Vanadium and ADA chemistry for liquid redox sulfur recovery units.
The Stretford process removes hydrogen sulfide from gas streams by absorbing it into an alkaline solution and oxidising it directly to elemental sulfur, which is then filtered out and the solution returned to the absorber.
Vanadium is the oxidising agent that converts the absorbed sulfide. Once reduced, it is regenerated by ADA (anthraquinone disulfonic acid), which is itself re-oxidised by air blown through the solution. The vanadium cycles rather than being consumed, but solution losses, upsets and blowdown mean units require ongoing replenishment.
Because the chemicals in a Stretford unit work as a system rather than individually, Riverside supplies them as a set and can match the balance an existing unit is already running.
Vanadium is the electron acceptor that turns absorbed sulfide into elemental sulfur, then hands those electrons to ADA for regeneration by air. It cycles continuously rather than being consumed, but every unit loses solution and needs make-up.