聚羧酸盐在煤/水界面的吸附及分散作用机理研究

The adsorption characteristics of the dispersant on the coal / water interface directly affect performances of coal water slurry. The dispersant adsorption law is particularly important for revealing the dispersion of mechanism the system. The performance of CWS is degrading because the dispersant is difficult to close on the low-rank coal surface adsorption. The structure of polycarboxylate is flexible and easy to control, and it can be designed to adapt to various coals to make slurry and produce a variety of structures dispersant, for the low-level coal (i.e. the Shenfu coal or Binchang coal) to prepare high concentration coal-water slurry. By X-ray photoelectron spectroscopy, environmental scanning electron microscopy, BET nitrogen adsorption method and surface tension meter, research polycarboxylate adsorption of coal / water interface, the structural characteristics of the dispersant, the nature of the coal surface, and a dispersing agent dosing quantity factors on the adsorption behavior of the adsorption amount of the coal / water interface, adsorption strength and the impact of the adsorbed layer thickness and the state of aggregation will be discussed. The relationship of the adsorption of dispersant and the rheology and stability of CWS will be elucidated. It can theoretically guide the design and preparation of the dispersing agent, and determine the performance of the dispersing agent and the minimum addition amount. By exploring the structure of polycarboxylate, adsorption, and performance of the relations between the in-depth study of its mechanism of action, it will be conducived to the screening of dispersants to improve the performance of low-rank coal into pulp, and explore ways for the development of highly efficient coal-water slurry additives.

分散剂在煤/水界面的吸附特性直接影响着其对煤成浆性能，为揭示水煤浆体系的分散机理，分散剂的吸附规律研究尤为重要。分散剂在低阶煤表面难以紧密吸附而导致浆体性能降低，聚羧酸盐结构灵活易控，可设计、生产出各种结构分散剂以适应各煤种制浆，将其用于低阶煤（神府煤和彬长煤）制备高浓水煤浆，通过X光电子能谱、环境扫描电镜、BET氮气吸附法和表面张力仪，研究聚羧酸盐在煤/水界面的吸附规律，讨论分散剂的分子结构特征、煤表面性质、分散剂的投加量等因素对其在煤/水界面的吸附量、吸附强度、吸附层厚度及聚集状态的影响，确定分散剂的吸附行为与水煤浆的流变性和稳定性的关系，从理论上指导分散剂的设计、制备，判定分散剂的性能和确定最小添加量。通过探讨聚羧酸盐结构、吸附和性能三者关系，深入研究其作用机理，有利于分散剂的筛选，提高低阶煤的成浆性能，为发展高效水煤浆添加剂探索途径。

分散剂在煤/水界面的吸附特性直接影响着其对煤成浆性能，为揭示水煤浆体系的分散机理，分散剂的吸附规律研究尤为重要。针对于低阶煤（神华煤、彬长煤和内蒙古霍林河煤）制浆性能差的问题，设计、制备了各种结构聚羧酸盐分散剂，将其用于低阶煤制备高浓水煤浆，并通过X射线光电子能谱、扫描电镜、BET 氮气吸附法、zeta电位和接触角，研究了聚羧酸盐在煤/水界面的吸附规律，讨论分散剂的分子结构特征、煤表面性质、分散剂的投加量等因素对其在煤/水界面的吸附量、吸附密度、吸附层厚度的影响，探索了分散剂的吸附行为与水煤浆的流变性和稳定性的关系。.研究发现聚羧酸盐对低阶煤制水煤浆流变呈现“剪切变稀”的特性，最接近于Herschel-Bulkley流变模型，其中侧链长度适中（侧链与主链聚合度之比为2左右）的PCm=11的流变性能最好，表观粘度最低，流动性为A级，水煤浆稳定性最好。随着分散剂添加量的增加，水煤浆浆体为均假塑性流体，然而其表观粘度先减小后增大；持续增大分散剂添加量，浆体流动性指数增大至接近于1，流变模型由Herschel-Bulkley向Bingham模型转变。.等温吸附实验发现，PC分散剂在煤粒表面是单分子层吸附，符合Langmuir吸附模型，其中饱和吸附量顺序为PCm=11> PCm=8> PCm=17> PCm=23，侧链长度适中的PCm=11在煤上的饱和吸附量和吸附密度最大；分散剂在煤表面的吸附层厚度顺序为PCm=11> PCm=23> PCm=17> PCm=8，PCm=11的吸附层厚度最大。.吸附热力学发现，在一定的温度内，升温有利于饱和吸附量的增大，最终趋于稳定；吸附焓变为负值，分散剂在煤表面吸附为放热过程，体系熵变为正值，吸附增加了体系的混乱程度。PC分散剂提高了煤粒表面带电量，使煤粒表面电位从-11.2mV变化到-41.5mV。分散剂的吸附层厚度和水煤浆的zeta电位之间的平衡关系对浆体分散稳定性至关重要，侧链长度和电荷密度都适中的PCm=11对煤粒的亲水改性较明显，其更容易使水煤浆吉布斯能降低，减弱煤粒间聚集程度，提高浆体分散稳定性。这些结论对开发低阶煤成浆的高效分散剂有较好的借鉴指导作用。