Effect of the Interfacial Agents with Different Types of Hydrophilic Functional Groups on the Rheological Properties of Coal-Water Slurry

Abstract

Five interfacial agents with different hydrophilic groups (DBS, SDS, SO, TX, CTAB) are used as model additives to prepare coal-water slurry (CWS). The effects of different interfacial agents on the rheological properties of CWS are systemically investigated, the microscopic aggregation behavior of coal particles in the suspensions and the zeta potentials in coal-water interface are also studied. Based on the interpretation of the results, the rheological behavior of CWS is greatly influenced by the adsorption pattern of the interfacial agents in coal-water interface. The adsorption patterns of anionic interfacial agents on coal surface are mainly influenced by the combining force between the anionic hydrophilic groups with Ca²⁺, the stronger combining force with Ca²⁺ leads to the apparent viscosity increase and heavier pseudo-plastic property of CWS. The adsorption pattern of nonionic interfacial agent on coal surface is seldom influenced by the hydrophilic polyoxyethylene chain, and the addition of nonionic interfacial agent reduces the apparent viscosity of CWS. The adsorption pattern of cationic interfacial agent on coal surface is determined by its cationic head, and the addition of cationic interfacial agent increases the apparent viscosity of CWS. The concluded adsorption models of the interfacial agents with different hydrophilic groups can be guidance for the molecular design of high-performance additives of CWS.

Keywords:

• Adsorption pattern
• coal-water slurry
• interfacial agent
• rheological property
• zeta potential

Acknowledgments

The authors are thankful for the financial support of the National Science Foundation for Distinguished Young Scholars of China (20925622), the National Natural Science Foundation of China (21006036, 20976064), the National Basic Research Program of China (2010CB732205), the Natural Science Foundation of Guangdong Province of China (8351064101000002), and the Fundamental Research Funds for the Central Universities.

Notes

_daf : dry ash-free basis; ad: air dried basis.