Removal of phenolic compounds from olive mill wastewater using chitosan/kaolinite/iron oxide nanocomposites

Olive mill wastewater (OMW) poses a serious environmental challenge, specifically in the Mediterranean region, due to its high content of phenolic compounds (PCs). In this study, eco-friendly nanocomposites made of chitosan, kaolinite, and iron oxide nanoparticles were prepared, characterized, and tested for their removal efficiency (RE) of PCs from OMW. The removal efficiencies of seven targeted PCs and the overall removal for the total phenolic content were evaluated. The nanocomposite powder cross-linked with glutaraldehyde exhibited the highest RE of 91% for the sum of the seven target PCs (Σ7PCs) using a 10 g/L of adsorbent dose, pH = 4.8, at a temperature of 25 °C within 2 h. Desorption studies showed that up to 85% of the adsorbed PCs were desorbed, allowing the efficient regeneration of the adsorbent for at least four cycles with RE exceeding 50%. These promising results suggest the potential of the large-scale utilization of the developed process for large-scale remediation of OMW.