Number

053-EN

Section

General Section

Use

Abstract

Hydrazine has been added in 2011 to ECHA’s Candidate List of substances of very high concern for Authorisation under REACH as carcinogen cat. 1B Alternatives to hydrazine as oxygen scavenger in the treatment of industrial water for boilers are presented with a brief comparison of the main technical advantages/limitations.

Substituted substances

Alternative Substances

Reliability of information

Internet information: data are from an internet document and only a basic and partial evaluation could be performed

Reason substitution

CMR
skin/respiratory sensitizing

Hazard Assessment

Hydrazine is classified as carcinogen cat. 1B and sensitisation agent (H317) and is listed on the Substance Database according to SUBSPORT Screening Criteria (SDSC). The alternatives have no official classification and are not listed on the SDSC. » Check the Substance Database according to SUBSPORT Screening Criteria (SDSC)

Description of Substitution

Introduction The so-called “oxygen scavengers” are used to treat industrial water in order to reduce the concentration of dissolved oxygen and its corrosion potential that has a negative impact on installations and processes. Hydrazine is an effective oxygen scavenger. It has been added 2011 to ECHA’s Candidate List of SVHC for authorization under REACH as carcinogen cat. 1B. Hydrazine was largely used due to its advantages: does not generate solids in the system or corrosive gases like CO2 and forms a protective film on the metal surface. Hydrazine is often catalysed by hydroquinone or cobalt salts. Due to its hazards hydrazine use should be ceased and several alternatives are available as described below. Diethylhydroxylamine (DEHA) is a volatile metal-passivating oxygen scavenger. In considering thermal and oxidative degradation products, DEHA generates dialkyl amines, acetaldehyde, acetaldoxime and acetic acid. DEHA may be used on its own but is more effective when catalysed by hydroquinone. Carbonohydrazide reacts readily with oxygen at low temperatures and pressures. It is volatile, passivates the metal and does not generate any solids to the system. Carbonohydrazide breaks down to hydrazine at temperatures over 180˚C but this product reacts further with oxygen. This means also that it won’t have hydrazine residues, defeating the purpose of substitution. Carbonohydrazide reaction with oxygen generates carbon dioxide gas that results in corrosive condensate. Erythorbate passivates metal and contributes no solids to the system. It is non-volatile and will not travel with the stream to control oxygen corrosion in the condensate. It is generally regarded as safe (GRAS) by the FDA and can be used in food processing applications. Sodium sulfite is fast reacting and effective. It does not create a protective magnetite film and is ineffective in re-passivating boilers with existing rust. Sulfite reaction with oxygen produces sodium sulfate, a solid, making sulfite inappropriate in high pressure and supercritical boilers. Sodium sulfite is nonvolatile and is not driven by the steam in the condensate system, thus providing no protection to this part. Sulfite breaks down to gases like SO2 and H2S that have a corrosive impact throughout the system. Quinones and cobalt salts are typically used as catalysts for sodium sulfite. Description of procedure or technology (including pre-/post-processing) Way of application: e.g. spraying, dipping, open/closed system etc. Risk management measures (technical, organizational and personal) Risk reduction by alternative: Human health: e.g. more/less safety measures e.g. technical/operational/personal protection measures Risk reduction by alternative: Environment: e.g. waste reduced/increased

Case/substitution evaluation

SUBSPORTplus Comments Hydroquinone (CAS No. 123-31-9) and 2-butanone oxime (CAS No. 96-29-7) are mentioned in the literature as alternatives too. According to the current state of knowledge, they do not meet the SUBSPORT criteria (SDSC) since they are classified as sensitizing substances according to CLP (H317). They could not be recommended on SUBSPORTplus. Operating conditions and the materials that the boilers and the rest of the steam system are made of can limit the use of some of the alternatives, as described above.

State of implementation

In use

Date and place of implementation

2001 in USA

Availability ofAlternative

Alternatives are available on the market.

Producer/Provider

https://www.arkema-americas.com/en/

Type of information supplier

Producer / distributor

Further information

1. IARC acetaldehyde monograph

2. Report on toxicology MEKO

3. Technical Rule for Hazardous Substances (TRGS) 608 Substitutes, substitution of working methods and restrictions on use for hydrazine in water- and vapour systems (1991, amended 1993) (in German)

Publication source: author, company, institute, year

https://www.arkema-americas.com/en/

Date, reviewed

February 27, 2020