DEVELOPMENt OF ACID-BASE INDICATOR FROM FLOWER
PETALS (HIBISCUS SABDARIFFA AND ALLAMANDA)
i'
IBy
OLA YIWOLA JACOB
(2006/24200EH)
DEPARTMENT OF CHEMICAL ENGINEERING
FEDERAL UNIVERSITY OF TECHNOLOGY, MINNA
NIGERIA
NOVEMBER, 2011
DEVELOPMENT OF ACID-BASE INDICATOR FROM FLOWER
PETALS (HIBISCUS SABDARIFFA AND ALLAMANDA)
By
OLAYIWOLA JACOB
(2006/24200EH)
A PROJECT SUBMITTED TO THE
DEP ARTMENT OF CHEMICAL ENGINEERING,
FEDERAL UNIVERSITY OF TECHNOLOGY, MINNA
NIGERIA
IN PARtIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF
BACHELOR OF ENGINEERING (B. ENG) DEGREE IN CHEMICAL
ENGINEERING
NOVEMBER, 2011
ii
ACKNOWLEGDEMENT
I want to express my profound gratitude to Almighty God for His Protection, provision and
abundant grace throughout my years in school.
I also want to appreciate the immense financial and moral support of my lovely mum Mrs. Alice
Olayiwola, my sisters Florence, Elizabeth, Deborah and Dorcas, my nieces and nephew Tosin,
Taye, Kehinde, Dami, Judah and Abigail and the families of the Makanjuola's, Aminu's and
Ado's.
I want to specially appreciate my project supervisor Engr. Dr D.O. Agbajelola, for his fatherly
guides and advice during this research work.I also want to express my gratitude to the Head of
Department of Chemical Engineering, Federal University, Minna, in person of Dr M.O Edoga
and all the lecturers I was opportune to learn from during my degree programme. Finally I want
j
to thank all my course mate in chemical engineering department, I love you all.
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ABSTRACT
The project report highlights the development of acid-base indicator from flower petals. It aims
at producing efficient indicator from flowers as substitutes or possible replacement for standard
indicators in use in chemical industries, research laboratories and schools for the determination
of acidity, alkalinity, humidity's, extent of reactions, etc. 20 g of various flower petals of
Hibiscus sabdariffa and allamanda, were collected, dried, crushed and their pigments separately
extracted in a soxhlet extractor at a temperature of 81°C using a mixture of ethanol and
hydrochloric acid. The extract was then stabilized by hydrolyzing if with concentrated HCI and
purified by crystallizing the hydrolyzed extract. The indicator properties of the flower pigments
were tested by observing its color change in acid and base. The solution of the indicator crystals
3
was prepared by dissolving Ig of the sample in 1000 cm ethanol and used for titrating O.lm
. NaOH and 0.117m HCI solutions to obtain the end point. The purity of the indicator producec;J
was tested with thin layer chromatography, which made it possible to classify the pigment
produced as anthocynanin. The sharp contrast between their colors in acid and base made the
pigment suitable for use as acid-base indicators.
vi
TABLE OF CONTENT
Cover Page
11
Title Page
Declaration
III
Certification
IV
Acknowledgement
v
Abstract
VI
List of Tables
Xli
List of Figures
Xlll
List of Appendices
XIV
xv
Nomenclature
CHAPTER ONE
1
l.0 Introduction
1.1 Aim and· obj ectives
1.2 Justification
2
1.3 Scope of study
2
1.4 Problem statement
2
CHAPTER TWO
3
2.0 Literature Review
2.1 The Structure of Pigments (Acid and Base)
3
2.2 Properties of Good Acid-Base Indicator
5
2.3 Acid-base Indicator
6
2.4 Theories ofIndicator Action
6
2.4.1 Chromaphore theory
8
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2.4.2 Resonance theory
8
2.5 Acid~Base theories
9
2.5.1 Theory of solvent system
9
2.5.2 Bronsted lowry theory
9
2.5.3 Lewis theory
10
2.5.4 Arrhenius theory
10
2.6 Classes of Acid ..Base Indicator
10
2.7 Disadvantages of Acid-Base Indicator
11
2.8 Errors in Indicator Titration
11
-2.9 Factors Influencing Indicator Action
11
2.10 Choice of Solvent for Acid-base Titration
12
2.11 Some Common Acid-Base indicators
13
2.12 Natural Indicator Ingredient
14
2.12.1 Occurrence of anthocyanins
14
2.12.2 Methods of isolating and identifying anthocyanin in plants
15
2.12.3 Uses of anthocyanin
15
2.12.4 Industrial application of anthocyanin
16
2.12.5 Chemistry of anthocyanin
16
2.12.6 Structure of anthocyartins
18
2.13 Identification and Characterization of Pigment
18
2.13.1 Chromatography identification
18
2.13.2 Spectral method of identification
19
20
. 2.14 Continuous Extraction
2.15 Solvent Recovery
21
2.15.1 Desirable solvent properties
21
2.15.2 Advantages and disadvantages of solvent extraction
23
2.16 General Methods of Flower Pigment Extraction
23
2.16.1 Mechanical pressing
23
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2.16.2 Rendering method
23
2.16.3 Solvent extraction
24
2.17 Factors Influencing the Rate of Extraction
24
2.17.1 Particle size
24
.
2.17.2 Solvent
24
2.17.3 Temperature
25
2.17.4 Agitation
25 .
CHAPTER THREE
3.0 Methodology
26
3.1 Equipments and Materials used
26
3.1 Pretreatment and Size Reduction
27
3.1 Extraction Procedure
28
3.1 Crystallization procedure
28
3.1 Pigment Characterization
28
3.5.1 Flower extracts indicator properties
28
3.5.1.1 Acid-base color change
28
3.5.1.2 Uses as an indicator and comparative titration
28
3.5.1.3 pH range determination
29
3.5.2 Purity Test
30
3.5.2.1 Chromatography charact~rization
30
3.5.3 Stability Test
30
3.5.3.1 Volume of change with time
30
CHAPTER FOUR
4.0 Results and Discussion
31
4.1 Results
31
ix
{.,
4.1.1 Extraction Results
31
4.1.2 Indicator Properties
32
4.1.3
Comparative Titration Results
32
4.1.4
Purity Test
34
4.1.5
Stability Test
35
4.2 Discussion of Results
37
CHAPTER FIVE
5.0 Conclusion and Recommendation
39
5.1 Conclusion
39
5.2 Recommendation
39
REFERENCES
40
APPENDIX
42
x
LIST OF TABLES
Table
P3ge
Table 2.1: Common Acid-Base Indicator
13
Table 2.2: Chlorides of Anthocyanin
17
Table 3.1: List of Apparatus Used
26
table 3.2: List of Materials ~r Reagents
27
Table 4.1: Flower Pigment Extracted Using Ethanol and HCI
31
Table 4.2: Acid. . Base Color Change Results
32
Table 4.3: Strong Acid Vs Strong base Titration
32
Table 4.4: Strong Acid Vs Weak Base Titration
33
Table 4.5: Weak Acid Vs Strong Base Titration
33
Table 4.6: pH Color Change
34
Table 4.7: the Rf Values in Thin Layer Chromatography Plat~
34
Table 4.8: Volume of Hydrolysed pigment Indicator Required to Color NaOH
35
Table 4.9: Volume ofUnhydrolysed pigment Indicator Required to Color NaOH
35
i
xi
LIST OF FIGURES
Figure
Page
Figure 2.1: Structure of Anthocyanin
18
Figure 4.1: Hydrolysed Indicator Stability Test
36
Figure 4.2: Unhydrolysed Indicator Stability Test
36
Figure 4.3: Flow Diagram for the Industrial Production of Pigment (Acid-Base) Indicator
38
xii
LIST OF APPENDICES
Appendix
Page
Appendix 1 Retention Factor, Rf
42
Appendix 2 Time to Remove 66% of Water from Flower Petals
42
Appendix 3 Amount of Extract (%)
43
Appendix 4 Specific Gravity
43
xiii