ABSTRACT
Mg-based metallic glass (MG) has attracted extensive attention in the field of wastewater treatment due to its high decolorization rate in degrading azo dyes. However, the azo dye degradation rate of Mg-based MGs is strongly dependent on the particle size. Improving the intrinsic degradation efficiency using large particles is of great interest for future applications. In this work, in-situ metallic glass matrix composites (MGMCs) with high Mg content were successfully prepared by melt spinning. It is found that when the Mg content is 79-82%, the as-spun sample shows typical glassy characteristics. The SEM and XRD tests confirm that the as-spun sample is composed of α-Mg dendrite, multiple Mg-Zn intermetallic particles and an MG matrix. The degradation experiment using Direct Blue 6 and a 500 µm particle sample demonstrate that the Mg82Zn14Ca3Sr1 MGMC sample degrades azo dyes faster than typical Mg-Zn-Ca MG alloy. It can be attributed to the galvanic cell effect on the α-Mg/MG interface, which reduces the waste of active Mg atoms in the MG matrix according to the corrosion protection mechanism by the α-Mg anode sacrifice. This result provides a new perspective and insight into the design of azo dye degradation alloys and the understanding of degradation mechanisms.
ABSTRACT
The development of novel antibacterial nano-materials with synergistic biological effects has attracted extensive interest of the researchers. In the study, 0.5 mol% Ag and 0.5 mol% Cu co-doped K2Ti6O13(0.5 Ag-0.5 Cu-KTO) nanomaterial was successfully synthesized using two-step method of sol-gel and hydrothermal synthesis. The crystal structure of 0.5 Ag-0.5 Cu-KTO was the same as that of monoclinic K2Ti6O13. Ag ions and Cu ions were uniformly loaded on K2Ti6O13by replacing partial Ti ions, so that these antibacterial ions could be slowly released. High specific surface area of 0.5 Ag-0.5 Cu-KTO (337.6 m2g-1) provided more surface active sites for Ag-Cu doping and adsorption. More negative surface zeta potential (-32.83 mV in phosphate buffer solution and -21.45 mV in physiological saline solution, respectively) would be beneficial to prevent the aggregation of the nanowires in physiological environment. Under the same doping amount, compared to 1.0 mol% Cu doped K2Ti6O13, 0.5 Ag-0.5 Cu-KTO exhibited better antibacterial performance against gram-positive and gram-negative bacteria at only 100 µg ml-1dose concentration, near to 1.0 mol% Ag doped K2Ti6O13(1.0 Ag-KTO). And 0.5 Ag-0.5 Cu-KTO showed more excellent biocompatibility than 1.0 Ag-KTO, which was attribute to the introduction of Cu ions effectively decreasing the hemolytic and cytotoxic risks from Ag ions. As expected, the synthesized 0.5 Ag-0.5 Cu-KTO nanowires demonstrated excellent structural stability, high antibacterial activity, good hemocompatibility and cytocompatibility owing to the synergistic effects of Cu and Ag ions. 0.5 Ag-0.5 Cu-KTO nanowires will be a promising antimicrobial candidate for biomedical applications.
