Ultraviolet radiation as an antimicrobial treatment in Brazilian diesel oil: Effect of biodiesel, sulfur, and water contents

This work aimed to use ultraviolet (UV) radiation to prevent microbial growth in diesel fuel with different compositions. Commercial samples of ultra-low-sulfur diesel (ULSD) and high-sulfur diesel (HSD) fuels with 11% of biodiesel were used as purchased. These samples were incorporated of 20% biodiesel and different amounts of free water (no addition, 2500, and 10,000 mL.m(-3)). All samples were stored for ten days and subjected to UV-C radiation treatment (55 W, 253 nm) for 360 min to reduce the number of microorganisms. Physicochemical parameters, such as water content, kinematic viscosity, density, and oxidative stability, were measured before and after UV-C treatment. The presence of microorganisms was detected by UV-vis spectrophotometry (600 nm) during the simulated storage, before and after UV-C treatment. An increase in the number of microorganisms was observed during the storage period due to the water content. The UV-C radiation reduced the microorganisms, especially in samples with high water content. Low sulfur levels did not affect the efficiency of the treatment. Significant variations in kinematic viscosity and oxidative stability were observed after the treatment. The presence of microorganisms was reduced by more than 50% after the incidence of UV-C radiation. Therefore, UVC radiation is a promising technique for microbiological control in diesel fuel. These effects can last up to ten days after the first incidence of radiation.

Automated summary

This study demonstrated that UV-C radiation treatment can effectively reduce the number of microorganisms in diesel fuel, especially in samples with high water content. Significant changes in kinematic viscosity and oxidative stability were observed after UV-C treatment.