Fabrication Of Nanohybrid Silica Used For Water Treatment

Heavy metal particles and organic pollutants are two important water pollutions posing fatal threat to human health and a threat to public heath. Silica nanomaterials have been used for adsorbents to remove POPs and heavy metal ions, but the main problems are: low removal rate, long adsorption equilibrium time and poor thermal stability. Therefore, it is very important to design novel structured silica nanomaterials for the removal of POPs and heavy metal from wastewater. This paper presents three simple, flexible and effective function of silica hybrid materials and explore its application in the field of water treatment.In order to solve low adsorption rate and long balance time of silica adsorbents, chelating-functionlized mesoporous silica was prepared with 3-aminopropyl-triethoxysilane followed by bromoacetic acid. The effects of the solution pH, metal ion initial concentrations, and contact time were investigated. The effects of the solution pH, Pb(II) initial concentrations, and contact time were investigated. The results showed that the chelating modified hybrid mesoporous silica adsorption of Pb²⁺ in water show a good performance. Adsorption efficiency can reach 99.4% with fast adsorption and high removal rate. The adsorption behavior of the modified adsorbent could be described by Langmuir model and adsorption process fit with the pseudo second order kinetics equation.To improve separation of nanosorbents, separable hybrid SiO₂ nanofiber films were prepared. Novel zonal mercaptopropyl silica nanofibers were fabricated for the removal heavy metal ions from water by the sol-gel polymerization of (3-mercaptopropyl)trimethoxysilane on the electrospun polyacrylonitrile (PAN) nanofibers, followed by removal of PAN nanofibers using DMF dissolution. Such zonal silica nanofibers are promising materials for use as heavy-metal ion-trapping agents because of low basis weight and high permeability. To clear POPs from water bromopropyl modified SiO₂ nanofibers were successfully prepared by modifying SiO₂ nanofibers with bromopropyltrichlorosilane. Some nanoparticles formed on surface of these SiO₂ fibers as a result of bromopropyltrichlorosilane ulteriorly growing. Removal efficiency of these fibers reached at 95% at low concentration due to larger specific surface area and large numbers of pores and hydrophobic bromopropyl sursace of these hybrid SiO₂ fibers.The lipid contained in the organisms can be effective concentration of lipid-soluble substances. Pure SiO₂ nanoparticles are not provided with clearance of organic pollutions. In order to solve this problem, from the point of view of bionics, the siloxane lipid was synthesized. Then use it to capture and remove POPs by sol - gel combined with self-assembly process. This approach is through ultrasonic dispersion of the siloxane lipid in water, then the double-stranded hydrophobic tails of lipid will capture hydrophobic POPs in the formation of lipid bilayers. To improve separability of it, a better method was developped using hybrid SiO₂ with lipid bilayer combined with hydrophobic Fe3O4 to capture dieldrin in water. The results showed that the lipid bilayer of SiO₂ containing magnetic particles showed good removal ability on dieldrin, so it is a potential efficient adsorption material of removing trace persistent organic pollutants. It is a new exploration of bionics applications in pollution control.