云南寻甸褐煤化学降解后腐植酸的理化性质分析

利用pH分级法将云南寻甸褐煤和褐煤氧化降解制备黄腐酸后残煤中的腐植酸分为酸性不同的组分,对每一组分进行元素、红外光谱、官能团含量定性、定量分析,测定了主要组分的凝聚限度值,从结构组成、性质方面将2种腐植酸进行对比研究.研究表明:降解前后腐植酸的结构性质存在明显的差异,降解后腐植酸(OHA)分子质量减小,主要组分的酚羟基、羧基含量分别由HA中的3.68 mmol/g,3.00 mmol/g增加到OHA中的4.76 mmol/g,3.61 mmol/g,主要组分的凝聚限度值由16.80 mmol/L增加到20.42 mmol/L;随着沉淀溶液酸度的增强,总酸性基团、羧基、酚羟基含量增大;元素氧含量,C/H原子比增加,元素碳、元素氢含量,C/O原子比减少.2种腐植酸都呈现出相似的变化趋势.

Physicochemical Properties of Humic Acid Separated from Chemolysis Brown Coal from Xundian Yunnan

The humic acids separated from original brown coal and residue of oxidation brown coal are fractionated into different pH fractions,whose chemical composition are then analyzed respectively by means of qualitative and quantitative techniques including elemental analyzer,Fourier transform infrared spectrometry as well as chemical function group content to determine the coagulation value of the main components of humic acids.It is shown through the results that the compositional and structural differences between the OHA from residue of oxidation brown coal and HA from original brown coal is remarkable.The molecular weight of the OHA is lower than that of HA relatively.The phenolic hydroxyl and carboxyl content of dominate constituents of humic acids increases from 3.68 mmol/g to 4.83 mmol/g,and from 3.00 mmol/g to 3.60 mmol/g respectively.The coagulation value increases from 16.80 mmol/L to 20.40 mmol/L.The similar phenomena are observed in the HA and OHA,that is,the total acidic group,carboxyl group,phenolic hydroxyl group,the content of O,the C/H molar ratio increase with the increasing acidity of the aqueous solution,but the content of C and H decrease,and so does the C/O molar ratio.