# The Biocatalytic Degradation of Organic Dyes Using Laccase Immobilized Magnetic Nanoparticles
## 3 Results and Discussion
### The Characterization of Synthesized Materials
According to Figure 1c, the Fe\({}_{3}\)O\({}_{4}\) nanoparticle-immobilized increase and CuFe\({}_{2}\)O\({}_{4}\) nanoparticle-immobilized increase showed a reduction in the saturation magnetization (M\({}_{3}\)) that equaled to 23.0 and 9.90 emu g\({}^{-1}\), respectively, when compared to the free Fe\({}_{3}\)O\({}_{4}\) nanoparticles and CuFe\({}_{2}\)O\({}_{4}\) nanoparticles, with M\({}_{8}\) values of 25.40 and 12.27 emu g\({}^{-1}\), respectively. The successful immobilization of nanoparticles was approved from the reduction in M\({}_{8}\) values, as the immobilized enzyme obstacles the magnetic domain of nanoparticles. There is an agreement between the magnetization results and the values in previous studies [35; 36]. Also, the thermogram outline of the synthesized nanoparticles and their nanoparticle-immobilized increase was investigated using thermogravimetric analysis (TGA), as shown in Figure 1d. In the studied temperature range (100.0 to 450.0 \({}^{\circ}\)C), the Fe\({}_{3}\)O\({}_{4}\) and CuFe\({}_{2}\)O\({}_{4}\) nanoparticles showed weight loss of 3.0 and 10.5%, respectively, while these values increased after the immobilization of lactose to 8.9 and 15.5%, which indicated the successful immobilization. At the temperature of 150.0 \({}^{\circ}\)C, an identical weight loss % was observed for the free lactose and nanoparticle-immobilized increase, due to the evaporation of adsorbed water molecules and light molecules. When the temperature increased from 150.0 \({}^{\circ}\)C to 300.0 \({}^{\circ}\)C, the immobilized nanoparticles showed a greater weight loss %, due to the decomposition of enzymatic proteins. While at a temperature higher than 300.0 \({}^{\circ}\)C, the organic molecules were completely decomposed, causing the highest increase in the weight loss %. For the study of synthesized Fe\({}_{3}\)O\({}_{4}\) and CuFe\({}_{2}\)O\({}_{4}\) nanoparticles' morphologies and sizes, SEM analysis was performed, as shown in Figure 2. Figure 2a shows the SEM image of Fe\({}_{3}\)O\({}_{4}\) nanoparticles with an average particle size of 60.0 nm, while Figure 2b shows the SEM image of CuFe\({}_{2}\)O\({}_{4}\) nanoparticles with an average particle size of 50.0 nm. According to the SEM images of Fe\({}_{3}\)O\({}_{4}\) and CuFe\({}_{2}\)O\({}_{4}\) nanoparticles, the particles are sponge-like,with a spherical shape and some agglomerations. Additionally, little plate-like particles appeared in the SEM images of the nanoparticles. Figure 2c shows the SEM image of the Fe\({}_{3}\)O\({}_{4}\) nanoparticle-immobilized increase, while Figure 2d shows the SEM image of the CuFe\({}_{2}\)O\({}_{4}\) nanoparticle-immobilized increase. The SEM images of the nanoparticle-immobilized increases show a large difference in morphology between the free increase and nanoparticle-immobilized increase, which indicated the successful immobilization process. Figure 1: XRD (**a**), FT-IR (**b**), TGA curves (**c**), and magnetization curves (**d**) of synthesized Fe\({}_{3}\)O\({}_{4}\) nanoparticles, CuFe\({}_{2}\)O\({}_{4}\) nanoparticles, and nanoparticle-immobilized increase.