FABRICATION OF NANOCOMPOSITES BASED ON CHITOSAN/Mn/MnO2 IN THE CONDITIONS OF "ex situ"
Creators: name: Ergashev K.X
name: Ashurov N.Sh
name: Vokhidova N.R
name: Rashidova S.Sh
Publisher: name: Zenodo
Year: 2025

description: Micro- or nanocomposites based on manganese and manganese oxides have been utilized in wastewater treatment, catalysis, sensors, supercapacitors, soluble rechargeable batteries and ecepts. The incorporation of metal oxide nanomaterials (MONMs) into a chitosan matrix can help control the crystal structure, shape, structural morphology and size of MONMs [1]. The sorbents for the removal of lead and lanthanum ions from water were investigated via the use of formaldehyde as a cross-link between manganese dioxide and chitosan to form a MnO2-F-chitosan nanocomposite. The MnO2-F-chitosan nanocomposite has a particle size of 19–25 nm, and the removal rates of lead and lanthanum ions from real water and wastewater samples were 95.6–96.4% and 91.2–92.3%, respectively. Hybrid composites of Mn3O4-chitosan and its derivative zinc manganese oxide-chitosan (ZnMn2O4–chitosan) were synthesized via a sol-gel reaction in a single reactor. The ZnMn2O4–chitosan nanocomposite demonstrated excellent immunoactivity against all the microorganisms. Thus, the literature analysis highlights the importance of Mn/MnO2 chitosan composites as materials with special properties in the abovementioned fields [2].


To obtain chitosan-stabilized Mn/MnO2 nanoparticles, chitosan from Bombyx mori (CS) with a molecular weight of 104×103, a degree of deacylation of 86%, and MnCl2 of "chemically pure" grade were used. The experiments were carried out under ex situ conditions.


First, on the basis of the above synthesis conditions, the effect of the reducing agent concentration on their composition was studied to obtain nanostructured polymer‒metal systems CS/Mn/MnO2. The effect of the reducing agent (NaBH4) concentration on obtaining the CS/Mn/MnO2 nanosystem was studied. The effect of the reducing agent (NaBH4) concentration on the production of the CS/Mn/MnO2 system was studied.


As shown in the figure, the chitosan solution consists of particles ranging in size from 5 (49%) to 90 μm. In all the composites, the particle diameter decreased by approximately 10–20 times compared with the size of the chitosan macromolecules, and 7–42% of the nanoparticles with a hydrodynamic diameter of 26–211 nm were formed. No clear pattern, i.e., an increase or decrease in the formation of nanoparticles in the system with increasing reducing agent concentration, was observed, but at a low NaBH4 concentration, relatively more particles with small radii formed. This may be due to the participation of chitosan macromolecules in their solutions as stabilizers around metal nanoparticles.





Figure. Effect of reducing agent concentration on the hydrodynamic size of particles present ex situ in solutions of the CS/Mn/MnO2 system: 1) CS (2 mol); 2) MnCl2 (1 mol); 3) 0.125; 3) 0.25; 4) 0.5; 5) 1; 6) 2 mol


Thus, in the preparation of nanosystems of Mn, chitosan acts as a stabilizer and plays an important role in the formation of nanoparticles regardless of the reducing agent concentration. The integration of polymeric structures and nanostructures has a strong effect on the dispersion and morphology of the latter and, consequently, endows them with novel and promising features. Owing to their environmentally friendly features and mild methods for synthesizing and functionalizing nanoparticles, biopolymers such as chitosan have attracted much attention in the design of novel materials.


References



	
Vokhidova, N.R., Rashidova, S.S. Influence of synthesis conditions on the film morphology of chitosan-stabilized silver nanoparticles. Polym. Bull. 2022, 79, 3419–3436. https://doi.org/10.1007/s00289-021-03669-y
	
Packirisamy R.G., Govindasamy Ch., Sanmugam A., Karuppasamy K., Kim H.S., Vikraman D. Synthesis and Antibacterial Properties of Novel ZnMn2O4–Chitosan Nanocomposites. Nanomaterials, 2019. 9(11), 1589–. doi:10.3390/nano9111589



      3. Binbin D., Pan Z., Ping’an M., Jun L. Manganese Oxide Nanomaterials: Synthesis, Properties, and Theranostic Applications/Adv. Mater. 2020, 1905823. doi.org/10.1002/adma.201905823