Ammonia-water neutralization with sulfuric acid to ammonium sulfate

A 2 wt% ammonia water (a scrubber or coke-oven bleed) is neutralized with 20 wt% sulfuric acid to pH 6.0. The neutralizer solves the acid dose (drawn from the acid supply, the rest returned) on the aqueous speciation (NH4+ pKa 9.25), so at pH 6 nearly every ammonia molecule is protonated and the dose lands at half a mole of sulfuric acid per mole of ammonia: the stream leaves as ammonium sulfate solution, reported from the speciation. The heat of neutralization is the ammonium dissociation enthalpy, 52.2 kJ per mole of ammonia protonated (110 kW here), and the outlet is adiabatic, so the liquor warms by about 12 K. Honesty notes: (1) only the proton-transfer heat is carried; diluting concentrated acid releases much more on its own, which is why a dilute acid is dosed here; (2) the aqueous package treats ammonia as non-volatile, so the ammonia a warm, alkaline liquor loses to the air is not shown; and (3) activity coefficients are B-dot, a screening model above about 1 mol/kg ionic strength.