanyakan peluntur bumi berasid menunjukkan kepingan pelbagai saiz pada permukaannya. Isoterma Freundlich didapati lebih dipatuhi daripada isoterma Langmuir dalam analisis penjerapan pigmen karotena and klorofil ke atas pelbagai jenis peluntur bumi. Namun, penjerapan logam surih, besi ke atas peluntur bumi lebih mematuhi model Langmuir daripada model Freundlich. Keputusan data mencadangkan bahawa luas permukaan yang tinggi tidak semestinya berkait v

6 rapat dengan keberkesanan peluntur bumi. Pure Flo, penjerap bumi neutral, adalah peluntur bumi yang paling berkesan untuk menjerap klorofil paling berkesan berbanding dengan bahan peluntur lain. Ini bertentangan dengan kepercayaan bahawa peluntur bumi berasid lebih berkesan menjerap klorofil. Minyak kelapa sawit mentah yang berkualiti rendah dinyahgum, diluntur dan dinyahbaukan untuk mengkaji keberkesanan pelbagai jenis peluntur bumi dengan menggunakan jumlah dos 0.8% dan 1.5%. Keputusan data menunjukkan attapulgite adalah berkesan untuk menjerap klorofil tetapi tidak berkesan untuk menjerap karotena. Satu jenis attapulgite diaktifkan dengan memanaskannya pada suhu yang berlainan. Sampel-sampel yang telah diaktifkan tersebut telah dianalisa untuk mengetahui kebolehannya melunturkan minyak kelapa sawit berbanding dengan peluntur bumi komercial. Attapulgite yang dipanaskan secara sederhana adalah paling berkesan menjerap klorofil berbanding dengan peluntur bumi yang lain. Proses meluntur berperingkat dan proses meluntur satu peringkat juga dibandingkan antara peluntur bumi berasid, attapulgite dan silica. Silica dapat menahan karotena daripada dimusnahkan dalam kedua-dua proses tersebut berbanding dengan proses yang hanya menggunakan silica sahaja. Namun, peluntur bumi berasid didapati lebih berkesan untuk menjerap bahan surih besi dalam proses meluntur berperingkat. vi

7 ACKNOWLEDGMENTS I would like to extend my heartfelt appreciation to my supervisors, Associate Professor Dr. Thomas Choong Shean Yaw, Dr. Norhafizah bt. Abdullah, Associate Professor Dr. Tan Ka Kheng, Dr. Siew Wai Lin and Dr. Cheah Kien Yoo for their invaluable guidance, unflagging enthusiasm, constructive criticisms and constant encouragement. My thanks also go out to Malaysian Palm Oil Board (MPOB) for the financial assistance to undertake this research work and for the use of the laboratory facilities and equipment there. Personal thanks should be recorded to the officers and laboratory staff of Malaysian Palm Oil Board (MPOB), as well as research assistants of Universiti Putra Malaysia for their crucial technical assistance rendered on several occasions. I wish to acknowledge with thanks to Madam Noraini, Madam Rosnani, Madam Suraya, Mr. Abdullah, Mr. Razali Wahab, Madam Norazila, Miss Rajini and Miss Lee. Moreover, I would like to thank many others who have provided special research materials and other forms of assistance in the completion of this work. To my dearest dad, Ng Yik Kong, who deserve a special note of thanks and gratitude for your ongoing moral support and understanding throughout. vii

8 Finally, my deepest appreciation to my friends, especially Eileen Khoo, who have extended their help and support throughout the thesis writing period. I certify that an Examination Committee has met on 24 March 2006 to conduct the final examination of Ng Sook Kuen on her Master of Science thesis entitled Characteristics and Efficiency of Bleaching Clays in the Physical Refining of Palm Oil in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows: Fakhru l-razi b. Ahmadun, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Luqman Chuah b. Abdullah, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Suraya bt. Abdul Rashid, PhD Lecturer Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Abu Bakar Mohamad, PhD Professor Faculty of Engineering Universiti Kebangsaan Malaysia (External Examiner) HASANAH MOHD. GHAZALI, PhD Professor/Deputy Dean School of Graduate Studies Universiti Putra Malaysia viii

9 Date: This thesis submitted to the Senate of Universiti Putra Malaysia has been accepted as fulfillment of the requirement for degree of Master of Science. The members of the Supervisory Committee are as follows: Thomas Choong Shean Yaw, PhD Associate Professor, Faculty of Engineering Universiti Putra Malaysia (Chairman) Norhafizah bt. Abdullah, PhD Lecturer Faculty of Engineering Universiti Putra Malaysia (Member) Siew Wai Lin, PhD Senior Research Officer Malaysian Palm Oil Board (Member) Cheah Kien Yoo, PhD Senior Research Officer Malaysian Palm Oil Board (Member) AINI IDERIS, PhD Professor / Dean School of Graduate Studies Universiti Putra Malaysia Date : ix

10 DECLARATION I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions. NG SOOK KUEN Date : x

11 TABLE OF CONTENTS Page DEDICATION ABSTRACT ABSTRAK ACKNOWLEDGEMENTS APPROVAL DECLARATION LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS/NOTATIONS/GLOSSARY OF TERMS ii iii v vii viii x xii xiv xvii CHAPTER 1 INTRODUCTION LITERATURE REVIEW Crude Palm Oil and Minor Components in Palm Oil Quality of Palm Oil Refining of Fats and Oils Degumming Bleaching Deodorization Adsorbents for Bleaching Montmorillonite Attapulgite Activated clay Chemical and Physical Properties of Clays Adsorptive Properties Acidic Properties Ion Exchange Properties Catalytic Properties Clay-Inorganic Compounds Interactions 2.24 xi

12 Clay-Water Interactions Particle Size and Shape of Clay Pore Structure of Clay Filtration Time and Oil Content METHODOLOGY Characterization of Crude Palm Oil Characterization of Adsorbents Determination of Moisture Content (Heating Method) Analysis of Pore Structure Determination of Particle Size (Low-Angle Laser Light Scatterring LALLS) Analysis of Surface Morphology (Scanning Electron Microscopy SEM) Determination of ph of Adsorbents Determination of Oil Filtration Time and Oil Content in Spent Bleaching Clays Adsorption Isotherm Effect of Different Dosages of Clays in Refining Effect of Clay Treatment in Refining Stepwise vs Single Step Bleaching RESULTS AND DISCUSSION Characterization of Adsorbents Moisture Content of Adsorbents ph of Adsorbents Analysis of Surface Morphology Scanning Electron Microscopy (SEM) Adsorption Isotherm Adsorption of Carotene and Chlorophyll Adsorption of Iron Adsorption of Tocopherols and Tocotrienols Effect of Different Dosages of Clays in Refining Colour Reduction Carotene Content in Bleached Oil Chlorophyll Content in Bleached Oil Vitamin E Content in Bleached Oil and RBD Oil Iron Content in RBD Oil E233 in Bleached Oil and RBD Oil E269 in Bleached Oil and RBD Oil Filtration Time and Oil Content 4.36 xii

13 Effect of Clay Treatment in Refining Colour Reduction Carotene Content in Bleached Oil Chlorophyll Content in Bleached Oil Vitamin E Content in Bleached Oil and RBD Oil Iron and Copper Content in RBD Oil E233 in Bleached Oil and RBD Oil E269 in Bleached Oil and RBD Oil Rancimat Hours in Bleached Oil and RBD Oil Stepwise vs Single Step Bleaching Colour Reduction Carotene Content in Bleached Oil Chlorophyll Content in Bleached Oil Vitamin E Content in Bleached Oil and RBD Oil Iron and Copper Content in RBD Oil E233 in Bleached Oil and RBD Oil E269 in Bleached Oil and RBD Oil Rancimat hours in Bleached Oil and RBD Oil CONCLUSION AND RECOMMENDATIONS 5.1 REFERENCES R.1 APPENDIX A.1 BIODATA OF THE AUTHOR B.1 LIST OF TABLES Table Page 3.1 Adsorbents used in this study Adsorbent mixtures and conditions used in this study Adsorbents and conditions used in clay treatment Conditions of the bleaching process used in stepwise bleaching process Conditions of the bleaching process used in single step bleaching process Summary of particle size distribution, BET surface area, pore volume, pore diameter, moisture content and ph of adsorbents Isotherm parameters of carotene adsorption 4.11 xiii

14 4.3 Isotherm parameters of chlorophyll adsorption Residual carotene in degummed-bleached palm oil Residual chlorophyll in degummed-bleached palm oil Isotherm parameters of iron adsorption Residual iron in degummed-bleached palm oil Isotherm parameters of Vitamin E adsorption Quality of CPO mixture and CPO PGEO used in this study % Decrease in chlorophyll content (ppb) in bleached oil after bleaching with different dosages of clay (CPO mixture) Quality of CPO Jomalina used in this study Physical characteristics of bleaching clays 4.48 LIST OF FIGURES Figure Page 2.1 Stages in Physical Refining (a)-(s) Electron micrographs of adsorbents used in this study Freundlich isotherm for the adsorption of carotene from CPO Freundlich isotherm for the adsorption of chlorophyll from CPO Langmuir isotherm for the adsorption of iron from CPO Vitamin E in the degummed-bleached palm oil after bleaching with various dosages 4.16 xiv

15 4.6 Lovibond Red colour of RBD palm oil after bleaching with different dosages of clays (CPO mixture) Lovibond Red colour of RBD palm oil after bleaching with 0.8% of clays (CPO PGEO) Carotene retained in bleached oil after bleaching with different dosages of clays (CPO mixture) Carotene retained in bleached oil after bleaching with 0.8% of clays (CPO PGEO) Relationship between carotene content and Lovibond Red of bleached oil after bleaching with 0.8% bleaching clays (CPO mixture) 4.11 Relationship between carotene content and Lovibond Red colour of bleached oil after bleaching with 1.5% bleaching clays (CPO mixture) 4.12 Relationship between carotene content of bleached oil and ph after bleaching with different dosages of clays (CPO mixture) Relationship between carotene content of bleached oil and ph after bleaching with 0.8% of clays (CPO PGEO) Chlorophyll residue in bleached oil after bleaching with different dosages of clays (CPO mixture) 4.15 Chlorophyll residue of bleached oil after bleaching with 0.8% of clays (CPO PGEO) 4.16 Relationship Between Chlorophyll Content and Lovibond Red of Bleached Oil after bleaching with 0.8% of clays (CPO mixture) 4.17 Relationship Between Chlorophyll Content and Lovibond Red of Bleached Oil after bleaching with 1.5% of clays (CPO mixture) 4.18 Relationship between chlorophyll content of bleached oil and ph after bleaching with different dosages of clays (CPO mixture) Relationship between chlorophyll content of bleached oil and ph after bleaching with 0.8% of clays (CPO PGEO) Vitamin E retained in bleached oil and RBD oil after bleaching with 1.5% of clays (CPO mixture) 4.30 xv

16 4.21 Amount of iron removed from CPO after bleaching with different dosages of clays (CPO mixture) Relationship between ph of bleaching clays and iron content of RBD oils after bleaching with different dosages of clays (CPO mixture) E233 in bleached oil and RBD oil after bleaching with different dosages of clays (CPO mixture) E269 in bleached oil and RBD oil after bleaching with different dosages of clays (CPO mixture) Relationship between Filtration Time and Oil Content after bleaching with 0.8% of clays (CPO PGEO) Relationship between filtration time and particle size of clays after bleaching with 0.8% of clays (CPO PGEO) Relationship between oil content and particle size of clays after bleaching with 0.8% of clays (CPO PGEO) Lovibond Red colour of bleached and RBD palm oil Carotene retained in bleached oil Chlorophyll residue of bleached oil Vitamin E retained in bleached oil and RBD oil Iron residue in RBD oil Copper residue in RBD oil E233 in bleached oil and RBD oil E269 in bleached oil and RBD oil Rancimat hours in bleached oil and RBD oil Colour of bleached oil after bleaching in a single step or stepwise Colour of RBD oil after bleaching in a single step or stepwise Carotene content of bleached oil after bleaching in a single step or stepwise Chlorophyll content in RBD oil after bleaching in a single xvi

17 step or stepwise Tocopherols and tocotrienols of bleached oil after bleaching in a single step or stepwise Tocopherols and tocotrienols of RBD oil after bleaching in a single step or stepwise Iron content in RBD oil after bleaching in a single step or stepwise Copper content in RBD oil after bleaching in a single step or stepwise E233 of bleached oil after bleaching in a single step or stepwise E233 of RBD oil after bleaching in a single step or stepwise E269 of bleached oil after bleaching in a single step or stepwise E269 of RBD oil after bleaching in a single step or stepwise Rancimat hours in bleached oil after bleaching in a single step or stepwise Rancimat hours in RBD oil after bleaching in a single step or stepwise 4.61 LIST OF ABBREVIATIONS/NOTATIONS/GLOSSARY OF TERMS A.O.C.S. Al Å AV BET BJH American Oil Chemists Society Aluminium Armstrong Anisidine Value Brunauer, Emmett, and Teller Barrett, Joyner, and Halenda xvii

18 CHL CPO DOBI FFA Fe HPLC H 2 O HRL Mg MPOA MPOB MS Na nm PA PC PE PGEO PHY PI POBE ppb ppm PV RBD Chlorophyll Crude Palm Oil Deteriobility of Bleaching Index Free fatty acid Iron High Performance Liquid Chromatography water Hudson Resources Limited Magnesium Malaysian Palm Oil Association Malaysian Palm Oil Board Malaysian Standard Sodium nanometer Phosphatidic acid Phosphatidylcholine Phosphatidylethanolamine Pasir Gudang Edible Oil Pheophytin Phosphatidylinositol an initial given to the mixture of SBE Gold and HRL200 parts per billion parts per million Peroxide value Refined, Bleached and Deodorized xviii

19 SBE SCOPA SEM w/w Southern Bleaching Earth The Seed Crushers and Oil Processors Association Scanning Electron Microscopy weight per weight xix