OPS are zero-valent iron nanoparticles encapsulated in a carbon matrix, green energy, and digestate that can be transformed into fertilizer, organic amendment, and/or compost. This process reduces polyphenols, enabling biogas generation using only vegetable water and alperujo as sole substrates.
OPS are produced from vegetable water using hydrothermal carbonization techniques, a new method for synthesizing iron nanoparticles. This process adheres to the principles of green chemistry and is a low-cost method for synthesizing reduced iron nanoparticles, with improved characteristics compared to currently produced reduced iron nanoparticles and up to six environmental applications, such as improved biogas and biohydrogen production, contaminated water treatment, fertilizers, and more.
OPS contain an average of 2.5% zero-valent iron (ZVI), 44.5% total iron, and 55.5% carbon. They are magnetic and have an average pore size of 150 nm, a surface area of 14.7 m2/g, and a total pore volume of 0.0696 cc/g. These values can be improved by applying an activation process, for example, obtaining a surface area of 190 m2/g and 10% ZVI. Furthermore, OPSs are a novel product, not found on the market, and are non-toxic within the framework of the circular economy.
