Diethylhydroxylamine (DEHA) Supplier South Africa

What Is Diethylhydroxylamine?

Diethylhydroxylamine (DEHA, N,N-diethylhydroxylamine) is an organic nitrogen compound that functions as a volatile oxygen scavenger and passivating agent in boiler and steam system water treatment. Unlike inorganic oxygen scavengers (sodium sulfite, hydrazine), DEHA is volatile — it distributes between the boiler water and the steam phase, travelling with the steam into the condensate system where it continues to scavenge oxygen and provides corrosion protection throughout the steam-condensate circuit. This makes DEHA uniquely effective in systems where oxygen ingress occurs throughout the condensate return, not only in the deaerator-to-boiler section.

Oxygen Scavenging and Passivation Mechanism

DEHA reduces dissolved oxygen in boiler feedwater through the reaction: 2(C₂H₅)₂NOH + O₂ → 2(C₂H₅)₂NO + H₂O (oxidised to diethylnitroxide). The scavenging reaction proceeds at temperatures above 60°C and is effective across the operating temperature range of low- to medium-pressure boilers. Beyond oxygen removal, DEHA’s most distinctive benefit is passivation: it promotes formation of a magnetite (Fe₃O₄) passivation film on steel surfaces in the boiler and condensate system, rather than the porous, less protective iron oxide (hematite, Fe₂O₃) that forms under less reducing conditions. This dense magnetite film provides superior long-term corrosion protection and reduces iron transport into the boiler.

Advantages Over Sodium Sulfite

Sodium sulfite, the conventional inorganic oxygen scavenger, introduces sulfate into the boiler water (Na₂SO₃ + ½O₂ → Na₂SO₄) and is non-volatile — it does not protect the condensate system. At boiler pressures above ~40 bar, sodium sulfite also thermally decomposes to SO₂ and H₂S gases, which cause condensate corrosion. DEHA avoids these issues — it produces no sulfate or corrosive decomposition products and travels with steam to protect the condensate return. Terracore Chemicals supplies DEHA (95% grade) in 25 kg and 200 kg drums for boiler water treatment programmes across Southern Africa.