AGGREGATION OF TWO D DISAZO ISAZO AGGREGATION OF TWO DIRECT DYES - - PowerPoint PPT Presentation

AGGREGATION OF TWO AGGREGATION OF TWO D DISAZO ISAZO DIRECT DYE DIRECT DYES

• S. EXPERIMENTAL AND

. EXPERIMENTAL AND THEORETICAL STUDY THEORETICAL STUDY

Simona Ga Simona Gab briela Muntean riela Muntean, ,1

1

Maria Grad, Maria Grad,1

1

Z Z. . Szabadai Szabadai 2

2

1 1Institute of Chemistry Timisoara of Romanian Academy,

Institute of Chemistry Timisoara of Romanian Academy, B-dul Mihai Viteazul 24, 300223 Timisoara, Romania; B-dul Mihai Viteazul 24, 300223 Timisoara, Romania;

2 2University of Medicine and Pharmacy “Victor Babes”, Faculty of Pharmacy Piata E.

University of Medicine and Pharmacy “Victor Babes”, Faculty of Pharmacy Piata E. Murgu 2-4, 300034 Timisoara, Romania Murgu 2-4, 300034 Timisoara, Romania

Introduction Introduction

 Adsorption of dyes on solid adsorbents is

Adsorption of dyes on solid adsorbents is influenced by the physicochemical properties influenced by the physicochemical properties

• f the dyes solutions.
• f the dyes solutions.

 Azo dyes are compounds whose molecules

Azo dyes are compounds whose molecules have a tendency to self-associate in the have a tendency to self-associate in the ground electronic state. ground electronic state. That can lead to the That can lead to the formation of dimers, trimers, and tetramers. formation of dimers, trimers, and tetramers.

 T

The main factors influencing aggregation are: he main factors influencing aggregation are: dye structure, dye concentration, electrolyte dye structure, dye concentration, electrolyte concentration, and temperature. concentration, and temperature.

n D Dn

Aim Aim



Investigation of the molecular aggregation of two direct dyes

Investigation of the molecular aggregation of two direct dyes in aqueous solution, as a function of dye concentration. in aqueous solution, as a function of dye concentration.



Mathematical analysis

Mathematical analysis

• f the aggregation of the studied dyes.
• f the aggregation of the studied dyes.

Experimental Experimental

N N H H N N O H H2NOC CONH2 OH SO3Na NaO3S

• Fig. 1. The structure of the studied disazo dyes

DSA

N N H H N N NaO3S SO3Na NH2 N H2 NaO3S SO3Na

DAN

Results and Discussions Results and Discussions

• Fig. 2. Direct dyes DSA and DAN absorption spectra at

different concentrations

300 400 500 600 0.0 0.2 0.4 0.6 0.8 1.0

DSA

ε / 10 4 (M

• 1 cm
• 1)

λ (nm)

1*10

• 3

5*10

• 4

1*10

• 4

5*10

• 5

1*10

• 5

5*10

• 6

1*10

• 6

300 400 500 600 700 800 0.0 0.2 0.4 0.6 0.8

DAN

ε / 10

4 (M

• 1 cm
• 1)

λ (nm)

1*10

• 3 M

5*10

• 4 M

1*10

• 4 M

5*10

• 5 M

1*10

• 5 M

5*10

• 5 M

1*10

• 6 M

Figure 3. The trend in studied dye’s absorption coefficient as concentration varies

0.0 0.2 0.4 0.6 0.8 1.0 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

DSA

ε / 10

4 (M

• 1 cm
• 1)

Initial concentration (mM)

Absorption coefficient (410 nm)

0.0 0.2 0.4 0.6 0.8 1.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

DAN

ε / 10

4 (M

• 1 cm
• 1)

Initial concentration (mM)

Absorption coefficient (500 nm)

Matematical analysis

 Using the experimental absorbance values, an n x m

Using the experimental absorbance values, an n x m (n: values of absorption at different wavelength, (n: values of absorption at different wavelength, m: concentrations) dimension matrix was build for a m: concentrations) dimension matrix was build for a series of analytical concentrations. series of analytical concentrations.



The number of eigenvalues of this matrix different

The number of eigenvalues of this matrix different from zero (within accepted experimental errors) is from zero (within accepted experimental errors) is equal to the number of chemical species (monomer, equal to the number of chemical species (monomer, dimer, etc.) presented in the system. dimer, etc.) presented in the system.

Matriceal Analysis Matriceal Analysis

The eigenvalues value of the absorption matrix for DSA and DAN dyes

DSA DAN

• 3.084 x 10-15
• 3.983 x 10-15

3.985 x 10-14 2.371 x 10-5 1.399 x 10-13 1.938 x 10-4 1.566 x 10-4 3.783 x 10-4 1.001 x 10-3 2.584 x 10-3 0.087 0.025 3.289 8.339 163.642 116.417

Conclusion

• UV-Vis spectroscopy has been used to study

UV-Vis spectroscopy has been used to study the aggregation of two disazo direct dyes the aggregation of two disazo direct dyes ( (DSA DSA, , DAN DAN) in aqueous solution; ) in aqueous solution;

• The

dyes aggregation depends

• n

the The dyes aggregation depends

• n

the concentration. concentration.

• From the matriceal analysis, the number of

From the matriceal analysis, the number of chemical species presented in the system was chemical species presented in the system was determined, in domain of concentrations determined, in domain of concentrations studied. studied.

Thank you! Thank you!