The Simulation Calculation Of Coal Pitch And Gemini Biquaternaryammonium Salt Surfactant Interaction

The wetting and adsorption of dispersing agent in coal pitch surface are the key factors which make the coal pitch water slurry of meeting the requirements. If it is necessary to study it systematically and thoroughly, the structural characteristics of the two molecular should be investigated. The composition of coal tar pitch are analyzed by means of elemental analysis,XPS, SEM and IR etc. But the results are only the elemental composition and content and the surface functional groups, the exact structure information of coal tar pitch could not be obtained. In view of the above reasons and the GC-MS analysis results, we select benzo [e] fluoranthene and benzo [ghi]perylene which have the largest group consists as the representative structure of coal tar pitch. We use quantum chemistry calculation method for simulation of benzene [e] fluoranthene, benzene [ghi] perylene and Gemini surfactant m-n-m type interaction respectivelly. It will explain the action principle of coal pitch and Gemini surfactant from theoretically clarify and provide the theoretical basis for the experimental results.In this paper, we study the interaction of coal tar pitch and Gemini surfactant by quantum chemical methods. We explore the thermodynamic parameters, the force and the charge changes, and study the effects of different hydrophobic chain length and the length of the linking group for the performance of coal pitch. The results found that:(1) For two configurations of the Gemini surfactant, the binding energy of non-linear type is lower than the binding energy of the straight-chain, and its structure is stable relatively. But the results of adsorpting with coal tar find that molecules m-8-m and m-4-m series of non-linear type of Gemini surfactant was lower than the binding energy of the straight-chain, the structure of non-linear type is stable relatively. The structure of linear-chain type 8-4-8 and8-8-8 are stable relatively in dispersants and coal pitch adsorption system while the non-linear type 12-8-12,12-4-12,14-4-14 are stable relatively. The12-8-12,14-8-14,8-4-8 and 14-4-14 of dispersant has relatively stable configuration after the solvent effect calculation.(2) The thermodynamic parameters of m-4-m and m-8-m series shows the surface adsorption is an endothermic and the entropy driven process. The spontaneity of overall dispersion process of m-4-m is better than m-8-m.But after the calculation of the solvation effect, the adsorption process is changed into an exothermic process, which is the effect of entropy enthalpy co-driven.The system of dispersion of the two series are not spontaneous, and Gibbs free energy of m-4-m becomes larger than the external energy demandof m-8-mseries and m-4-m series. After the addition of solvent, it has great influence on the whole dispersion system.(3)The main site of dispersants and coal tar are the carbon atoms of coal tar pitch structure and the hydrogen atoms of dispersant. The charged of carbon atoms and hydrogen atoms themselves are changed before and after reaction.