high technical interest as renewable and biobased feedstock [7] due to their aromatic backbone and high availability. [8][9][10][11] Consequently, the targeted degradation of the respective lignin fractions to value-added products is highly desired. [12,13] The difficulty of this process lies in the different functionalization and the structure of the polyphenolic backbone, which depends on many factors such as pulping process, harvesting time, and type of tree. [10,14] Therefore, the industry uses only small fractions for further production, while the majority is incinerated to recover energy costs. [4,9] Lignin, as a renewable feedstock, offers a promising alternative to petroleum refining and shows tremendous potential for bio-based products such as surfactants and fine chemicals. [5,13,15] Nevertheless, selective degradation is challenging, and several studies focused on this complex topic to degrade lignin into value-added products such as aromatic intermediates. [8,[16][17][18] Lignin degradation shows a broad and diverse spectrum of products, such as aldehydes, [19][20][21]22] alcohols, [21] arenes, [18,23,24] quinones, [25] and carboxylic acids, [16,26,27] obtained in previous research. Different metal-based catalysts were studied to improve degradation and increase selectivity including noble metals like ruthenium, palladium, and platinum. [28] The disadvantages of these processes are the very high costs and limited availability of the metals, which might also cause uncontrolled over-hydrogenation, decreasing the yield of the phenolic products. Another approach is using ionic liquids as solvents in combination with catalysts or oxidizers. [29] However, the high costs for ionic liquids restrict their application for industrial operations. Additionally, the separation process is complex due to interactions with aromatic moieties of residual lignin.Promising electrochemical pathways are reported to yield aldehydes, [3,21,30] carboxylic acids, [27,31] and other phenolic products in good yields. [19,21,27,30] These methods are cost-effective and environmentally friendly. [32] Also, a well-known alternative is the use of oxidizers for lignin degradation. [3,20,23] However, only a few oxidizers, such as periodate, [3] nitrobenzene, [33,34] or hydrogen peroxide, [35] have high availability, and are safe in handling. Moreover, lignin conversion is not limited to the electrode surface since the respective oxidizers are dissolved. The monomer yields out of lignin using oxidizers vary significantly due to different wood types and experimental conditions. In a previous report, we showed that platform oxidizers, such as periodate, are highly beneficial for lignin degradation. This method significantly improves the vanillin yield (8.9 wt%) or selectively produces 5-iodovanillin using different workup conditions. [3] A new method is presented using electrochemically generated ferrate to degrade the technically relevant bio-based side-stream products, lignin and lignosulfonate. An exclusive degradation to vanillic ac...
