The Wetting Of Coal Tar Pitch Surface By Gemin Surfactant And Its Effects On The Preparing Of Low Coal Pitch Water Slurry

The coal tar pitch is main product in coking process, it has a largeproduction. However, the efficient utilization of coal tar pitch seriously affectsthe efficiency of comprehensive utilization of coal resources and development ofcoal-tar pitch indirectly alleviates our country’s energy crisis. The concept ofCoal Pitch Water Slurry (CPWS) which is learn from pulping technology of coalwater slurry was brought up by our research group, which is prepared by acertain particle size of coal tar pitch powders and dispersant solution.In order to understand the surface composition and surface topography,surface properties of coal tar pitch were characterized by a varied of means suchas elemental analysis, industry analysis, scanning electron microscopy withenergy dispersive spectrometry and XPS. Wetting and adsorptive mechanism ofcoal tar pitch by aqueous solutions of Gemini surfactant of C12-m-C122Br(m=4,6,8,10) Cn-8-Cn2Br (n=8,10,12,14,16) were investigated by the sessiledrop analysis and electrophoresis. Based on these study results, spreadingcoefficient, immersion wetting work and adhesion work were calculated, andZisman theory was proved to be fitting for this wetting system. The obtained results indicate that the surface tension decreases with increasing surfactantconcentration up to the CMC (critical micelle concentration) of the surfactantsolution, which contact angle (θ) and S have the similar trend to surface tension.Within the whole range of concentration, the Zisman theory is in accordancewith the wettability on the coal tar pitch when spacer chain length value reachesto10. Meanwhile, there is liner dependence between adhesion tension (γlgcosθ)and surface tension (γlg). C8-8-C8and C10-8-C10are in accordance with theZisman theory wetting on the coal tar pitch. Meanwhile, there is not linerdependence between adhesion tension (γlgcosθ) and surface tension (γlg). Zetapotential on the surface of the coal tar pitch increases with the increasingsurfactant concentration from negative to positive, and finally levels off. Andthe concentration of the zero potential is lower than CMC at least an order ofmagnitude. C12-8-C12Gemini surfactants can significantly change the wetting onthe surface of the coal tar pitch. According to the wetting data and Zeta potentialof Gemini surfactant on coal tar pitch, it can be inferred that wetting is aconcerted action result of electrostatic interaction and van der waals adsorption,Therefore, wetting process of C12-m-C12and Cn-8-CnGemini surfactant can begenerally divided into three phases.The adsorption amount and Zeta potential of C12-m-C12and Cn-8-Cnonsurface of coal pitch was studied by UV spectrophotometry and Zetapotentiometer. Adsorption amount increased rapidly at first and finally leveledoff with increasing concentration of cationic C12-10-C12and C12-8-C12Gemini surfactants, which maximum adsorption amount are9.35mg/g and10.32mg/g,respectively. All dispersants were used to prepare CPWS in order to find theappropriate ones.The results showed that the main element of coal pitch is Carbon whoseamount is more than90%. Dispersants used in the experiment can reducesurface tension of the solution. When the Space of cationic Gemini surfactant isthe same, the performance of the slurry ability of coal pitch-water slurry is morepronounced with the increased carbon number of hydrophobic chain; When thehydrophobic chain of cationic Gemini surfactant is the same, the performance ofcoal pitch-water slurry becomes better as the increased carbon number of Space.