Desenvolvimento de produtos químicos biodegradáveis com ação protetora à corrosão do aço AISI 1018 e ao desgaste do aço AISI 52100 causado por combustíveis

Abstract

Few decades ago pollutant agents were seen as an inevitable consequence of technological progress. However, due to the intense degradation of global environment, new practices have been adopted in order to control environmental impacts, which include development of clean technologies. In this sense, less aggressive products are a sustainable alternative for controlling metal deterioration. The aim of this study was to evaluate the efficiency of biodegradable surfactants, sodium dodecylbenzene sulfonate (SDBS) and saponified coconut oil (OCS) loaded in a microemulsion system (ME) as corrosion inhibitors on carbon steel AISI 1018 in saline medium. The tested samples (SDBS-AS, SDBS-ME and SDBS-OCS-ME) were evaluated by Galvanostatic and Linear Polarization Resistance (LPR) methods, as well as Weight Loss (WL), showing maximum anticorrosion efficiencies ranging from 70.4% to 77.6%. The surfactants SDBS was solubilized in aqueous solution (SDBS-AS) or loaded on colloidal systems such as: SDBS on microemulsion system (SDBS-ME) containing 30% of C/S [15% of butan-1-ol, as co-surfactant (C), and 15% of SDBS, as surfactant (S)], 10% of oil phase (kerosene) and 60% of water], and also SDBS mixed with OCS (saponified coconut oil, a semisynthetic surfactant) on a microemulsion system called SDBS-OCS-ME), containing 40% C/S {[1% of SDBS and 99% of OCS, with C/S=1 [20% of OCS/DBS (99:1) and 20% of butan-1-ol, 5% of kerozene and 55% of water). Comparatively, the AISI 52100 metal deterioration, caused by fuels, was studied for diesel, a B7-OC mixture with 93% of diesel S10 and 7% of coconut oil biodiesel, a B7-OS mixture with 93% of diesel S10 and 7% of soybean oil biodiesel, as well as a soybean oil additive biodiesel so called B7-OS-AD. Semisynthetic surfactant prepared from vegetable, source were used as additive agents aiming at biodiesel fuel production with lower damage on surfaces of metal alloys. Tribological tests showed that the S10 diesel, B7-OC and B7-OS samples were more susceptible to oxidative processes than the B7-OS-AD, which showed greater stability, viscosity and lower wear action on metal (32.9% of reduction). Therefore, B7-OS-AD is herein indicated as an efficient fuel with lower environmental impacts.