Study On Chemical Modification Of Humic Acid And Its Anti Flocculation Performance

This paper takes Yunnan lignite as the research object,adopts different processing methods,uses orthogonal experiments to explore the best process parameters for preparing humic acid YHA and NHA,uses the anti-flocculation limit value as an index,and uses response surface CCD method to explore the preparation of YGHA and NGHA The best process parameters,through the characterization of humic acid samples,to study their structure and properties;To study the biological stimulating activity of YGHA and NGHA by measuring the growth indicators of wheat seedlings;Combining elemental analysis,FT-IR analysis,and ¹³C-NMR analysis,use Guassian 09W software to optimize the molecular models of YGHA and NGHA,a molecular model with good matching degree can be obtained.Taking humic acid yield as an indicator,Na OH concentration of 4%,liquid-solid ratio of 4,time of 1.5 h,and temperature of 80?are the best process parameters for preparing YHA.The average yield can reach 40.00%,and the flocculation limit of YHA Value is 7.20 mmol/L;The single-factor experiment result using YGHA's flocculation limit value as an index is time 60 min,temperature 80?,mass ratio of sulfonating agent to YHA is 1.5:1,and the best process parameters obtained in response surface experiment are time 62.46 min and temperature 78.75?,the ratio is 1.64,at this time the flocculation limit value of YGHA is 9.80 mmol/L;Taking humic acid yield as an indicator,HNO₃ concentration 8%,liquid-solid ratio 8,nitrification time 30min,and nitrification temperature 70?are the best process parameters for NHA nitrification treatment,and the average yield can reach 65.23%,the flocculation limit of NHA is9.60 mmol/L;Using YGHA's single-factor experiment results,taking the flocculation limit of NGHA as an indicator,the best process parameters obtained from the response surface experiment are time 70 min,temperature 70?,mass ratio of sulfonating agent to NHA 1:1,NGHA flocculation The limit value is 14.60 mmol/L.The flocculation limit value of NGHA is much greater than that of YGHA.HNO₃ pretreatment of YM and sulfonation modification improves the solubility of humic acid,while sulfonation modification increases the content of humic acid oxygen-containing acid groups;Elemental analysis showed that the S content of YGHA and NGHA increased,and the S content of NGHA increased significantly;UV-Vis analysis showed that the molecular weight of NGHA was the smallest and the degree of aromatization was low;In the FT-IR analysis,the four samples are rich in functional groups.The pretreatment of HNO₃ changes the content types of functional groups of humic acid,and the sulfonation modification increases the functional groups containing S;¹³C-NMR analysis shows that YGHA and NGHA were mainly composed of aromatic carbon structures and aliphatic structures.The XPS analysis of YGHA and NGHA shows that the surface C elements are diverse,the O element is mainly carbonyl oxygen and hydroxyl oxygen,and the S element is mainly sulfone sulfur.YHA,NHA,YGHA and NGHA have biological stimulating activity.Among them,YGHA and NGHA have better biological stimulating activity on plants than YHA and NHA,and NGHA has stronger biological stimulating activity on plants than YGHA;Constructing the molecular structure model of YGHA and NGHA can better reflect the structural characteristics of YGHA and NGHA.The molecular formula of YGHA is C₅₅H₅₂N₂O₃₁S,and the relative molecular mass is Mr=1268.The molecular formula of NGHA is C₃₅H₃₉N₃O₂₇S and the relative molecular mass is Mr=965.Both contain benzene ring,carboxyl group,phenolic hydroxyl group,alcoholic hydroxyl group,ether bond,etc.There were 43 figures,47 tables and 120 references in this paper.