Preparation And Properties Of A New Type Of Dust Suppressant With Modified Chitosan

With the development of the mining industry,the environmental problem of dust pollution in mining areas has become increasingly prominent.How to effectively control mine dust pollution is an environmental problem that needs to be solved urgently.The traditional water spray dust suppression method and cover dust suppression method can no longer meet the existing dust suppression needs.At present,most dust suppressants still have many shortcomings such as insufficient water absorption and water retention capacity,frequent application,and short action time,and few studies have discussed the impact of dust suppressant application on the surrounding soil environment.Therefore,the development of products with excellent dust suppression effect and no negative impact on the surrounding soil environment is an important direction for the development of dust suppressants in the future.Chitosan has excellent hygroscopic and moisturizing properties,film-forming properties and biocompatibility,and has excellent potential as a dust suppressant material,but its poor water solubility limits its application.Therefore,in this paper,carboxymethyl chitosan was prepared by chemical modification method with chitosan as raw material,and its water solubility was improved,and a new multifunctional dust suppressant with excellent dust suppression effect and soil improvement effect was prepared.The main research contents and results of this thesis are as follows:(1)In this study,three kinds of modified materials with different substitution sites were prepared from chitosan by chemical modification.Through the comparison of water retention,N,o-cms was selected as the modification target,and the reaction conditions were optimized with the degree of substitution as the index.The optimum preparation conditions were determined as follows:the mass ratio of NaOH,chloroacetic acid and chitosan was 7:4.5:1,the dosage of isopropanol was 110 ml,and the reaction time was 4 h.(2)N,O-carboxymethyl chitosan was screened as water-retaining agent,dodecyl dimethyl betaine as surfactant and carboxymethyl cellulose type I as binder by monomer test.A three-factor and three-level orthogonal test table was designed,the dust suppression performance and soil improvement performance of each orthogonal test group were tested,and the dust suppression agent ratio was optimized.The optimum ratio was determined to be:0.6%N,O-carboxymethyl chitosan,0.2%dodecyl dimethyl betaine,0.3%carboxymethyl cellulose type Ⅰ.(3)In this study,the SEM characterization and contact angle test of the dust suppressant were carried out.The results show that the dust suppressant developed in this study can effectively improve the wettability of dust,and form a three-dimensional network structure on the surface of dust samples through bonding and coagulation.The anti-destructive performance test was carried out on the dust samples after spraying the dust suppressant.The results showed that the cured layer had good wind erosion resistance,and the wind erosion rate was 7.895%under the wind speed of 20 m/s;The compressive strength is basically unchanged within 60 d,the resistance is maintained at about 70 kpa,and it can withstand common external force damage such as man-made trampling;good rain erosion resistance,the rain erosion rate after 5 rains is 21.637%;good freeze-thaw resistance,the surface hardness can still reach 69.5 HA after 6 freeze-thaw cycles.(4)It can be seen from the field test that the dust suppressant developed in this study has a good inhibitory effect on TSP,PM 10 and PM2.5.The larger the dust particle size is,the more obvious the inhibitory effect is.It still has a considerable inhibitory effect at 90 days.Compared with the control group of clear water,it has a good timeliness.Through the comparative analysis of the performance and cost of three commercial dust inhibitors,it can be seen that the dust inhibitor developed in this study has better water retention and film-forming performance,good dust suppression effect and controllable cost.After use,it can improve soil water holding capacity and nutrient level,have higher comprehensive environmental benefits and expand the prospect.