Study on antibacterial characteristics and mechanism of synergistic modification of calcined gypsum from phosphogypsum by inorganic antibacterial materials

Mold on the phosphogypsum wallboard seriously hinders the resource utilization of phosphogypsum, and incorporating inorganic antibacterial materials can effectively inhibit mold growth. In this study, Escherichia coli and wallboard mold were used as experimental strains, and the antibacterial activity of antibacterial material-modified calcined gypsum from phosphogypsum (CPG) was determined using the inhibition zone method and mold surface growth area analysis. Characterization techniques such as XRF, XRD, and SEM were used to study the phase composition and microstructure of the samples, and an antibacterial model was constructed to explore the antibacterial mechanism. The results indicated that using E. coli as an indicator bacterium, ZnO-0.05TiO₂-CPG exhibited the best bactericidal effect, while ZnO-CPG exhibited the best bacteriostatic effect. Against mold, ZnO contents of 2.5% or 5% demonstrated strong antibacterial properties, with compressive strengths of 10.1 MPa and 9.95 MPa, respectively, meeting the requirements of ≥3.50 MPa for compressive strength according to the ‘Lightweight Partition Plates for Building’ standard (GB/T 23451 2009). The superior antibacterial performance of ZnO compared to TiO₂ is attributed to the slow release of Zn²⁺, which disrupts cell membranes and the generated reactive oxygen species inhibit cell growth.