Reactions, characterization and uptake of ammoxidized kraft lignin labeled with 15N

Ammoxidation of kraft lignin was carried out in a Parr reactor using 15NH3 as the main nitrogen source. Reaction parameters were set up until a total nitrogen content of ≈13 wt.% in lignin was achieved, in accordance with conditions of previous studies. Analytical tools such as FTIR, Py-GC/MS, and solid state NMR were used in this research. The nature of nitrogen bondings is discussed. The incorporation of the 15N from ammoxidized lignin was followed in pumpkins (Zucchini cucurbita pepo L.) by means of 15N emission spectroscopy.