Chapter III: DEVELOPMENT OF TEACHING MATERIALS
III. DETERGENT ANALYSIS BY FABRIC DYEING
63
Fig. 3-13: The decrease in area of marbling ink against detergent concentration
Since detergent lowered the surface tension of the water, samples containing detergent produced smaller areas of marbling ink than in the case of pure water. The area decreased according to the increase of detergent concentration.
III. DETERGENT ANALYSIS BY FABRIC DYEING
64
1983). PONAL KIT ABS method is another technique using the purple-dye cobalt (III) complex cation to produce a neutral compound with anionic detergents and benzene as the extraction solvent (Dojindo). However, the above methods all require organic solvents which are harmful and modern lab equipment for analysis such as an atomic absorption spectrometer, anodic stripping voltammeter and spectrophotometer that are troublesome for high school students to handle.
Since the use of harmful organic solvents in classrooms has become a critical issue of concern in the field of chemistry education, one aim of this study was to seek a safer method.
The method here used fabrics instead of organic solvents as media to extract the neutral compounds made between the dye and detergent from the solution. A calibration curve was obtained by dyeing pieces of fabric in dye solutions of several different detergent concentrations. A hand-made reflection photometer, which could be assembled from inexpensive materials, was used to determine the color depth of dyed fabric.
2. Experiment
<Materials>
Assemble of a hand-made Reflection photometer: The body was an L-shaped PVC tube usually used for tap water. The light source was a light emitting diode (LED) placed in a hole in a PVC cap connected to two 1.5 V dry cells. Light reflected from the dyed fabric was detected by a Cadmium Sulfide (CdS) device attached to another PVC cap, which showed low resistance in the light and high resistance in the dark. The CdS resistance value was measured by a multimeter (Fig. 3-14 & 3-15).
Several types of white fabrics (see Table 3-3) collected from the home economics laboratory were cut into pieces of ca. 4 cm x 4 cm. A pair of tweezers was used for picking up the fabric pieces from the dye solution. Several 100 mL beakers were used as dyeing containers (any plastic cups also can be used instead of beakers).
65
(a) (b)
Fig. 3-14: (a) Assemble of the hand-made reflection photometer; (b) measuring color depth of dyed fabric
Various different concentrations from 0 to 12 ppm of detergent solution [sodium dodecyl sulfate (SDS)] were prepared. Then several kinds of dye solutions, including anionic dyes and cationic dyes as seen in Table 3-4, were investigated in this research.
Table 3-3: Types of fabrics and their polymer structures used in the study (Menachem Lewin, 1983 & 19984; Lauren J, 1999)
Fabric type Polymer Structure
acrylic (Cashimilon): Cashimilon contains a few co-polymers
* *
CN
n
Polyester (PET) *
O
O O
O * n
Multimeter showing the depth of color as resistance
in 103 ohm.
LED end is connected to
battery CdS sensor end is
connected to multimeter
Dyed fabric is placed under the
photometer
Light source Reflected light
detected by CdS sensor
Dyed fabric LED
CdS sensor PVC tube
Cut along this line with a saw
Seen from above Seen from
below
66
Acetate * O O
O O
O
O
O O
n *
65% Polyester and 35% Cotton *
O
O O
O * n
&
O
* O
HOH2C
OH
OH n*
Nylon 6,6 * N
H O
O
NH n*
Viscose Rayon
O
* O
HOH2C
OH
OH n*
Cuprammonium Rayon [CuC6H8O5] n
Silk * N
H
NH
* R
O R
O n
Wool * N
H
NH
* R
O R
O n
Cotton
O
* O
HOH2C
OH
OH n*
Table 3-4: Types of anionic and cationic dyes used in the research (Aldrich, (2003-2004); Panreac website)
Name of dye Color Color index
number
Molecular structure and ionic type
Methyl Violet Violet/purple Extra pure
NH
N
N+ Cl
67
Methylene Blue Blue 52015
N
S+
N N
Cl
Cobalt (III)
complex tablet Violet/purple - Co
N N O Cl
N C2H2
C2H2 N
N N
C2H2
H2C2
O
Cl
Rhodamine B Red 45170
O OH
N O N+
Cl
Brilliant Blue
FCF Blue 42090
SO3 N
SO3
N+
SO3Na+
Na+
Acid fuchsine Red 42685
CH3 NH2
SO3
SO3 N+ O3S
N H2
H H
Na+ Na+
New coccine Brown 16255
N N O3S
SO3 O H
O3S Na+
Na+ Na+
Cal Red
(Calcocarboxylic Acid)
Violet - HO3S
OH N
N O
H COOH
Indigo Carmine Blue 730 N
H NH O
O
SO3 O3S
Na+
Na+
68
<Procedure>
Ten milliliters of pure water (blank) and each SDS solution were put into separate 100-mL beakers. Then 2 mL of dye solution was added and stirred well. Pieces of fabric were dipped into each resulting solution for 15 minutes maintained at 25oC in a water bath. The pieces of dyed fabric were picked out from the solutions and air dried with an electric dryer.
Finally, the color depth of each dried fabric was measured as the resistance value on the multimeter in 103 ohm (k) by using the hand-made reflection photometer, as shown in Fig.
3-14b. It was necessary to use an LED light source which was the complimentary color to the color of the dyed fabric in the measurement of color depth (Table.3-5). For instance, according to the color wheel above, the yellow LED was used to measure the color depth of the purple dyed fabric, and the orange LED was used for the blue dyed fabric, etc.
Property of Light and CdS Sensor
Lowest resistance
Resistance of CdS sensor
Intensity color of dyed fabric
Detergent Concentration
CdS sensor gives high resistance in the dark, and low resistance in the light
Light source
More reflected Light
Highest resistance Higher resistance
Less reflected light
30
Fig. 3-15: The relationship of CdS sensor property with the light
69
Table 3-5: Approximate wavelength of color and its complementary color (Complementary color, 2006)
Main Color Wavelength (nm) Complementary Color
Purple 380-435 Yellow
Blue 435-480 Orange
Blue-Green 480-500 Red-Orange
Green 500-560 Red
Yellow-Green 560-580 Red-Purple
Yellow 580-595 Purple
Orange 595-605 Blue
Red 605-750 Green
Red-Purple 750-780 Yellow-Green
Note: Main Color + Complementary Color = White color
<Hazards>
No chemicals or procedures used by students cause any significant hazards in this experiment.
2. Result and discussion
Table 3-6 The combination of fabrics and dyes used in the research Dye
Fabric
D1 D2 D3 D4 D5 D6 D7 D8 D9
Acrylic (Cashimilon)
Polyester
Acetate
65% Polyester & 35%
Cotton
Nylon 6,6
Viscose Rayon
70
Cuprammonium Rayon
Silk
Wool
Cotton
Note: () means the color depth of dyed fabric affected by detergent, and () means there was no effect.
D1: Methyl Violet, D2: Methylene Blue, D3: Cobalt Complex, D4: Rhodamine B, D5: Brilliant Blue, D6: Acid Fuchsine, D7: New Coccin, D8: Cal Red, D9: Indigo Carmine
Table 3-6 shows the test results of combinations of the ten kinds of fabrics and nine kinds of dyes. Only six combinations of the three kinds of fabrics and five kinds of dyes showed clear relationships between color depth and detergent concentration. There were a few different patterns of results which will be described according to the type of the dyes involved; cationic or anionic.
<Dyeing in cationic dye>
Fig. 3-16: The increase of color intensity when Cashimelon acrylic fabric dyed in methyl violet solution in the increase of detergent concentration
Color depth of the dyed fabric increased with the increase of detergent concentration in acrylic fabric dyed with methyl violet, rhodamine B, and cobalt (III) complex, and in acetate fabric with methylene blue. Fig. 3-16 is an example of dyeing acrylic fabric in methyl violet. In this case, acrylic and acetate fabrics acted like an organic solvent such as
71
chloroform or benzene to extract the neutral compound formed by the anionic detergent and cationic dye as seen in the illustration of Fig. 3-17. Increasing detergent concentration produced an increase in the amount of neutral compound which was adsorbed onto the fabric.
The color depth on the dyed fabric corresponded to the concentration of detergent.
Fig. 3-17: The association between cationic dye and anionic detergent, (a) JIS MB method and (b) fabric dyeing
As the results, the graphs in Fig. 3-18 showed the linear relationship between the resistance of the CdS device and detergent concentrations. These graphs could be used as calibration curves for the determination of detergent concentration.
The color depth decreased against increasing detergent concentration when 65%
Polyester and 35% Cotton fabric was dyed with cationic methyl violet (See Fig. 3-18). In this case, the fabric decreased in ability to adsorb neutral compounds. Instead, it adsorbed more cationic dye than neutral compounds. In the solution, the neutral compounds produced from the combination of cationic methyl violet and anionic detergent increased when the concentration of detergent increased, but the color depth on the fabric decreased. This means
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the 65% Polyester and 35% Cotton fabric could not act as an organic solvent as the case of acrylic and acetate fabrics.
(a) (b)
(c) (d)
Fig. 3-18: Calibration curves of CdS resistance against SDS concentration (a) Acrylic fabric dyed in 0.005%w/v methyl violet measured with yellow LED. (b) Acrylic fabric dyed in 0.01%w/v Rhodamine B measured with green LED. (c) Acrylic fabric dyed in 1.5%w/v cobalt (III) complex measured with yellow LED; and (d) Acetate fabric dyed in 0.01%w/v methylene blue measured with orange LED.
<Dyeing in anionic dye>
This investigation showed that increasing the concentration of detergent in the solution could also decrease the color depth on the dyed fabric. As shown in Fig. 3-19, the color depths decreased against the increase in concentration of detergent when acrylic fabric was dyed in an anionic dye, brilliant blue. As the results, the resistant decreased drastically
y = 7.8387x + 233.9 R2 = 0.995 200
220 240 260 280 300 320
0 1 2 3 4 5 6 7 8 9 10
Resistance/kilo-ohm
SDS concentration/ppm
y = 3.426x + 308.15 R2 = 0.9848 300
310 320 330 340 350
0 1 2 3 4 5 6 7 8 9 10
Resistance/kilo-ohm
SDS concentration/ppm
y = 0.918x + 143.6 R² = 0.984
142 144 146 148 150 152 154
0 1 2 3 4 5 6 7 8 9 10
Resistance/kilo-ohm
SDS concentration/ppm
y = 16.48x + 411.7 R² = 0.974 400
420 440 460 480 500 520 540 560 580 600
0 1 2 3 4 5 6 7 8 9 10
Resistance /kilo-ohm
SDS concentration/ppm
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(Fig.3-20) and similar result is shown in Fig. 3-21 for the dyeing of polyester and 35% cotton fabric in 0.001%w/v methyl violet. This result indicated that acrylic fabric prevented the adsorption of anionic dye by anionic detergent due to electronic repulsion.
Fig. 3-19: The decrease of color intensity when Cashimelon Acrylic fabric dyed in Brilliant Blue in the increase of detergent concentration
Fig. 3-20: Calibration curve of CdS resistance against SDS concentration when acrylic fabric was dyed in 0.02%w/v brilliant blue for 5 min. The resistances were measured with an orange LED
y = -18.34x + 1022.4 R2= 0.9815
850 900 950 1000 1050 1100
0 1 2 3 4 5 6 7 8 9 10
Resistance/kilo-ohm
SDS concentration/ppm
74
Fig. 3-21: Calibration curve of CdS resistance against SDS concentration when 65% polyester and 35% cotton fabric was dyed in 0.001%w/v methyl violet. The resistances were measured with a yellow LED.
Further observation clearly proved that anionic detergent could prevent anionic brilliant blue from adsorbing onto fabric. In Fig. 3-22, the color depth did not change much at the high concentrations of detergent (site A), although the dipping time was increased. In contrast, when the dipping time was extended the color depth increased drastically (Area B).
This means that acrylic fabric can adsorb brilliant blue dye more easily at the lower concentration of detergent, but not at the higher concentration.
y = 0.252x2- 5.189x + 237.6 R² = 0.980
205 210 215 220 225 230 235 240 245
0 1 2 3 4 5 6 7 8 9 10 11 12
Resistance/kilo-ohm
SDS concentration/ppm
75
Fig. 3-22: Curves of CdS resistance against SDS concentration when Acrylic fabric was dyed in anionic brilliant blue for different length of times.
Fig. 3-23: Chemical interaction when acrylic fabric dyed in anion dye
In this case, the interaction between acrylic fabric and anionic detergent is considered to be stronger than the interaction between acrylic fabric and anionic brilliant blue. Also the repulsion force between anions of detergent and brilliant blue can prevent acrylic fabric from being dyed by anionic brilliant blue (Fig. 3-23).
800 900 1000 1100 1200 1300
0 1 2 3 4 5 6 7 8 9 10
Resistance/kilo-ohm
SDS concentration/ppm
3 min 5 min 10 min 15 min 30 min
Linear (3 min) Linear (5 min) Poly. (10 min) Poly. (15 min) Poly. (30 min) B
A
76 IV. APPLICATION IN CLASSROOM