Investigation On Polymeric Janus Short Fibers Stable Pickering Emulsion And Oil-water Separation

With the close communication between countries and the vigorous development of transportation in industry,the mixtures of industrial and living wastewater become more and more serious.The water polution not only threats the survival of wild animals and plants and human health,but also impact the water,atmospheres,crop growth and natural landscape.Therefore,physical,chemical and physichemical methods have been used to recover,separate and recycle oily wastewater.But the.separation efficacy is poor and serious pollution problems caused by secondary pollution have not yet been solved.In addtition,the existing technology is not effective for the separation of a small amount of suspended oil and some special oil.With the scientific development,solid particles that replace the surface active agents form Pickering emulsion between oil and water surface,which can not only form a uniform size of solid particles,but also enhace the emulsion stability.In our paper,Janus fibers were prepared by electrospinning method with coumarin 6-labeled poly(styrene-maleic anhydride)-g-(p-benzy lamino)-1,2,4,5-tetrazine-6-(2-cyanopyrimidine)copolymers on one side and rhodamine B-labeled poly(styrene-maleic anhydride)on the other side.Then,Janus short fiber with different aspect ratios were obtained by freeze-cutting technique.The Janus short fibers with different aspect ratios and different grafting ratios were obtained.The hydrophobic chain norbomene-(bicyclo[2.2.1]hept-5-ene-2-palmitamide)was grafted to poly(styrene-maleic anhydride)-g-(p-benzylamino)-1,2,4,5-tetrazine-6-(2-cyanopyrimidine)side by Diels-Alder click chemistry and the temperature responsive hydrophilic chains of poly(N-isopropylacrylamide)was grafted to poly(styrene-maleic anhydride)side by the amide reaction.The optimal stability of the Janus short fibers was obtained by orthogonal designing experiment,including difference and variance squared sum analysis,variance analysis,interaction analysis and linear regression analysis.Peickering emulsions were formed from Janus short fibers,Janus microspheres and Janus short fiber with gratfed of poly(N-isopropylacrylamide)of different molecular weights,and the stability results showed that the Janus short fibers with molecular weight of 2200 kDa achieved a good stability.When the outside temperature gradually rised to the minimum critical temperature of poly(N-isopropylacrylamide),the pickering emulsion underwent demulsification.The results showed that the separation tcycles of oil and water by Janus short fibers could reach more than 20 times,and the separation effect was over 95%.