The separation of
phenolic compounds from coal-based liquid oil
is of economic value and practical significance. Conventional separation
techniques for phenolic compounds always produce a large amount of
wastewater. Herein, deep eutectic solvents (DESs) are considered as
effective alternatives to traditional solvents. To complete the separation
of phenolic compounds from coal-based liquid oil, DESs should have
stronger interactions with phenols than the oil and form new DES-phenol
aggregates, breaking the original molecular aggregates in the oil.
Initially, density fuunctional theorycalculations were used to explore
and prove the feasibility of phenolic compound separation by a choline
chloride (ChCl)-glycerol DES from the perspective of interaction type
and intensity, and the calculation results were verified by spectral
experiments. Then, based on the phenol removal efficiency and neutral
oil entrainment, the influences of the mole ratio of glycerol to ChCl,
separation temperature, and DES dose were investigated and followed
by discussions on the reuse of DES and a comparison of its separation
capacity with that of a reported separation agent. Finally, this DES
was applied to separate phenolic compounds from real coal-based liquid
oil. The results show that H-bonds between the DES and phenolic compounds
are the main driving force of this separation process. Under optimal
conditions, the ChCl-glycerol (1:1) DES can extract 98.3% of the phenolic
compounds with only 4.2% entrained neutral oil, and the selectivity
is better than that of ChCl alone. Additionally, satisfactory results
were obtained in the separation of phenolic compounds from real coal
liquefaction oil and real coal tar, providing a universal method for
the separation of phenolic compounds from coal-based liquid oil.
We present a three-dimensionally configured cathode with enhanced fieldemission performance formed by combining carbon nanotube (CNT) emitters with a nickel foam (NiF) substrate via a conventional screen-printing technique. The CNT/NiF cathode has low turn-on electric field of 0.53 V lm À1 (with current density of 10 lA cm À2 ) and threshold electric field of 0.87 V lm À1 (with current density of 0.1 mA cm À2 ), and a very high field enhancement factor of 1.4 9 10 4 . The porous structure of the NiF substrate can greatly improve the field-emission properties due to its large specific surface area that can accommodate more CNTs and increase the emitter density, as well as its high electrical and thermal conductivities that facilitate current transition and heat dissipation in the cathode. Most importantly, the local electric field was also enhanced by the multistage effect resulting from the rough metal surface, which furthermore leads to a high field enhancement factor. We believe that this improved field-emission performance makes such cathodes promising candidates for use in various field-emission applications.
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