Organic bio-based aerogel from food waste: preparation route and surface modification

Recently, alongside the use of biopolymers, the concept of organic waste management has gained the attention of scientists where the “reduce, reuse and recycle” strategy has been awarded. In this context, food waste is a promising raw material for the production of bio-based aerogels for different applications, including food applications as well. General food waste or by-products from food transformation process are a serious issue for both the economy and the environment. New strategies are required to implement the waste and resource management. Organic aerogels are a good example of how the scientific community works on sustainable alternatives of traditional processes. Inside this group of materials, it is possible to identify two main branches: recycle-based and organic waste-based aerogels. The basic principle is that they exploit the lignocellulosic content of waste to produce aerogels. Although the research is still at its beginning, waste-based aerogels are a potential solution for developing sustainable nanoporous materials. An alternative solution to reduce the preparation steps is to use the pure biomass, reducing the chemicals and thermal or mechanical processes involved. Some example are: banana [1], watermelon [2], and pomelo peel [3] were used as carbon source for bio-aerogels and carbon aerogel preparation as well. In this work we offer an overiew about the aerogels prepared from the waste materials and also open some new routes to their coating towards the tailoring of the surface properties. Particularly, organic waste-based aerogels were prepared using spent ground coffee, apple pomace and protein waste sources. Because of their innovative origin, physical and chemical characterizations were performed. In order to use these materials inside a water media, preventing the disrupt of the porous structure, two surface treatments were carried out: silanization and cold plasma coating. Here we discuss the both processes and their potential for food and biomedical applications. We hope, this work can open up new avenues for the utilization of biopolymer waste streams by converting them into valuable aerogels.