22

MMAATTEERRIIAALLSS AANNDD MMEETTHHOODDSS

MATERIALS

3.1 Collection of the Adsorbent

The adsorbent used in this work, Blue-Green Algae, was collected from the nearby

ponds of agricultural land area situated in Coimbatore district, Tamilnadu, India. The

impurities and contaminants are removed by washing with water. It is dried in sunlight for

fifteen days, then it is grinded to powder using laboratory pulveriser. The powdered

biomass is sieved using 250 - mesh wire sieve and stored in airtight container.

3.1.1 Characteristics of the Adsorbent

Scientific Classification of Blue-Green Algae (Appendix I)

KINGDOM : Plant

PHYLUM : Cyanobacteria

CLASS : Cyanophyceae

ORDER : Oscillatoriales

FAMILY : Pseudanabaenaceae

GENUS : Geitlerinema

SPECIES : Geitlerinema Splendidum

Algae are simple aquatic plants that occur naturally in habitats such as rivers, lakes,

dump soil, tree trunks, hot springs and snow. Blue-Green Algae are small organism and

can be seen under the microscope as a strings of cells (trichomes). Some accumulations

may be so large that they are easily seen with the naked eye.

3

23

Blue - Green Algae

3.2 Preparation of the Adsorbate

The dyes Methylene Blue, Methyl Violet, Acid Violet and Acid Blue used in the

present study are procured commercially from the dyeing powder agents, Coimbatore. All

the chemicals used in this study are of analytical-grade. The stock solution of the dyes

used in this study is prepared by accurately weighing 5g of the dye and dissolving it in

1000ml of distilled water.

The dyes Methylene Blue, Methyl Violet, Acid Violet and Acid Blue used as adsorbate

in this study are denoted as MB, MV, AB and AV respectively throughout this thesis.

23

Blue - Green Algae

3.2 Preparation of the Adsorbate

The dyes Methylene Blue, Methyl Violet, Acid Violet and Acid Blue used in the

present study are procured commercially from the dyeing powder agents, Coimbatore. All

the chemicals used in this study are of analytical-grade. The stock solution of the dyes

used in this study is prepared by accurately weighing 5g of the dye and dissolving it in

1000ml of distilled water.

The dyes Methylene Blue, Methyl Violet, Acid Violet and Acid Blue used as adsorbate

in this study are denoted as MB, MV, AB and AV respectively throughout this thesis.

23

Blue - Green Algae

3.2 Preparation of the Adsorbate

The dyes Methylene Blue, Methyl Violet, Acid Violet and Acid Blue used in the

present study are procured commercially from the dyeing powder agents, Coimbatore. All

the chemicals used in this study are of analytical-grade. The stock solution of the dyes

used in this study is prepared by accurately weighing 5g of the dye and dissolving it in

1000ml of distilled water.

The dyes Methylene Blue, Methyl Violet, Acid Violet and Acid Blue used as adsorbate

in this study are denoted as MB, MV, AB and AV respectively throughout this thesis.

24

Methylene Blue Dye

Methyl Violet Dye

24

Methylene Blue Dye

Methyl Violet Dye

24

Methylene Blue Dye

Methyl Violet Dye

25

Acid Blue Dye

Acid Violet Dye

25

Acid Blue Dye

Acid Violet Dye

25

Acid Blue Dye

Acid Violet Dye

26

Table 1

Dyes used in this Study

Name of the Dye Structure of the Dye

Methylene Blue

C14H18N3SCl

C.I No : 52015

CAS No : 61-73-4

λmax : 665nm

S

N

NNCH3

CH3CH3

CH3+

Methyl Violet 7

C25H30N3Cl

C.I No : 42555

CAS No: 548-62-9

λmax : 590nm

Acid Violet 17

C41H44N3NaO6S2

C.I No : 42640

CAS No: 4321 -69-1

λmax : 548nm

Acid Blue 9

C37H34N2Na2O9S3

C.I No : 42755

CAS No : 28631-66-5

λmax : 602nm

26

Table 1

Dyes used in this Study

Name of the Dye Structure of the Dye

Methylene Blue

C14H18N3SCl

C.I No : 52015

CAS No : 61-73-4

λmax : 665nm

S

N

NNCH3

CH3CH3

CH3+

Methyl Violet 7

C25H30N3Cl

C.I No : 42555

CAS No: 548-62-9

λmax : 590nm

Acid Violet 17

C41H44N3NaO6S2

C.I No : 42640

CAS No: 4321 -69-1

λmax : 548nm

Acid Blue 9

C37H34N2Na2O9S3

C.I No : 42755

CAS No : 28631-66-5

λmax : 602nm

26

Table 1

Dyes used in this Study

Name of the Dye Structure of the Dye

Methylene Blue

C14H18N3SCl

C.I No : 52015

CAS No : 61-73-4

λmax : 665nm

S

N

NNCH3

CH3CH3

CH3+

Methyl Violet 7

C25H30N3Cl

C.I No : 42555

CAS No: 548-62-9

λmax : 590nm

Acid Violet 17

C41H44N3NaO6S2

C.I No : 42640

CAS No: 4321 -69-1

λmax : 548nm

Acid Blue 9

C37H34N2Na2O9S3

C.I No : 42755

CAS No : 28631-66-5

λmax : 602nm

27

3.3 Equipments

Elico - 110 pH meter is used to measure pH. The pH meter is standardised using

buffer potassium hydrogen phosphate (pH 4).

Digital Systronics Colorimeter-112 is used for spectrophotometric work.

Horizontal electrical bench shaker with temperature control and 120-200 rpm speed

(sub zero make) is used for agitation of the solution containing the adsorbate and

adsorbent BGA.

pH meter Colorimeter

Electrical shaker with Horizontal electrical bench shakertemperature control

28

METHODS

3.4 Analytical Procedures – Characterisation of the Adsorbent

3.4.1 Determination of pH

About 15g of the dried Algae is weighed and transferred to 500ml beaker, then 300ml

of freshly boiled and cooled water (adjusted to pH 7.0) is added and heated to boiling. After

digesting for 10minutes, the solution is filtered and the first 50ml of the hot filtrate is

decanted. The remaining filtrate solution is cooled to room temperature and is analysed for

pH using Elico pH meter (Shanmugavalli, 2003).

3.4.2 Determination of Moisture Content

About 5g of the dried Algae is weighed in a Petridish, the dish is placed in an electric

oven maintained at 110 ± 5°C for about 5 hours. The dish is covered and cooled in a

desiccator. Heating, cooling and weighing are repeated at 30 minutes interval until the

difference between the two consecutive weights are less than 5mg. The loss in weight

gives the moisture content (Shashi Chawla, 2009).M - X

Moisture Content (%) = x 100M

where,M = Weight of the adsorbent (g)

X = Weight of the adsorbent taken after drying (g)

3.4.3 Determination of Surface Area (BET method)

Surface area of the adsorbents used in this study namely, Blue-Green Algae and

Commercial Activated Carbon are determined using surface area analyser (TriStar 3000V

6.07A) by BET (Brunauer, Emmett and Teller) method at Sud-Chemie India Private (Ltd),

Research and Development Division, Cochin, Kerala, India and the results obtained are

shown in Appendix II & III.

The Commercial Activated Carbon used in this study is denoted as CAC and the

selected low cost adsorbent Blue-Green Algae is denoted as BGA throughout this thesis.

3.5 Adsorption Experiments

Batch mode experiments are carried out to study the adsorption capacity of the

adsorbent BGA. Batch experiments are simpler and effective for evaluating the basic

parameters affecting the adsorption.

29

3.5.1 Effect of variation of initial concentration of the dye on the adsorption

Batch mode experiments are performed with 500mg of adsorbent BGA by varying

the initial concentration of dye solutions used in this study at pH 7.0 ± 0.2 and at 32 ± 2˚C.

100ml of dye solutions containing 60, 80, 100 and 120mg dye (Methylene Blue, Methyl

Violet, Acid Blue and Acid Violet) are prepared from the stock solution. The dye solutions

are taken into Pyrex bottles containing 500mg of the adsorbent (BGA) each, and are

agitated at 150 rpm speed thoroughly on a horizontal electrical bench shaker at 32 ± 2˚C

for various time intervals (10, 20, 30, 40, 50, 60, 90, 120, 150 and 180minutes). The

solutions are filtered and the dye concentrations are estimated colorimetrically at 480nm for

Methylene Blue & Acid Blue dyes and at 420nm for Methyl Violet & Acid Violet dyes.

3.5.2 Effect of variation of pH on the adsorption of dye

The effect of pH on dye removal is studied by varying the pH from 5 to 9 (5, 6, 7, 8

and 9). 100ml of the dye solution containing 100mg of the dye (Methylene Blue, Methyl

Violet, Acid Blue and Acid Violet) are prepared from the stock solution. The pH of the dye

solutions are adjusted to a desired pH using 0.1N H2SO4 or 0.1N NaOH and the solutions

are taken in Pyrex bottles containing 500mg of the adsorbent. These solutions are shaken

using horizontal electrical bench shaker by varying the contact time from 10 to 180minutes.

The solutions are filtered and analysed colorimetrically at 480nm for Methylene Blue & Acid

Blue dyes and at 420nm for Methyl Violet & Acid Violet dyes to find the amount of dye

adsorbed.

3.5.3 Effect of variation of adsorbent dosage on the adsorption of dye

The effect of adsorbent dosage on the adsorption of dyes (Methylene Blue, Methyl

Violet, Acid Blue and Acid Violet) is studied at pH 7.0 ± 0.2 and 32 ± 2˚C. 100ml of dye

solutions containing 100mg of dye are prepared from stock solution. The solutions are

taken in Pyrex bottles containing 200, 300, 400 and 500mg of the adsorbent BGA. The

Pyrex bottles containing adsorbent and adsorbate are shaken using horizontal electrical

bench shaker at room temperature by varying the contact time from 10 to 180 minutes.

Then the solutions are filtered and analysed colorimetrically at 480nm for Methylene Blue &

Acid Blue dyes and at 420nm for Methyl Violet & Acid Violet dyes to find the amount of dye

removed by the adsorbent BGA.

30

3.5.4 Effect of variation of temperature on the adsorption of dye

To study the effect of temperature, 100ml of dye solutions containing 100mg of the

dyes (Methylene Blue, Methyl Violet, Acid Blue and Acid Violet) are prepared from the

stock solution and taken in Pyrex bottles containing 500mg of BGA. The pH of the dye

solution is maintained as 7.0 ± 0.2 for this study. These solutions are taken in a

temperature controlled horizontal electrical bench shaker and agitated by varying the

contact time from 10 to 180minutes at 22˚C, 32˚C and 42˚C. Then the solutions are filtered

and analysed colorimetrically at 480nm for Methylene Blue & Acid Blue dyes and at 420nm

for Methyl Violet & Acid Violet dyes to find the amount of dye adsorbed by the adsorbent

BGA.

3.5.5 Removal of Methylene Blue, Methyl Violet, Acid Blue and Acid Violet dyes byAdsorption from Dyeing Industrial Effluent using the adsorbent BGA

The textile dye effluent containing Methylene Blue and Acid Violet are collected from

Sri Ram Dyeing, Angeripalayam, Tiruppur, Tamilnadu, India. Dye effluent containing Acid

Blue and Methyl Violet are collected from Dhanalakshmi Dyeing Company, Tiruppur,

Tamilnadu, India. Batch mode experiments are conducted using the adsorbent BGA and

the dyeing industrial effluent containing Methylene Blue, Methyl Violet, Acid Blue and Acid

Violet dyes. The pH of the dyeing industrial effluent collected varied from 8.76 to 10.57.

Therefore, the pH of the dyeing industrial effluent is adjusted to pH 7.0 ± 0.2 using 0.1N

H2SO4. 100ml of the effluent containing 100mg of the dyes (Methylene Blue, Methyl Violet,

Acid Blue and Acid Violet) are prepared from the industrial effluent and taken in the Pyrex

bottles containing 500mg of the adsorbent BGA and agitated using horizontal electrical

bench shaker at 32 ± 2˚C for predetermined time intervals of 10 to 180minutes. The

solutions are filtered and analysed colorimetrically at 480nm for Methylene Blue & Acid

Blue dyes and at 420nm for Methyl Violet & Acid Violet dyes to find the amount of dye

adsorbed.

Batch mode experiments are also conducted using Commercial Activated Carbon

(CAC) as an adsorbent. The pH of the dyeing industrial effluent is adjusted to pH 7.0 ± 0.2

using 0.1N H2SO4. 100ml of the effluent containing 100mg of the dyes (Methylene Blue,

Methyl Violet, Acid Blue and Acid Violet) are prepared from the dyeing industrial effluent

and taken in the Pyrex bottles containing 500mg of the adsorbent CAC and agitated using

horizontal electrical bench shaker at 32 ± 2˚C for predetermined time intervals of 10 to

180minutes. The solutions are filtered and analysed colorimetrically at 480nm for

Methylene Blue & Acid Blue dyes and at 420nm for Methyl Violet & Acid Violet dyes to find

the amount of dye adsorbed.

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3.6 Kinetics, Adsorption Isotherm and Thermodynamic Studies for the Removal ofDyes

The results of the above mentioned studies are used to determine the rate constants

for the adsorption of the dyes from aqueous solution and also from dyeing industrial effluent

using Lagergren rate equation, Intraparticle diffusion rate equation and Elovich rate

equation. Langmuir & Freundlich adsorption isotherms and Thermodynamic parameters

(∆S, ∆G and ∆H) are evaluated for the adsorption of Methylene Blue, Methyl Violet,

Acid Blue and Acid Violet dyes.

3.7 Scanning Electron Microscope and FTIR Spectral Analysis

The Scanning Electron Microscope is a microscope that uses electrons, instead of

light to form an image. Since their development in the early 1950’s has developed new

areas of study. The SEM has allowed researchers to examine a much bigger variety of

specimens.

The Scanning Electron Microscope has many advantages over traditional

microscopes. The SEM has a large depth of field, which allows more of a specimen to be in

focus at one time. The SEM also has much higher resolution, so closely spaced specimens

can be magnified at much higher levels, because the SEM uses electromagnets rather than

lenses and the researcher has much more control in the degree of magnification. All of

these advantages, as well as the actual strikingly clear images, make the Scanning

Electron Microscope is one of the most useful instruments in research today. The surface

morphology of the adsorbent BGA before and after adsorption of the dyes used in this

study is observed using Scanning Electron Microscope (FEI Quanta 200 SEM).

32

The SEM photographs of the following are obtained:

The adsorbent Blue-Green Algae (BGA)

Adsorbent BGA with the adsorbed Methylene Blue dye from aqueous solution

Adsorbent BGA with the adsorbed Methyl Violet dye from aqueous solution

Adsorbent BGA with the adsorbed Acid Blue dye from aqueous solution

Adsorbent BGA with the adsorbed Acid Violet dye from aqueous solution

Adsorbent BGA with the adsorbed Methylene Blue dye from Industrial Effluent

Adsorbent BGA with the adsorbed Methyl Violet dye from Industrial Effluent

Adsorbent BGA with the adsorbed Acid Blue dye from Industrial Effluent

Adsorbent BGA with the adsorbed Acid Violet dye from Industrial Effluent

FTIR Spectral Analysis of the Adsorbent Blue-Green Algae

Infrared spectrum of the adsorbent, Blue-Green Algae is obtained using a Fourier

Transform Infrared spectrometer (Perkin Elmer Model Spectrum RX1 in the wavenumber

range 4000 – 400cm-1, using KBr pellet technique).

32

The SEM photographs of the following are obtained:

The adsorbent Blue-Green Algae (BGA)

Adsorbent BGA with the adsorbed Methylene Blue dye from aqueous solution

Adsorbent BGA with the adsorbed Methyl Violet dye from aqueous solution

Adsorbent BGA with the adsorbed Acid Blue dye from aqueous solution

Adsorbent BGA with the adsorbed Acid Violet dye from aqueous solution

Adsorbent BGA with the adsorbed Methylene Blue dye from Industrial Effluent

Adsorbent BGA with the adsorbed Methyl Violet dye from Industrial Effluent

Adsorbent BGA with the adsorbed Acid Blue dye from Industrial Effluent

Adsorbent BGA with the adsorbed Acid Violet dye from Industrial Effluent

FTIR Spectral Analysis of the Adsorbent Blue-Green Algae

Infrared spectrum of the adsorbent, Blue-Green Algae is obtained using a Fourier

Transform Infrared spectrometer (Perkin Elmer Model Spectrum RX1 in the wavenumber

range 4000 – 400cm-1, using KBr pellet technique).

32

The SEM photographs of the following are obtained:

The adsorbent Blue-Green Algae (BGA)

Adsorbent BGA with the adsorbed Methylene Blue dye from aqueous solution

Adsorbent BGA with the adsorbed Methyl Violet dye from aqueous solution

Adsorbent BGA with the adsorbed Acid Blue dye from aqueous solution

Adsorbent BGA with the adsorbed Acid Violet dye from aqueous solution

Adsorbent BGA with the adsorbed Methylene Blue dye from Industrial Effluent

Adsorbent BGA with the adsorbed Methyl Violet dye from Industrial Effluent

Adsorbent BGA with the adsorbed Acid Blue dye from Industrial Effluent

Adsorbent BGA with the adsorbed Acid Violet dye from Industrial Effluent

FTIR Spectral Analysis of the Adsorbent Blue-Green Algae

Infrared spectrum of the adsorbent, Blue-Green Algae is obtained using a Fourier

Transform Infrared spectrometer (Perkin Elmer Model Spectrum RX1 in the wavenumber

range 4000 – 400cm-1, using KBr pellet technique).