Role of sodium dodecyl benzene sulfonate in enhancing coal dewatering: Experiments and theoretical calculations

Abstract

The surface of low-rank coal has many oxygen functionalities, which leads to poor coal slime dehydration. To improve the effect of coal slime dewatering, sodium dodecyl benzene sulfonate (SDBS) was used as accelerator in the coal slime dehydration process. In addition, the mechanism of acceleration was studied using X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations. The results of dehydration experiments showed that adding a certain amount of SDBS into the slurry water was conducive to promoting the removal of water. When the concentration of the SDBS solution was 0.06 g/L, the water content of the filter cake decreased from an initial value of 59.98% to 54.55%. XPS measurements and MD simulations show that the polar groups (sulfonic acid) of SDBS are adsorbed on the oxygen-containing functional groups on the coal surface, thus, exposing the nonpolar groups (alkyl chains) of the molecule to the solution. The calculation of the self-diffusion coefficient (D) of water molecules in the simulated system indicate that the presence of SDBS improves the mobility of water at the coal surface, which is helpful in improving the loss of water from the coal surface, thus, improving its hydrophobicity. Crucially, the results of the MD simulations are consistent with those from experiment.

Highlights

• Addition of a certain amount of SDBS helps to remove moisture from the coal slime.

• Oxygen-containing functional groups on the coal surface are effectively covered by SDBS.

• The interaction mechanism of SDBS at coal/water interface was studied by combining experiments and theoretical calculations.

Keywords:

• Low-rank coal
• dehydration
• SDBS
• MD simulation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China (Grant No. 51904174, 52074175), Young Science and Technology Innovation Program of Shandong Province (Grant No. 2020KJD001), Shandong Provincial Natural Science Foundation (Grant No. ZR2020ME103), Key Research and Development Project of Shandong (Grant No. 2019GGX103035), SDUST Research Fund (Grant No. 2018TDJH101) and Project of Shandong Province Higher Educational Young Innovative Talent Introduction and Cultivation Team.