Desenvolvimento de sistema para piroidrólise para o preparo de papelão hidráulico visando a determinação de halogênios

Abstract

A pyrohydrolysis system was developed for sample preparation for halogen determination in hydraulic cardboard. These materials are used for sealings, mainly engines and nuclear reactors. Because of the contact of the sealing material with the cooling liquid of these engines leaching of halogens may occur forming their respective acids which cause corrosion of the equipment and release these compounds to the environment. In relation to previous systems cited in the literature, changes of the sample introduction systems, quartz reactor tube and the condenser of water vapor have been made. Sample boat is introduced in the system through a stainless steel tube and quartz reactor is integrated with the water vapor generator. Water vapor is condensed through two glass serpentines, one being refrigerated by Peltier effect. Parameters of the system were evaluated, being the samples heated during 7 min at temperatures of 1000 °C with a gas flow rate (O2) of 0.2 mL min-1, water flow rate of 1 mL min-1, 300 mg of sample mass and no absorption solution was used. Oxygen was used as carrier gas to assist the sample combustion. The results were compared with the ones obtained by microwave-induced combustion (MIC) and fusion. The pyrohydrolysis results are comparable (at a confidence level of 95%, t-test) with those obtained by MIC, used as reference method for sample preparation. The precision of the results was good (RSD < 10%). In this way, the pyrohydrolysis system developed can be used to hydraulic cardboard sample preparation for halogens analysis.