Application of waste rigid polyurethane foam for oil removal from water

This study investigated the use of rigid polyurethane (PUR) foam for demulsifying oil-containing emulsions, focusing on improving oil removal from water. Emulsions with 5 V/V% oil content were treated using PUR foams of different geometries to evaluate how foam structure affects separation efficiency. During demulsification, the coalescence of fine oil droplets led to the formation of larger aggregates, which increased turbidity; therefore, in this study, higher turbidity indicated a more advanced demulsification stage rather than poorer water quality. Both larger PUR surface area and higher foam volume enhanced the coalescence process and improved oil removal efficiency. The results demonstrate that waste PUR foam can be effectively repurposed for oil–water separation, supporting sustainable and resource-efficient wastewater treatment.