Sodium Hydrosulfide (NaHS) Storage & Tank Compatibility

Storing Sodium Hydrosulfide (NaHS)? Start Here

Sodium hydrosulfide, NaHS, is the sodium salt of hydrosulfide ion and one of the workhorse sulfur chemicals of industry. It is supplied mainly as a yellow-to-amber aqueous solution (commonly 40 to 45 percent) and as a flake, both carrying a strong rotten-egg odor. The solution is markedly alkaline and a powerful reducing agent. In water it slowly evolves hydrogen sulfide gas, and that release accelerates sharply if the liquid is acidified, making pH control and ventilation central to safe storage. Major uses include kraft pulp digestion, leather de-hairing, ore flotation and copper-molybdenum separation, dye and chemical manufacture, and as a sulfide source for heavy-metal precipitation in wastewater treatment. Because the bulk product is an alkaline salt solution rather than an organic solvent, it pairs naturally with polyethylene storage. The dominant engineering hazards are its corrosivity, its aquatic toxicity, and the toxic _H2S headspace it generates.

Is Sodium Hydrosulfide Compatible With Polyethylene Tanks?

Yes. Sodium hydrosulfide in its normal commercial form is a strongly alkaline aqueous sulfide-salt solution, and that is squarely within the comfort zone of polyethylene. HDPE and crosslinked polyethylene (XLPE) tanks resist sulfide salts and caustic solutions well, which is why polyethylene is the standard material of construction for NaHS bulk storage. Published resistance data for the closely related salt sodium sulfide rate HDPE as resistant at both 20 C and 60 C, and the alkaline character of NaHS poses no oxidative or solvent attack on the resin.

The cautions are practical rather than chemical. Specify gaskets in EPDM rather than FKM, vent the tank to a scrubber because the solution continuously liberates toxic hydrogen sulfide, and keep all wetted and headspace metal out of the service or use a verified resistant alloy. Confirm the temperature rating against your delivered product, and always validate the final selection against the specific supplier SDS and the tank manufacturer resistance chart for your grade and concentration.

Material compatibility at a glance

Sodium hydrosulfide is normally handled and stored as a strongly alkaline aqueous solution. That chemistry is well matched to polyethylene: HDPE and crosslinked polyethylene (XLPE) tanks are the standard choice, with PP, PVC, and CPVC also serving in fittings and ancillary equipment. The real failure mode is metallic, not plastic. Carbon steel and non-ferrous metals are corroded and embrittled by both the dissolved sulfide and the hydrogen sulfide gas the solution slowly liberates, so wetted metal paths and head-space metals should be avoided or specified in resistant alloys. EPDM is a reliable seal elastomer; FKM (Viton) is not recommended.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Releases toxic, flammable hydrogen sulfide gas; the release intensifies dramatically if the solution contacts acid. Never co-store with or allow accidental mixing of acids, and vent storage to a scrubber.
• Severely corrosive: causes severe skin burns and serious eye damage (H314, H318). Wear chemical goggles, face shield, and chemical-resistant gloves and apron.
• Toxic if swallowed and harmful through skin (H301, H312); may damage organs (H371). Use respiratory protection rated for hydrogen sulfide where exposure is possible.
• The solid is a self-heating, combustible material liable to spontaneous heating in moist air (H251, H226); keep dry product cool, sealed, and away from ignition sources.
• Very toxic to aquatic life (H400); bund and curb tanks to prevent any release to drains or surface water.
• Corrosive to metals (H290); use polyethylene tanks and non-metallic or verified-alloy wetted parts, and monitor for hydrogen-sulfide-driven attack on nearby steelwork.

Common questions

Can I store sodium hydrosulfide solution in an HDPE or XLPE tank?

Yes. NaHS solution is an alkaline aqueous sulfide salt, and polyethylene is the standard tank material for it. Resistance data for the related salt sodium sulfide rate HDPE as resistant at 20 C and 60 C. Use EPDM gaskets, vent to a scrubber for hydrogen sulfide, and confirm against your supplier SDS and the tank maker resistance chart.

Why does sodium hydrosulfide smell like rotten eggs and is the gas dangerous?

The solution slowly liberates hydrogen sulfide, which has the characteristic rotten-egg odor. Hydrogen sulfide is toxic and flammable, and it deadens the sense of smell at higher concentrations, so odor is not a reliable warning. Storage must be vented to a scrubber and the area monitored with hydrogen sulfide detection.

What must never be mixed with sodium hydrosulfide?

Acids. Adding acid to NaHS drives rapid evolution of toxic hydrogen sulfide gas. Keep it away from acids, oxidizers, and reactive metals, and design the facility so accidental cross-contamination cannot occur.

Is sodium hydrosulfide compatible with stainless steel or carbon steel?

Carbon steel and non-ferrous metals are corroded and embrittled by sulfide and by evolved hydrogen sulfide and should be avoided. Stainless steel can be attacked under some conditions; verify the specific alloy and service before relying on it. Polyethylene avoids the problem entirely.