Adsorption of nickel ions from aqueous solution by exhausted coffee grounds

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ADSORPTION OF NICKEL IONS FROM AQUEOUS SOLUTION BY EXHAUSTED COFFEE GROUNDS

NURUL HAIZA BINTI SIDEK

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For my beloved family and best of friends. For the love, motivation and patience.

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ACKNOWLEDGEMENT

First and foremost, Alhamdulillah, my highest gratitude and praise to Allah S.W.T. for His blessings and permission, finally I have completed this dissertation. For giving me the strength and guidance in facing all sort of challenges, obstacles and sweet memories in life.

I would like to thank my supervisor Professor Dr. Mohd Razman Salim and my previous supervisor, Dr. Handojo D. Utomo, for giving me the opportunity to work on this project and for their invaluable assistance, continuous guidance, support and extraordinary patience in guiding me from the starting point through the end of this project. I would like to extend my sincere appreciation to MLA Course Coordinator, Dr. Zainura Zainon Noor and Professor Madya Dr. Azmi Aris, and lecturers who taught MLA students for their continuous guidance and knowledge sharing throughout the semesters. My appreciation is extended to all staff of School of Graduate Studies, Faculty of Civil Engineering and to other faculty and institutions related for their enormous help with my study.

I wish to thank those who have helped me directly or indirectly; who extended their time of working, provided me with technical assistance and encouragement during my study. A million thanks to the staff of Environmental Engineering Lab, FKA; especially Miss Rahimah, Miss Syuhada and Head of Laboratory, Dr. Shamila Azman for their invaluable assistance, advice and sharing during my research. My deepest gratitude to Hanim, Siti Nadiah, Mazni, Munirah, Noor Ashima, Siti Sakinah, and Umusa’adah for their wonderful friendship,and moral support. Million thanks to my course-mates (Nor Liyana, Ikmalazatul, Aishah and Hafizan)and fellow lab members for their invaluable assistance towards the completion of this project.

Finally, I thank my beloved family for their unconditional love, never-ending support and high tolerance and patience regardless of the time and condition. Thank you.

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ABSTRACT

The possible use of exhausted coffee grounds as an adsorbent for the removal of nickel (II) ions from aqueous solution was investigated as a potential low-cost an alternative treatment to treat wastewater containing nickel (II) and other heavy metal ions. The effects of relevant parameters including contact time, initial concentration and particle size on nickel(II) adsorption were examined. This experiment was conducted at room temperature and no pH adjustment was made prior to the analysis. Batch adsorption studies also revealed that the amount of nickel (II) ions adsorbed per gram weight of exhausted coffee grounds increased with an increased in initial Ni (II) ions concentration with 75.10 to 98.17% of nickel ions removed. The effect of particle size of the exhausted coffee grounds varied for different initial nickel(II) ions concentration studied. Kinetic studies and adsorption isotherm were performed to investigate the mechanism of adsorption of nickel (II) ions. Adsorption data indicated that the adsorption of nickel(II) ions by exhausted coffee grounds was best described by pseudo-second-order kinetic model and Freundlich isotherm model. The exhausted coffee ground from Arabica origin with particle size of 420 - 212µm exhibited a better adsorption than other origin and particle size with a percentage of 96.00 to 98.00% of nickel(II) ions removal for all initial ion concentration tested.

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ABSTRAK

Penggunaan sisa kopi sebagai bahan penjerap untuk menyingkirkan ion nikel(II) dari larutan akues telah dikaji sebagai salah satu bahan penjerap berpotensi yang murah dan merupakan alternatif untuk rawatan sisa air yang mengandungi ion nikel(II) serta lain-lain ion logam berat. Penjerapan ion nikel (II) telah dijalankan dengan mempelbagaikan pembolehubah seperti masa olakan, kepekatan awal logam nikel (II) dan saiz partikel sisa kopi. Kajian ini telah dijalankan pada suhu bilik dan sebarang pelarasan pH tidak dijalankan sebelum analisis. Kajian penjerapan berkelompok juga menunjukkan bahawa jumlah ion nikel(II) yang dijerap per gram jisim sisa kopi meningkat sejajar dengan peningkatan kepekatan awal ion nikel (II) dengan 75.10 hingga 98.17% ion nikel(II) disingkirkan. Kesan saiz partikel sisa kopi terhadap penjerapan ion nikel(II) oleh sisa kopi adalah berubah-ubah mengikut kepekatan awal ion nikel(II) yang dikaji. Kajian kinetik dan isoterma penjerapan juga telah dijalankan untuk mengkaji mekanisma penjerapan ion nikel(II). Data penjerapan menunjukkan bahawa penjerapan ion nikel(II) oleh sisa kopi adalah sesuai dengan model kinetik pseudo-tertib-kedua dan model isoterma Freundlich. Sisa kopi dari jenis Arabica dengan saiz 420 - 212µm menunjukkan penjerapan yang lebih baik berbanding jenis dan saiz partikel yang lain, dengan peratusan penyingkiran ion nikel(II) sebanyak 96.00 hingga 98.00% untuk semua kepekatan awal ion yang dikaji.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION iv DEDICATION v ACKNOWLEDGEMENT vi ABSTRACT vii ABSTRAK viii TABLE OF CONTENTS ix

LIST OF TABLES xiii

LIST OF FIGURES xvi

LIST OF ABBREVIATIONS xviii

LIST OF APPENDICES xx

1 INTRODUCTION 1

1.1 Introduction 1

1.2 Problem Statement 2

1.3 Objectives 3

1.4 Scopes of the Study 3

1.5 Significance of the Study 4

2 LITERATURE REVIEW 5

2.1 Heavy Metals in the Environment and Health 5 Effects

2.1.1 Heavy Metals Contamination in 8 Wastewater

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2.2 Nickel 10

2.2.1 Production and Consumption of Nickel 12 2.3 Techniques for Removal of Heavy Metals from 13 Wastewater 2.4 Adsorption 13 2.4.1 Types of Adsorbents 14 2.4.2 Activated Carbon 14 2.4.3 Low-Cost Adsorbent 15 2.4 Coffee 23

2.4.1 The Chemical Composition of Coffee 24 2.4.2 Production of Coffee 26

2.4.3 Waste Products 26

2.5 Adsorption Isotherm Model 28

2.5.1 The Freundlich Isotherm 29 2.5.2 The Langmuir Isotherm 30

2.6 Conclusion 31

3 MATERIALS AND METHODS 32

3.1 Introduction 32

3.2 Chemicals and Reagents 32

3.3 Instruments 33

3.4 Preparation of Coffee Adsorbent 34 3.5 Preparation of Synthetic Solution 34

3.6 Batch Adsorption Experiment 35

3.7 Kinetic Study 37

3.8 Adsorption Isotherms Study 38

3.9 HACH DR/5000 UV-Vis Spectrophotometer 38 3.9.1 Determination of Nickel (II) Ion using 39 HACH DR/5000 UV-Vis Spectrophotometer

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4 RESULTS AND DISCUSSION 40

4.1 Introduction 40

4.2 Batch Adsorption Experiment 40

4.2.1 The Effect of Contact Time and Initial 41 Concentration on the Adsorption of Ni(II) ions

from Aqueous Solution

4.2.2 The Percentage of Ni (II) Ion Removal from 44 Aqueous Solution

4.2.3 The Effect of Particle Size of Exhausted 49 Coffee Grounds on the Adsorption of Ni(II) Ions

4.3 Kinetic Study 51

4.3.1 Kinetic study of Exhausted Coffee Grounds: 53 The Lagergren Pseudo-First-Order Model

4.3.2 Kinetic study of Exhausted Coffee Grounds: 57 The Lagergren Pseudo-First-Order Model

4.3.3 Conclusion 62

4.4 Adsorption Isotherm 63

4.4.1 The Langmuir Isotherm 63 4.4.1.1 The Langmuir Isotherm for Exhausted 65 Robusta Coffee Grounds

4.4.1.2 The Langmuir Isotherm for Exhausted 66 Arabica Coffee Grounds

4.4.1.3 The Langmuir Isotherm for Exhausted 68 Java Coffee Grounds

4.4.1.4 Conclusion 70 4.4.2 The Freundlich Isotherm 71 4.4.2.1 The Freundlich Isotherm for Exhausted 72 Robusta Coffee Grounds

4.4.2.2 The Freundlich Isotherm for Exhausted 73 Arabica Coffee Grounds

4.4.2.3 The Freundlich Isotherm for Exhausted 75 Java Coffee Grounds

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CHAPTER TITLE PAGE 4.4.2.4 Conclusion 76 4.5 Conclusion 77 5 CONCLUSIONS 80 5.1 Conclusions 80 5.2 Recommendations 81 6 REFERENCES 83 7 APPENDICES 94 APPENDIX A 94 APPENDIX B 95 APPENDIX C 119 APPENDIX D ₁₂₇

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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Anthropogenic sources of eight common heavy metals 6

2.2 Toxic metals in industrial effluents 7

2.3 Possible chronic metal toxicities 8

2.4 Some Parameter Limits of Effluents of Standards A and B, Environmental Quality Act 1974: Environmental Quality (Sewage and Industrial Effluents) Regulations 1979

9

2.5 Natural and anthropogenic sources of nickel in the environment

11

2.6 Global Nickel Production (2004 – 2009) 12

2.7 Global Nickel Consumption (2004 – 2009) 12

2.8 Characteristics of granular and powdered activated carbon

15 2.9 Some treatment of different wastewater using low-cost

adsorbents

17

2.10 A summary of compositional data (%db) for green and roasted Coffea arabica and Coffea robusta beans and instant coffee powder.

25

2.11 Some component of spent coffee grounds 27

4.1 Adsorption capacity of exhausted coffee grounds at different initial Ni(II) ions concentration and different particle size

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4.2 Lagergren pseudo-first-order rate constant (k1),

correlation coefficient (R2) and amount of Ni(II) ions adsorbed (qe), experimental and calculated using the

model for exhausted Arabica coffee grounds. (Experimental condition: C0 – 20, 40, 60, 80 and 100 mg

L-1, dose of coffee grounds – 2000mg/L solution, time – 5, 10, 15, and 20 min, size - <212µm, 420 – 212µm and 1180 – 850µm)

55

model for exhausted Arabica coffee grounds. (Experimental condition: C0 – 20, 40, 60, 80 and 100 mg

56

model for exhausted Java coffee grounds. (Experimental condition: C0 – 20, 40, 60, 80 and 100 mg L

-1

, dose of coffee grounds – 2000mg/L solution, time – 5, 10, 15, and 20 min, size - <212µm, 420 – 212µm and 1180 – 850µm)

57

4.5 Pseudo-second-order rate constant (k2), correlation

coefficient (R2), initial adsorption rate (h0) and amount of

Ni(II) ions adsorbed (qe), experimental and calculated

using the model for exhausted Robusta coffee grounds. (Experimental condition: C0 – 20, 40, 60, 80 and 100 mg

60

using the model for exhausted Arabica coffee grounds. (Experimental condition: C0 – 20, 40, 60, 80 and 100 mg

L-1, dose of coffee grounds – 2000mg/L solution, time – 5, 10, 15, and 20 min, size - <212 µm, 420 – 212 µm and 1180 – 850µm)

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using the model for exhausted Java coffee grounds. (Experimental condition: C0 – 20, 40, 60, 80 and 100 mg

L-1, dose of coffee grounds – 2000mg/L solution, time – 5, 10, 15, and 20 min, size - <212µm, 420 – 212µm and 1180– 850µm)

62

4.8 Separation factor for shape of isotherm 64

4.9 Langmuir constants for the adsorption of Ni(II) ions with different particle sizes of exhausted Robusta coffee grounds.

66

4.10 Langmuir constants for the adsorption of Ni(II) with different particle sizes of exhausted Arabica coffee grounds

68

4.11 Langmuir constants for the adsorption of Ni(II) with different particle sizes of exhausted Java coffee grounds.

70 4.12 Freundlich constants for the adsorption of Ni(II) with

exhausted Robusta coffee grounds.

72 4.13 Freundlich constants for the adsorption of Ni(II) with

exhausted Arabica coffee grounds.

74

4.14 Freundlich constants for the adsorption of Ni(II) with exhausted Java coffee grounds.

75

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

3.1 Research procedures 33

3.2 Batch experiment procedure 37

4.1 Effect of contact time and initial concentration on the adsorption of Ni(II) ion by different type of exhausted coffee grounds at <212 µm

42

4.2 Effect of contact time and initial concentration on the adsorption of Ni(II) ion by different type of exhausted coffee grounds at 420 - 212 µm

42

4.3 Effect of contact time and initial concentration on the adsorption of Ni(II) ion by different type of exhausted coffee grounds at 1180 - 850 µm

43

4.4 Percentage of removal of Ni (II) ions by the Robusta exhausted coffee grounds.

45

4.5 Percentage of removal of Ni (II) ions by the Arabica exhausted coffee grounds

45

4.6 Percentage of removal of Ni (II) ions by the Java exhausted coffee grounds.

46

4.7 Percentage of Ni (II) ions removal from aqueous solution by different sizes of exhausted coffee grounds

50 4.8 Effect of particle size of exhausted coffee grounds onto

the removal of Ni (II) ions from aqueous solution

50

4.9 Lagergren plots for Ni(II) adsorption by exhausted Robusta coffee grounds. Experimental condition: Contact time – 5,10, 15 and 20 min, Dose – 2000mg coffee grounds/L and Size – 1180 – 850µm

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FIGURE NO. TITLE PAGE

4.10 Lagergren plots for Ni(II) adsorption by exhausted Arabica coffee grounds. Experimental condition: Contact time – 5,10, 15 and 20 min, Dose – 2000mg coffee grounds/L and Size – 1180 – 850µm

54

4.11 Lagergren plots for Ni(II) adsorption by exhausted Java coffee grounds. Experimental condition: Contact time – 5,10, 15 and 20 min, Dose – 2000mg coffee grounds/L and Size – <212µm)

55

4.12 Pseudo-second-order plots for Ni(II) adsorption by exhausted Robusta coffee grounds. Experimental condition: Contact time – 5,10, 15 and 20 min, Dose – 2000mg coffee grounds/L and Size – <212 µm

59

4.13 Pseudo-second-order plots for Ni(II) adsorption by exhausted Robusta coffee grounds. Experimental condition: Contact time – 5,10, 15 and 20 min, Dose – 2000mg coffee grounds/L and Size – 1180 – 850µm

59

4.14 Pseudo-second-order plots for Ni(II) adsorption by exhausted Java coffee grounds. Experimental condition: Contact time – 5,10, 15 and 20 min, Dose – 2000mg coffee grounds/L and Size – 1180– 850µm

60

4.15 Langmuir plot of Ni(II) onto exhausted Robusta coffee grounds (Particle size - <212 µm).

65

4.16 Langmuir plots of Ni(II) adsorption onto exhausted Arabica coffee grounds

67

4.17 Langmuir plots of Ni(II) onto exhausted Java coffee groundsv

69

4.18 Freundlich plots of Ni(II) onto exhausted Robusta coffee grounds (Particle size – 1180 – 850 µm)

72

4.19 Freundlich plot of Ni(II) onto exhausted Arabica coffee grounds

74

4.20 Freundlich plots of Ni(II) onto exhausted Java coffee grounds

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LIST OF ABBREVIATIONS R2 - Correlation Coefficient Ni - Nickel As - Arsenic Cd - Cadmium Cr - Chromium Cu - Copper Pb - Lead Zn - Zinc

mg l-1 - milligram per liter

PAC - powdered activated carbon GAC - granular activated carbon

K - Kelvin

mg - milligram

SEM - Scanning Electron Microscope EDTA - Ethylenediaminetetraacetic acid

nm - nanometer

µm - micrometer

mm - millimeter

g - gram

l - liter

ppm - part per million

ml - milliliter

g l-1 - gram per liter

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UV-Vis - Ultraviolet-Visible mg g-1 - milligram per gram

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LIST OF APPENDICES

APPENDIX TITLE PAGE

A Preparation of Synthetic Nickel Solution (1000 mg Ni /l) from nickel (II) nitrate hexahydrate,

Ni(NO3)2.6H2O.

94

B Experimental Results 95

C Kinetic Study 119

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CHAPTER 1

INTRODUCTION

1.1 Introduction

One of the major sources of aquatic pollution is industrial wastewater. Heavy metals are one of the pollutants that have gained significance due to their persistence, bio-magnification and toxicity (Tolani et al., 2009; Kadirvelu et al., 2001; Khan et al., 2004). The release of toxic heavy metals to water streams has been seriously contributed by rapid industrialization. Sources of heavy metal contamination include mining, electroplating, metal processing, textile and battery manufacturing (Amarasinghe and Williams, 2007; Kadirvelu et al., 2001). Restrictive regulations of allowable level of heavy metals discharge have been introduced and practiced in many countries in order to minimize the impact to the environment (Tolani et al., 2009) and later have accelerated the developments of highly efficient technologies for heavy metal removal.

Recently, the removal of heavy metals such as nickel, lead and zinc from contaminated waters has become a major topic of research, due to the toxicological effects on environment and human health. The conventional methods of removal used are ion-exchange, reverse osmosis, electrodialysis, dilution, adsorption, filtration, precipitation, flotation, air-stripping, steam stripping and chelation (Nityanandi et al., 2006; Sud et al., 2008; Tolani et al., 2009). However, current treatment processes proposed by most researchers and scientists are expensive and not suitable to be used in most developing countries due to economic factor (Bailey et al., 1999; Utomo and Hunter, 2007). Though adsorption could provide a cost

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effective solution among other method of removal, some adsorbents are yet expensive. Therefore, natural waste materials from various industrial processes have been re-used for additional purposes in removing heavy metal, rather than simple disposal. Due to environmental and commercial sense, researchers and scientists have focused on the used of agricultural and food industry wastes such as coffee grounds, tea and rice hull (Low et al., 2000; Oliveira et al., 2008). Tannin-containing materials such as coffee grounds are believed to be good low-cost adsorbents for dissolved heavy metals (Utomo and Hunter, 2007).

Coffee has become an established beverage in many parts of the world including Europe, America and Asia (Tokimoto et al., 2005). Significant amount of waste is generated by coffee processing industries. Most of these grounds are burned as waste, dumped in landfill, as animal feed or boiler fuel (Tokimoto et al., 2005; Utomo and Hunter, 2007). Development of researches to reuse coffee grounds for useful purpose would definitely help to convert this waste into a new resource. Part of the development is using exhausted coffee grounds as alternative adsorbent to remove hazardous pollutant from wastewater (Adachi et al., 2008; Khenniche and Aissani, 2009; Oliveira et al., 2007; Tan, 1985; Utomo and Hunter, 2007).

This study, however, focus on the removal of nickel ion from aqueous solution using various types of exhausted coffee grounds. Batch study was conducted and the Langmuir and Freundlinch isotherm models were tested for the adsorption of nickel by exhausted coffee grounds.

1.2 Problem Statement

Adsorption with activated carbon has attracted the eyes of many researchers because of the effectiveness for the removal of heavy metal ion at trace quantities. However, it has not been used extensively for its high cost. For that reason, the use of low cost adsorbents as alternative for metal removal from wastewater has been highlighted. Great effort has been contributed to develop and improve existing

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adsorbents. The use of agricultural waste is one of the exploitation, due to its high availability and no need of complicated regeneration processes. Exhausted coffee grounds were used in this research as adsorbent for nickel ions. However, its effectiveness is unknown and needs to be determined_.

1.3 Objectives

The objective of the study is to propose an alternative use for exhausted coffee grounds, as adsorbents for the removal of nickel ions from aqueous solutions. The specific objectives are can be categorized as follows:

i. To investigate the effect of contact time, initial ion concentration, and effect of different types and sizes of exhausted coffee grounds for the removal of Ni(II) ion from aqueous solution;

ii. To determine the adsorption kinetics and adsorption isotherms for the removal of Ni(II) ions from aqueous solution

1.4 Scopes of the Study

i. Three different types of exhausted coffee grounds were used in this study. The grounds were the result from the steam extraction to produce instant coffee and were collected from various locations in Malaysia. No chemical treatment was performed on the grounds prior to the adsorption experiments.

ii. The concentration of nickel (Ni(II)) ion was measured using HACH DR/5000 Spectrophotometer.

iii. The effect of contact time and initial Ni(II) ion concentration, percentage of Ni(II) ion removal from aqueous solution, effect of particle size of the exhausted coffee grounds were studied.

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iv. The Lagergren pseudo-first-order and pseudo-second order models were used to study the kinetic of the adsorption for the Ni(II) ion removal.

v. Adsorption isotherm was investigated using Langmuir and Freundlich isotherm models.

1.5 Significance of the Study

The findings will be used in further research and the exhausted coffee grounds can be used as an alternatively low-cost adsorbent in heavy metal removal especially in removing nickel from aqueous solution. The knowledge obtained from this research will allow the selection of the more efficient, effective and economic treatment for industrial wastewaters using adsorption method.

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REFERENCES

Abbasi, S. A., Abbasi, N.and Soni, R. (1998). Heavy Metals in the Environment, New Delhi, Mittal Publication.

Adachi, A., Ioku, A., Taniyama, K.and Okano, T. (2008). Use of Tea or Coffee Lees as Adsorbent for Removal of Benzene from Wastewater. Journal of Health Science, 54, 478 - 481.

Adams, M. R.and Dougan, J. (1987). Waste Products. In: Clarke, R. J.andMacrae, R. (eds.) Cofee Volume 2: Technology. London: Elsevier Applied Science Publisher Ltd.

Adi, A. J.and Noor, Z. M. (2009). Waste Recycling: Utilization of Coffee Grounds and Kitchen Waste in Vermicomposting. Bioresource Technology, 100, 1027 - 1030.

Agarwal, S. K. (2009). Heavy Metal Pollution, New Delhi, APH Publishing Corporation.

Ahmadpoura, A., Tahmasbi, M., Bastami, T. R.and Besharati, J. A. (2009). Rapid Removal of Cobalt Ion from Aqueous Solutions by Almond Green Hull. Journal of Hazardous Materials 166, 925–930.

Aklil, A., Mouflih, M.and Sebti, S. (2004). Removal of Heavy Metal Ions from Water by Using Calcined Phosphate as a New Adsorbent. Journal of Hazardous Materials, A112 183–190.

(23)

Amarasinghe, B. M. W. P. K.and Williams, R. A. (2007). Tea Waste as a Low Cost Adsorbent for the Removal of Cu and Pb from Wastewater. Chemical Engineering Journal 132, 299–309.

Aziz, H. A., Adlan, M. N.and Ariffin, K. S. (2008). Heavy Metals (Cd, Pb, Zn, Ni, Cu and Cr(III)) Removal from Water in Malaysia: Post Treatment by High Quality Limestone. Bioresource Technology, 99, 1578-1583.

Bailey, S. E., Olin, T. J.and Bricka, R. (1999). A Review of Potentially Low-Cost Sorbents for Heavy Metals. Water Resources, 33, 2469-2479.

Bansal, M., Garg, U., Singh, D.and V.K.Garg (2009a). Removal of Cr(VI) from Aqueous Solutions using Pre-Consumer Processing Agricultural Waste: A Case Study of Rice Husk. Journal of Hazardous Materials, 162, 312–320.

Bansal, M., Singh, D., V.K.Gargand Rose, P. (2009b). Use of Agricultural Waste for the Removal of Nickel Ions from Aqueous Solutions: Equilibrium and Kinetics Studies. International Journal of Civil and Environmental Engineering 1, 108 - 114.

Bhatnagar, A., Minocha, A. K.and Sillanpää, M. (2010). Adsorptive Removal of Cobalt from Aqueous Solution by Utilizing Lemon Peel as Biosorbent. Biochemical Engineering Journal, 48, 181 - 186.

Bhatnagar, A.and Sillanpää, M. (2010). Utilization of Agro-Industrial and Municipal Waste Materials as Potential Adsorbents for Water Treatment—A Review. Chemical Engineering Journal 157 277–296.

Bhattacharya, A. K., Mandal, S. N.and Dasa, S. K. (2006). Adsorption of Zn(II) from Aqueous Solution by Using Different Adsorbents. Chemical Engineering Journal 123 43–51.

Birge, W. J.and Black, J. A. (1980). Aquatic Toxicology of Nickel. In: Nriagu, J. O. (ed.) Nickel in The Environment. Canada: John Wiley & Sons.

(24)

Curcovic, L. C.-S.and Rastovean-Mioe, A. (2001). Batch Pb2+ and Cu2+ Removal by Electric Furnace Slag. Water Resources, 35, 3436 - 3440.

Demirbas, A. (2004). Adsorption of Lead and Cadmium Ions in Aqueous Solutions onto Modified Lignin from Alkali Glycerol Delignication Journal of Hazardous Materials, B109, 221 - 226.

Demirbas, E., Kobya, M.and Konukman, A. E. S. (2007). Error Analysis of Equilibrium Studies for the Almond Shell Activated Carbon of Cr(VI) from Aqueous Solution. Journal of Hazardous Materials, 154, 787 - 794.

Demirbas, E., Kobya, M., Oncel, S.and Sencan, S. (2002). Removal of Ni(II) from Aqueous Solution by Adsorption onto Hazelnut Shell Activated Carbon: Equilibrium Studies. Bioresource Technology, 84, 291 - 293.

Din, A. T. M., Hameed, B. H.and Ahmad, A. L. (2009). Batch adsorption of phenol onto physiochemical-activated coconut shell. Journal of Hazardous Materials, 161, 1522–1529.

Duffus, J. H. (2002). "Heavy Metals" - A Meaningless Term? (IUPAC Technical Report). Pure Appl. Chem.: International Union Pure and Applied Chemistry

Hadjmohammadi, M. R., Salary, M.and Biparva, P. (2011). Removal of Cr(IV) from Aqueous Solution Using Pine Needles Powder as a Biosorbent. Journal of Applied Sciences in Environmental Sanitation, 6, 1 - 13.

Halstead, T. (2010). Coffee: World Markets and Trade. June 2010. United States

Department of Agriculture. Available: http://www.fas.usda.gov/htp/coffee/2010/June 2010/2010_June_Coffee.pdf

[Accessed April 16 2011].

Hameed, B. H. (2009). Spent Tea Leaves: A New Non-Conventional and Low-cost Adsorbent for Removal of Basic Dye from Aqueous Solutions. Journal of Hazardous Materials 161 753–759.

(25)

Hameed, B. H.and Daud, F. B. M. (2007). Adsorption Studies of Basic Dye on Activated Carbon Derived from Agricultural Waste: Hevea brasiliensis Seed Coat. Chemical Engineering Journal 139, 48–55.

Hassanien, M. A.and Shahawy, A. M. E. Year. Environmental Heavy Metals and Mental Disorders of Children in Developing Countries. In: Simeonov, L. I., Kochubovski, M. V.and Simeonova, B. G., eds. NATO Advanced Research Workshop on Environmental Heavy Metal Pollution and Effects on Child Mental Development - Risk Assessment and Prevention Strategies, (2010) Sofia, Bulgaria. Springer.

Ho, Y. S. (2006). Second-order kinetic model for the sorption of cadmium onto tree fern: A comparison of linear and non-linear methods Water Research, 40, 119 - 125.

Ho, Y. S.and Mckay, G. (1999). Pseudo-second order model for sorption processes. Process Biochemistry 34 451–465.

Huang, C. P.and Blankenship, D. W. (1984). The Removal of Mercury (II) from Dilute Aqueous Solution by Activated Carbon. Water Resources, 18, 37-46.

I. N. S. G. 2010. World Nickel Statistic: Monthly Bulletin April (2010). In: Consumption, G. N. P. A. (ed.) http://www.insg.org/stats.aspx. Lisbon

Kadirvelu, K., Kavipriya, M., Karthika, C., Radhika, M., Vennilamani, N.and Pattabhi, S. (2003). Utilization of Various Agricultural Wastes for Activated Carbon Preparation and Application for the Removal of Dyes and Metal Ions from Aqueous Solutions. Bioresource Technology, 87, 129-132.

Kadirvelu, K., Thamaraiselvi, K.and Namasivayam, C. (2001). Removal of Heavy Metals from Industrial Wastewaters by Adsorption onto Activated Carbon Prepared from an Agricultural Solid Waste. Bioresource Technology, 76, 63 - 65.

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Kalibantonga, P. D. (2005). Adsorption of Heavy Metals from Solution by a South African Industrial Clay. Master of Technology, Tshwane University of Technology.

Kannan, A.and Thambidurai, S. (2008). Comparative Studies on the Removal of Nickel (II) from Aqueous Solution by Using Carbon Derived from Palmyra Palm Fruit Seeds and Commercial Activated Carbon. International Journal of Science & Technology, Volume 1, 93-107.

Kawasaki, N., Bun-Ei, R., Ogata, F., Nakamura, T., Tanei, S.and Tanada, S. (2006). Water Treatment Technology Using Carbonaceous Materials Produced from Vegetable Biomass. Journal of Water and Environment Technology, 4, 73-82.

Kazemipour, M., Ansari, M., Tajrobehkar, S., Majdzadeh, M.and Kermani, H. R. (2008). Removal of Lead, Cadmium, Zinc, and Copper from Industrial Wastewater by Carbon Developed from Walnut, Hazelnut, Almond, Pistachio, Shell, and Apricot Stone. Journal of Hazardous Materials, 150, 322 - 327.

Khan, N. A., Ibrahim, S.and Subramaniam, P. (2004). Elimination of Heavy Metals from Wastewater Using Agricultural Wastes as Adsorbents. Malaysian Journal of Science, 23, 43 - 51.

Khantisuk, T. (2005). Upgrading Coffee Ground Waste as Activated Carbon using Chemical Activation with Zinc Chloride and Potassium Carbonate. Master of Science (Appropriate Technology for Resources and Environmental Development), Mahidoly Universit.

Khenniche, L.and Aissani, F. (2009). Characterization and Utilization of Activated Carbons Prepared from Coffee Residue for Adsorptive Removal of Salicylic Acid and Phenol: Kinetic and Isotherm Study. Desalination and Water Treatment, 11 192–203.

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Kiipper, H.and Kroneck, P. M. H. (2007). Nickel in the Environment and Its Role in the Metabolism of Plants and Cyanobacteria. Met. Ions Life Sci., 2, 31-62.

Kobya, M. (2004). Removal of Cr(VI) from Aqueous Solutions by Adsorption onto Hazelnut Shell Activated Carbon: Kinetic and Equilibrium Studies. Bioresource Technology, 91, 317 - 321.

Kobya, M., Demirbas, E., Senturk, E.and Ince, M. (2005). Adsorption of Heavy Metal Ions from Aqueous Solutions by Activated Carbon Prepared from Apricot Stone. Bioresource Technology, 96, 1518–1521.

Kondamudi, N., Mohapatra, S. K.and Misra, M. (2008). Spent Coffee Grounds as a Versatile Source of Green Energy. J. Agric. Food Chem., 56, 11757 - 111760.

Krishnan, K. A.and Anirudhan, T. (2003). Removal of cadmium(II) from aqueous solutions by steam-activated sulphurised carbon prepared from sugar-cane bagasse pith: Kinetics and equilibrium studies. Water SA Vol. 29 147 - 156.

Kumar, U. (2006). Agricultural Products and By-Products as a Low Cost Adsorbent for Heavy Metal Removal from Water and Wastewater: A Review. Scientific Research and Essay Vol. 1 033-037.

Kurniawan, T. A., Chan, G. Y. S., Lo, W. H.and Babel, S. (2006). Physico-Chemical Treatment Techniques for Wastewater Laden with Heavy Metals. Chemical Engineering Journal, 118, 83 - 98.

Landner, L.and Reuther, R. (2004). Metals in Society and in the Environment : A Critical Review of Current Knowledge on Fluxes, Speciation, Bioavailability and Risk for Adverse Effects of Copper, Chromium, Nickel and Zinc, Dordrecht, Kluwer Academic Publishers.

Low, K. S., Lee, C. K.and Wong, S. Y. (2000). Metal Sorption Enhancement of Rice Hull Through Chemical Modification. Environmental Technology, 21, 1239-1244.

(28)

Malaysia (2009). Peraturan-Peraturan Kualiti Alam Sekeliling (Effluen Perindustrian) 2009. P.U. (A) 434.

Malek, N. A. N. N.and Yusof, A. M. (2007). Removal of Cr(III) from Aqueous Solutions using Zeolite NaY Prepared from Rice Husk Ash. The Malaysian Journal of Analytical Sciences, 11 76-83.

Masters, G. M. (1998). Introduction to Environmental Engineering and Science 2nd Edition, New Jersey, Prentice Hall.

Meena, A. K., Mishra, G. K., Rai, P. K., Rajagopal, C.and Nagar, P. N. (2005). Removal of Heavy Metal Ions from Aqueous Solutions using Carbon Aerogel as an Adsorbent. Journal of Hazardous Materials, B122, 161 - 170.

Mittal, A., Kaur, D.and Mittal, J. (2008). Applicability of Waste Materials—Bottom Ash and Deoiled Soya—as Adsorbents for the Removal and Recovery of a Hazardous Dye, Brilliant Green. Journal of Colloid and Interface Science.

Mondal, P., Majumder, C. B.and Mohanty, B. (2007). Effects of adsorbent dose, its particle size and initial arsenic concentration on the removal of arsenic, ion and manganese from simulated ground water by Fe3+ impregnated activated carbon. Journal of Hazardous Materials, 150, 695 - 702.

Moodley, K., Singh, R., Musapatika, E. T., Onyango, M. S.and Ochieng, A. (2011). Removal of Nickel from Wastewater Using an Agricultural Adsorbent. Water SA Vol. 37

Nieminen, T. M., Ukonmaanaho, L., Rausch, N.and Shotyk, W. (2007). Biogeochemistry of Nickel and Its Release into the Environment. Met. Ions Life Sci., 2, 1 - 22.

Nityanandi, D., Subbhuraam, C. V.and Kadirvelu, A. (2006). Adsorption of Nickel from Aqueous Solution by Coir Based Adsorbent, Puresorbe. Environmental Technology, 27, 15-24

(29)

Nordberg, G. F., Fowler, B. A., Nordberg, M.and Friberg, L. T. (2007). Handbook on the Toxicology of Metals, London, Academic Press.

Oliveira, L. S., Franca, A. S., Alves, T. M.and Rocha, S. D. F. (2007). Evaluation of Untreated Coffee Husks as Potential Biosorbents for Treatment of Dye Contaminated Waters. Journal of Hazardous Materials, Article in Press.

Oliveira, W. E., Franca, A. S., Oliveira, L. S.and Rocha, S. D. (2008). Untreated Coffee Husks as Biosorbents for the Removal of Heavy Metals from Aqueous Solutions. Journal of Hazardous Materials, 152, 1073-1081.

Parab, H., Joshi, S., Shenoy, N., Lali, A., Sarma, U. S.and Sudersanan, M. (2006). Detemination of kinetic and equilibrium parameters of batch adsorption of Co(II) and Ni(II) onto coir pith. Process Biochemistry, 41, 609 - 615.

Patil, A. K.and Shrivastava, V. S. (2010). Adsorption of Ni(II) from aqueous solution on Delonix regia (Gulmohar) tree bark. Archives of Applied Science Research, 2, 404 - 413.

Periasamy, K.and Namasivayam, C. (1995). Removal of Nickel (II) from Aqueous Solution and Nickel Plating Industry Wastewater using an Agricultural Waste : Peanut Hulls. Waste Management, 15, 63 - 68.

Prasad, M., Xu, H.and Saxena, S. (2008). Multi-Component Sorption of Pb(II), Cu(II) and Zn(II) onto Low-Cost Mineral Adsorbent. Journal of Hazardous Materials, 154, 221-229.

Rajalakshmi, R., Subashini, S.and Lalitha, P. (2009). Usefulness of activated carbon prepared from industrial wastes in the removal of nickel from aqueous solution. E-Journal of Chemistry, 6, 361 - 370.

Ravenscroft, P., Brammer, H.and Richards, K. S. (2009). Arsenic Pollution : A Global Synthethis, West Sussex Wiley-Blackwell.

(30)

Rehman, M. S., Ahmad, N., Sawar, M.and Hussain, W. (2006). Pretreatment of Complex Industrial Wastewater by Ozonation. Journal of Water and Environment Technology, 4, 52 - 59.

Richter, R. O.and Theis, T. L. (1980). Nickel Speciation in Soil/Water System. In: Nriagu, J. O. (ed.) Nickel in The Environment. Canada: John Wiley & Sons.

Sawyer, C. N., Mccarty, P. L.and G.F. Parkin (2003). Chemistry for Environmental Engineering and Science 5th Edition, New York, McGraw Hill.

Sengupta, A. K. (ed.) (2002). Principles of Heavy Metals Separation: An Introduction, Florida: Lewis Publishers.

Sharma, N.and Singh, J. (2007). Removal of Zn2+ Ions from Aqueous Solution Using Rice (Oryza Sativa) Husk in a Sequential Bed Adsorption Column. In: Sengupta, M.andR., D., eds. Taal 2007: The 12th World Lake Conference, 2007 Jaipur, India. 944 - 951.

Shuhaimi-Othman, M., Mushrifah, I., Lim, E. C.and Ahmad, A. (2008). Trend in Metals Variation in Tasik Chini, Pahang, Peninsular Malaysia. Environ Monit Assess 143, 345–354.

Smith, A. W. (1985). Introduction. In: Clarke, R. J.and Macrae, R. (eds.) Coffee Volume 1: Chemistry. London: Elsevier Applied Science Publishers Ltd.

Spiller, M. A. (1998a). The Chemical Components of Coffee. In: Spiller, G. A. (ed.) Caffein. New York: CRC Press LLC.

Spiller, M. A. (1998b). The Coffee Plant and Its Processing. In: Spiller, G. A. (ed.) Caffein. New York: CRC Press LLC.

Sud, D., Mahajan, G.and Kaur, M. P. (2008). Agricultural Waste Material as Potential Adsorbent for Sequestering Heavy Metal Ions from Aqueous Solutions – A Review. Bioresource Technology 99, 6017–6027.

(31)

Sutherland, J. E.and Costa, M. (2002). Nickel. In: Sarkar, B. (ed.) Heavy Metals in the Environment. New York Marcel Dekker Inc.

Tan, W. T. (1985). Copper(II) Adsorption by Waste Tea Leaves and Coffee Powder. Pertanika, 8, 223 - 230.

Tchobanoglous, G., Burton, F. L.and Stensel, H. D. (2004). Wastewater Engineering Treatment and Reuse , Metcalf & Eddy, Inc., Singapore, McGraw-Hill.

Tokimoto, T., Kawasaki, N., Nakamura, T., Akutagawa, J.and Tanada, S. (2005). Removal of Lead Ions in Drinking Water by Coffee Grounds as Vegetable Biomass. Journal of Colloid and Interface Science 281 56–61.

Tolani, S., Mugweru, A., Craig, M.and Wanekaya, A. K. (2009). Rapid and Efficient Removal of Heavy Metal Ions from Aqueous Media Using Cysteine-Modified Polymer Nanowires. Journal of Applied Polymer Science 116, 308– 313

Utomo, H. D.and Hunter, K. A. (2007). Recycling Agricultural Waste Products for Sustainability: Coffee Waste for Heavy Metal Removal. Ultrapure Water, 57- 62

Utomo, H. D.and Hunter, K. A. (2010). Particle Concentration Effect: Adsorption of Divalent Metal Ions on Coffee Grounds. Bioresource Technology, 101 1482– 1486.

Wang, X. S., Huang, J., Hu, H. Q., Wang, J.and Qin, Y. (2007). Determination of kinetic and equlibrium parameters of the batch adsorption of Ni(II) from aqueous solutions by Na-mordenite. Journal of Hazardous Materials, 142, 468 - 476.

Wasewar, K. L., Atif, M., Prasad, B.and Mishra, I. M. (2009). Batch Adsorption of Zinc on Tea Factory Waste. Desalination, 244, 66 - 71.

(32)

Wintgens, J. N. (2004). Coffee: Growing, Processing, Sustainable Production. A Guidebook for Growers, Processors, Traders and Researchers, Germany, Wiley-VCH Verlag GmbH & Co.

Yao, P. (2010). The Removal of Heavy Metal Pollutants With Electrowinning Techniques. Doctor of Philosophy, Brown University.