ABSTRACT
This research aimed to synthesize magnesium silicate (MgSiO3) used as a support for Ni-Fe cocatalysts in the depolymerization of kraft lignin. Magnesium silicate was prepared by a hydrothermal method, followed by metal solution impregnation to obtain lignin depolymerization catalysts. The catalytic efficiency of kraft lignin depolymerization to valued phenolic compounds was studied by varying the ratios of Ni and Fe on the MgSiO3 support. Moreover, other factors such as temperature, reaction time, and catalyst recycling affected both the quality and quantity of the products studied. The results illustrated that the catalyst 10Ni10Fe/MS produced all lignin depolymerization products with the highest yield (14.29 wt %) using reaction conditions of 300 °C and 1 h. In addition, the main products were found to be catechol (11.38 wt %), guaiacol (1.51 wt %), and phenol (0.79 wt %). More importantly, the 10Ni10Fe/MS catalyst showed good reusability even after two recycling processes, and the obtained phenol and guaiacol were found to be 0.63 and 1.01 wt %, respectively.
ABSTRACT
Functionalities of 3D printing filaments have gained much attention owing to their properties for various applications in the last few years. Innovative biocomposite 3D printing filaments based on polylactic acid (PLA) composited with ZnO nanoflowers at varying contents were successfully fabricated via a single-screw extrusion technique. The effects of the varying ZnO nanoflower contents on their chemical, thermal, mechanical, and antibacterial properties were investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and tensile testing, as well as qualitative and quantitative antibacterial tests, respectively. It was found that the ZnO nanoflowers did not express any chemical reactions with the PLA chains. The degrees of the crystallinity of the PLA/ZnO biocomposite filaments increased when compared with those of the neat PLA, and their properties slightly decreased when increasing the ZnO nanoflower contents. Additionally, the tensile strength of the PLA/ZnO biocomposite filaments gradually decreased when increasing the ZnO nanoflower contents. The antibacterial activity especially increased when increasing the ZnO nanoflower contents. Additionally, these 3D printing filaments performed better against Gram-positive (S. aureus) than Gram-negative (E. coli). This is probably due to the difference in the cell walls of the bacterial strains. The results indicated that these 3D printing filaments could be utilized for 3D printing and applied to medical fields.
