Honglei Chen

Facile Control of the Porous Structure of Larch-Derived Mesoporous Carbons via Self-Assembly for Supercapacitors

Mesoporous carbons have been successfully synthesized via self-assembly using larch-based resins as precursors and triblock copolymers as soft templates. The porous structure of mesoporous carbons can be tailored by adjusting the ratio of hydrophilic/hydrophobic (EO/PO) units owing to interfacial curvature. Interestingly, the porous structures show a distinct change from vortex-like to worm-like pores, to stripe-like pores, and to ordered two-dimensional hexagonal pores as the ratio of hydrophilic/hydrophobic units increases, indicating the significant effect of EO/PO ratio on the porous structure. The mesoporous carbons as supercapacitor electrodes exhibit superior electrochemical capacitive performance and a high degree of reversibility after 2000 cycles for supercapacitors due to the well-defined mesoporosity of the carbon materials. Meanwhile, the superior carbon has a high specific capacitance of 107 F·g−1 in 6 M KOH at a current density of 10 A·g−1.

Sudanese Dicots as Alternative Fiber Sources for Pulp and Papermaking

The suitability of the stems from two Sudanese dicotyledonous annual plants, namely castor bean (Ricinus communis) and Leptadenia pyrotechnica (L. pyrotechnica) were investigated for pulp and papermaking. Chemical compositions, elemental analysis, fi ber dimensions, paper physical properties and morphology revealed a relatively high α-cellulose content (46.2 and 44.3 %) and low lignin (19.7 and 21.7 %) in the stems of castor bean and L. pyrotechnica, respectively. The average fi ber length of castor bean and L. pyrotechnica is 0.80 and 0.70 mm with fi ber width of 16.30 μm and 18.20 μm, respectively, which makes them acceptable candidates. SodaAQ pulping of castor bean stem led to a higher pulp yield of 43.2 % at kappa number 18.2 compared to 40.3 % at kappa 20.3 for L. pyrotechnica. This yield is less than that obtained for wood plants and similar to that observed for annual plants. Paper handsheets produced from castor bean showed better mechanical properties than L. pyrotechnica. SEM images indicated that the produced papers were quite homogeneous, compact, closely packed, and well assembled.

Facile synthesis of elemental silver by the seed nucleus embedding method for antibacterial applications

The preparation method of Silver (Ag)-loaded cellulose paper based on the formation of seed nuclei has been proposed as a functional material with high antibacterial performance. Metal palladium (Pd) was employed for the formation of seed nuclei, followed by sodium potassium tartrate tetrahydrate reduction to create Pd–Ag-cellulose paper. The properties in term of micro morphology, distribution of silver particles, antibacterial activity and silver release behavior were investigated. The results verified the formation of Pd-nucleus on surface of fiber, and revealed that silver particles were steadily deposited on the fibers based on the seed nuclei embedded. Pd–Ag-cellulose paper, comparing with Ag-cellulose paper produced with direct deposition method, exhibited a thick closely silver layer and uniform distribution of silver particles. The antibacterial test indicated that the lethality rate of Pd–Ag-cellulose paper against E. coli is 99.92% which is very close to that of Ag-cellulose paper (99.93%). Nevertheless, the silver release regression equation provided a high slope value (0.075) to Ag-cellulose paper, which explains a rapid release of silver. Pd–Ag-cellulose paper, by contrast, the slope value is only 0.021, and that indicates the silver slower release was achieved. Ag-loaded cellulose paper prepared using the proposed method shows the prominent properties in silver loading, antibacterial and silver slow-release.Graphical abstract