Study On Synthesis Of Composite Hydrogel And Its Mechanism Of Coal Dust Inhibition

In actual production,due to the wide application of mechanized coal mining technology,a large amount of coal dust was produced and was easy to cause catastrophic risks such as pneumoconiosis,environmental pollution,and coal dust explosion.Most of the existing coal dust inhibitors had disadvantages such as difficulty in wetting coal dust,short bonding time,weak mechanical properties,and poor atomization effect.Therefore,a composite hydrogel dust suppressant was developed by chemical modification,and the wetting-bonding-solidification mechanism of the dust suppressant was investigated in depth using experimental and theoretical simulations and a wind-pressure device was designed to test its dust suppression performance.The main research content and results of this study were as follows:（1）A sodium cardanol polyoxyethylene ether sulfate（SCPES）wetting agent was synthesized by graft copolymerization,sulfonation and alkalization.The synthesis of SCPES and its wetting mechanism on coal dust were investigated by using pyrene fluorescence spectroscopy,Fourier infrared spectroscopy,quantum chemistry and molecular dynamics software.The results showed that 0.10 g/L and 0.25 g/L were the critical association concentration and critical micelle concentration of SCPES,respectively,and the surface tension and contact angle at the critical micelle concentration were 32.18 m N/m and 39.5°,respectively.The simulation results showed that compared to the H₂O-lignite system,the H₂O-SCPES-lignite system exhibited an increase in the total number of hydrogen bonds from 2082 to 2136,a decrease in the interaction energy from-13863.35 to-17817.77 kcal/mol,and an increase in the diffusion coefficient of water molecules from 0.12 to 0.73.The longer hydrophobic tail chains of SCPES were entangled in the hydrophobic sites on the coal surface and SCPES acted as an intermediate carrier between water and coal to improve the wettability of coal dust.（2）The hydrogel binder DG-PAA with a typical three-dimensional network structure was synthesized by a free radical copolymerization reaction using acrylic acid and ammonium persulphate as monomers and levodopa and glutathione as dual cross-linkers.The adhesion mechanism of DG-PAA was studied by using ultraviolet spectroscopy,liquid chromatography,Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance experiments combined with density functional theory calculations.The results showed that the strong adhesion of DG-PAA was attributed to the fact that the catechol and quinone groups of levodopa,the-NH₂,-COOH and other groups of glutathione can be grafted on the polyacrylic acid skeleton through intermolecular hydrogen bonding to form three-dimensional hydrogen crosslink network.The-OH,-NH₂ and-COOH groups contained in DG-PAA can act as active sites of hydrogen or ionic bonds and are firmly bound to the coal dust surface,resulting in a bonded film with a hardness of 32.5 HD and a high crust strength.（3）The contact angle of DG-PAA on the coal surface was reduced from 76.9°to50.8°after the addition of 0.25 g/L SCPES;the head group SO₃^-of SCPES can form dynamic covalent cross-linking with the hydrogel network of DG-PAA through hydrogen bonding;and its long hydrophobic chains can be adsorbed on the coal surface through van der Waals interaction and hydrophobic interaction,thereby increasing the penetration of DG-PAA into the coal surface pores and better consolidating coal dust.The wind pressure test results showed that the crust film formed by the SCPES/DG-PAA compound dust suppressant solidified coal dust did not raise at a wind speed of 20m/s and had a long-lasting effect of binding coal dust.