| Summary: | MnO<sub>2</sub> and MnO<sub>2</sub> blended with 1 and 2 weight percent of activated carbon (AC), MnO<sub>2</sub>/AC1 and MnO<sub>2</sub>/AC2 were synthesized through the sol–gel method. The pure chitosan (CS) films were cast in the form of films. Similarly, 5 weight% of each MnO<sub>2</sub>, AC, MnO<sub>2</sub>/AC1 and MnO<sub>2</sub>/AC2 was intermingled with the CS to produce different films, such as CS-AC, CS-MnO<sub>2</sub>, CS-MnO<sub>2</sub>/AC1 and CS-MnO<sub>2</sub>/AC2. Zero-valent Co NPs were then supported on these films through the chemical reduction method and expressed as CS@Co, CS-AC@Co, CS-MnO<sub>2</sub>@Co, CS-MnO<sub>2</sub>/AC1@Co and CS-MnO<sub>2</sub>/AC2@Co NPs. All the catalysts were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The synthesized catalysts were used as a dip catalyst against the hydrogenation of 4-nitrophenol (4NP), and for the degradation of methyl orange (MO) and Congo red (CR) dyes. The <i>k</i><sub>app</sub> and R<sup>2</sup> values were deduced from pseudo-first-order kinetics for 4NP and MO and zero-order kinetics for CR dye. The <i>k</i><sub>app</sub> values of CS-AC@Co and CS-MnO<sub>2</sub>/AC1@Co NPs for 4NP hydrogenation were higher than those for any other member of the series, at 1.14 × 10<sup>−1</sup> and 1.56 × 10<sup>−1</sup> min<sup>−1</sup> respectively. Similarly, the rate of CR degradation was highest with CS-AC@Co. The R<sup>2</sup> values for 4NP, MO and CR dyes were above 0.9, which indicated that the application of pseudo-first- and zero-order models were appropriate for this study. Furthermore, the antibacterial activity of all the catalysts was evaluated against <i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i>. The CS-AC@Co NPs exhibited the highest zone of inhibition compared to other catalysts against <i>P. aeruginosa</i>, while all the catalysts were inactive against <i>E. coli</i>. This study reveals that the catalyst can be used for the degradation of other pollutants and for microbial inhibition.
|
|---|