Research Of Thiol-Modified Nano-silica And Its Supported FeS

With the development of nanotechnology,nano-Si O₂ is widely used in the fields of catalyst loading,drug loading and sustained release.However,the environmental instability of Si O₂ limits its scope of application.At the same time,the stability of the nano-Si O₂ loaded bivalent nano-iron material is not satisfactory,and it cannot exert excellent catalytic effect.Therefore,in this paper,the surface of nano-Si O₂ was first modified with mercapto groups to study its stability.Subsequently,nano-Fe S was loaded on the surface of nano-Si O₂ modified with mercapto groups,and its stability was studied and applied to the degradation of methylene blue and Cr?VI?.1.Synthesize nano-silica particles by the St?ber method and modify the surface by the silane coupling agent modification method.The modifier is 3-?mercaptopropyl?triethoxysilane?Mc PTS?.Scanning electron microscopy?SEM?was used to characterize the surface morphology of the product,and it was determined that the surface-modified nano-silica particles with good dispersion and uniform particle size distribution?200 nm?were obtained.In addition,the effects of reaction conditions?temperature,time,p H?and inorganic salt solutions on the stability of the modified nano-silica particles were studied in this paper.The results show that:?1?With the increase of the reaction temperature or the extension of the reaction time,it has little effect on the stability of the surface-modified nano-silica particles;?2?The reaction p H has a great influence on the stability of the surface-modified nano-silica particles.When the reaction p H is greater than 13,the surface thiol-modified nano silica particles are almost completely dissolved into free silicon;?3?The effect of inorganic salts on the stability of nano-silica particles after modification is Ca Cl₂>Mg Cl₂?>Na NO₃>Na₂SO₄>Na Cl.In Ca Cl₂ solution,the stability of silica nano particles is reduced,but the content of free silicon in the solution increases first and then decreases.The reason is that when the content of free silicon dissolved in the solution reaches a certain value?14%of the dissolved silicon?,the free silicon in the solution will combine with Ca²⁺to form calcium silicate precipitation.?4?For the free silicon in the aqueous phase,this paper studied the effect of different inorganic salt environments?Na Cl,Ca Cl₂,Na₂SO₄,Na NO₃?on its re-precipitation.The experiment found that the content of free silicon decreased with time.Inorganic salts accelerate the deposition of silicon ions,and the rule of inorganic salts that affects precipitation is:Na NO₃?Na₂SO₄>Ca Cl₂>Na Cl.2.The Fe S·7H₂O and thioacetamide?TAA?are used as raw materials to load Fe S on the surface of thiol-modified nano-silica particles.The stability of Fe S-loaded nano-silica and its catalytic degradation of methylene blue&Cr?VI?are studied.By optimizing the reaction conditions and characterizing the products by SEM,TEM and XRD,the best reaction conditions were obtained,which is the reaction temperature of 35?,the reaction time of 2 h,the reactant concentration of 2.5 mmol/L,and the ratio of silicon oxide to reactant is 1:5.The thermal stability and anti-ion interference ability of nano-silica before and after loading Fe S on the surface were studied.The result shows that the thermal stability of nano-silica with Fe S on the surface is about 8%lower than that of nano-silica before loading.The anti-iron interference ability of nano-silica with Fe S loaded on the surface was studied.The results show that Na NO₃ and Ca Cl₂ are the most conductive to the precipitation of free silicon,for both the system without Fe S-loaded nano-silica and the system with Fe S-loaded nano-silica.The Fe S loaded on Si O₂ synthesized under the optimal reaction conditions was used for the degradation of methylene blue and the removal of Cr?VI?in water.The catalytic effect was compared with pure Fe S with the same Fe S content,and it was found that Fe S loaded on Si O₂ shows better catalytic capacity.The degradation efficiency of methylene blue is increased by about 10%,the removal capacity is up to 125 mg/g.The removal rate of Cr?VI?is increased by 14%,and the removal capacity is up to 96 mg/g.