Desenvolvimento do precesso de reduÃÃo de Ãcido nitroso por Ãcido amino sulfÃmico. Modelagem cinÃtica associada à transferÃncia gÃs-lÃquido

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The combustion of organic products, in particular, the natural gas, leads to the generation of nitrogenated oxides (NOx = NO and NO2; N2O) from both sources, the nitrogenous originated from the combustion air and nitrogenated compounds present in the fuel. NOx emissions can damage the human health and environment. They have been contributing widely to the formation of the ozone in the troposphere and also to its destruction in the stratosphere (smog). The reaction of the NO2 with water produce nitrous acid that can harm both the skin and also the respiratory system of human and animals. These facts together with the actual restrictions regulation of NOx emission, have led researchers to develop new clean-up technologies in order to treat gaseous industrial effluents comprised of NOx combustion products. In the light of this and the fact that the nitrous oxides usually appears dissolved in water, the present work studied the process of chemical transformation of the nitrous acid in aqueous solution through the evaluation of the kinetic of nitrous acid (HNO2) reduction reaction by the amine sulfamic acid (HSO3NH2). A mechanically agitated reactor was used in this study. It was investigated the effect on the reaction kinetic of the following operational parameters: velocity of impeller, pH, temperature, reagents initial concentration and stoichiometric ratio. According to this study, the nitrous acid transformation (XA= 98,54%) is favoured in pH acid (<2,5). The reaction follows a kinetic law of first order in relation to the reagents. Two distinct methods of analyse were used to evaluate the evolution of the process. They allowed to verify the discrepancy in the valour of the nitrite concentration obtained in the liquid phase and that one in the gaseous phase by means of the relative nitrogenous pressure. The nitrite concentration measured in liquid phase led to a kinetic more representative e intrinsic for the consume of the nitrite during the reduction reaction of the nitrous acid. Through the manometric method it was verified the influence of the nitrogenous transference from the liquid phase to the gaseous one. Thus, allowing the development of a heterogeneous model which includes the production of nitrogenous and the effects of the gas-liquid mass transfer. The empirical valours of both the reaction velocity constant (0.0310s-1) and the gas-liquid volumetric mass transfer coefficient (0.0069s-1), were compared with those from literature. The same order of magnitude was found in both cases

ASSUNTO(S)

Ãcido amino sulfÃmico modelagem cinÃtica gas-liquid mass transfer amine sulfamic acid reaÃÃo de reduÃÃo transferÃncia de massa gÃs-lÃquido Ãcido nitroso engenharia quimica nitrous acid kinetic modelling reduction reaction

ACESSO AO ARTIGO

Documentos Relacionados