Preparation And Modification Of SiO₂ Aerogel Based On Boron Sludge And Its Adsorption Properties For Toluene

Boron mud is a solid waste generated during the production of borax and boric acid by boron ore through carbon-alkali method and pressurized alkali leaching method.The amount is huge and the cumulative amount is increasing year by year.Research on the utilization of objects is imminent.The use of low value-added boron mud waste cannot fundamentally solve the problem of boron mud accumulation.This paper designs the production process of extracting silicon and magnesium elements from boron mud and preparing silicon elements in boron mud into SiO2 aerogel Optimized experimental conditions,further studied the hydrophobic modification of SiO2 aerogel,two nontoxic,harmless and low-cost hydrophobic modifiers were found,and the toluene adsorption properties of hydrophobically modified SiO2 aerogels were studied.In the second chapter of the dissertation,the best technology for extracting silicon and magnesium elements from boron mud is studied,and the process for preparing SiO2 aerogel from sodium silicate extracted from boron mud is studied.During the element extraction process,the acid leaching and alkali leaching processes of boron mud were studied.Under the optimal process conditions,the extraction rate of magnesium in boron mud can reach 94.64%,and the extraction rate of silicon can reach 78.4%.During the preparation of SiO2 aerogel,the effects of water glass hydrolysis conditions,gel pH,and aging process on the tap density and porosity of SiO2 aerogel were studied.Under the optimal process conditions,a tap density of 0.1877 g SiO2 aerogel with a porosity of 91.47%and a water contact angle of 131°.Considering that the modifier TMCS used in the modification process of SiO2 aerogel is expensive and toxic,it is urgent to find a low-cost,safe and non-toxic modifier,and further research on hydroxy silicone oil(PDMS-OH)and hydrogen Modification of SiO2 aerogel by silicone oil(PMHS).It is found that the use of these two modifiers has a good hydrophobic modification effect on SiO2 aerogel.Under the optimal process conditions,a tap density of 0.4012 g/m3 and pores were prepared.Superhydrophobic SiO2 aerogel with a rate of 81.76%and a water contact angle of 161.8°.In order to reduce the experimental cost of SiO2 aerogel,the process of preparing SiO2 aerogel using PDMS-OH and PMHS as auxiliary silicon sources was further studied.Under the optimal process conditions,SiO2 with a hydrophobic angle of 113 °～127 ° Aerogel,this aerogel has better thermal stability than TMCS,PDMS-OH and PMHS modified SiO2 aerogels.This production process saves half the time compared with traditional processes,which is of great significance to industrial production.Leakage of organic reagents such as toluene will cause water pollution,endanger personal safety,and may explode if severe,endangering life.Organic reagents such as toluene are denser than water and are not miscible with water.Traditional adsorption materials cannot efficiently adsorb leaked toluene.In order to solve the problem that organic reagents such as toluene cannot be disposed of in a timely manner after largescale leakage,Chapter 3 SiO2 The adsorption of toluene on toluene was studied.We first studied the adsorption of pure toluene liquid by SiO2 aerogel using a weighing method.It was found that the low-density,hydrophobic SiO2 aerogel had an effect on toluene adsorption,and 60%PDMS-OH modified SiO2 was used in the water glass The aerogel has the best adsorption effect,the adsorption amount can reach 2.655 g/g,and then simulates the situation of toluene leaking on the water surface.It is found that this aerogel can quickly and efficiently absorb toluene floating on the water surface.The reusability was evaluated,and its adsorption capacity was still 91.43%when it was used for the first time.