2,7-Naphthalenedisulfonic acid, 4-amino-3,6-bis[2-[4-(ethenylsulfonyl)phenyl]diazenyl]-5-hydroxy-, sodium salt (1:2)

Surface tension

Description of key information

The surface tension of the aqueous solution at 20°C is below 33.7 mN/m. The test item has surface-active properties.

Key value for chemical safety assessment

Surface tension:

33.7

in mN/m at 20°C and concentration in mg/L:

1

Additional information

The surface tension of the test item was determined using a plate tensiometer according to DIN EN 14370 -corresponding to A.5, Council Regulations EC No 440/2008 and OECD 115. A commercially available tensiometer based on the plate method has been used to measure the force which was required to withdraw a horizontally suspended plate from the surface of the test solution.
The surface tension was determined in a concentration of 1 g/L Reactive Black 5 bis-vinyl diluted in demineralized water at 20°C. For verification of the measured values demineralized water was also measured. With a correspondence of 100% of the measured value σ(20°C) = 72.5 mN/m, to the theoretical value σ(20°C) = 72.75 mN/m, cited in literature,the determination of the surface tension of the test item was considered as valid.

 

Result:

 

Test	Time [Minutes]	Surface tension at 20 °C [mN/m]
		Initial value	Final value after 10 measurements	Mean value
1^stvalue	10	36.2	34.6	35.3
2^ndvalue	39	35.5	33.7	34.3
3^rdvalue	59	35.1	33.3	34.1
4^thvalue	144	34.8	33.1	33.8
5^thvalue	179	34.8	32.9	33.7

 

Decreasing values of the surface tension of the test item Reactive Black 5 bis-vinyl were observed. No endpoint could be detected. The test substance is the vinyl form of a reactive dye and reacts via Michael addition with the water molecules to the alcohol form of the dye. Therefore, no stable surface value could be measured during the test.

The surface tension of the aqueous solution at 20°C is below 33.7 mN/m. The test item has hence surface-active properties.