用于油水分离的超疏水-超亲油沙子的制备及其性能

Preparation and Properties of Superhydrophobic-Superoleophilic Sand for Oil-Water Separation

目的对沙漠中的沙子进行表面改性并将其应用于油水混合物的分离。方法以沙子为基底,利用层层自组装法构筑纳米银粗糙结构表面,再经十二烷基硫醇修饰后,显示出超疏水-超亲油特性。采用低真空扫描电子显微镜、接触角测定仪,分别表征超疏水-超亲油沙子的表面形貌、润湿性能。结果改性后的沙子表面负载“乳突”状纳米银薄层,水在该表面的接触角高达156°±1°,而油的接触角为0°,表现出良好的超疏水-超亲油特性。利用沙子表面对水和油显示出的相反润湿性,不但可以选择性分离水上轻油与水下重油,还可以高效分离油和水形成的乳液,且对不同类型油品和水混合物分离效率均在95.6%以上,经过20次连续分离,分离效率无明显变化,表现出良好的循环利用性。经强酸、强碱、NaCl溶液浸泡24 h及60~300℃不同温度加热30 min后,均表现出良好的超疏水特性。结论通过自组装法在沙子表面负载纳米银晶体,随后用十二烷基硫醇进行表面接枝,所得到超疏水沙子不但能够分离具有明显界面油水混合物,还可以分离油和水形成的乳液,经连续分离,分离效率无明显降低。相关研究有望为沙子广泛利用及污水治理材料的制备提供一种新的思路。

The surface modification of sand in desert was studied and applied to the separation of oil-water mixture.The nano-silver rough surface was constructed with sand as substrate by layer-wise self-assembly method,and then modified by dodecyl mercaptan,to show superhydrophobic and superlipophilic properties.The surface morphology,wettability and oil-water separation performance of superhydrophobic and superlipophilic sand were characterized by low vacuum scanning electron microscopy,contact angle measuring instrument and separation efficiency,respectively.The surface of the modified sand was loaded with a"papiloid"nanometer silver layer.The contact angle of water on the surface was up to 156°±1°,while the contact angle of oil was 0°,showing good superhydrophobic-superlipophilic properties.Making use of the opposite wettability of sand surface for water and oil,not only can selective separation of heavy oil under water and light oil on water can also separate of emulsion from oil and water efficiently,and separation efficiency for different types of oil and water mixture is over 95.6%,after 20 successive separation,separation efficiency has no obvious changement,showing excellent recycling.After soaking in strong acid,strong alkali and NaCl solutions for 24 h and heating at different temperatures from 60~300℃for 1 h,they showed good superhydrophobic properties.Loading with nano-silver crystals on the surface of sand by self-assembly method,and then use dodecyl mercaptan for surface grafting,the superhydrophobic sand obtained can not only separate the oil-water mixture with obvious interface,but also separate the emulsion formed by oil and water.After continuous separation,the separation efficiency is not significantly reduced.The related research is expected to provide a new idea for the extensive utilization of sand and the preparation of wastewater treatment materials.