For decades, lead-acid batteries have been supplying power to electrical systems through redox reactions involving Pb and PbO2. However, the energy supply capacity is inherently constrained by low energy density and challenges associated with charge/discharge cycles. Studies have indicated that additions of C to the composition of the active mass improve the electrochemical properties of batteries. This work aims to produce, characterize the microstructure and evaluate the electrochemical properties of Pb-Carbon composites, comparing different types of C (graphite, graphene and xerogel). The samples were produced through powder metallurgy, pressed at 550 MPa and sintered at 320°C-48 h. The microstructure was characterized by XRD, SEM/EDS, and Vickers microhardness. Electrochemical analyses were evaluated through OCP, polarization, and cyclic voltammetry (CV) measurements in a solution of 4.91 mol•L-1 of H2SO4. Microstructural characterizations revealed dispersions of C particles in the Pb matrix and an increase in the microhardness of the composites. Electrochemical analyses showed an increase in polarization resistance and a reduction in the corrosion rate compared to Pb. CV curves, demonstrated that C particles enhanced electrical conductivity for the formation of PbSO4 and PbO2, allowing greater absorption of electrical overpotentials when compared to Pb, thereby improving charge/discharge cycles in positive grids. decades leadacid lead acid PbO2 PbO However chargedischarge charge discharge produce PbCarbon Carbon composites graphite, graphite (graphite xerogel. xerogel . xerogel) metallurgy 55 320°C48 320C48 320°C 48 320 320°C-4 h XRD SEMEDS SEM EDS SEM/EDS OCP (CV 491 4 91 4.9 mol•L1 molL1 molL mol•L 1 mol L mol•L- H2SO4 HSO H SO curves PbSO grids 5 C48 320°C4 320C4 320C 32 320°C- 49 9 4. L1 H2SO C4 3

Antioxidants are an alternative to prevent or slow the degradation of the biofuel. In this study, it was evaluated the oxidative stability of B100 biodiesel from soybean oil in the presence of three commercial synthetic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ), pure or blended, from the experimental design of simplex-centroid mixture. The reaction order and rate constant were also calculated for all tests. The treatment containing pure TBHQ proved to be the most effective, proven by design, the optimum mix obtained and the rate constant. Binary and ternary mixtures containing TBHQ also showed appreciable antioxidant effect.