Study On The Chelating Adsorption Characteristics Of Sulfonic Acid Collectors On Kaolinite Surface Based On Density Functional Theory

Coal is an important fossil energy in China.At present,coal washing and processing produced a large amount of slime.Due to the existence of a large number of clay minerals in the coal slime,these coal slime have many adverse conditions such as fine particle size,high ash content,high viscosity,high water holding capacity,low calorific value,and it is difficult to realize industrial utilization.It will bring adverse effects on the economic benefits of the coal preparation plant,and the stacking of slush will also cause environmental problems such as dust pollution.Kaolinite is one of the most important components of clay minerals in coal slime.Therefore,focuse on selecting a kind of sulfonic acid collector capable of characteristic adsorption on the surface of kaolinite and optimize design the molecular structure of different agents so that it can accurately collect fine kaolinite particles from coal slime water,which can provide a large number of fine kaolinite raw materials for industrial and agricultural applications,reduce the ash content of coal slime,improve the calorific value,and realize the high value resource utilization of coal slime.The main difference between kaolinite and other clay minerals in coal slime is that the surface of kaolinite contains a large amount of exposed Al-O octahedron,while the surface of other clay minerals is dominated by Si-O tetrahedron.Therefore,studying the difference in adsorption strength of sulfonic acid collectors on the Al-O octahedron and Si-O tetrahedron of kaolinite can be seen as the difference in adsorption strength of sulfonic acid collectors on kaolinite and other clay minerals.The thesis focuses on kaolinite and quartz,the analytical method combining simulation and experiment is used to determine the chelating configuration of sulfonic acid collectors on the surface of kaolinite,calculate the adsorption energy,and analyze the adsorption properties,thereby determining the adsorption strength of the reagents on the surface of kaolinite.Select and purchase five existing sulfonic acid collectors,including potassium methanesulfonate,potassium hydroxyethyl sulfonate,p-aminobenzenesulfonic acid,sodium dodecyl sulfonate,and sodium dodecyl benzenesulfonate,for experimental analysis such as flotation test,adsorption capacity measurement test,and infrared spectrum analysis,and compare and verify with simulation results.The results show that the selected 21 kinds of sulfonic acid collectors have strong adsorption strength on the surface of kaolinite（001）,and generally have poor adsorption effect on the surface of kaolinite（00（?））.According to the adsorption results of polar head group functional groups with different structures on the surface of kaolinite,the adsorption effect of polar head group functional groups on the surface of kaolinite（001）shows the best result without substituent sulfonic acid,which the optimal adsorption energy reaching-121.41KJ/mol,and the adsorption effect on the surface of kaolinite（00（?））is relatively poor,with the optimal adsorption energy reaching-22.08KJ/mol.The bonding atoms are single bond O atoms and double bond O atoms on the polar head group functional groups.All possible chelation configurations of sulfonic acid collectors on the surface of kaolinite were analyzed.Finally,based on the radius of metal Al and O atoms,the chelation configuration was determined to be the double bond O atoms on the polar functional group head group combine with metal Al on the surface of kaolinite to form a cyclic chelate through coordination.By analyzing the effects of carbon chain length,spatial structure,isomers,and different substituents of nonpolar groups on the electronic density of bonding atoms of polar head group functional groups in sulfonic acid collectors,the effect of differences in nonpolar groups on the reactivity of polar head group reactions was determined.The length of nonpolar carbon chains has a small impact on the reactivity of polar head group functional groups.The presence of nonpolar isomers can increase the activity of bonding atoms on polar head group functional groups,and the closer the side chain structure is to the functional group,the more significant the effect is.The presence of double bond structures and benzene rings in nonpolar groups are not conducive to the reaction,and the substitution of atoms with high electronegativity also reduces the reactivity of polar head group functional groups.According to the final simulation calculation results,the carbon chain length of the nonpolar group between C₃ to C₅ and the presence of isomers were determined as the optimal pharmaceutical structure.The three pharmaceutical structures of isopropyl sulfonic acid,isobutyl sulfonic acid,and neopentyl sulfonic acid were determined.It can provide a theoretical basis for the subsequent pharmaceutical synthesis.Screening of kaolinite samples to four particle sizes:500-250μm,250-125μm,125-75μm and 75-45μm.According to the flotation test results,the five sulfonic acid collectors were used in the test.The flotation recovery increases as the particle size of kaolinite decreases.When sodium dodecyl sulfonate is used as a collector and the particle size of kaolinite is 75-45μm,the flotation recovery reaches a maximum of 83%.When potassium hydroxyethyl sulfonate is used as a collector and the particle size of quartz is 75-45μm,the flotation recovery reaches a maximum of 42%.This indicates that sulfonic acid collectors have good collection effects on kaolinite,but poor collection effects on quartz.The adsorption capacity of kaolinite samples with full particle size was measured,and it was found that five sulfonic acid collectors had good adsorption effects on the surface of kaolinite.The content of organic matter in the solution with different concentrations of potassium methanesulfonate after adsorption is about 10 mg/L,and the content of organic matter in the solution with different concentrations of sodium dodecylbenzene sulfonate after adsorption is between 20 to80 mg/L.The organic content of the other three sulfonic acid collectors after treatment is similar to potassium methanesulfonate about 10 mg/L.According to the infrared spectrum analysis results,after the adsorption of the five sulfonic acid collectors on the surface of kaolinite,obvious absorption peaks appeared at 1660cm^-1 and 1764cm^-1.Comforming to the comparison standard diagram,it shows the absorption peaks of sulfur oxygen double bonds.Combined with the adsorption amount and flotation results,it indicates that sulfonic acid collectors has strong adsorption on the surface of kaolinite.Assembling with the simulation results,it has been concluding that sulfonic acid collectors have significant adsorption differences between the surface of kaolinite（001）and the surface of kaolinite（00（?））.Meeting the research needs and the important research value for extracting and adsorbing fine kaolinite from coal slime water.