烷基伯胺作用下煤泥水中粘土颗粒聚团特性及机理研究

Study on characteristics and mechanism of agglomeration of clay particles in coal slurry water under the action of alkyl primary amine

为探寻烷基伯胺类疏水改性剂作用下煤泥水中粘土颗粒的聚团特性及机理,构建了烷基伯胺阳离子极性头基甲基伯胺阳离子(CH-6N^+),以煤泥水中主要粘土高岭石和蒙脱石为研究对象,采用密度泛函理论计算方法,对甲基伯胺阳离子在不同粘土层面的吸附机理进行了模拟研究,研究结果表明:甲基伯胺阳离子能够在不同粘土颗粒表面发生稳定吸附,在高岭石(001)面、高岭石(001)面及蒙脱石(001)面较为稳定构型的吸附能分别为-125.385、-140.96、-299.31kJ/mol;甲基伯胺阳离子在不同粘土层面的吸附机理主要是静电引力和氢键的共同作用,其中起主导作用的是静电引力作用。通过表面润湿性、Zeta电位、聚团观测、吸附量及聚团沉降试验,对十二烷基伯胺(DDA)作用下高岭石和蒙脱石颗粒的聚团特性进行了试验研究,以验证DFT模拟结果,试验结果表明:十二烷基伯胺在粘土颗粒表面吸附可改善粘土颗粒表面疏水性,降低颗粒表面电负性,促进颗粒形成疏水聚团,进而加速粘土颗粒的聚团沉降。

In order to explore the characteristics and mechanism of agglomeration of clay particles in coal slurry water under the action of alkyl primary amine, the polar head base methyl primary amine cation (CH-6N^+) of alkyl primary amine cationic is developed. The kaolinite and montmorillonite, 2 kinds of main clay matters in coal slurry water are taken as the object of study. The mechanism of adsorption of methyl primary amine cation on different clay surfaces is investigated through simulation and calculation based on density functional theory (DFT). Study result shows that: methyl amine cation can adsorb stably onto surfaces of the clay matters and form relatively stable configurations on kaolinite (001) surface, kaolinite (001) surface and montmorillonite surfaces with adsorption energies of -125.385,-140.96 and -299.31 kJ/mol respectively;and the adsorption mechanism of methyl amine cation is principally a result of the combined effects of electrostatic attraction and hydrogen bonding, with the former playing the predominant role. Experimentary study is also made of the characteristics of agglomeration of kaolinite and montmorillonite particles under the action of dodecyl primary amine (DDA) through surface wettability, zeta potential, agglomeration observation, adsorption amount and agglomeration sedimentation tests, so as to verify the DFT simulated result. As evidenced by test result, the adsorption of DDA on surface of clay particles can lead to improved hydrophobicity and reduced electronegativity of particle surface, which are helpful for clay particles to form hydrophobic agglomerates and speed up sediment of clay particles.