Effect of C12H25-(HG)hydrophilic group on the wetting of anthracite:Experiment-al and molecular simulation

ZHANG Jiangshi; JIA Hongfu; REN Xiaofeng; WANG Yanan; ZHANG Qi; TONG Linquan; WANG Yanhui

doi:10.13225/j.cnki.jccs.2023.0590

Abstract：Surfactants are widely used in water-based dust suppression technology,with the main controlling factor for wetting coal dust being hydrophilic groups(HG).To clarify the impact of HG in surfactants on the wettability of coal dust,macroscopic wettability performance tests,quantum chemical calculations(DFT),and molecular simulations were used to investigate the wettability differences and solid-liquid interface regulation mechanisms of common hydrophilic groups(SO4-,PO4H,OH,COO-)in dodecyl surfactants(C12H25-[HG])on anthracite surfaces.The results show that the wettabil-ity effect of hydrophilic groups on anthracite is ranked as follows:SO4-＞COO-＞PO4H＞OH;The adsorption of HG on the anthracite surface relatively increases the content of hydrophobic sites(C—O),which easily forms hydrogen bonds and helps improve the wettability of anthracite.The intrinsic reason for the poor wettability of anthracite is that most of the positive and negative potential regions in anthracite are smaller than the positive and negative potential extremes between water molecules.The difference in extreme values between HG and water molecules(△ESP)is linearly negatively correl-ated with the contact angle,which can serve as a reference index for evaluating the wettability performance of surfactants.In the micro-wetting interface of the surfactant solution-coal,the adsorption capacity of surfactants containing different HGs on the anthracite interface,as judged by the radial distribution function(RDF),is in the order:SO4-＞COO-＞OH＞PO4H.Compared to other hydrophilic groups,HG(SO4-)has the greatest interaction energy between coal and water,the highest number of hydrogen bonds,an increase in the diffusion coefficient of water molecules by 46.3％,and an adsorp-tion increase of 27.43％.HG not only has a strong interaction with water molecules,easily forming strong hydrogen bonds,but also,when adsorbed at the coal-water interface,enhances the diffusion coefficient of water molecules towards the coal surface,leading to an increase in water molecule adsorption,thereby enhancing the wettability of coal dust.When select-ing or designing dust suppressants,introducing strongly polar HG(SO4-)can be considered to improve the wettability of anthracite.The research results provide theoretical basis and reference for the application of surfactants in mine dust con-trol.