竹浆黑液高效减水剂的结构表征及吸附研究

研究了竹浆黑液混凝土高效减水剂(GCL1-JB)的结构和吸附特征.将GCL1-JB先通过超滤和离子交换树脂提纯,再通过凝胶柱层析分级,然后选择4种窄分子量分布的GCL1-JB级分进行结构表征和吸附研究.结果表明,GCL1-JB具有高分子量和高磺化度的结构特征.不同分子量级分的GCL1-JB的化学分子结构相似,但其中磺酸基含量随着分子量增大而减少,而芳香环含量随着分子量增大而增大.GCL1-JB在阳离子表面能形成平整的自组装吸附膜,其中高分子量级分的GCL1-JB因磺酸基含量较低,分子较卷曲,故吸附量较大.

STRUCTURAL CHARACTERIZATION AND ADSORPTION BEHAVIOR OF SUPERPLASTICIZER PREPARED BY MODIFICATION OF BAMBOO PULP BLACK LIQUOR

The structure and adsorption characteristics of a lignin-type superplasticizer(GCL1-JB).GCL1-JB was prepared by graft sulfonation of alkali lignin from bamboo pulp black liquor and purified by ultrafilter and ion exchange resin.Four GCL1-JB fractions with narrow molecular weight distribution were obtained from gel column chromatography separation and selected to study the structural and adsorption characteristics.Results showed that GCL1-JB had structure features of both high molecular weight and a high degree of sulfonation.The four GCL1-JB fractions had no obvious difference in chemical structure,but with increasing molecular weight,the content of sulfonate groups decreased and the content of aromatic groups increased.Four GCL1-JB fractions were used as polyanions to build up multilayer films on planar substrate by using poly-(diallydimethylammonium chloride)(PDAC) as the polycation.The surfaces of GCL1-JB/PDAC layer-by-layer self-assembled films were generally flat,and their surface roughness was about 1～2 nm.The GCL1-JB with higher molecular weight had a larger adsorbed amount.This phenomenon could be explained in this way.The GCL1-JB with higher molecular weight had a less content of sulfonate groups,inducing less electrostatic repulsion.Therefore,the GCL1-JB with higher molecular weight had larger molecular curling,which caused a larger adsorbed amount.