# Investigation of Biochars in Terms of Vitamin E Adsorption Capacity  
[PERSON]  
1 DIL German Institute of Food Technologies, Prof.-v.-Klitzing-Str. 7, 49610 Quakenbrueck, Germany;  
1 [EMAIL_ADDRESS]
2 Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany  
3  
[PERSON]  
1 DIL German Institute of Food Technologies, Prof.-v.-Klitzing-Str. 7, 49610 Quakenbrueck, Germany;  
1 [EMAIL_ADDRESS]  
[PERSON]  
1 DIL German Institute of Food Technologies, Prof.-v.-Klitzing-Str. 7, 49610 Quakenbrueck, Germany;  
1 [EMAIL_ADDRESS]  
[PERSON]  
1 DIL German Institute of Food Technologies, Prof.-v.-Klitzing-Str. 7, 49610 Quakenbrueck, Germany;
properties are altered [7], resulting in a shorter shelf life and possibly accompanied by negative organoleptic properties [8; 9]. To prevent illnesses, it is crucial to keep animals' health optimal. One pillar of achieving this is the supplementation of an adequate amount of fat-soluble vitamin E [10; 11]. The reasons lie in the important effects on metabolism caused by its antioxidative, anti-inflammatory, and immune-modulating effects [12; 13]. As a result of rumination, vitamin E is partly metabolised in the rumen, which diminishes its availability and therefore its resorption in the small intestine [14; 15]. To transport sufficient vitamin E in the small intestine, the use of a vitamin E carrier is recommended. Adding vitamins or porous substances to feed is common practice to improve animal productivity and health [16]. For instance, zeolite materials have been used as a dry delivery or antioxidant carrier system to transport vitamin E in humans [17]. Available carriers for ruminant feed include mineral silicates, such as zeolites [18], which occur naturally, but can also be produced synthetically for specific purposes [19]. Zeolites belong to the class of crystalline aluminosilicates, due to their rigid anionic framework, which has defined channels intersecting in cavities. Their specific inner surface is 600 to 700 m\({}^{2}\)/g, with a homogenous distribution of pores with a specific diameter, allowing them to be used as molecular sieves [19]. Due to the synthetization of specific pore diameters, zeolites can be used for specific ion exchange, molecular sieving, or adsorption [18; 20]. However, zeolite has been shown to be destroyed in the rumen due to its lack of pH resistance [21]. Bentonite, a clay mineral with a three-layer structure [22], can be applied to dairy cows to adsorb aflatoxin. However, bentonite has also been shown to interfere in the rumen metabolome, indicating possible consequences on cows' metabolism [23]. The molecular size of the adsorptive defines the minimum pore diameter required for effective adsorption [24]. To effectively adsorb vitamin E, the porous carrier should have a pore size diameter larger than the volume of the vitamin E molecule. [PERSON] et al. [25] calculated that \(\alpha\)-tocopherol, a form of vitamin E, has a size of 1.19 \(\times\) 0.95 nm, indicating that this two-dimensional shape would fit in micropores with a pore size smaller than 2 nm [19; 26]. This assumption is supported by [PERSON] [27], who determined that the surface area of vitamin E is 0.52 nm\({}^{2}\)/molecule, and by [PERSON] et al. [28], who showed that \(\alpha\)-tocopherol containing four to nine isopentane units has a surface area of 0.65 nm\({}^{2}\)/molecule. In their study, [PERSON] and [PERSON] [29] stated that the vitamin E molecule has a diameter of 26 A, which corresponds to 2.6 nm. Besides pore size, the shape of the adsorbent also impacts its transportation and delivery in biological systems [30; 31]. An adsorbent with a specific homogenous diameter, which is the case for, e.g., molecular sieves and zeolite [32], can pose a challenge for the adsorption of substances with the possibility of a varying molecular arrangement, such as vitamin E [25; 33]. Activated carbons have been described to adsorb bulky organic molecules, such as vitamin E [34].