Study On Surface Modification And Its Performance Of Silica

The method of “desiliconizing fly ash first and then extracting aluminum from it”was originally proposed by China Coal Pingshuo Group Co., Ltd. and our university.The method was evaluated to be reliable, efficient, and cost effective; therefore, it hasbeen industrialized. Moreover, various environmental and economic benefits areobtained by using this method in the industrial environment. Further, alumina exhibitsvarious applications across a broad range of industries; therefore, market demand foralumina has been increasing rapidly. In this study, sodium silicate was used to preparerubber silica. However, its application to silica will be limited if it is used to prepareonly rubber silica. It is expected that popularization of this method will lead to thesurplus production of silica; therefore, its demand will also be saturated. However, adrop in the market price of silica will influence the profit of the entire process ofextraction of silicon from fly ash. Based on the enterprise and social demand, in thisstudy, surface modification on silica using its special surface structure was performed,without changing its fundamental performances such as absorbency, thickening,porosity, large internal surface area, good dispersity, thixotropy, and smoothingproperties. Our investigation will expand the application market of silica, and improvethe profit of the entire process of extracting silicon from fly ash, which enhances thediversification of silicon products. The research contents of this paper as follows：(1) Copper (Cu)-loaded antibacterial silica was prepared using sodium silicate(Na2SiO3) and copper sulfate as sources, and the influences of temperature, time,rotating speed, and original Cu2+concentration on the actual absorption efficiency wereinvestigated by single-factor and orthogonal experiments. The optimal experimentalparameters were obtained as follows: Cu2+concentration of0.05mol L1, reaction timeof4h, reaction temperature of90°C, and rotating speed of300r min1, with the finalabsorption efficiency of47.08%. Moreover, the microstructure and morphology of theCu-loaded antibacterial silica were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The antibacterial property was alsoinvestigated by enumeration tests using Escherichia Coli as experimental bacterium.(2) Hydrophobic silica was successfully prepared using Na2SiO3as source andKH-570as modifying agent, and the influences of temperature, time, KH-570dosage,and pH value on the modification of silica were investigated by single-factor andorthogonal experiments, The optimal experimental parameters were obtained as follows:reaction time of35h, reaction temperature is60℃, the dosage of modifier is3ml, pHvalue of solution is4, at this time, activation index of Modified silica is94.1%, theamount of its absorption is2.73ml, the products were investigated by Fourier transforminfrared spectroscopy， X-ray diffraction, laser particle size distributing and thermalgravimetric analysis. The results indicated that the modified silica were synthesisthrough reactive hydroxyl silica surface bonding with KH-570.(3) Pentacoordinate organosilicon compounds were prepared using hydrophobicsilica as raw material, ethylene glycol as organic nucleophilic reagent, NaOH as alkalinemedium, Distilling reaction5h at atmospheric pressure,200℃, nitrogen protection, thedosage of NaOH was4.00g, relative distillate ethylene glycol was80%, the productswere investigated by Fourier transform infrared spectroscopy and X-ray diffraction. Theresults indicated that product was a target product.