不同分子质量木质素磺酸钠对煤粉的分散作用研究

Dispersion of coal particles by sodium lignosulphonate with different molecular weights

应用超滤分级方法,将木质素磺酸钠分成不同分子量范围的级分.傅立叶红外光谱(FTIR)分析结果表明,分子量为5 000～10 000的木质素磺酸钠分子中亲水基团如羟基、酚羟基、磺酸根质量分数最大,随着分子量的增加,亲水基团质量分数降低.实验结果发现分子量为10 000～50 000的木质素磺酸钠级分在煤粒表面的吸附等温线近似为L型,吸附量较大,并且使煤粒的表面动电电位(ζ电位)达到-52mV,在各个级分中对盘江煤具有最好的分散降黏作用.进一步得出结论,分散剂的分散降黏作用与其在煤粒表面的吸附量和ζ电位的高低密切相关.

Sodium lignosulphonate was fractionated by means of ultrafiltration, and 4 fractions of different molecular weights were collected. It is showed by FTIR that the 5000 - 10000 fraction has the maximum hydrophilic group such as hydroxyl, phenolic hydroxyl and sulfonic group. With the increase of molecular weight, the content of hydrophilic group decreases. The results show that the adsorption curve of 10000 - 50000 fraction on coal particles approximates L type which means more adsorptive capacity, and this fraction makes the zeta potential reach -52 mV. The slurrying experiment shows that the 10000 - 50000 fraction has the best dispersing performance to Panjiang coal among all fractions. Furthermore, it is concluded that the adsorptive capacity of the dispersant on coal particles and the zeta potential are the main factors affecting the dispersing performance.