Preparation of PTFE-glass composite filter with low surface free energy by sandblasting

The filter media of baghouse systems should exhibit high collection and filter cleaning efficiencies. This requirement can be met by increasing the surface roughness and contact angle (and thus, by decreasing the surface free energy) of these media via surface treatment. One of the simplest surface treatment methods, sandblasting, relies on the bombardment of the filter surface with small particles. Herein, microscopy, oil/water contact angle, and pressure drop measurements are used to determine the optimal conditions for the sandblasting-based fabrication of a superhydrophobic filter with low surface free energy. The surface-treated filter prepared under optimal conditions exhibits superb water repellency (water contact angle > 150°) and a low surface free energy of ∼1.5 mJ/m² while featuring a pressure drop similar to that of the untreated filter. Moreover, a general rule of thumb is established, i.e., the area-normalized kinetic energy of impacting particles should not exceed 8.0 J/m² to avoid filter surface damage.