The objective of the present study was to prepare CuFe2O4 ferrite nanoparticles using the sol-gel combustion method, employing lemon juice as a surfactant and energy agent. This method is located within the green chemistry, representing an environmentally friendly and less expensive approach compared to other methods. The nanoparticles were subsequently evaluated as antibacterial agents against different pathogenic bacteria. Before the antibacterial assays, a cytotoxicity test was conducted to evaluate their safety when applied to organisms. The structural, morphological, elemental composition, and magnetic properties of the samples were analyzed using Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), and Energy Dispersive X-Ray Detection (EDX). The X-ray diffraction patterns confirmed both the phase purity and the particle size to be 24.27 nm. The results demonstrated that the CuFe2O4 nanoparticles exhibited substantial antibacterial activity against both Gram-negative bacteria (Sphingomonas paucimobilis) and Gram-positive bacteria (Staphylococcus lentus and Bacillus subtilis). The antibacterial efficacy was more pronounced against Gram-negative bacteria, with inhibition diameter 5.46mm and 10.64mm at concentrations of 5000 ppm and 10000 ppm, respectively. When making a comparison, the effectiveness against Gram-positive bacteria displayed a slight reduction. Inhibition zones measured 2.76 mm and 8.33 mm for Staphylococcus lentus, while they were 3.58 mm and 5.35 mm for Bacillus subtilis. These measurements were observed at nanoparticle concentrations of 5000 ppm and 10000 ppm, respectively. Furthermore, the study confirmed the safety of the CuFe2O4 nanoparticles by assessing their toxicity on human red blood cell at different concentrations (50, 100,250,500,1000,5000, and 10000 ppm).

Preparation of an efficient hybrid structure photocatalyst for photocatalytic decomposition has been considered a great option to develop renewable technologies for environmental remediation. Herein, ternary magnetic Fe3O4/GQD/g-C3N4 nanocomposite (FGC) was prepared using the ball mill method. Binary nanocomposites Fe3O4/g-C3N4 (F/CN) and GQD/g-C3N4 (G/CN) were prepared to compare photocatalytic activity with FGC. The performance of photocatalysts for degradation of rhodamine B (RhB) was studied. EDX results showed that Fe3O4, GQD and g-C3N4 nanoparticles (NPs) are uniformly distributed in the FGC. The FGC nanocomposite shows superparamagnetic behaviour with a saturation magnetization of 12 emu. g-1, which makes it favourable compound for magnetic separation procedure. Photocatalytic activity of FGC (100%) was much higher than those of the G/CN (88%) and F/CN (77%) photocatalysts. The superior activity of FGC compared to binary composites was attributed to broader absorption in the visible light band and greater suppression of electron-hole recombination. The photocatalytic degradation of RhB using FGC was consistent with pseudo-first-order kinetics. The reusability of FGC was examined for four runs and no noticeable decrease was observed with the same irradiation time for each run. Finally, it can be argued that FGC photocatalyst can be an efficient semiconductor for the degradation of organic dyes from wastewater.