Study On The Optimum Preparation Process Conditions Of Nano-Iron Oxide And Nano-Silicon Oxide Coated Sand

The nano-Iron Oxide and nano-Silicon Oxide Coated Sand (nano-OCS) are prepared with ordinary quartz sands and the modifier (nano-Fe2O3、nano-Si02)and using the epoxy resin as a adhesive,the surface loading capability and the adhesion strength as the evaluation index.By using the orthogonal test method and the Continuity test method, effects of different factors on surface loading and adherent strength on the surface of nano-OCS are analyzed. Factors are:stirring frequency N, dosage ratio of nano-Fe2O3、 nano-SiO2and epoxy resin,drying temperature T and time t, appearance of nano-OCS and etc, the amount of nano-SiO2evaluates with the amount of total surface coating,the optimum preparation conditions of nano-OCS are investigated. Results are obtained:(1) in the process of water bath heating,modifiers and binders mix at a slow speed, the optimal speed is50r/min, the optimal temperature is45min.(2) the optimal drying time is1h, the optimal drying temperature is120℃±5(3) The optimal dosing ratio of nano-Fe2O3(65.8g/L) to Raw Quartz Sand (RQS) is0.23mL/g RQS. Add to the solution of the epoxy resin (99%), The optimal dosing ratio of epoxy resin is0.03mL/g RQS, The optimal dosing ratio of nano-SiO2(10g/L) is0.17mL/g RQS,organic adsorption rate reaches92%. dosage is excessive, organics adsorption rate is significantly reduced:(4) As compared with nano-OCS prepared by the alkaline deposition method at low temperature (T≤110℃)and nano-OCS which is prepared by calcining at high temperature (T≈300℃), Add a binder epoxy resin in the preparation process,a method of curing with low-temperature water bath of the obtained nano-OCS, Surface loading increases by about8times, the desorption rate decreased more than70%(5) Adhesive dosage directly affect the size surface loading and the adhesion strength at the Preparation Process of Nano-OCS, changing the water bath temperature T, control the Nano-OCS surface adhesive curing strength and curing time.Analytical SEM Scanning electron micrographs and X-ray spectroscopy (EDS) results:RQS has smooth surface, small specific surface area, adsorption capacity. EDS analysis results show that the C elements accounted for87.23%of the total weight of Al element accounted for11.53%, Si element is1.25%, while the surface of the nano-OCS showing a pore-like shape, its shape is similar to a cellular, there are a large number of surface grooves, this form of large specific surface area, the adsorption capacity is high, it is easy to adsorb organic particles in its pores.the interception effect show.the purpose of the removal of organic matter is better to achieve,the C element in nano-OCS accounted for45.31%of the total, the Fe element accounting for21.53%, the O elements accounting for23.48%Si elements accounted for9.68%frcom the EDS results that nano-OCS Fe content than unmodified RQS significantly improved, the surface of modified quartz sand attached to Fe3+to increase the positively charge of RQS surface and make nano-OCS have better adsorption effect to the negative valence organic pollutantsits in water, the SEM images shows, the pore size on the surface of the nano-OCS is approximately20-40nm, this feature is able to adapt to different size organic adsorption, the5000times magnification SEM images of nano-OCS and RQS have obviously discrimination,it shows that the application of nano-oxide combined with epoxy resin modified ordinary quartz sand surface effect is remarkable.To compare the adsorption curve with the isotherm patterns.select the Langmuir isotherm or Freundlich adsorption isotherm to describe the adsorption process of the modified sand filter media,the correlation coefficient KF and n of two adsorption isotherm of the difference filter medium can require,the results of analysis showed that the two nano materials composite modified sand,whose adsorption effect of organic matter is significantly better than those of other ordinary modified sand and iron oxide modified quartz sand, the Langmuir adsorption isotherm correlation coefficient R is greater than that of the Freundlich isotherm, the role of physical adsorption in the adsorption process is greater than the chemical adsorption effect.