| The preparation of novel three-dimensional porous superhydrophobic composite materials and its application in oil absorption is of great significance. The three-dimensional porous materials possess large and rough surface area, which can reach adsorption equilibrium quickly in oil absorption. Besides, the macro-porous and micro-porosity in its structure can act as a reservoir space, which makes it be an ideal potential oil adsorbent. Thus, a novel and simple method to prepare three-dimensional porous superhydrophobic materials and investigate its application in O il-water separation is therefore important. Generally, the establishment of three-dimensional porous superhydrophobic materials should combining binary micro/nanostructures and low-surface-energy materials on its surface structure. It is well known that dopamine could oxidative self-polymerize under alkaline environment to produce polydopamine. The amphiphilic polydopamine(PDA) is able to adhere well onto a wide range of hydrophobic or hydrophilic substrates. The abundant group of resultant PDA can graft amino-/thiol-containing molecules by Schiff base reaction/Michael Addition, which promote the development of non-wetting research and provide opportunities to develop novel hydrophobic or superhydrophobic materials. In this dissertation, we study on the preparation and application of three kinds of oil adsorbent materials. The detailed results were summarized as follows:(1) Using raw melamine(ME) sponge as the supporting matrix, a one-step approach for the fabrication of a superhydrophobic/superoleophilic sponge with excellent adsorption performance and flame-retardancy characteristics was established. The superhydrophobic sponge was constructed by fabricating a hierarchical structure using in-situ forming of PDA nanoaggregates with n-dodecylthiol motifs on the surface of the ME sponge. The optimization condition to synthesise ME/p DA/DM composite materials reaction: The volume ratio of Tris-HC l and ethanol was set as 3:1; the reaction temperature was 35 ℃. At this temperature, the reaction time for 12 h was effective. And the maximum water contact angle of the modified sponge was obtained when dopamine concentration reached 8 mg/mL. Benefitting from its inherent material properties, superhydrophobic ME/PDA/DM can remove oils and organic solvents from water with high absorption capacity(weight gains ranging from 5122%- 10789% g/g). Also, the ME/PDA/DT sponge could be used for continuous organic solvent/water separation. More interestingly, the ME/PDA/DT sponge demonstrated improved flame-retardant property compared to the raw melamine sponge. Consequently, the risk of fire and explosion was expected to reduce when the fabricated sponge was used as an absorbent for flammable oils and organic compounds. However, when the ME/PDA/DM superhydrophobic sponge was immersing into the strong alkaline solution, the adhesive layer of PDA would drop down.(2) In order to investigate the versatility of one-step method for preparing a superhydrophobic sponge, the method was used to const ruct N i-3DG/PDA/DM composites. Using original N i-3DG as the supporting matrix, we presented a facile and one-step approach to prepare superhydrophobic and superoleophilic Ni-3DG/PDA/DM composites. The simple immersion of the original N i-3DG to the mixed solutions containing high concentrations of DA and n-dodecanethiol may leads to the spontaneous deposit PDA nanoaggregates with n-dodecylthiol motifs over the entire surface. The formation of PDA nanoaggregates via in-situ self-polymerization of dopamine and the covalent grafting of n-dodecylthiol to PDA were combined in a feasible alkaline medium(Tris-HC l/ethanol at pH 8.5). The synthesis of Ni-3DG/pDA/DM composite materials was optimized. The optimization reaction concentration of DM was set 8.35 mmol/L. The obtained N i-3DG exhibited excellent absorption performance, including a high absorption capacity(4576%-10708% g/g), excellent selectivity, high specific surface area and and extraordinary recyclability Furthermore, this modification processes was much more convenient, economical, environmentally friendly and universality than conventional approach. N ickel matrix not only gave graphene with better mechanical stability and recyclability, but also endowed graphene with magnetic, which can be separated simply by a magnet.(3) In order to improve the anti-alkali stability of superhydrophobic sponges, we presented a facile and one-step approach to prepare the superhydrophobic. By depositing PDA nanoaggregates with octadecylamine motifs over the sponges surface can greatly improve the stability of ME/PDA/ODA sponges. ODA was conjugated with PDA nanoparticles through Schiff base reaction, which not only imparts modified sponge strong hydrophobicity, but also plays a key role in the anti-alkali stability of sponge. The optimization reaction to synthesise ME/p DA/ODA composite are as follow: the concentration of ODA and temperature ware set as 10 mmol/L and 55℃, respectively. The fabricated sponge not only exhibits high absorption capacity(2463%-6411% g/g), superb selectivity, excellent mechanical strength, excellent elasticity, extraordinary recyclability, but also stays flame-retardant and stability when touch with fire and alkaline solution water, respectively. |
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