Assessment of Two Local Plant Dyes as Colourants for Petroleum Products (Petrol, Kerosene and Diesel)
CHAPTER ONE
Objectives of the study
This study has the following objectives:
- To assess the stability of the heartwood of P. osun and young leaf of L. inermis plant extract respectively, as colourants for petroleum products (petrol, kerosene and diesel).
- To determine alternative sources of colouring petroleum products rather than using synthetic dyes, and
- To determine the stability of the dye colours when added to petroleum products.
CHAPTER TWO
Literature review
Historical development
The art of dyeing was as old as civilization. From the historical records over 5000 years, it is learnt that natural colourants were available to people during Greco-Roman periods particularly in India, Egypt and Phoenicia8,9,41. The use of natural dyeing materials is evident with the wall paintings and they still demonstrate the efficacy of dyeing craft that had been inherited from ancient times in India. Ancient Egyptian hieroglyphs contain a thorough description of the extraction of natural dyes and their application in dyeing42. Further developments extending over many thousands of years led to rather complicated dyeing process and high quality dyeing.
Natural dyes have been used since ancient times for colouring and printing fabrics43. Until the middle of last century, most of the dyes were derived from plants, mineral or animal sources by long and elaborate processes. Among these Indigo, Tyrian purple, Alizarin, Cochineal, Lawsone and Logwood dyes deserve special mention.
Synthetic dyes were an early result of the development of chemistry as a science. Chemistry radically changed the findings of Gebelein (1997) when in 1856, William Perkin, an English chemist working in London, made an accidental discovery of a purple dye while trying to synthesize quinine by reacting aniline sulphate with an oxidizing agent14.
This purple dye, which Perkin called mauve, was found to dye silk and although it was not particularly fast, it became popular. This first synthetic dye influenced the development of the synthetic dye industry. Today, industry uses synthetic dyes almost entirely because they hold their colour better than natural dyes.
Perkin’s discovery showed chemists that dyes and pigments could be produced synthetically in a laboratory. It was only a decade ago when toxicological effects of dyes during wearing dyed garments became more known and caused a great concern about the use of synthetic dyes.
In the late 1994, Germany struck a severe blow to dyestuff industries and subsequently other European countries executed ban on importation of textile and garments coloured with a series of azo dyes made from aromatic compounds, which are carcinogenic, allergic and poisonous. For instance, in the diazotization reaction hydrochloric acid reacts with sodium nitrite to form a nitrous acid, which combines with the amine to form a diazonium compounds. The diazonium compounds are active chemically and combine with various naphthoic, phenolic and amino intermediates to form the acid azo dyes through coupling.
CHAPTER THREE
Materials and Methods
Reagents
- n-hexane
- Dichloromethane
- Ethyl acetate
- Acetone
- Benzene
- Methanol
- Ethanol
- Distilled water
All the chemicals used were of analytical reagent grade and were made by Sigma Aldrich® (Germany) while distilled water was purchased from the National Center for Energy Research and Development (NCERD) University of Nigeria, Nsukka.
Equipment
- Buckner funnel
- Buckner flask (500 cm3)
- Filter paper (Whatmann, 11 cm)
- Electric Milling Machine made by Thomas Wiley Laboratory Mill Model 4 ( U.S.A)
- Rotary Evaporator (BÜCHI ROTAVAPOR – R, Germany).
- Edward High Vacuum Pump Machine ( England)
- Freeze Drier Machine (YORCO, India)
- Conical flask (1000 cm3)
- Mortar
- Glass funnel
- Glass beaker (1000 and 250 cm3 respectively)
- Shunsum flask
- Measuring cylinder (500 and 250 cm3 respectively)
- Spatula
- High sensitive analytical weighing balance (OHAUS)
- FTIR – 8400S Fourtier Transform Infrared Spectrophotometer (SHIMADZU, Japan)
- Ultraviolet Visible Spectrophotometer (UV-2500PC series, Japan)
- Lovibond Tintometer F Model ( United Kingdom)
Plant materials
The heartwood of Pterocarpus osun Craib and young leaf of Lawsonia inermis Linn. were collected from Eha-Alumona and Nsukka both in Nsukka L.G.A in Enugu State, Nigeria. The plants materials were identified by Dr. A. O. Ozioko of INTERCEED and the specimen was submitted through voucher No H–1070 to the herbarium of the Institute and kept for future reference.
Extraction procedure
The heartwood of Pterocarpus osun Craib and young leaf of Lawonia inermis Linn. were washed with distilled water to remove dirt and air-dried before milling into powder with electric milling machine which has a sieving size of 1mm according to the method reported in the literature75.
About six hundred gram (600 g) each of the plant materials were soaked in 2.5 L of 96 % ethanol and methanol respectively and extracted by cold maceration at room temperature for 48 hours. The filtrates were concentrated in vacuo using rotary evaporator at reduced pressure (300 Psi) and temperature (40 oC) to obtain the dry extract.
Purification of the extracts
The ethanol extract of P. osun was purified further using column chromatography (CC) method as previously reported in the literature76 while the extract of L. inermis was purified using vacuum liquid chromatography (VLC) according to the method reported in the literature77.
Column chromatographic purification of P. osun extract
About twenty seven gram (27.0 g) of the extract was chromatographed on silica gel (60–230 mesh, 250 g) packed into a glass column (15 cm long x 1.5 cm, i.d). The elution was done with ethanol (2.5 L) and the percentage yield calculated.
CHAPTER FOUR
Results and Discussion
Physical data of the dyes
The physical properties of the dyes extracted from P.osun Craib and L. inermis Linn.
Solubility test of the dyes
The solubility of the dyes in different organic solvents shows that the dyes are very soluble in ethyl acetate, methanol and ethanol while they are sparingly soluble or insoluble in the other solvents.
CHAPTER FIVE
Conclusion
In this present work, it has been established that the dye extracted from the young leaf of L. inermis dye can be used as alternative source of colourant for petrol in the oil industry. They cannot be used for the same purpose for kerosene and diesel. The dye extracted from the heartwood of Pterocarpus osun Craib cannot be used in colouring petrol, kerosene and diesel because the colour of the dye was not stable in the petroleum products.
Hence, individual manufacturers, companies and organizations can now use these dyes extracted from the leaves of L. inermis as trademark to differentiate their petrol from those of other manufacturers. Most especially, this period that many nations are returning to the use of natural colourants based on the alarming rate of environmentally unfriendliness caused by synthetic dyes.
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- Mc Graw-Hill (1983). Encyclopedia of Chemistry, 1st ed., Mc Graw-Hill, Inc., New York, 276-277.
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