RESUMEN
Plastic waste is causing serious environment pollution and its efficient disposal is attracting more and more attention. The use of catalysts not only reduced the degradation temperature of plastic wastes but also facilitated the production of valuable chemicals. Herein, mesopores were introduced into HZSM-5 zeolites by alkali and acid treatment, which was expected to eliminate the diffusion resistance caused by bulky polymer molecules and improve the catalytic activity. It was found that HZSM-5 zeolites enhanced PE, PP and PS degradation, and an increase of mesopore volume further improved the catalytic activity and reduced the activation energy. For example, the use of HZSM-5 in PP degradation decreased the activation energy from 146.9 kJ mol-1 to 93.1 kJ mol-1, and mesopore-rich HZSM-5 further decreased the activation energy to 84.0 kJ mol-1. The molecular diameter of the PP fragment was obtained by theoretical calculations, and it was close to 1.6 nm, which was significantly higher than the micropore diameter of HZSM-5 zeolites (0.5-0.6 nm) while lower than the mesopore diameter. It was concluded that the presence of mesopores provided the place and space for plastics degradation.
RESUMEN
The effects of cephradinum and ceftazidime on the metabolism of Escherichia coli (E. coli) DH5alpha was determined by microcalorimetry. The microbial activity was recorded as power-time curves through an ampoule method with a TAM Air Isothermal Microcalorimeter at 37 degrees C. The parameters such as the growth rate constant (k), inhibitory ratio (I), the maximum power output (Pm) and the time (tm) corresponding to the maximum power output were calculated. The results show that the ceftazidime has a better inhibitory effect on E. coli DH5alpha than cephradinum.