Surface functionalization of coal and quartz with aniline: A study on work function and frictional charge

Abstract

The present study deals with the surface functionalization of coal and quartz using aniline with an intention to achieve a higher differential charge facilitating their separation in an electric field. The Fourier Transform Infrared (FT-IR) spectroscopic studies confirm the adsorption of aniline on the coal and quartz surface after chemical conditioning. The surface work function of both coal and quartz are found to decrease after being treated with aniline. However, the work function of coal decreases to a greater extent (3.464%) in comparison to quartz which decreases by 1.016%. Thereby, the net work function difference between the coal and quartz particles increases by 129% (from 0.089 eV to 0.204 eV) after chemical treatment. The work function of the copper tribo-charging medium falls between the work function values of both the original and the aniline treated coal and quartz samples. Therefore, the charge density of the treated coal particles increases on contact with copper while there is a minor reduction in charge of the treated quartz. The charge acquisition data corroborates well with the surface work function data. Density Functional Theory (DFT) based simulation has been carried out to validate the trend of the decrease in work function after the treatment with aniline. The DFT calculations are found to be in good agreement with the experimentally measured change in the surface work function data of both coal and quartz sample after chemical treatment. (C) 2018 Elsevier B.V. All rights reserved.