Dye Solution
The anthocyanin extraction of the two different colors of coleus blumei leaves were made
following procedures. 5g of each freshly collected plant sample was used to extract the
pigments. The pigments were initially extracted using
150 ml of 70% ethanol (w/v%)
and stored overnight at 4°C. On the following day, the extraction was mixed thoroughly
by using a magnetic stirrer for two hours at 25°C, 45°C and 65°C. The extractions were
filtered using 110 mm filter paper to remove solid residues. Subsequently, the extract was
centrifuged at 4000 rpm using centrifuge machine for five minute to separate all residues.
Similar procedures were applied by taking same amount of leaves and solvents for all the
rest extracting solutions.
Fig 1(a) Purple Coleus leaves.
Fig 1(b) Pink Coleus leaves.
Fig 1(c) Puple leaves mixed with eathonl.
Fig 1(d) Pink leaves mixed with
.
Fig 1 (d) The mixture was filtering with
filter paper.
Fig 1(f) The dye solution of Purple
Coleus
ethanol.
Fig 1 (e) The mixture was filtering with
filter paper.
Fig 1(g) The dye solution of Pink Coleus.
5g of fresh coleus leaves+ 150ml of 70% ethanol(w/v)%
Store overnight at 4˚C
Mixture ( coleus + ethanol )
Stirrer with magnetic stirrer at
25˚C, 45˚C,65˚C :2h
Fine Mixture
Filtering at (110 mm) filter paper
solution
Applied with centrifuge at 4000 rpm : 5min
Dye solution
Fig 2 Block diagram of extraction of dye solution by using ethanol solvent.
RESULTS AND DISCUSSION
UV-Analysis
UV-Vis absorption spectra analysis of poinsettia (Coleus Blumei) dye Fig 3(a) showed the
optical absorption spectra of Pink Coleus Blumei dye with different growing temperature,
25 °C, 45 °C and 65°C for the same concentration. It was found that the absorption peaks
of dye solution of pink Coleus Blumei dye with ethanol 150 ml at 25°C, 45°Cand 65°C
are 400nm (anthocyanin ) and 665 nm (chlorophyll) while that of Pink Coleus Blumei dye
with methanol 150 ml at 25°C, 45°C and 65°C as shown in Fig 3(e) are 435nm
(anthocyanin ) and 665 nm (chlorophyll). The optical absorption spectra of Purple Coleus
Blumei dye were shown in Fig 4 (a) and it was found that the absorption peaks of dye
solution of Purple Coleus Blumei dye with ethanol 150 ml at 25°C, 45°C and 65°C are
430nm (anthocyanin ) and 665 nm (chlorophyll) while that of purple (Coleus Blumei) dye
with methanol 150 ml at 25°C, 45°C and 65°C (as shown in Fig 4(e) ) are
440 nm
(anthocyanin ) and 665 nm (chlorophyll). Then, the optical absorption spectra of mixed
(Coleus BlumeiBenth) dye were shown in Fig 5 (a) and it was found that the absorption
peaks of dye solution of mixed (Coleus Blumei)dye with ethanol 150 ml at 25°C, 45°C
and 65°C are 440nm (anthocyanin ) and 665 nm (chlorophyll) and that of mixed (Coleus
Blumei) dye with methanol 150 ml at different temperatures are the same values(440 nm
and 665 nm). And also the absorption peaks of dye solution of (Coleus Blumei) at 25°C,
45°C and 65°C are 400-700nm in the visible range. So the absorption peaks of poinsettia
at different temperatures are in UV range. The energy band gaps (Eg) of these samples at
different temperatures were calculated by using Tauc Method equation and Fig 3 (b, c, d)
showed the relation between energy (hν) and (αhν )2 for Pink Coleus dye with ethanol 150
ml at 25°C,45°C,65°C,2h and Fig 4 (f, g ,h) showed the relation between energy (hν)
and (αhν )2 for Pink Coleus dye with methanol 150 ml at 25°C,45°C,65°C, 2h. And Fig
4 (b, c, d) showed the relation between energy (hν) and (αhν )2 for Purple Coleius dye
with ethanol 150 ml at 25°C,45°C,65°C, 2h and Fig 4 (f,g,h) showed the relation
between energy (hν) and (αhν )2 for purple coleus dye with methanol 150 ml at
25°C,45°C,65°C, 2h.The relation between energy (hν) and (αhν )2 for Mixed (pink &
purple) Coleus dye with ethanol 150 ml at 25°C,45°C,65°C, 2h are shown in Fig 5(b, c,
d) and while that of mixed (pink & purple) Coleus dye with methanol 150 ml at 25°C,
45°C and 65°C , 2h are shown in Fig 5(f,g, h).
Tauc Method ,
(αhν) =A(hν–Eg)n
-----------
(1)
Where, α = absorption coefficient (α= 2.303 A/ thickness )
Eg = Energy Bandgap of the material
n = order of transition (1/2,3/2,2,3)
The measured and calculated values of UV-vis for Coleus Blumei dyes at
°C and 65 °C with two solvents were described in Table (1(a) to 3(b)).
25 °C, 45