聚丙烯酰胺对机制砂亚甲蓝值的影响机理研究

Influence of polyacrylamide on the methylene blue value of manufactured sand

机制砂已成为我国建设用砂的主要来源。通过亚甲蓝试验考察了阴离子型聚丙烯酰胺(HPAM)的分子量及水解度对机制砂亚甲蓝(MB)值的影响规律,借助循环伏安(CV)试验、扫描电镜和傅里叶变换红外光谱分析,探究了HPAM与MB之间的作用机理。研究结果表明:随着HPAM质量浓度的增加,机制砂MB值呈现阶梯式增大的趋势;在相同水解度和浓度时,随着HPAM分子量增大,分子链中的酰胺基团数量和水解产生的阴离子活性基团含量增多,与MB溶液中的阳离子(C16H18N3S+)结合形成的电化学活性复合物增加,HPAM水解产生的含氧官能团与MB分子中的苯环间的氢键作用力增强,导致机制砂MB值增大;在相同分子量和浓度时,随着HPAM水解度提高,水解HPAM的分子链有效长度增大,与MB分子之间的静电引力以及氢键作用力增强,导致机制砂MB值增大。

The manufactured sand has become the main source of sand for construction in China.The effects of molecular weight and hydrolysis degree of anionic polyacrylamide(HPAM)on the methylene blue(MB)value of manufactured sand are investigated by methylene blue test.The mechanism of action between HPAM and MB is explored by means of cyclic voltammetry(CV)test,scanning electron microscope and Fourier transform infrared spectroscopy.The results show that with the increase of anionic polyacrylamide concentration,the methylene blue value of manufactured sand shows a stepwis increase trend.At the same hydrolysis degree and concentration,with the increase of molecular weight of HPAM,the number of amide groups in the molecular chain and the content of anionic active groups produced by hydrolysis increases,and the electrochemical active complexes formed by the combination with the cations(C16H18N3S+)in the MB solution increase.The hydrogen bonding force between the oxygen-containing functional groups produced by HPAM hydrolysis and the benzene ring in the MB molecule is enhanced,resulting in an increase of the MB value.At the same molecular weight and concentration,with the increase of the hydrolysis degree of HPAM,the effective length of the molecular chain of the hydrolyzed HPAM increases,and the electrostatic attraction and hydrogen bonding force between the MB molecule and the HPAM molecule are enhanced,resulting in the increase of the MB value.