Preparation Of Nano-ZnO Deposited On Metal Mesh And Study On Oil-water Separation Performance

A trace amount of polar impurities in oil can cause serious issues in many technical applications.When oil contains a relatively large amount of polar organic impurities,such as water,glycerol,and ester,the polar impurity phase is well separated from the polar oil phase as a result of the poor compatibility between them.To address this issue,a great deal of efforts has been devoted to development of oil-water separation membranes.On the other hand,the technical performance of oil can be significantly reduced by the presence of a fairly small amount of polar impurities.For example,the presence of aromatics and polar organic sulfur or nitrogen compounds in engine fuels significantly deteriorates the combustion performance,which further has adverse environmental and health impacts.Up to date,a number of inorganic oxides have been deposited on metal meshes to produce oil-water separation membranes.In this content,the present thesis was aimed to development of nanostructured ZnO membranes not only for oil-water separation but also for removal of polar impurities from oil.This thesis consists of the following two parts: 1.We studied the growth of ZnO nanorods from NH₃·H₂O and Zn?NO₃?₂ · 6H₂O via a hydrothermal process.The experimental results show that the reaction time has great influence on growth of ZnO nanorods and their adhesion on the supporting substrates.Under optimum condition,we demonstrated that ZnO nanorods could be strongly deposited on the surface of copper meshes to produce effective oil/water separation membranes;the apertures of the copper meshes should be smaller than 500 ?m for effective oil and water separation.The resulting ZnO nanorods coating is superhydrophilic in air;the water contact angle of water being close to 0°.Built on this excellent hydrophilicity,the resulting membranes can readily remove of a small amount of oil from water.2.The surface of the resulting ZnO membranes can be easily wetted by oil in air;the contact angle of oil is close to 0°.Because of super olepophilicity,we succeeded removal of a trace of water from oil by using the resulting ZnO membranes.The nanostructured surfaces of as-prepared ZnO membranes have high suface area,high surface energy and strong polarity,thus enabling the materials with low surface energy to absorb to reduce their surface energy.When hydrophilic dyes such as Nile Red were dissolved in hexadcane at the concentration of 20 ppm,the immersion of as –prepared ZnO membranes into the dye solution reaches to the adsorption efficiency close to 23%.Provided the dyes can form hydrogen bonds with the ZnO membrane surface such as Oil Red O were dissolved in hexadcne the adsorption efficient of ZnO can reach up to 70%.The resulting ZnO membranes remain highly effective for dye adsorption when the dye concentration is as low as 1 ppm.These results highlight the promising potential of the ZnO membranes in oil purification.