Alkali salt of sulfonated aryl azo amino sulfonyl aryl azo sulfonyl aryl azo aryl sulfonate

Endpoint summary

Additional information

The test substance, Reactive Brown 0331/0334 , is a solid under all environmental conditions and is highly soluble in water. It has a low volatility (based on the high melting / boiling point and high molecular weight) and a low affinity for soil / sediment (based on the partition coefficient value of log Kow < -6 and the calculated adsorption coefficient of log Koc < - 0.9). As such, any environmental release will result in virtually all of the substance compartmentalising into water compartments, with little release directly to atmosphere or compartmentalising to soil/sediment compartments.

Any potential exposure to the environment is predicted to result in rapid redistribution to water; due to its low volatility, high water solubility and partitioning values indicates that the majority of the substance would eventually partition to water rather than to soil and sediment should it be released to the environment.

A Level III fugacity model was conducted in the US EPA EPISUITE which assumes steady-state but not equilibrium conditions. The Level III model in EPI Suite predicts partitioning between air, soil, sediment and water using a combination of default parameters and various input parameters. This model has been used to calculate the theoretical distribution of the highest % component substance between four environmental compartments (air, water, soil, sediment) at steady state in a unit world.

Partitioning model Reactive Brown 0331/0334

 

Compartment

Distribution [%]

Half-life [h]

			DYHY0331	DYHY0334		DYHY0331	DYHY0334
Air			2.05E-005	3.4E-006		12.7	5.7
Water			0.992	0.619		4.32E+003	4.32E+003
Soil			58	53		8.64E+003	8.64E+003
Sediment			41	46.3		3.89E+004	3.89E+004

It is proposed that although the majority of the substance distributes to the soil/sediment compartments within the model, the high solubility in water indicates that the substance is more likely to distribute to water – e. g. soil pore water.

This assumption is confirmed by the model for the STP Overall Chemical Mass Balance in the US EPA EPI SUITE, which shows that 98% of the influent of the dye is in the water phase:

STP Overall Chemical Mass Balance

 

g/h

mol/h

percent

	DYHY0331	DYHY0334	DYHY0331	DYHY0334	DYHY0331/0334
Influent	1.00E+001	1.00E+001	9.1E-003	8.4E-003	100.00
Primary sludge	2.50E-002	2.50E-002	2.3E-005	2.1E-005	0.25
Waste sludge	1.50E-001	1.50E-001	1.4E-004	1.3E-004	1.50
Primary volatilization	2.02E-024	3.66E-025	1.8E-027	3.1E-028	0.00
Settling volatilization	5.51E-024	9.98E-025	5.0E-027	8.3E-028	0.00
Aeration off gas	1.36E-023	2.46E-024	1.2E-026	2.1E-027	0.00
Primary biodegradation	1.76E-003	1.76E-003	1.6E-006	1.5E-006	0.02
Settling biodegradation	5.27E-004	5.27E-004	4.8E-007	4.4E-007	0.01
Aeration biodegradation	6.93E-003	6.93E-003	6.3E-006	5.8E-006	0.07
Final water effluent	9.82E+000	9.82E+000	9.0E-003	8.2E-003	98.15
Total removal	1.85E-001	1.85E-001	1.7E-004	1.5E-004	1.85
Total biodegradation	9.22E-003	9.22E-003	8.4E-006	7.7E-006	0.09