面向溢油污染治理的SiO_(2)气凝胶疏水改性的研究进展

Research progress of hydrophobic modification of silica aerogel for oil spill pollution treatment

二氧化硅气凝胶(Silica aerogel,SA)具有高孔隙率、低密度、高比表面积等特性,可成为一种良好的吸油材料,然而亲水表面和珍珠项链的结构限制了其在吸油领域的广泛应用.疏水改性后的疏水SiO_(2)气凝胶(Hydrophobic silica aerogel,HSA)不仅具有SA的优异特性,而且疏水/亲油性好,是一种优异的轻质吸油材料.本文以表面后处理法和共前驱体法制备HSA为主线,系统介绍了这两种方法结合超临界干燥和常压干燥制备HSA的研究进展,分析总结了两种方法的优缺点.其中,共前驱体法主要结合超临界干燥工艺制备HSA,表面后处理法则常结合常压干燥,两种方法主要都采用硅烷化剂为疏水改性剂.表面后处理法改性不改变已形成的孔隙结构,HSA的孔径和粒径比较均匀,但可能存在内部改性不彻底的问题.共前驱体法在凝胶结构形成的同时完成改性,制备的HSA比表面积更大,疏水性更好,但是其孔径不均匀,引入的疏水基团有限.此外,本文还综述了目前常用的提高HSA机械性能的方法以及HSA吸油性能的研究进展.最后,立足于当前HSA用作吸油材料发展的趋势,对HSA吸油材料朝着开发低成本且环境友好的原料、开发周期短的疏水改性流程、制备大块体HSA、提高HSA的机械性能以及提高其吸油性能等发展方向进行了展望.

Oil spill pollution seriously endangers human and ecosystem health.Therefore,it is urgent to develop oil-absorbing materials to effectively remove oil spill pollution.Among the traditional oil-absorbing materials,natural organic adsorption material has low oil absorption capacity and hydrophilicity;inorganic adsorption materials are difficult to recover and have low oil absorption efficiency and high price;and although the synthetic organic adsorbent has outstanding oil absorption capacity,its biodegradation is poor.Silica aerogel(SA)has the characteristics of high porosity,low density,and high specific surface area,which make it an excellent oil-absorbing material.However,the hydrophilic surface and pearl necklace structure of SA limit its wide applications in the oil absorption field.Hydrophobically modified hydrophobic silica aerogel(HSA)has not only excellent SA characteristics but also good hydrophobic/lipophilic properties.In this paper,focusing on HSA preparation by surface posttreatment modification and coprecursor modification,the research progress on these two methods combined with supercritical drying and ambient pressure drying is systematically introduced,and the advantages and disadvantages of the two methods are analyzed and summarized.The coprecursor modification is mainly combined with a supercritical drying process to prepare HSA,while the surface posttreatment modification is often combined with an ambient pressure drying process.Both methods normally use silylating agents as hydrophobic modifiers.The surface posttreatment modification does not change the formed pore structure,and the pore size and particle size of HSA are relatively uniform.However,the modification process of surface posttreatment is long,the solvent consumption is large,and the cost is high.In addition,incomplete internal modification may be a problem.In the coprecursor modification method,wet gel is formed and modified simultaneously,shortening the modification time and saving costs.The prepared HSA of coprecursor modification has a larger specific surface area and better hydrophobicity,but its pore size is uneven,and the introduced hydrophobic groups are limited.Excessive silylating agents affect the sol–gel process of HSA.In addition,the current methods for strengthening HSA mechanical properties and the research progress on HSA oil absorption properties are reviewed.Finally,based on the current development of HSA as oil-absorbing materials,the development direction of these materials is discussed,for example,developing low-cost and eco-friendly raw materials,shortening the hydrophobic modification process,preparing bulk HSA,strengthening the mechanical properties,and improving the oilabsorbing properties of HSA.