Number

179-EN

Section

General Section

Use

Abstract

The Danish EPA and some Danish companies carried out a project on substitution of polyfluorinated (PFOS) surfactants for use in non-decorative hard chrome plating. Experiments on both laboratory scale and larger industrial scale have shown that it is possible to substitute PFOS as mist suppressant in the non-decorative hard chrome plating process.

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
PBT
ecotoxicity

Other type of alternative

Three non-chemical alternatives were tested in the study: PTFE (polytetrafluoroethylene) coated balls, a mesh or blanket placed on top of the chrome bath and prevention of air convection. For further information please see the case description.

Hazard Assessment

There is an official classification for PFOS on, but it has not been possible to find a MSDS on either Fumetrol® 21 or TIB Suract CR-H. In the report from the Danish EPA there is a summary (table 4-1) of the environmental and health data for PFOS and the alternatives. Substance to be substituted: Perfluorooctane sulfonic acid (PFOS) may cause cancer cat. 1B, according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). It fulfils the criteria to be listed in the Substance Database according to SUBSPORTplus Screening Criteria (SDSC). There is no information available about the chemical substances in TIB Suract CR-H, because this is confidential. The Danish EPA, however, find Fumetrol® 21 to be a safer alternative to PFOS. Alternative substance: 3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooctanesulphonic acid has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation) and is not listed in the Substance Database according to SUBSPORTplus Screening Criteria (SDSC).

Description of Substitution

Hard chrome plating is a surface treatment process where a layer of chromium is electrochemically deposited on the surface of metals. The electrochemical process produces a significant amount of gas to be released from the process tank. These gases rise to the surface as bubbles. Most bubbles burst at the surface and form aerosols which are released to the atmosphere. The aerosols consist of process liquid containing chromic acid and thus may expose the environment if no mist suppressant agent is used. Some years ago it was discovered that addition of polyfluorinated surfactants (PFOS and derivatives) to the chromic acid bath would lower the surface tension by forming a thin foamy layer on the surface of the chrome bath. That mist suppressant layer significantly reduced the formation of chromium-VI aerosols (Cr6+), which are well-known as carcinogenic, allergenic and dangerous for the environment. Thus, it was thought that the introduction of PFOS as mist suppressant helped solving huge occupational safety problems as well as environmental problems in the hard chrome plating industry. The main conclusions of the project are: • A non-PFOS mist suppressant chemical alternative (Fumetrol® 21 from Atotech – based on 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctanesulphonic acid ) was found to be useful as an alternative to PFOS. The effectiveness, the durability, and the price level were similar to that of PFOS. The non-PFOS alternative is an environmental improvement as it is less persistent, less bioaccumulative, and less toxic than PFOS. • A non-fluorinated mist suppressant chemical alternative (TIB Suract CR-H from TIB Chemicals - no information about the chemical substance is available, as this is confidential) was found and might be a promising substitute for PFOS. However, as continuous addition of the mist suppressant is needed, the usefulness of the alternative seems to be limited for automated hard chrome processes and must be assessed in each case. Two physical alternatives were tested. • A physical alternative – in the form of PTFE (polytetraethylene) coated balls – does not seem to lower the chromium emissions from the chroming bath. Quite the contrary, the chromium emissions seem to increase compared to when using no mist suppressant at all. • A physical alternative – in the form of a mesh or blanket – could be suitable for large scale series plating of uniform products. However, this kind of alternative was not investigated further in this project. The laboratory results of this project showed that the Cr6+ emission can be reduced radically by avoiding air convection. This indicates that large scale tests of the described physical methods that prevent air convection could turn out to be an alternative to PFOS. Such method would be a suitable alternative to PFOS in mass production systems. However, in plating system for frequently varying productions, it will be more difficult to establish a closed system because of the flexibility required to such systems. However, this alternative solution was not investigated further in the project, but would be a very interesting solution to investigate further.

Case/substitution evaluation

There is an official classification for PFOS in EU. PFOS dos not pass the SUBSPORTplus Screening Criteria (SDSC). PFOS are restricted in the EU by Regulations 756/2010/EU and 757/2010/EU. However, in this case, there is an exemption for spray suppression of non-decorative hard chrome plating in closed loop system as long as there is no alternative. The ingredients of TIB Suract CR-H are confidential and not known to SUBSPORTplus. Therefore SUBSPORTplus has not been able to assess the product. One of the substances in Fumetrol® 21 is known (the tridecafluorooctanesulphonic acid) and this substance does pass the SDSC. Due to the fact, that the rest of the substances in the alternative products are unknown, it has not been possible for SUBSPORTplus to determine whether or not the alternatives pass the SDSC. In the report from the Danish EPA there is a summary (table 4-1) of the environmental and health data for PFOS and the alternatives. The conclusion in the report is that Fumetrol® 21 is a safer alternative than PFOS. SUBSPORT recommend further investigation of the contents of the alternative products.

State of implementation

Pilot study

Date and place of implementation

29.06.2011

Enterprise using the alternative

The pilot study was managed by Force Technology in cooperation with IPU, DTU Mechanical Engineering  and the surface treatment company a.h. nichro Haardchrome A/S that was assisted by the development company SurfCoat A/S .

Availability ofAlternative

The chemical alternatives are on the market.

Producer/Provider

Fumetrol(R) 21 www.atotech.com TIB Suract CR-H www.tib-chemicals.com

Type of information supplier

Authority

Type of publication and availability

Freely available on www.mst.dk

Publication source: author, company, institute, year

Miljøstyrelsen (Danish EPA) www.mst.dk

Publication source

Type of publication and availability

http://www2.mst.dk/udgiv/publications/2011/06/978-87-92779-10-6.pdf

Date, reviewed

November 26, 2021