The Calculation Of Clusters And Mechanism Of Inhibition At Gas/Liquid Interface On The Process Of Liquid Hazardous Chemicals Volatilization

The leakage of liquid hazardous chemicals that are important chemical raw materials will lead to the formation and transportation of poisonous gas, which has high risk to environment and people. In this study, a new method that using self-assembly monomolecular film as evaporation inhibitor was proposed based on the traditional dilution method. A new kind of evaporation inhibitor was synthesized, which could effectively inhibit volatilization of hazardous chemicals. The evaporation characteristic of ammonia, formaldehyde and saltpeter as well as inhibitor performance was investigated through experiments. In addition, energy barrier theory and quantum chemistry method were used in order to study the mechanism of evaporation and volatilization inhabitation. The main studies are as follows:(1) The experimental results of evaporation indicated that it was obvious that evaporation possessed interval characteristics and mass transfer coefficient had exponent relation to temperature, while there was a negative relationship between the concentration of solution and the temperature, which was different among those three chemicals. In particular, the evaporation of ammonia was notably influenced by temperature, which concentration decreased exponentially with experimental time. As for formaldehyde, there was a negative linear relation between concentration and experimental time; the valorization was intensified in the temperature range from 60℃ to 80℃. The relationship for saltpeter was parabolic and there was no evaporation until the temperature increased to 25℃. The rank of evaporation rate under the same condition was ammonia> formaldehyde> saltpeter.(2) The inhibition experiments showed that evaporation inhibitor performed well from 5℃ to 45℃. The inhibition rate was up to 90% in the temperature range from 5℃ to 35℃. Despite the decrease of inhibition rate with the increasing temperature, it was still higher than 70% up to 45℃. However, when the temperature reached 50℃, the order degree and compactness was decreased, which result in destroy of film structure and lose of inhibition ability.(3) The most stable structure of ammonia clusters, formaldehyde clusters and saltpeter clusters were obtained by molecular simulation. The calculation results indicated that the energy that needed for structure change of cluster were gradually increased as the evaporation was processed, which was consistent with the experimental results about mass transfer coefficient.(4) The theoretical study based on energy barrier theory and thermodynamics demonstrated that the energy barrier generated by inhibitor increased with temperature rise, which was much greater than the maximum energy required for volatilization in the temperature range from 25℃ to 50℃. Meanwhile, the change of Gibbs free energy for mass transfer on the gas-liquid surface was always greater than 0, which means that the volatilization caused by temperature change was restrained.