Synthesis of a novel dispersant with topological structure by using humic acid as raw material and its application in coal water slurry preparation

This work reports the synthesis and performance of a novel dispersant for coal water slurry (CWS). The dispersant is derived from humic acid (HA) and has a topological structure, named humic acid-graft-poly(sodium styrene sulfonate) (HA-g-PSSNa). A series of HA-g-PSSNa with simultaneous presence of hydrophobic humic acid skeleton and hydrophilic poly(sodium styrene sulfonate) side chains were synthesized via surface acylation reaction of HA and followed by atom transfer radical polymerization. The structure and chemical composition of HA-g-PSSNa were verified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy observation suggests that the incorporation of PSSNa segments onto HA skeleton remarkably affects its morphology. The performances of CWS prepared using HA-g-PSSNa, PSSNa, and naphthalene sulfonic formaldehyde condensate (NSF) as dispersants were studied and systematically compared using various technologies. The results show that the slurry-making performance of HA-g-PSSNa enhanced with the increase in the length of PSSNa side chains. In the case of HA-g-PSSNa with appropriate PSSNa chain length, the CWS prepared using HA-g-PSSNa as dispersant exhibits excellent apparent viscosity as well as static stability, even superior to those of PSSNa and NSF. The dispersing and stabilizing mechanism of HA-g-PSSNa is proposed as follows: When used as a dispersant for CWS, HA skeleton provides sufficient hydrophobic interaction to coal surface and drives the adsorption of HA-g-PSSNa molecules. Hydrophilic PSSNa side chains are oriented to water, thus forming a dense electrical layer and steric hindrance surrounding the coal particles. Accordingly, the aggregation of coal particles was suppressed.

本工作报道了一种新型水煤浆分散剂的合成及其性能。该分散剂由腐植酸（HA）衍生而来，具有一种拓扑结构，名为腐植酸接枝聚苯乙烯磺酸钠（HA - g - PSSNa）。通过腐植酸的表面酰化反应，接着进行原子转移自由基聚合，合成了一系列同时具有疏水腐植酸骨架和亲水聚苯乙烯磺酸钠侧链的HA - g - PSSNa。利用傅里叶变换红外光谱和X射线光电子能谱对HA - g - PSSNa的结构和化学成分进行了验证。扫描电子显微镜观察表明，将PSSNa链段引入HA骨架显著影响其形态。使用HA - g - PSSNa、PSSNa和萘磺酸甲醛缩合物（NSF）作为分散剂制备的水煤浆性能通过各种技术进行了研究和系统比较。结果表明，随着PSSNa侧链长度的增加，HA - g - PSSNa的制浆性能提高。在具有合适PSSNa链长的HA - g - PSSNa的情况下，使用HA - g - PSSNa作为分散剂制备的水煤浆表现出优异的表观粘度以及静态稳定性，甚至优于PSSNa和NSF。HA - g - PSSNa的分散和稳定机制如下：当用作水煤浆分散剂时，HA骨架为煤表面提供足够的疏水相互作用，推动HA - g - PSSNa分子的吸附。亲水的PSSNa侧链朝向水，从而在煤颗粒周围形成致密的电层和空间位阻。因此，煤颗粒的团聚受到抑制。