Preparation, analyses and application of cobalt–manganese oxides/nylon 6,6 nanocomposites

Efficient photodegradation of methyl red dye by kaolin clay supported zinc oxide nanoparticles with their antibacterial and antioxidant activities

Kaolin clay-supported Zinc oxide (ZnO/KC) and ZnO NPs nanoparticles (NPs) were prepared by a chemical reduction process and used for the photodegradation of methyl red (MR) dye as a photocatalyst. Due to the interlayered porous structure of the KC, we achieved an extremely good association between ZnO NPs and KC. The product confirmation was conducted by Scanning electron microscopy (SEM), X-Ray diffraction (XRD), energy dispersive X-Ray (EDX), and Fourier transforms infrared (FTIR). SEM showed the irregular morphology of ZnO NPs, while ZnO/KC NCs were predominately round-shaped. Moreover, in both cases, NPs were present in both dispersed as well as agglomerated forms with an average particle size below 100 nm. The results acquired from photodegradation analyses show that ZnO NPs and ZnO/KC NCs degraded about 90 and 99% of MR dye respectively, under UV light in a short irradiation time of 10 min. The recovered and re-recovered ZnO NPs and ZnO/KC NCs also considerably photodegraded MR dye in an aqueous medium. The same NPs also exhibit promising bioactivities against two pathogenic bacteria, i.e., Citrobacter and Providencia. The antioxidant activity of ZnO/KC NCs reached to reasonable 70% compared to the 88% activity of the standard ascorbic acid.

Manganese dioxide nanoparticles/activated carbon composite as efficient UV and visible-light photocatalyst

Manganese dioxide nanoparticles/activated carbon (MnO₂/AC) composites and manganese dioxide nanoparticles (MnO₂ NPs) are prepared through chemical reduction method. Morphological study shows that MnO₂ NPs had cylindrical and spherical shape. The morphological study also revealed that MnO₂ NPs were well dispersed on AC while neat Mn NPs present both in dispersed and in agglomerated form. The FT-IR study confirms the synthesis of MnO₂ NPs. Zetasizer study presented that the Mn NPs had uniform size and below 100 nm in size and had zeta potential of - 20 mV, which represent its stability in the suspension form. The synthesized Mn/AC composite and Mn NPs were utilized as photocatalysts for the photodegradation of Congo red (CR) dye. The degradation study shows that MnO₂/AC composite degraded CR dye more efficiently than MnO₂ NPs under UV and normal light irradiation. The efficient degradation of dye by Mn/AC composite is due to the synergistic effect between dye adsorption on AC and rapid photodegradation by supported MnO₂ NPs. The results revealed that Mn/AC composite degraded about 98.53% of CR dye within 5 min while MnO₂ NPs degraded 66.57% of dye within the same irradiation time. The recycled catalyst also significantly degraded dye which verifies its sustainability. The effect of catalyst dosage and initial dye concentration was conducted. The degradation rate of dye was found drastically faster in tap water (in presence of catalyst), which might be due to the presence of various mineral ions in the tap water.