You are here:
MEASUREMENT OF PARTIAL VAPOR PRESSURE OF AMMONIA OVER ACID AMMONIUM SULFATE SOLUTIONS BY AN INTEGRAL METHOD
Citation:
Koutrakis, P. AND B. Aurian-Blajeni. MEASUREMENT OF PARTIAL VAPOR PRESSURE OF AMMONIA OVER ACID AMMONIUM SULFATE SOLUTIONS BY AN INTEGRAL METHOD. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/446.
Description:
We present a simple, integral, passive method for measuring partial vapor pressure. ntegral methods are useful tools when dealing with very low concentrations because collection over extended periods increases the analytical sensitivity. assive methods have the advantage of not introducing constraints external to the system. he principle of the method used here is to selectively react the substance in the atmosphere over a solution with an immobilized coating on an appropriate support. he reaction product is not volatile, but is soluble and can be extracted in an appropriate solvent and analyzed. he method has been applied to measuring the vapor pressure of ammonia over aqueous solutions. he vapor pressure over ammonium sulfate solutions depends on the acidity of the solutions as well as on the salt concentration. he dependence can be explained with a simple model. urthermore, using the same model, we calculated the ammonia vapor pressure above different ammonium sulfate/ sulfuric acid aqueous solutions as a function of sulfate molarity and percentage of sulfuric acid. he results from the calculations suggest that for ambient ammonia concentrations less than 10 ppb, acid sulfate aerosols are not completely neutralized.