Structure Study And Preparation Of Humic Acid From Coal

Humic acid is a kind of the macromolecular organic compound owning Colloid and hyperspace structure,mainly having the following properties: 1)acid;2)complexation;3)ion exchange;4)adsorption;5)ibiological activity,therefore humic acid is widely used in agriculture,industry and medical et al.Humic acid was usually prepared through using Na OH dissolving and acid precipitation with the brown coal.In order to improve the yeild of humic acid,there used H₂O₂ as Oxidizing agent,increasing stirrer hotplates,ultrasonic and Cu O technologies in this paper.The structure of humic acid was characterized by FT-IR,XPS and ion exchange process of Ba（OH）2and（CH3COO）2Ca to analyze the structure of humic acid.The main conclusions are as follows:（1）The yeild of raw humic acid by Na OH dissolving and acid precipitation was43.7%;The great yeild of secondary humic acid by H₂O₂ direct oxidating brown coal was 55.4%.The great yeild of secondary humic acid by H₂O₂-ultrasound oxidating brown coal was 52.3%;The great yeild of secondary humic acid by H₂O₂-Cu O oxidating brown coal was 57.5%.Because oxidative activity of H₂O₂-ultrasonic is very strong,easy to make the humic acid degrade into CO_x,NO_x,and water,so solution of H₂O₂-Cu O oxidation is best.（2）The FT-IR spectra of prepared of raw humic acid showed that they had the same carbon functional groups such as C-H,O-C=O,and C-C,C-O.By using XPS to characterize functional groups of C,N,S and P,the results showed that the contents of C = O and C-H,O-C = O,C-O and C-C were different in three kinds of humic acid.But the black humic acid had no C=O structure.Yellow humic acid did not exist Pyrrole（N-5）and Pyridine（N-6）structure;Brown humic acid did not have N-6structure;Sp3structure of nitrogen also did not exist in black humic acid;Yellow humic acid was without sulfur structure,brown and black humic acid did not exist mercaptan structure;Three kinds of humic acid is without phosphorus structure.（3）By comparing the contents of carboxyl groups and phenolic hydroxyl groups between the three kinds of oxidation methods,it was found that the content of carboxyl groups of humic acid increased and the content of phenolic hydroxyl groups decreased.The content of carboxyl groups in yellow humic acid was increased from5.22 to 6.67,content of black humic acid was increased from 6.39 to 7.46,and the content of black humic acid was changed from 3.49 to 4.63mmol/g.