Effect of the D. desulfuricans bacterium and UV radiation on nitrocellulose oxidation

Resumo

The oxidation of nitrocellulose (NC) containing 13.38% nitrogen has been investigated. The oxidation process under the action of hard UV radiation and ozone has been conducted for 27 h. As result, the nitrogen content of NC has decreased by less than 4.0%. For oxidation using Desulfovibrio (D.) desulfuricans sulfate-reducing bacteria, NC has been incubated with these bacteria for 65 days. This processing has reduced the nitrogen content of NC by 1.66–2.8%. D. desulfuricans incubation with NC pretreated with UV light + ozone has decreased the nitrogen content of the sample by at most 2.75% (compared to the baseline). UV + ozone pretreatment enables subsequent NC oxidation by D. desulfuricans: the resulting samples are richer in low-molecular-weight fractions and nitrate and nitro groups, and they reach their maximum extent of oxidation within 16 h of incubation with the bacteria, whereas the untreated samples oxidize to the maximum extent in 38 h. It is likely that the UV + ozone treatment cleaves carbon–carbon bonds in the polymer chain and lowers the degree of polymerization of individual chains, thereby facilitating the penetration of bacteria into the bulk polymer globules and the bacterial oxidation of ester bonds.