Preparation Of Silica Nanoparticles From The Environment Waste Silicon Sludge

In integrated electric circuits, solar cells and other industries, silicon line cuttingprocess will produce a lot of waste silicon sludge. After removing the1,2-ethanedioland large particles carborundum, the remaining part of the waste silicon sludge iscalled environmental waste silicon sludge. The main components of theenvironmental waste silicon sludge are silicon dioxide, silicon, silicon carbide and asmall amount of small particles of metal impurities. However, the environmentalwaste silicon sludge tends to breeding-fire. People seldom study the utilization of theenvironmental waste silicon. Generally sealed landfill disposal, not only a waste ofresources, but also bring enormous disadvantages to the environment. This thesispresents the recycling technology of the environmental waste silicon sludge to preparehigh added value and widely used silica. Simultaneously, study recycling siliconcarbide from the environment waste silicon sludge. It has more significance onenvironmental protection and circular economy.First of all, by silicon molybdenum yellow method, and scatter method todetermine the content in environmental waste silicon. The determination consequentsare as below:29%silica,53.5%silicon,17.5%silicon carbide.Then, the mass ratio of sodium hydroxide and the environmental waste silicon,reaction temperature and reaction time are first determined through the single factorexperiments. Furthermore, use the response surface analysis to optimize the operatingprocedures of silica dissolution rate to prepare water glass. By the variance analysis,the order of the three factors that affect silica dissolution rate is as bellow: reactiontime> mass ratio> reaction temperature. The optimum process parameters of theenvironmental waste silicon are as follows: quality ratio is1.73, reaction temperatureis118.81℃, reaction time is4h, the dissolution ratio of the models is97.27%. Underthe above experimental conditions, do three groups of experiments, the average datewas97.15%. This fitted with the model prediction value.Use the above-prepared water glass as the raw material to prepare silica byprecipitation method. The influence factors that reaction temperature, hydrochloricacid, aging time and the end of reaction pH and other effects on the silica surface areaand the oil absorption value of DBP are researched. The optimum technologyparameters: reaction temperature80℃; the density of hydrochloric acid20%; aging time1.5h; the end of reaction pH6. The physicochemical detection shows that theindexes of silica accord with national standard. By XRD, FTIR and SEM to evaluatesilica the results indicate that the prepared silica is amorphous, and the surface has thephenomenon of accumulating.Finally, we use hexamethyl disilylamine, trimethylchlorosilane, cetrimoniumbromide and sodium dodecylbenzenesulfonate to study the modified of silica.Meanwhile, we measure the transmittance of ethanol and activation index of silica;and characterize the modified silica through FTIR and XRD. The results illustrate thatthe hydroxyl silanol and physical adsorption of water stretching vibration of modifiedsilica absorption peak has decreased in about3400cm-1, the bending vibration ofphysical adsorption of water absorption peak also weakened in about1630cm-1. Itindicates that the silica has been modified and the modified silica is amorphous.Preliminary explore the ability of oil adsorption, the silica indicate has a certainimpact on oil absorption.