| In recent years,porous oil absorbent has been studied extensively.Boron nitride is an ideal inorganic material that can withstand harsh conditions due to its excellent chemical inert,high-temperature resistance,non-toxicity,hydrophobic and lipophilic properties.However,the high cost of preparation,the extremely high temperature of firing and the dangerous atmospheres are the challenges of preparing porous boron nitride materials.Therefore,the development of a simple,green,sintering-free porous boron nitride method has become a research hotspot.However,the weak van der Waals force between the hexagonal BN sheets leads to macroscopic instability,and the agglomeration of the hexagonal BN sheets due to strong conjugation makes it difficult to prepare porous BN materials.The purpose of this thesis is to further improve the oil absorption performance of BN-based porous materials on the premise of ensuring the stability of monoliths.Before using CMC and boron nitride composite crosslinking,surface modification was carried out first to improve the crosslinking efficiency of boron nitride and CMC,thus improving its stability.The modification of BN by co-milling with sodium cholic acid as a modifier is accompanied by the increase of specific surface area,lattice distortion and other phenomena,and promotes the production of BN active sites.After qualitative measurement of BN by XPS,the highest content of B-O was 24.5%of the total element B,and the stable dispersion concentration reached 6.0mg·m L-1,which played a key role in the further processing and utilization of BN.Then,the effective process conditions of BN-based porous materials were prepared by freezing casting method to ensure the oil absorption performance.The results show that the intercalation effect of polymer distorts the lattice of h-BN.With the increase of solid content and polymer,the polymer chain is easy to curl and fold,which increases the shrinkage rate of atmospheric gel and the density of monolith.The increase of crosslinking agent can also lead to the edge passivation of the h-BN sheet and improve the bonding effect.Its decomposition temperature in air is about 280?.The composite process improves the temperature range of materials and widens the application scenarios.In order to further understand the relationship between the pore structure and oil absorption performance of BN-based porous materials,a series of methods such as the mercury-injection method and surface contact Angle method were used to characterize and analyze.It was found that there were some bottleneck holes in the matrix based on boron nitride.The surface was rough,the highest water contact angle is up to 141.5°,which meets the hydrophobic requirements of oil-absorbing materials.The pore diameter of most volumes is concentrated in the range of 10-300?m,and the pore diameter is adjustable.Due to the high specific surface area of the prepared material,the oil absorption capacity can reach 31.55 g·g-1(?97%m L·cm-3).In addition,the capacity of the material did not decrease significantly after six cycles.Therefore,BN-based porous materials are expected to be used in the oil absorption field and have potential applications in biochemical and nuclear fields. |
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