Preparation And Research On Properties Of Polysilsesquioxane/PPTA Fibers Composites

With the development of modern industry and economy,heavy metal pollution has become a serious worldwide environmental problem that threatens the survival of all living beings.By and large,the heavy metal pollution included water pollution and soil pollution.In general,the methods for treating heavy metals include adsorption,solvent extraction,etc.The chelating adsorbent,a novel material,has a series of outstanding advantages,such as,low cost,high efficiency and fast adsorption rate,has become a research hotspot.Polysilsesquioxane as one kind of chelate adsorbent,and has many excellent adsorption properties,such as high specific surface area,high adsorption capacity,stable physicochemical properties,fast adsorption rate and so on.Although polysilsesquioxane has the potential to remove heavy metals in soil and wastewater,as a powdered adsorbent when the adsorption finished,it is difficult to recycle,so that it limits its applications.In order to solve this problem,we hope to find a kind of superior physical and chemical stability fibrous material.Therefore,we can load the powder-like polysilsesquioxane onto the fiber surface to produce a good adsorption properties of fibrous composite adsorbent.PPTA fiber,as one kind of fiber materials,has outstanding properties: superior temperature resistance,corrosion resistance,high strength,high modulus,and so on,which has been widely used in petrochemical,aerospace and other fields.More importantly,the PPTA fiber,has two groups : Benzene ring and amide bonds,so that it made it possible to synthesis a series of high performance fiber composites.In this paper,a series of epoxidation poly(p-phenylenetherephthal amide)(PPTA)fibers named as PPTA-ECH-1 ~ PPTA-ECH-5 were synthesized by using PPTA fibers as the raw material,DMSO as solvent via metallization and epoxidation.The amino-functionalized polysilsesquioxane coated poly(p-phenylenetherephthal amide)fibers(PPTA-APTES-1 ~ PPTA-APTES-5)were obtained by reacting amino groups of aminopropyltriethoxysilane(APTES)with PPTA-ECH.Subsequently,PPTA-APTES were modified with amino-propyltriethoxysilane(APTES)and mercapto-propyltriethoxysilane(MPTES)respectively by the method of sol-gel to synthesize modified PPTA composites(PPTA-PMPSQ-1~PPTA-PAPSQ-5)and(PPTA-PMPSQ-1~ PPTA-PAPSQ-5).The synthesized materials were characterized by IR,FE-SEM,XRD,BET,TA and EA and so on.The results of FE-SEM indicated that the polysilsesquioxane on the PPTA-PMPSQ surface was porous,polysilsesquioxane on the PPTA-PMPSQ surface was gel-like.It can be indicated that the target materials were successfully synthesized,and the other characterizations could indicate that the different surface polysilsesquioxane morphology was due to the synthesis mechanism difference of the two functional groups polysilsesquioxane on the PPTA surface.In this paper,we studied the static adsorption of PPTA-PAPSQ and PPTA-PMPSQ.Meanwhile the adsorption performance of Au(Ⅲ),Hg(Ⅱ)and Ag(Ⅰ)were investigated which included adsorption thermodynamics,selective adsorption,pH effect,adsorption kinetics,elution performance test,etc.The result of kinetic experiments reveals that the adsorption process of Au(Ⅲ),Hg(Ⅱ),and Ag(Ⅰ),by PPTA-PAPSQ and PPTA-PMPSQ followed well pseudo second-order kinetics model.The thermodynamics experiments indicate that the adsorption of Au(Ⅲ),Hg(Ⅱ),and Ag(Ⅰ)by PPTA-PAPSQ and PPTA-PMPSQ can better fit Langmuir adsorption model,and the process of adsorption is spontaneous,entropy and endothermic.The result of adsorption selectivity experiments shows that the two kinds of materials have good adsorption selectivity for the adsorption of Au(Ⅲ),Hg(Ⅱ),and Ag(Ⅰ).In summary,we have successfully synthesized two kinds of fiber adsorbent containing amino group and mercapto group,and they have great potential for the treatment of Au(Ⅲ),Hg(Ⅱ),and Ag(Ⅰ)in soil and wastewater.