Influence of terminal group structure in hydrophilic long side chains of polycarboxylate dispersants on the properties of coal water slurry: experimental and simulation insights

Polycarboxylate dispersants (PCs) are high-performance additives with a structure – activity relationship that is crucial for the preparation of low-rank coal water slurry (LCWS). This study investigates how variations in the terminal group structures of hydrophilic long side chains grafted onto PCs affect the dispersion performance of LCWS. Three PCs with the terminal group of hydrophilic long-side chains as methyl, naphthalene ring, and multi-benzene ring were synthesized, denoted as PC-PEG, PC-BNO, and PC-AE, respectively. The results indicate that the apparent viscosity of LCWS prepared with PC-BNO and PC-AE, is approximately 200 mPa·s lower than that of PC-PEG. Additionally, all three LCWS samples exhibited strong shear-thinning behavior. A combination of experiments and molecular dynamics simulation (MD) was adopted to investigate the dispersion mechanism of the three PCs. The experimental results reveal that the dispersant adsorption capacity of PC-BNO and PC-AE is significantly enhanced, and compared with PC-PEG, the absolute zeta potential of PC-BNO increases apparently. The results of MD simulation indicate that the terminal group modification primarily affects the adsorptivity or optimizes the adsorption behavior of PC, thereby enhancing their dispersion performance. Based on this study, PC-AE has a stronger compatibility with low-rank coal to prepare high-performance LCWS.