weight percentages unless otherwise indicated a nano particle zinc oxide dispersed in mineral spirits is used to treat a 58 28 grade asphalt bottoms product from an oil refinery the zinc oxide has a particle size range of from 50 80 nm the zinc oxide dispersion is introduced into a clean paint can in the amounts shown below in table 1 500 ml of asphalt is introduced into the paint can the paint can is sealed the sample within the paint can is maintained at 350 u00b0 c using an oven the additive is admixed with the asphalt by shaking the paint cans using a shaker table at the times indicated in table 1 the paint cans are pierced and the hydrogen sulfide concentration in the head space within the paint can is determine using a dr u00e4ger u00ae tube results are shown below in table 1 example 1 is reproduced except that a different sample of asphalt is used and in samples 2a and 2c the zinc oxide has different particle sizes and in sample 2b the particles are about 90 wt zno and 10 wt znco 3 the results as shown below in table 2 example 1 is reproduced except that other hydrogen sulfide scavengers are used instead of the nano particle zinc oxide of the invention sample 3 a is an iron carboxylate prepared using ethylhexanoic acid it is present at a concentration of 5 6 fe metal example 3 b is the condensation product of butyl aldehyde and ethanol amine it is present at a concentration of 70 percent by weight in kerosene the results are displayed below in table 3 a nano particle zinc sulfonate dispersed in mineral spirits is used to treat a 58 28 grade asphalt bottoms product from an.