Recycled polyamide 6 nanofiber medium with bead-on-string structures for oily aerosol filtration

Semi-volatile oily aerosols are released into the environment during industrial processes, causing air pollution and significant health problems for workers, as well as corrosion of equipment in the industry. Therefore, oil-free air is a prerequisite in many industrial activities. However, the removal of oily aerosols from the air has become an important issue due to their properties such as small particle size, high concentration, easy adherence to surfaces, and the ability to spread and form a film-like structure on the surface they adhere to. While fibrous filters are commonly used materials for separating oily aerosols from the air, separating submicron oily aerosols with both high filtration efficiency and low resistance remains challenging. In this study, functional nanofibrous media were produced using centrifugal nanofiber spinning (CS) method from recycled polyamide 6 (PA6) yarns. The negative capillary effect observed in nanofibrous filters in oil filtration was improved by oleophobic beaded-on-string morphology through the addition of modified fluoroalkyl siloxane (mFAS) to the solution. Then, ternary composite samples were produced in different combinations. As a result, a high filtration efficiency of 99.62 % was obtained at an expense of low pressure drop value (around 264 Pa). The produced recycled composite sample had a quality factor value of 3.87 kPa⁻¹ when subjected to an 8 mg/m³ oily-aerosol load.