In this work, cobalt/polypyrrole (Co/PPy) nanocomposites were prepared via an in situ oxidation polymerization of pyrrole in an aqueous dispersion of Co nanoparticles (NPs). The Co/PPy nanocomposites showed good electromagnetic properties because of the coexistence of magnetic loss and dielectric loss to electromagnetic waves. The electromagnetic wave absorbing bandwidth (reflection loss < -10 dB) for Co/PPy (30 wt% in a paraffin matrix) was located at 11.7-16.47 GHz with a thickness of 2 mm, and with a maximum reflection loss (around -33 dB) at 13.6 GHz. More interestingly, the electromagnetic wave absorbing properties of the nanocomposites can be easily controlled by tuning the ratio of the two components in the composites. This improved electromagnetic wave absorption may be attributed to the excellent electromagnetic match at the corresponding resonance peaks for dielectric and magnetic loss. These magnetic nanoparticles/conducting polymer nanocomposites are great potential candidates for use as electromagnetic wave absorbents due to their excellent properties such as wide absorbing frequency, strong absorption, good compatibility, low density and controllable absorbing properties.

The present study evaluated inactivation efficiency of a sonophotocatalytic process using ZnO nanofluids including ultrasonic parameters such as power density, frequency and time. The result showed that inactivation efficiency was increased by 20% when ultrasonic irradiation was combined with photocatalytic process in the presence of natural light. Comparison of inactivation efficiency in photocatalytic, ultrasonic and sonocatalytic processes using Escherichia coli as a model bacteria identified that inactivation efficiencies are shown in the following order: ultrasonic irradiation

The iron cobalt/polypyrrole nanocomposites show an excellent tunable electromagnetic performance due to the synergetic effect between the dielectric and magnetic losses of the nanocomposites.

This study investigated the inactivation efficiency of ZnO nanofluids against E. coli in sonophotocatalysis with the aeration of nitrogen, oxygen, argon and their mixtures. The results showed that inactivation efficiency was increased when aeration was combined with sonophotocatalysis. Addition of different types of gases could lead to the different inactivation efficiency. The inactivation efficiencies were shown in the following order: no aeration < nitrogen < argon < oxygen < Ar/O(3:7) < Ar/O(7:3) < Ar/O(5:5). The production of hydroxyl radicals was explored to understand the inactivation mechanism. Compared with sonophotocatalysis without aeration, more hydroxyl radicals were produced in sonophotocatalysis with aeration, which could lead to changes of cellular substances. Furthermore, characterization of E. coli cells using Raman spectroscopy and FTIR illustrated that sonophotocalysis could affect the cellular substances containing carbohydrates, proteins and P containing molecules. Results suggested that the enhanced antimicrobial activity with aeration was originated from stronger cavitational activity, together with the formation of hydroxyl radicals. Compared to sonophotocatalysis without aeration, more dissolved oxygen was existed in sonophotocatalysis with aeration, which could enhance the formation of hydroxyl radicals.