During the sugar production process, undesirable compounds such as dextrans are produced and contaminate the flow of the sugar mill, reaching levels in the fluid of more than 10,000 ppm. Dextranase is an enzyme that has different industrial applications, since it catalyzes the hydrolysis of the bonds in random sites of the dextran. Therefore, the enzyme was immobilized using synthesized ferrite magnetic nanoparticles to degrade dextran in the fermented mash, because it is suitable to reuse and has a large surface area to bind dextranase on a solid carrier for easy magnetic separation. The synthesized bare and modified nanoparticles were characterized using SEM, EDS, FTIR, and XRD and confirmed the core–shell silica by increasing the silica composition from 0.2% of bare Fe3O4 NPs to 31.3% of modified Fe3O4 NPs. Ultrasonic treatment reduced the calculated crystal size with Scherer’s equation from 91.3 to 13.5 nm, providing more particles for immobilization. The solvothermal process synthesized ferrite nanoparticles (Fe3O4) and modified them with TEOS and PEI. The obtained immobilization efficiency was 28%. Perhaps it was lower; Fe3O4 degraded almost the same as the free enzyme. The percentage of dextran degradation with free enzymes and immobilized enzymes with Fe3O4 magnetic nanoparticles was 61 and 52%, respectively.
Due to its multiple applications, zinc oxide (ZnO) is one of the most used materials in science and technology. Therefore, this research carried out the synthesis of ZnO and Pt-ZnO nanoparticles (NPs) by the direct precipitation method, which is characterized by being simple and reproducible, using two different precipitating agents, potassium hydroxide (KOH) and sodium hydroxide (NaOH); for the doping of Pt-ZnO NPs was used platinum acetylacetone. To evaluate the effect of the precipitating agent on the properties of each doped material, they were characterized by Fourier transform infrared spectroscopy, where the Zn-O vibrations were more pronounced using KOH. X-ray diffraction analysis shows a hexagonal structure (wurtzite) formation for ZnO with NaOH, obtaining a smaller crystal size than the other synthesized materials. Scanning electron microscopy analysis showed hexagonal and hemispherical shapes for ZnO (with NaOH and KOH) and Pt-ZnO (with NaOH), respectively; also, cylindrical shapes were obtained for Pt-ZnO (with KOH). The highest band gap obtained was for the Pt-ZnO material synthesized with KOH.
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