论文部分内容阅读
采用电位、电导、量热法测定了几种腐植酸(HA)及硝基腐植酸(NHA)的酸性功能团含量、表观解离常数(pK 值)及热力学参数(⊿H,⊿S)。结果表明,用不同方法测得的羧基及酚羟基含量吻合良好。腐植酸的羧基和可滴定的酚羟基在热力学性质上同简单的羟基苯羧酸相似。当腐植酸来源不同时,其酸性功能团的结构特征会不同。如山东黄县褐煤及日本亚炭HA、NHA 含有较多的水杨酸型结构,而山西灵石风化烟煤HA、NHA 中则似乎不存在。它们的弱羧基具有较高的活性,彼此间差异也比较大。用硝酸氧化能使HA 中羧基含量增加,酚羟基减少,酸性功能团活性提高。
The acid functional groups, apparent dissociation constants (pK) and thermodynamic parameters (⊿H, ⊿S) of several humic acids (HA) and nitro humic acid (NHA) were determined by potentiometry, . The results showed that the contents of carboxyl groups and phenolic hydroxyl groups measured by different methods were in good agreement. Humic acid carboxyl and titratable phenolic hydroxyl thermodynamic properties similar to simple hydroxy benzene carboxylic acid. When humic acid comes from different sources, the structural features of acidic functional groups will be different. Such as Shandong Huangxian lignite and Japanese carbon HA, NHA contains more salicylic acid type structure, Shanxi Lingshi weathering bituminous coal HA, NHA does not seem to exist. Their weak carboxyl group has high activity, the difference between them is relatively large. Oxidation with nitric acid can increase the content of carboxyl groups in HA, reducing the number of phenolic hydroxyl groups and improving the activity of acidic functional groups.