Ultrafiltration purification of biological dust suppressant for enhanced interfacial properties

• Developed an ultrafiltration-based method for purifying biological dust suppressant. • Determined optimal ultrafiltration conditions for efficient purification of biological dust suppressant. • Compared and analyzed interfacial properties of biological dust suppressant produced by different methods. The addition of a biological dust suppressant (BDS) can effectively enhance wet dust control performance in coal mines. However, efficient separation and purification remain key challenges during BDS production. In this study, ultrafiltration was used for the separation and purification of BDS, and the effects of operating parameters were systematically investigated using response surface methodology. The optimal ultrafiltration conditions were a fermentation supernatant pH of 9.99, a temperature of 37.87 °C, and a transmembrane pressure of 0.54 MPa. Two ultrafiltration process routes were proposed, and the appropriate route was selected according to the initial BDS concentration. When the initial concentration of fermentation-derived BDS exceeded the critical micelle concentration (CMC), a 100 kDa membrane was employed to remove small-molecule components, followed by the addition of 50% ethanol to disrupt micellar structures and subsequent retention of macromolecular proteins using a 10 kDa membrane. Under these conditions, a purity of 91.99% and recovery of 86% were achieved. Wettability tests demonstrated that the BDS solution obtained via two-stage ultrafiltration exhibited a significantly smaller contact angle with coal dust than that prepared by acid precipitation. A two-stage ultrafiltration strategy based on the CMC was proposed to selectively remove impurities and preserve the interfacial activity of BDS, providing higher purity and improved wettability compared with conventional acid precipitation methods. Overall, this study provides important theoretical insights and technical support for the scalable production of mining biological dust suppressant and establishes a foundation for its field application.