Elimination of Escherichia coli in Water Using Cobalt Ferrite Nanoparticles: Laboratory and Pilot Plant Experiments

Preparation of antibacterial Zn and Ni substituted cobalt ferrite nanoparticles for efficient biofilm eradication

Zinc (Zn) and, alternatively, nickel (Ni) substituted cobalt ferrite (CF) nanoparticles (NPs) were prepared by sol-gel method. X-ray diffraction analysis revealed the formation of cubic structure of cobalt ferrite. FTIR analysis confirmed the vibrational band located at 550-580 cm^-1 that belongs to the M - O bond (M = Ni, and Zn). The alteration of the surface morphology of CF after the addition of Zn and Ni ions was observed from scanning electron microscopic images. The additional peaks in the energy dispersive X-ray diffraction (EDX) analysis spectra were found to correspond to Zn and Ni. The presence of Zn and, alternatively, Ni ions enhanced the biocidal properties of CF NPs against gram negative organisms, in a concentration and time-dependent manner. Furthermore, exposure to CF, CF-Zn and CF-Ni NPs decreased metabolic activity due to the damage of extra polymorphic substances, live/dead cell variation, architecture and surface integrity of the cells. Altogether, the present investigation provides the basis of metal ion substituted metal oxide NPs as anti-biofilm agents against gram-positive and gram-negative bacteria.

Coal fly ash supported CoFe2O4 nanocomposites: Synergetic Fenton-like and photocatalytic degradation of methylene blue

Rapid industrialization is causing a serious threat for the environment. Therefore, this research was aimed in developing ceramic cobalt ferrite (CoFe₂O₄) nanocomposite photocatalyst coated with coal fly ash (CFA-CoFe₂O₄) using facile hydrothermal synthesis route and their applications against methylene blue. The pristine cobalt ferrite photocatalyst was also prepared, characterized, and applied for efficiency comparison. Prepared photocatalyst were characterized by X-ray diffraction (XRD), fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Optical response of catalysts was check using photoluminescence spectroscopy (PL). pH drift method was used for the surface charge characteristics of the material under acidic and basic conditions of solution pH. The photocatalytic degradation potential of all the materials were determined under ultra-violet irradiations. The influencing reaction parameters like pH, catalyst dose, oxidant dose, dye concentration, and irradiation time, were sequentially optimized to obtain best suited conditions. The 99% degradation of 10 ppm methylene blue was achieved within 60 min of reaction time under pH = 5 and 7, catalyst dose = 10 and 12 mg/100 mL, oxidant = 12 mM and 5 mM for cobalt ferrite and CFA-CoFe₂O₄ photocatalysts, respectively. Afterwards, the radical scavenging experiments were conducted to find out the effective radical scavengers (˙OH, h⁺, and e^-) in photocatalytic degradation process. The kinetic study of the process was done by applying 1st order, 2nd order, and BMG models. Statistical assessment of interaction effect among experimental variables was achieved using response surface methodology (RSM).