Zhong Liu

This study indicates that superior performance of novel ternary deep eutectic solvents (DES) system, formulated from choline chloride (ChCl) mixture of formic acid (Fa), pyruvic acid (Pa), and tartaric acid (Ta), exhibits remarkable efficacy in selective separation and purification of lignin from biomass. The woody biomass of Elm was pretreated with ternary of carboxylic-acid-based DES of ChCl as hydrogen bond acceptor (HBA), Lac, Fa, Pa, and Ta served as hydrogen bond donors (HBD) under the predetermined conditions. Benefitting from the efficient process, using optimized DES system (ChCl/Lac/Fa, 1:6:1, 6 h and 120 °C), it showed that the yield and purity of lignin obtained from material was 86.53 % and 90.45 %, which was more efficient than the results of binary DES system of the pretreatment process. In addition, the recovered lignin was subjected to comprehensive structural characterization employing Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance techniques. DES lignin was found to have a complete aromatic structure, that consisted mainly of β-β, β-O-4 bonds in different contents. These findings confirm the significant advantages of the new novel ternary DES system, which facile separated lignin from the lignocellulosic matrix under mild conditions, that providing a new reference value for efficient separation of biomass resources.

A mesoporous porous carbon (PC-KOH + Urea) with ultra-high specific surface area (SSA) was prepared from steam exploded poplar through urea-assisted KOH activation. The obtained PC-KOH + Urea had an ultra-high SSA of 3316 m² g⁻¹ and a total pore volume (V_T) of 1.96 cm³ g⁻¹, much higher than that of PC-KOH and PC-Urea, produced by KOH and urea activation alone, respectively. Meanwhile, PC-KOH + Urea possessed extremely high mesopores surface area (S_meso) (2183 m² g⁻¹) and mesopore volume (V_meso) (1.46 cm³ g⁻¹). In addition, urea can also serve as nitrogen source to dope nitrogen into PC-KOH + Urea, resulting in nitrogen content of 3.29%. To study the effects of urea on pore-forming, thermogravimetric analysis (TG) and thermogravimetric infrared technology (TG-IR) were adopted. It can be assumed that the ultra-high SSA of PC-KOH + Urea was mainly attributed to the reactions between pyrolysis products of urea and carbon. With ultra-high SSA, mesopore-dominated structure, and nitrogen doping, PC-KOH + Urea exhibited a high specific capacitance of 335.3 F g⁻¹ at current density of 0.5 A g⁻¹ in 6 M KOH aqueous electrolyte. In cyclic stability measurement, the capacitance retentions of PC-KOH + Urea were 99.6% after 4000 cycles. Thus, urea-assisted KOH activation was a feasible method to produce porous carbon with excellent performance.

Developing fluorine-free superhydrophobic and biodegradable materials for oil/water separation has already become an irresistible trend. In this paper, we designed two biopolymer oil/water separation routes based on cellulose stearoyl ester (CSE), which was obtained via the acylation reaction between dissolving pulp and stearoyl chloride homogeneously. The CSE showed a superhydrophobic property, which could selectively adsorb oil from the oil/water mixture. Additionally, the CSE was emulsified with an oxidized starch (OS) solution, and the resulting latex was used to impregnate commercial, filter base paper, finally obtaining a hydrophobic and oleophilic membrane. The SEM revealed the membrane had hierarchical micro/nanostructures, while the water contact angle indicated the low surface energy of the membrane, all of which were attributed to the CSE. The membrane had high strength and long durability due to the addition of OS/CSE, and the separation efficiency was more than 99% even after ten repeated uses.

The electrochemical performance of supercapacitors using porous carbon as electrodes is strongly affected by the fabrication process of carbon material. KOH is commonly used as an activator combined with urea as a nitrogen dopant. However, the roles of KOH and urea in pore structure configuration and the electrochemical behavior of porous carbon electrodes are still ambiguous. Herein, the optimum porous carbon is obtained when KOH and urea are used simultaneously. KOH is used as a pore-forming substance, whereas urea is employed as a nitrogen source for the nitrogen doping of porous carbon, which increases its defect sites while reducing the graphitization degree. More importantly, urea also expands pores as a pore-enlarging agent, inducing interconnected porous structures. As a result, a hierarchical porous structure is formed and ascribed to the synergistic effect of KOH and urea, and the specific surface area reached 3282 m² g⁻¹ for sample PC800-4. The specific capacitance is 319 F g⁻¹ at 0.5 A g⁻¹ with excellent cycling stability over 2500 cycles. Furthermore, the symmetric supercapacitor reaches an excellent energy density of 11.6 W h kg⁻¹ under 70.0 W kg⁻¹ in a 6 M KOH electrolyte. Our work contributes to the rational designation of the porous carbon structure for supercapacitor applications.

In this work, hydrogels composed of cellulose nanofibril (CNF) and sodium alginate (SA) were prepared as a pH‐responsive release system by controlling the amount of CNF and SA. Scanning electron microscopy, thermogravimetric analysis, and swelling rate methods were used to characterize. The results showed that when the mass ratio of CNF to SA was 2:1, CNF/SA hydrogels with better morphology were obtained. Due to the deprotonation or protonation of calcium alginate, as the pH changing from 1.5 to 11.0, the swelling ratio increased from 7 times to 19 times compared with its dry weight. The drug release behaviors of the CNF/SA hydrogels using ibuprofen (IBU) as a model drug were investigated in vitro. The release of IBU was faster in alkaline conditions and slower in acidic conditions. The drug release mechanism under pH stimulation could be interpreted by the Fickian diffusion and erosion effect based on Korsmeyer‐Peppas model.