The Preparation And Research Of A New Environmentally Friendly Sand-fixation&Dust Suppressant By Xanthan Gum Grafted Copolymerization

In this paper,we used seed emulsion copolymerization,choosing xanthan gum(XG)as the grafting substrate,methyl acrylate(MA)&vinyl acetate(VAc)as monomers and ammonium persulfate(APS)as the initiator,sodium dodecyl benzene sulfonate(SDBS)as the emulsifier to synthesize a water-soluble grafted xanthan gum copolymer.Then we applied this material as a new environmentally friendly sand-fixation&dust suppressant,which was applicable in the edge of desert,places suffering from land degradation and urban areas with dust pollution,and could cooperate with the bio-method treating desertification,even be positive to the vegetation recovery.We also discussed factors such as monomer ratio,amount of initiator,emulsifier and grafting substrate,and temperature for the copolymerization that affected the quality and performance of polymer emulsion.We assessed the products mainly based on their maximum compressive strength of sand column,and other indexes like the viscosity,fluidity,appearance,texture and stability of the emulsion were also considered.The optimal process conditions was determined:monomer mass ratio(mMA:mVAc)= 3:5,amounts of APS,SDBS,XG were 5.0%,1.2%,4.0%,seperately,and temperature for the copolymerization was 65℃.Under these conditions,the polymer emulsion owned not only the best appearance,viscosity,fluidity and stability,but also could enhance the compressive strength of the sand column in maxium extent.By measuring soild content and viscosity of the emulsion,grafting rate of the product,analyzing results of FTIR,XRD,SEM,TG-DTA,we characterized the physicochemical properties of our product.According to these results,we knew that solid content of the emulsion was 15.7%,grafting rate and grafting efficiency were 134.0%and 78.8%,respectively.The fluidity of the emulsion was pretty good and the viscosity was not disturbed by the temperature fluctuation,but it would linearly grow along the increase of the solid content.In addition,the fluidity still met the application requirements after 50 days.By comparing FTIR spectrums of the product,grafting substrate and MA-VAc copolymer,we concluded that the graft copolymerization was successful.From the XRD result,we could see that the grafting mainly happended in the amorphous region and the crystallinity improved slightly.Through SEM,we observed the surface of grafted XG became much rougher,showing its layered structure.The curves of TG-DTA showed that the emulsion owned better hydrophilicity and water retention under high temperature than vinegar emulsion,and the product was stable below 283 ℃.Finally,we exploited the performance of grafted xanthan gum copolymer for sand-fixing and dust depression.All the application testings we designed were as follows:the consolidation of sand pile surface,the water absorption,degradability of the product film,the compressive strength,water retention,freeze-thaw resistance of sand column,the wind erosion and water erosion resistance of sand pile,possible impacts on seed germination and growth of the plant.Through these testings mentioned above,we could evaluate the performance of the grafted xanthan gum in sand fixation and dust suppression comprehensively.The research showed that the performance of this sand-fixation&dust suppressant met the demands during fighting against desertification and dust pollution.Also,it could act in an environment-friendly way.In conclusion,we chose xanthan gum as grafting substrate,which could not only broaden the application of the modificated xanthan gum,but also provide many valuable theoretical explanation and experience in preparation and characterization of new sand-fixation&dust suppressants.