Molecular Mechanisms by Which Linear Versus Branched Alkyl Chains in Nonionic Surfactants Govern the Wettability of...

Improving the wettability of coal dust with nonionic surfactants is crucial for mitigating environmental pollution. Here we compare two nonionic surfactants with distinct architectures-n-octyl-α-D-glucoside (OG) and Isooctyl glucoside (APG08)-to dissect how linear versus branched C8 chains govern the wetting of long-flame bituminous coal dust. Sedimentation and contact-angle measurements show that the linear OG, with reduced steric hindrance, assembles into a denser interfacial layer and delivers superior wetting. Corroborating spectroscopic and microscopic analyses (FTIR, XPS, and SEM) reveal that OG treatment increases hydroxyl functionalities and the O-element fraction at the coal surface; OG also drives stronger particle aggregation, consistent with markedly enhanced adsorption on coal. Molecular dynamics simulations further indicate tighter OG adsorption, a more homogeneous coal-water interfacial structure, and stronger binding of water to OG-modified surfaces. Collectively, these results identify chain linearity as a key design lever for nonionic glucosides and establish OG as a more effective wettability promoter for long-flame coal dust.