不同溶剂提取宝清褐煤腐植酸的工艺优化及其特性研究

以褐煤的高效利用为出发点,以提高宝清褐煤腐植酸提取率为目标,探索了三种不同溶剂(KOH,NaOH,Na4P2O7)提取褐煤腐植酸的最优工艺条件。实验采用响应曲面法考察了反应温度、反应时间、溶剂浓度及其交互作用对腐植酸提取率的影响。结果表明:反应温度对目标值影响最大,且不同影响因素之间的交互作用对目标值有一定的影响,KOH提取时反应温度与反应时间的交互作用影响最大,NaOH和Na4P2O7提取时反应温度与溶剂浓度的交互作用影响最大。得到了不同溶剂下提取宝清褐煤腐植酸的最优工艺参数为:KOH为溶剂时,反应温度86℃,KOH浓度0.04 mol/L,反应时间2.0 h,此时腐植酸提取率为82.99%;NaOH为溶剂时,反应温度94℃,NaOH浓度0.047 mol/L,反应时间1.7 h,此时腐植酸提取率为87.96%;Na4P2O7为溶剂时,反应温度72℃,Na4P2O7浓度0.027 mol/L,反应时间2.0 h,此时腐植酸提取率为86.13%。通过分析三种溶剂提取的腐植酸特性可知,不同溶剂提取的腐植酸的提取率、总酸性基含量及分布不同,使用KOH溶液提取时腐植酸提取率最低,腐植酸相对分子质量最小;使用NaOH溶液提取时腐植酸提取率最高,腐植酸芳香缩合性较高;使用Na4P2O7溶液提取时腐植酸酸性官能团含量最高。

Study on Process Optimization and Characteristics of Humic Acid Extraction from Baoqing Lignite with Different Solvents

Based on the high-efficiency utilization of lignite,this study aimed to increase the humic acid yield from Baoqing lignite,and explored the optimal process conditions for extracting humic acid from lignite with three different solvents(KOH,NaOH,Na4P2O7).The experiment used the response surface method to investigate the influence of reaction temperature,reaction time,solvent concentration and their interaction on the extraction rate of humic acid.The response surface method experiment show that the reaction temperature has the greatest influence on the target value,and the interaction has a certain effect on the target value.The interaction between temperature and time during KOH extraction has the greatest impact,and the interaction between temperature and concentration during extraction of NaOH and Na4P2O7 has the greatest impact.The optimal process parameters for preparing Baoqing lignite humic acid under different solvents are:when KOH is the solvent,the reaction temperature is 86℃,the KOH concentration is 0.04 mol/L,and the reaction time is 2.0 h,the humic acid extraction rate is 82.99%;when NaOH is the solvent,the reaction temperature is 94℃,the NaOH concentration is 0.047 mol/L,and the reaction time is 1.7 h,the humic acid extraction rate is 87.96%;when Na4P2O7 is the solvent,the reaction temperature is 72℃,and the Na4P2O7 concentration is 0.027 mol/L,the reaction time is 2.0 h,the humic acid extraction rate is 86.13%.By analyzing the characteristics of the humic acid extracted from the three solvents,it can be seen that the extraction rate,total acidic base content and distribution of humic acid extracted by different solvents are different.The extraction rate of humic acid is the lowest when the KOH solution is used for extraction,and the relative molecular weight of humic acid is the smallest;the extraction rate of humic acid is the highest when the NaOH solution is used,and the humic acid has good aromatic condensation;the content of acidic functional groups of humic acid has the highest when extracted with Na4P2O7 solution.