PREDICTION OF THE SOLUBILITY OF H2S IN NACL AQUEOUS-SOLUTION - AN EQUATION OF STATE APPROACH

A model is developed for the prediction of H2S solubility in NaCl-bear ing aqueous solutions up to about 300 bar, 320 degrees C and 6 m NaCl. Although many H2S solubility measurements have been published, most o f them are limited to low pressures (just above water saturation press ure). In order to predict solubilities to higher pressures, we have de veloped an equation of state (EOS) for the H2S-H2O binary, which allow s us to calculate chemical potentials of both H2S and H2O in liquid or in vapor phase. Below 350 degrees C NaCl has negligible effect on the vapor phase but has substantial effect on the activities of H2S in th e liquid phase. This salt effect is accounted for by specific ion inte ractions. Comparison of this model with all the available data indicat es that predictions are within experimental uncertainty, even for pres sures well above that covered by the data used for parameterization.