| With the rapid development of the economy of China as well as the whole world,all kinds of oil spills and the discharge of oily wastewater have increased the oil pollution on both water and ecological environment,which thus intensified great harm to mankind.In order to protect the ecological environment and prevent the oil pollution of our country and the world,applications of oil absorbents with high efficiency and oil-water separation materials become a top priority,which has a great practical significance and scientific research value.Oil-absorbing materials should have excellent superhydrophobic and superoleophilic properties,which include high oil absorption capacity,good oil-keeping effect,easy recovery of absorbed oil,also with great recyclability and biodegradability.Mambrane based oil-water separation material should have high efficiency of oil-water separation.However,the existing oil-absorbing materials have their drawbacks in the oil absorption capacity and oil recyclability as well as other aspects.Meanwhile,the water separation membranes also have their drawbacks in the oil-water separation abilities.All of the above drawbacks limit their practical applications.Thus,based on these problems,this study used polyurethane sponge,stainless steel mesh and nylon cloth as the basic materials.By using dip coating and grafting methods for the modification,high-efficient oil absorbents(modified polyurethane sponge)and oil-water separation membranes(modified stainless steel mesh and nylon cloth)were fabricated in this study.The modification greatly improved the oil-absorbing ability of the oil-absorbents and oil-water separation ability of the prepared oil-water separation membranes.Based on the characterization of the prepared materials,the performance of different types of oil-water separation materials were compared,and the oil-water separation mechanism was discussed.(1)Polyurethane(PU)sponge was used as the basic material.Graphene was used as the modification material.By dip coating method,the graphene was coated onto the surface of the PU sponge.The modified polyurethane sponge was modified from superhydrophilic to superhydrophobic,of which the water contact angle of the material was increased into 156.1°.What’s more,the oil absorption capacity of the modified PU sponge was greatly improved,which can absorb oil up to 59 times of its own weight(58.98 g/g).Besides,the way to reuse the modified oil sponge was very simple and quick,which can be achieved by just squeezing the material.Without changing their maximum oil absorption capacity,its recycling times were up to 60 times.(2)Using polyurethane sponge as the basic material,the graphene was modified,which as a result made the coating material much more stable than before.In order to improve the recyclability of the modified polyurethane sponge and to improve the stability of the modified surface of the sponge.We choose γ-methacryloxypropyl trimethoxy siloxane(KH-570)to modify graphene oxide.After reduction,the modified graphene was obtained.Then use the modified graphene to coat the PU sponge to prepare superhydrophobic and superoleophilic oil absorbent with enhanced recyclability.The results demonstrated that the oil absorption capacity and the hydrophobicity of the modified graphene have been greatly improved.The maximum adsorption capacity of the oil was up to 39 times of its own weight.The water contact angle of the prepared sponge was up to 161°,which was superhydrophobic.Most importantly,the recyclability of the modified sponge was greatly improved without changing the maximum amount of oil absorption capacity.This kind of material can be reused more than 120 times.(3)The modified polyurethane sponge(ZnO-PA sponge)was prepared with the modification of nano zinc oxide(ZnO)and palmitic acid(PA).After the modification,the oil absorption capacity of the modified sponge was up to 41 g/g,which increased a lot than the original sponge.Besides,its water contact angle of the prepared sponge was 168.9°,which reached great superhydrophobic.What’s more,the recyclability of ZnO-PA modified polyurethane sponge was up to 95 times,which also showed good stability.(4)Using stainless steel mesh as the base film,ultra hydrophobic and superoleophilic stainless steel mesh was prepared.In the experiment,the dip-coating method and secondary crystallization method were used to prepare silica nanoparticles.The results demonstrated that the hydrophobic property of the modified stainless steel mesh with different sizes has been greatly improved.The water contact angle of the modified stainless steel mesh was increased from 100.1° to 135.3°,which increased a lot but did not reach the superhydrophobic effect.Because of the loading of nano silicon particles,oleophilic properties of various sizes of stainless steel meshes have also been significantly improved.The oil contact angle of the modified stainless steel mesh with 180 μm was decreased from 40.6° to 0 °,which achieved superoleophilic property.In addition,there was no need to add external force during the oil-water separation process when using this membrane.The oil can rapidly get through the modified stainless steel mesh using its own gravity to achieve the effect of oil-water separation.(5)Using nylon cloth as the base film and three methyl chlorosilane as the modification material,superhydrophobic and superoleophilic oil-water separation membrane was prepared.Due to its own strong toughness and mechanical properties,nylon cloth has been used for the study of oil-water separation membrane.The surface of the modified nylon cloth became much rougher and the modified nylon cloth became superhydrophobic.The water contact angle was up to 150.3°.As the same,there was no need to add external force during the oil-water separation process when using this membrane.The oil can rapidly get through the modified nylon cloth using its own gravity to achieve oil-water separation.On the other hand,the water droplets were blocked on nylon cloth during the oil-water separation process.(6)The economic feasibility and the mechanism of oil-water separation were discussed after the comparative analysis of the properties of two kinds of oil-water separation materials.According to the market research of the cost of oil-water separation material and on the basis of economic analysis,the KH-Gr sponge had lowest cost and highest income among the three kinds of oil absorbing material,while the economic feasibility of the modified nylon is better than modified stainless steel mesh,which is more suitable for the market sales and applications.Through the hydrophobic-oleophilic model analysis,it showed that the oil-water separation performance of oil-water separation materials is mainly determined by the surface roughness and surface energy of the material. |
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