Construction of an Anion/Nonionic Complex System to Synergistically Promote the Performance of Dust Suppression

To enhance the wettability of bituminous coal dust, the effects of surfactant type and formulation were systematically investigated. Surface morphology characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed a rough and heterogeneous granular structure, which impedes effective wetting. Experimental results indicate that wettability improves with increasing surfactant mass fraction up to a critical threshold, beyond which further enhancement becomes negligible; an optimal mass fraction of 0.05% was identified for individual surfactants. Among the tested systems, a composite formulation consisting of SDBS, CTAB, OP-10, and BS-12 exhibited superior stability. In particular, anionic–nonionic surfactant combinations demonstrated pronounced synergistic effects. The SDBS–OP-10 system achieved optimal performance at a mass fraction of 0.05%–0.05%, where both contact angle and surface tension reached their minimum values. Further optimization revealed that an SDBS/OP-10 ratio of 2:4 delivers the best wetting performance, with a maximum wetting work of 28.70 mN m–1 and a near-zero spreading work of −1.32 mN m–1. This optimized formulation significantly enhances spreading and encapsulation of coal dust, providing an effective strategy for dust suppression in coal-related applications.