Research And Preparation Of Silicon-based Oil-water Separation Materials

The substantial discharge of oily wastewater,daily human activities and accident oil spill have caused abundant environmental and healthy problems,which greatly promoted the development of late-model materials and technology.Many scientists have researched abundant oil-water separation techniques,whereas there still exist some deficiencies such as complex separation technology,secondary pollution,high energy consumption,low separation efficiency and large equipment conditions.By considering of the wide application and one-up status of membrane in the water treatment field,we conduct research on membrane separation technology.In the manucript,we adopted simple method of one-step hydrothermal treatment,modifying the stainless steel surface with nanoparticles to preparation super hydrophilic-underwater super hydrophobic surface.Based on the secondary reaction of SiO2 under the alkaline condition to design our experiment,the precursor ethyl orthosilicate will be cracked into Si4+ and hydrolyze into SiO2.And after that SiO2 will continue to react with NaOH,eventually generating Na2SiO3.However,it takes a long time to make a complete reaction,therefore,we can obtain the mixed solution of SiO2 and Na2SiO3 via time controlling.After the drying process,we can gain the SiO2-Na2SiO3 membrane and SiO2-Na2SiO3-TiO2 stainless steel fiber.Na2SiO3 is an ideal adhesive with advantageous film forming properties.Also,it is worth mentioning that SiO2 is low-cost and environmental,so it an accurate choice when using extensively.However,TiO2 differs from other metallic oxide in providing better super hydrophilic performance.We carried out our research by EDS,SEM and XRD.By analyzing the micro-and nano-structure surface,elemental composition,phase analysis and the wettability of the stainless steel fiber,along with several applied tests to the sample such as oil-water separation tests,water flux calculations,50 times cycling separation tests,acid base salt tests,sand paper grinding tests and the stability tests etc.The result shows that,with Na2SiO3 interlayer,SiO2 nanoparticles and SiO2-Na2SiO3-TiO2 nanoparticles can be applied to the stainless steel fiber successfully,also the stainless steel fiber with SiO2-Na2SiO3 coating and SiO2-Na2SiO3-TiO2 composite membrane shows excellent super hydrophilicity in the air and super hydrophobic to different kind of oil under the water.After oil-water separation tests,the separation efficiency of stainless steel fiber covered with SiO2-Na2SiO3 is more than 99.7%and the SiO2-Na2SiO3-TiO2 composite membranes have higher efficiency which are all more than 99.9%.After sand paper grinding tests,stability tests and 50-time cycling separation tests,the separation efficiency is still all up to 99.9%,the reason for this phenomenon is the adhesion strength of Na2SiO3 is not also physical,but also chemical,the electrostatic force and the hydrogen bond are attached to SiO2 and Fe2O3,hence SiO2 and the stainless steel fiber form strong bonding force.By calculating the water flux of the membrane,the water flux of SiO2-Na2SiO3 coating is up to 76433 Lm-2h-1,and the water flux of SiO2-Na2SiO3-TiO2 composite membrane is much highher,which is up to 81752 L m-2h-1,these are all at the forefront of the current researches.Current study shows that the stainless steel fiber with SiO2-Na2SiO3 coating and SiO2-Na2SiO2-TiO2 composite membrane is a promising candidate material for oil-water separation.