The use of modified Fe3O4 particles to recover polyphenolic compounds for the valorisation of olive mill wastewater from Slovenian Istria

Olive mill waste water (OMWW), a by-product created during the processing of olive oil, contains high amounts of polyphenolic compounds. If put to further use, these polyphenolic compounds could be a valuable resource for the speciality chemical industry. In order to achieve this, isolation of the polyphenolic compounds from OMWW is needed. Several techniques for this process already exist, the most widely used of which is adsorption beds. This research describes new ways of collecting polyphenolic compounds by using unmodified iron oxide (Fe₃O₄) particles and Fe₃O₄ modified with silica gel (Fe₃O₄@C18), citric acid (Fe₃O₄@CA), and sodium dodecyl sulphate (Fe₃O₄@SDS). This approach is superior to adsorption beds since it can be used in a continuous system without clogging, while the nano-sized shapes create a high surface area for adsorption. The results of this study show that, if used in a loop system of several adsorption and desorption cycles, (un)modified Fe₃O₄ has the potential to collect high concentrations of polyphenolic compounds. A combination of different modifications of the Fe₃O₄ particles is also beneficial, as these combinations can be tailored to allow for the removal of specific polyphenolic compounds.