Gradient Composite Filtration Material With High Efficiency and Low Resistance for <scp>PM</scp> 2.5 Protection

ABSTRACT This study develops a gradient composite filtration material for high‐efficiency, low‐resistance PM2.5 protection. The use of a bio‐based gelatin‐carboxymethyl cellulose (CMC) adhesive (6% gelatin+3% CMC) enhanced interlayer bonding while minimizing pore blockage, resulting in a filtration efficiency of 98.6% at a pressure drop of 113.9 Pa. This pressure drop is 20%–30% lower than that achieved with petroleum‐based adhesives, leading to a superior quality factor (QF = 0.037). The gradient structure, which integrates spunbond (S) and meltblown (M) layers, employs synergistic mechanisms—inertial impaction in the outer layer, diffusion capture in the middle layer, and secondary adsorption in the bottom layer—to enhance performance. Experimental results demonstrated exceptional stability under dynamic airflow (10–100 L/min), extreme environmental conditions (temperature: −10°C to 50°C; humidity: 30%–90% RH), and long‐term use (retaining &gt; 95% efficiency over 6 h). The material also showed superior performance and cost‐effectiveness compared to commercial N95 masks, with a material cost of approximately 15 CNY/m 2 . The material also exhibits robust performance under simulated heavy rain, sandstorms, and UV/ozone aging, with filtration efficiency fluctuations below 3.9%. The integration of bio‐adhesive point‐bonding with gradient layering results in a quality factor (QF) 40% higher than that of N95 masks, offering a sustainable alternative for industrial and personal protection.